Neuro Flashcards

Question

Causes of gyriform enhancement (intra-axial)?

Answer 1

Herpes encephalitis Meningitis Subacute infarct - 6 days to 6 weeks after ischemic event PRES

Answer 2

Hematogenously disseminated metastatic disease - arterial

Answer 3

Posterior fossa through the retroclival venous plexus and Batson prevertebral venous plexus

Answer 4

``` MAGIC DR Metastasis Abscess Glioma Infarct Contusion Demyelination - C-shaped Radiation ```

Answer 5

Diffusion restriction centrally due to high viscosity of central necrosis

Answer 6

Incomplete and "C" shaped. Lack of significant mass effect

Answer 7

Dural enhancement. No BBB in dura, but no water molecules in dura. Dural enhancement on MRI is an indication of dural edema rather than BBB breakdown.

Answer 8

Intracranial hypotension - vasogenic edema of dura Postoperative Post-lumbar puncture Meningeal neoplasm - such as meningioma - can produce focal area of dural enhancement called dural tail, due to reactive changes in the dura. Granulomatous disease - typically basal meninges (skull base)

Answer 9

Breast and Prostate - irregular dural enhancement.

Answer 10

Pia-arachnoid enhancement

Answer 11

Meningitis Leptomeningeal carcinomatosis - primary or metastatic disease Viral encephalitis Slow vascular flow

Answer 12

GEMCLOG ``` Glioblastoma Ependymoma Medulloblastoma Choroid plexus tumor Lymphoma Oligodendroglioma Germinoma ```

Answer 13

Meningitis and leptomeningeal carcinomatosis - with leptomeningeal enhancement SAH - no enhancement - has susceptibility Oxygen or propofol therapy.

Answer 14

Glioblastoma

Answer 15

Melanoma, RCC, thyroid, and choriocarcinoma. Lung and breast are less frequently hemorrhagic.

Answer 16

Metastases containing desiccated mucin - such as GI adenocarcinomas. Hypercellular metastases - including lymphoma, germinoma, and some glioblastomas.

Answer 17

Metastatic melanoma Fat-containing tumors- such as dermoid or teratoma. Hemorrhagic metastasis - RCC, thyroid, choriocarcinoma, and melanoma.

Answer 18

Low-grade tumors

Answer 19

Primary CNS tumor arising from a glial cell - astrocytes, oligodendrocytes, ependymal cells, and choroid plexus cells.

Answer 20

Provide biochemical support to the endothelial cells that maintain the BBB, to maintain extracellular ion balance, and aid in repair after neuronal injury. Throughout brain and spinal cord.

Answer 21

Maintain myelin around CNS axons. Single can maintain myelin of dozens of axons. Throughout brain and spinal cord. Counterpart is a schwann cell in a peripheral nerve.

Answer 22

Circulate CSF with its multiple cilia. Line ventricles and central canal of the spinal cord.

Answer 23

Pilocytic = "hair-like" Benign, typically in the posterior fossa in children. Well-circumscribed cystic mass with an enhancing nodule and relatively little edema. May compress 4th ventricle if in posterior fossa. Can occur along the optic pathway with NF1. Posterior fossa JPA is not associated with NF1.

Answer 24

Hyperintense mass on T2 without enhancement

Answer 25

Range of appearances from thickened cortex (similar to low-grade astrocytoma) to an irregularly enhancing mass that may appear identical to glioblastoma. Will eventually progress to glioblastoma.

Answer 26

GBM, lymphoma, or demyelinating disease.

Answer 27

Diffuse infiltrative mid-grade astrocytoma that affects multiple lobes. Diagnostic criteria- involvement of at least two lobes plus extra-cortical involvement of structures such as the basal ganglia, corpus callosum, brainstem, or cerebellum. Poor prognosis and may degenerate into GBM. Exerts mass effect, but does not enhance.

Answer 28

Slow-growing cortical-based mass. Young to middle aged patient with seizures. Propensity to calcify (about 75%).

Answer 29

Tumor of ependymal cells that tends to occur in the posterior fossa in children and in the spinal cord in older adults.

Answer 30

Dysplastic cerebellar gangliocytoma - part hamartoma and part neoplasm. Associated with Cowden syndrome. Corduroy or tiger-striped striated lesion in the cerebellar hemisphere. Enhancement is rare.

Answer 31

Atypical teratoid/rhabdoid tumor (ATRT) | Medulloblastoma

Answer 32

Agrgressive tumor that may appear similar to medulloblastoma, but occurs in slightly younger patients. Majority occur in posterior fossa. Associated with malignant rhabdoid tumor of kidney.

Answer 33

Small-blue-cell origin tumor. One of the most common pediatric brain tumors. MC occurs in midline cerebellar vermis. Slightly hyperattenuating on CT due to densly packed cells and is hypointense on T2 and has low ADC values. Avidly enhancing and may appear heterogeneous due to internal hemorrhage and calcification.

Answer 34

Medulloblastoma, ependymoma, and pilocytic astrocytoma.

Answer 35

Juvenile Pilocytic Astrocytoma Hemangioblastoma Pleomorphic Xanthoastrocytoma Ganglioglioma

Answer 36

Cystic mass with enhancing mural nodule. Prominent vessels are often seen as tubular areas of flow void. Often associated with syrinx in spinal cord. Highly vascular tumor associated with VHL Most commonly in the cerebellum, medulla, or spinal cord. 30% of hemangioblastomas have VHL. Hemangioblastoma in patient with VHL has a worse prognosis.

Answer 37

Low grade astrocytoma variant. Rare tumor of childhood and adolescents- typically with history of chronic epilepsy. MC location is temporal lobe- supratentorial cortical cystic mass with an enhancing mural nodule. The overlying dura may be thickened and enhancing. Main DDx is a ganglioglioma- however, ganglioglioma does not usually cause dural thickening.

Answer 38

PXA causes dural thickening

Answer 39

Rare, slow-growing neuroglial tumor- adolescent or young adult with medically refractory temporal lobe epilepsy. Temporal lobe cyst and enhancing mural nodule, often with calcification. May cause calvarial remodeling and scalloping.

Answer 40

Pleomorphic Xanthoastrocytoma and Ganglioglioma

Answer 41

``` Central neurocytoma Choroid Plexus Papilloma/carcinoma Intraventricular Meningioma Subependymal Giant Cell Asrocytoma (SEGA) Subependymoma ```

Answer 42

Low-grade tumor likely of neuronal origin that occurs in young adults. Lobulated mass attached to the septum pellucidum with numerous intratumoral cystic areas. Calcification is common.

Answer 43

Central Neurocytoma

Answer 44

Rare intraventricular tumor. Arising from choroid plexus epithelial cells. Lobulated, heterogeneous mass that avidly enhances. MC in the atrium of the lateral ventricle in children. In adults, the fourth ventricle is the most common.

Answer 45

Trigone of the lateral ventricle.

Answer 46

Low-grade astrocytoma variant that is associated with tuberous sclerosis. Other findings of tuberous sclerosis - subependymal nodules and hamartomas (cortical and subcortical). Classically- enhancing mass in the lateral ventricle near the foramen of Monro.

Answer 47

Nonehancing low-grade tumor- thought to arise from subependymal astrocytes, ependymal cells lining the ventricles, or common precursor cells. Tumor of middle age and older adults. MC in obex of 4th ventricle (inferior 4th ventricle) or at formen of Monro in the lateral ventricle. Doesn't enhance.

Answer 48

Subependymoma

Answer 49

Most commonly diffuse large B-cell lymphoma. Immature blast cells form lymphoid aggregates around small cerebral blood vessels in a periventricular location. Brain does not contain native lymphoid tissue.

Answer 50

Appearance of PCNSL depends on the immune status of the patient, but always periventricular location and high cellularity (hyperattenuating on CT, relatively hypointense on T2 and reduced diffusivity.

Answer 51

Enhancing periventricular mass in immunocompetent, often crossing the corpus callosum. Involvement of the frontal lobes and basal ganglia is most common.

Answer 52

Periventricular ring-enhancing lesion in the basal ganglia, due to central necrosis.

Answer 53

In immunocompromised- ring-enhancing due to central necrosis.

Answer 54

Lymphoma and toxoplasmosis

Answer 55

Emperitcal anti-toxoplasmosis therapy and short-interval follow-up. Thallium scanning- Lymphoma is thallium avid and toxo is not. PET- lymphoma tends to be high grade and metabolically active. Toxo usually does not have avid FDG uptake. Perfusion scanning- lymphoma has increased relative cerebral blood volume while toxo is hypovascular.

Answer 56

Tends to involve the meninges and may cause leptomeningeal carcinomatosis or epidural cord compression. Less commonly may present as a parencymal mass.

Answer 57

Lung, breast, and melanoma.

Answer 58

Meningoepithelial cells called arachnoid "cap" cells.

Answer 59

NF-2 or following radiation therapy.

Answer 60

Breast (MC), lymphoma, small cell lung cancer, and melanoma.

Answer 61

Medulloblastoma

Answer 62

Juvenile Pilocystic Astrocytoma

Answer 63

Ependymoma

Answer 64

Hemangioblastoma

Answer 65

Atypical teratoid/rhabdoid tumor

Answer 66

Metastasis

Answer 67

Hemangioblastoma

Answer 68

Astrocytoma

Answer 69

Medulloblastoma

Answer 70

CNV, CNVII, CNVIII, and AICA

Answer 71

Hemangioblastoma - cerebellar hemisphere fluid-secreting tumor with a cyst and enhancing nodule. Prominent flow voids feeding the tumor. Endolymphatic sac tumor - occurs along the posterior petrous ridge.

Answer 72

V3 - Exits inferiorly from Meckel's cave through foramen ovale.

Answer 73

Dorello's canal

Answer 74

Maxillary nerve (V2) - exits the foramen rotundum.

Answer 75

Rathke's pouch - superior invagination from the primitive oral cavity.

Answer 76

Pituitary adenoma, Rathke's cleft cyst, and hypophysitis. Craniopharyngioma may rarely occur in the sella, but essentially never occurs within the pituitary gland itself.

Answer 77

<10 mm in size Usually symptoms due to hormone excess, not mass effect.

Answer 78

>10 mm in size. Usually present with mass effect (compression of optic chiasm) rather than endocrine dysfunction. Usually encase the carotid, but tend not to narrow it. In contrast, meningiomas or metastases can narrow the carotid.

Answer 79

Macroadenoma usually encase the carotid, but tend not to narrow it. Meningiomas or metastases can narrow the carotid.

Answer 80

Clinical syndrome of severe headache and endocrine dysfunction caused by hemorrhage into an otherwise normal pituitary.

Answer 81

Autoimmune inflammatory disorder usually seen in peripartum women that may affect the pituitary and infuncibulum. Present with DI, HA, visual impairment, and endocrine dysfunction. Thickening and enhancment of the pituitary stalk.

Answer 82

Granulomatous inflammation of the pituitary and infundibulum- can be secondary to sarcoid, Wegener granulomatosis, TB, and LCH.

Answer 83

Child- craniopharyngioma. Adult- Pititary macroadenoma that has extended superiorly.

Answer 84

SATCHMO Sarcoidosis/Suprasellar extension of an adenoma Aneurysm Teratoma (dermoid cyst)/Tolosa Hunt Craniopharyngiomia/Cleft cyst (Rathke's) Hypothalamic glioma (adults)/Hypothalamic hamartoma (children) Meningioma/Metastasis Optic nerve glioma

Answer 85

Optic pathway astrocytoma. Craniopharyngioma is MC. Low-grade tumor in children. Aggressive tumor in adults.

Answer 86

Germinoma - 80% arise from the pineal region. 20% parasellar. Primarily seen in children and adolescents.

Answer 87

Ectopic hypothalamic neural tissue. Presents with precocious puberty and gelastic seizures (laughing spells). Characteristically appears as a sessile mass between the pituitary stalk and the mammillary bodies. Does not enhance and is isointense to gray matter.

Answer 88

Craniopharyngioma

Answer 89

Optic pathway glioma

Answer 90

Germ cell tumor

Answer 91

Hypothalamic hamartoma

Answer 92

Langerhans Cell Histiocytosis Hypophysitis

Answer 93

Pituitary macroadenoma extension

Answer 94

Meningioma

Answer 95

Craniopharyngioma

Answer 96

Rathke's cleft cyst

Answer 97

Lymphocytic or granulomatous hypophysitis Lymphocytic if peripartum; granulomatous if otherwise

Answer 98

Pinealocyte - modified retinal neuronal cell that is innervated by the sympathetic plexus originating in the retina. Releases melatonin. Does not have a blood brain barrier.

Answer 99

Compression of the midbrain, compression of the cerebral aqueduct of Sylvius, or compression of the tectal plate - produces Parinaud syndrome- inability to look up, pupillary light dissociation, and nystagmus.

Answer 100

Upward gaze paralysis, pupillary light dissociation, and nystagmus. Caused by compression of tectal plate - pineal gland lesion.

Answer 101

Extra-axial

Answer 102

Germ cell tumor, Pineal cyst, Pineocytoma, Pineaoblastoma, or metastases

Answer 103

Germinoma and teratoma

Answer 104

Low-grade slow-growing pinealocyte tumor. Any solid component should enahnce. Pineocytoma may feature cystic change, however, which can make differentiation from a pineal cyst difficult.

Answer 105

Highly malignant tumor of young children, of same primitive neuroectodermal tumor (PNET) type as medulloblastoma. Trilateral retinoblastoma is used with bilateral retinoblastomas are also present (retina and pineal gland are light-sensing organs). The sella is additionally involved in quadrilateral retinoblastoma. Presents with obstructive hydrocephalus. Poorly defined pineal mass that may invade into adjacent structures. High cellularity = restricted diffusion.

Answer 106

Bilateral retinoblastomas and a pineoblastoma. When sella is involved = quadrilateral retinoblastoma.

Answer 107

Pineocytoma - low-grade, slow-growing pinealocyte tumor. Pineoblastoma - highly malignant tumor of young children.

Answer 108

Germinoma - engulfs and induces calcification of the pineal gland. Pineoblastoma - peripherally calcifies in a pattern that looks like "exploded" calcifications.

Answer 109

Not a true aneurysm. Dilation of the vein of Galen due to an AVF between the anterior or posterior circulation and the venous plexus leading to the vein of Galen.

Answer 110

Can be seen in isolation or associatd with agenesis or hypoplasia of the corpus callosum.

Answer 111

Grade I - only the gray-white matter junctions Grade II - involves the corpus callosum Grade III - involves the dorsolateral midbrain

Answer 112

Central sulcus.

Answer 113

``` Cervical (C1) Petrous (C2) Lacerum (C3) Cavernous (C4) Clinoid Segment (C5) Supraclinoid (C6-C7) ```

Answer 114

Meningohypophyseal trunk - supplies the pituitary tentorium, and dura of the clivus. Inferolateral trunk - Supplies the 3rd, 4th, and 6th cranial nerves as well as the trigeminal ganglion.

Answer 115

Opthalamic artery - just above carotid ring - can cause SAH, treated more aggressively. Posterior Communicating Artery Anterior Choroidal Artery - supplies the optic chiasm, hippocampus, and posterior limb of internal capsule.

Answer 116

Just above superior carotid ring, can cause SAH.

Answer 117

Optic chiasm, hippocampus, and posterior limb of internal capsule. Most distal branch of ICA before bifurcation into ACA and MCA.

Answer 118

A1 segment - supplies the caudate head and anterior limb of the internal capsule.

Answer 119

A1 segment - supply the medial basal ganglia.

Answer 120

MCA - supply the lateral basal ganglia including the lateral putamen, extrnal capsule, and the posterior limb of the internal capsule.

Answer 121

Posterior communicating artery and posterior cerebral artery - supplies the thalamus.

Answer 122

CN III palsy.

Answer 123

Variant where there is a dominant thalamic perforator supplying the ventromedial thalami bilaterally and the rostral midbrain. Arises from the P1 PCA segment. Infarct will cause bilateral ventromedial thalamic infarction, with or without midbrain infarction.

Answer 124

Infarct of bilateral ventromedial thalami with or without midbrain infarction.

Answer 125

Double or plexiform A-comm

Answer 126

azygos ACA - common ACA

Answer 127

From the ICA terminus to the origin of the sylvian fissure

Answer 128

Extends from the bottom to the top of the sylvian fissure

Answer 129

Extends from the top of the sylvian fissure to the cortical surface

Answer 130

Represents small cortical branches.

Answer 131

MC from the A1 segment of the ACA, proximal to the AComm. Supplies the head of the caudate and the anterior limb of the internal capsule.

Answer 132

Persistent trigeminal artery - courses adjacent to the trigeminal nerve. Trident or tau sign on angio. Associated with aneurysms.

Answer 133

Otic, hypoglossal, and proatlantal intersegmental arteries are rare. Persistent trigenimal artery is most common.

Answer 134

Recurrent artery of Heubner. Along with the head of the caudate.

Answer 135

Anterior Choroidal artery. Along with the optic chiasm and hippocampus.

Answer 136

Who would benefit from therapy.

Answer 137

Hemorrhage.

Answer 138

6 hours of stroke onset who are not candidates for IV tPA. No time frame for posterior circulation.

Answer 139

Larger (>1/3 MCA territory) Occlusion of distal ICA and proximal MCA and ACA (T-shaped occlusion). Absence of penumbra of salvagable brain that represents at least 20% of the region of abnormal perfusion may preclude treatment with IV tPA.

Answer 140

Does receive some perfusion, but reduced. <20 mL/100g tissue per minute compared to ~60mL/100g tissue per minute for normal gray matter.

Answer 141

``` Hyperacute (0-6 hours) Acute infarct (6-72 hours) Early subacute infarct (1.5 days - 5 days) Late subacute infarct (5 days - 2 weeks) Chronic ```

Answer 142

Na-K ATPase pump that maintains normal low intracellular Na fails. Sodium and water diffuse into cells - cell swelling and cytotoxic edema. Calcium diffuses into cells - triggers cascades that contribute to cell lysis. DWI hyperintensity with ADC map hypointensity.

Answer 143

0-6 hours Shift from extracellular to intracellular water due to Na/K ATPase pump failure. Increased viscosity of infarcted brain due to cell lysis and increased extracellular protein.

Answer 144

6-72 hours Characterized by increase in vasogenic edema and mass effect. Damaged endovascular cells cause leakage of extracellular fluid and increase the risk of hemorrhage. Sulcal effacement and mass effect which peaks at 3-4 days - overlap between acute and early subacute phases. Hyperintense on T2 of infarct core, best seen on FLAIR. Usually confined to the gray matter. DWI still positive. May see arterial enhancement via collateral flow.

Answer 145

Increase in vasogenic edema and mass effect. Endothelial cell damage causes leakage of extracellualr fluid and increase risk of hemorrhage.

Answer 146

1.5 days to 5 days Blood flow to affected brain is re-established by leptomeningeal collaterals and ingrowth of new vessels into the region of infarction. Have incomplete BBB = increase in vasogenic edema and mass effect, peaks 3-4 days. Marked hyperintensity on T2 in both gray and white matter (early is just gray matter). ADC maps becomes less dark or even resolves, but DWI remains bright due to T2 shine through

Answer 147

Early subacute (1.5 -5 days). DWI still positive due to T2 shine through.

Answer 148

5 days - 2 weeks Resolution of vasogenic edema and reduction in mass effect. Key imaging finding is gyriform enhancement - may be confused with neoplasm, but no mass effect. Enhancement can be seen from about 6 days to 6 weeks after initial infarct. "2-2-2 rule" - enhancement begins at 2 days, peaks at 2 weeks, and disappears by 2 months. DWI remains bright due to T2 shine through. ADC back to normal or show increased diffusivity.

Answer 149

Enhancment of subacute infarct begins at 2 days, peaks at 2 weeks, and disappears by 2 months.

Answer 150

>2 weeks Cellular debris and dead brain tissue are removed by macrophages and replaced by cystic encephalomalacia and gliosis.

Answer 151

Atrophy of contralateral corticospinal tract due to cortical infarct.

Answer 152

Deposition of lipid-laden macrophages after ischemia - hyperintensity of T1 and T2 images. Can be seen instead of encephalomalacia.

Answer 153

AVM and dural AVF

Answer 154

Cavernous malformation (cavernoma) DVA (venous angioma) Capillary telangiectasia

Answer 155

Congenital high-flow vascular malformation. Directly connecting arteries and veins without capillary bed. Present with seizures or bleeding Spetzier-Martin scale helps evaluate surgical risk of AVM resection. Large draining to a deep vein in eloquent cortex is high risk. AVM replaces rather than displaces brain - minimal mass effect.

Answer 156

Helps evaluate surgical risk for AVM resection. Large AVM draining to a deep vein in eloquent cortex is high risk. Small AVM draining into a superficial vein in non-eloquent cortex is low risk.

Answer 157

Replaces rather than displaces brain. Minimal mass effect.

Answer 158

AVF from thalamoperforator branches into the deep venous system. The enlarged vein is actually an enlarged median prosencephalic vein. MC cause of extracardiac high output cardiac failure. Can cause Parinaud syndrome due to mass effect in the pineal region.

Answer 159

High-flow lesions characterized by AV shunts between the meningeal arterioles and dural venules. Primary prognostic feature - presence and degree of cortical venous drainage. Cognard classification. Carotid-cavernous fistula (CCF) is subtype of dAVF - often caused by trauma with resultant fistula between cavernous carotid artery and the cavernous sinus. Enlargement of the superior orbital vein and shunting within the cavernous sinus can lead to eye symptoms such as proptosis and CN palsy.

Answer 160

Prognostic indicator of dural AVFs. Shows increased risk of bleeding. I: No cortical venous drainage. Lowest risk. II: Reflus into dural sinus but not cortical veins. IIB: Reflux into cortical veins: 10-20% hemorhage rate. III: Direct cortical venous drainage: 40% hemorrhage rate IV: Direct cortical venous drainage with venous ectasia: 66% hemorrhage rate V: Spinal venous drainage. May cause myelopathy.

Answer 161

Subtype of dAVF often caused by trauma. Fistula between cavernous carotid artery and the cavernous sinus. Enlargement of the superior orbital vein and shunting within the cavernous sinus can lead to eye symptoms such as proptosis and CN palsy.

Answer 162

CC fistula. Fistula between the cavernous carotid artery and the cavernous sinus.

Answer 163

AKA - cavernoma. Vascular hamartoma with very small but definite bleeding risk. May cause seizures. Often associated with adjacent developmental venous anomaly (DVA). Increased bleeding risk if DVA present, but DVA itself does not have any bleeding risk. Multiple = familial cavernomatosis Can be induced by radiation.

Answer 164

Familial cavernomatosis

Answer 165

Abnormal vein that provides functional venous drainage to normal brain. If resected, the patient will suffer a debilitating venous infarct.

Answer 166

Astymptomatic vascular lesion of dilated capillaries with interspersed normal brain. Do not touch. Faint, brush-stroke-like enhancing lesion in the brainstem or pons, without mass effect or surrounding edema. GRE may show blooming. Angiographically occult, like cavernous malformation.

Answer 167

Trauma. Aneurysm rupture is by far the MC of non-traumatic SAH.

Answer 168

SAH (by far MC) Meningitis Leptomeningeal carcinomatosis Intrathecal contrast administration

Answer 169

LP for xanthochromia.

Answer 170

SAH, meningitis, leptomeningeal carcinomatosis, and residual contrast material. Recent oxygen or propofol can also cause.

Answer 171

AComm (33%) PComm (33%) MCA (20%) Basilar tip (5%)

Answer 172

Clinical grading scale for aneurysmal SAH based solely on symptoms without imaging.

Answer 173

Classifies CT appearance of SAH. Grade 1 is negative on CT; grades 2 and 3 are <1 mm and >1mm thick respectively; grade 4 is diffuse SAH or intraventricular or parenchymal extension.

Answer 174

Iron overload of pial membranes due to chronic repeated SAH. Present with sensorineural deafness and ataxia. Iron causes hypointensity on T2-weighted images outlining the affected sulci.

Answer 175

Type of nonaneurysmal SAH that is Dx of exclusion with much better prognosis than hemorrhage due to ruptured aneurysm. Must be limited to cisterns directly anterior to the midbrain. Standard of care is to do perform catheter anigio twice, one week apart. Must be negative. Unknown cause, but thought to represent angiographically occult venous bleeding.

Answer 176

Cause of nontraumatic, nonaneurysmal SAH and ischemia. Presents with thunderclap HA and is characterized by prolonged (but reversible) vasoconstriction.

Answer 177

Inherited: Connective tissue diseases such as Marfan and Ehlers-Danlos, polycystic kidney disease, and NF 1. Non-inherited: HTN and inflammatory vascular disease such as Takayasu or giant cell arteritis. Fusiform aneurysms are usually due to atherosclerosis.

Answer 178

Segmental arterial dilation w/o a defined neck. Usually due to atherosclerosis, but may arise from chronic dissection Do not occur at branch points. Vertebrobasilar system affected more commonly than anterior circulation. Much less common than saccular

Answer 179

Aneurysm caused by neoplasm. Benign left atrial myxoma may peripherally embolize and cause a distal oncotic aneurysm.

Answer 180

Left transverse sinus

Answer 181

Torcular Herophili

Answer 182

Superior sagittal sinus- drains the motor and sensory strips Paired transverse sinuses Sigmoid sinuses - connects to the jugular bulbs Torcular Herophili is confluence.

Answer 183

Paired internal cerebral veins, basal vein of Rosenthal, and Vein of Galen Venous angle is intersection of the septal vein and the thalamostriate veins. Angiographic landmark for the foramen of Monro.

Answer 184

Intersection of the septal vein and the thalamostriate veins. Angiographic landmark for the foramen of Monro.

Answer 185

Venous angle - intersection of the septal vein and the thalamostriate veins.

Answer 186

Vein of Troclard - connects superficial cortical veins to the superior sagittal sinus. Vein of Labbe - drains the temporal convexity into the transverse or sigmoid sinus. Traction on during surgery can cause venous infarction and aphasia.

Answer 187

Connects the superficial cortical veins to the superior sagittal sinus

Answer 188

Drains the temporal convexity into the transverse or sigmoid sinus.

Answer 189

Pregnancy, oral contraceptives, thrombophilia, malignancy, and infection.

Answer 190

Superior sagittal sinus thrombosis

Answer 191

Deep venous system thrombosis

Answer 192

Transverse sinus thrombosis

Answer 193

Intracellular oxyhemoglobin --> deoxygenation --> Intracellular deoxyhemoglobin --> oxidation --> Intracellular methemoglobin --> cell lysis --> extracellular methemoglobin --> chelation --> Hemosiderin and ferritin

Answer 194

Methemoglobin stages - all others are dark on T1 Bright on both T1 and T2

Answer 195

Bright on T1 and T2, except for intracellular methemoglobin, which is dark on T2.

Answer 196

``` Hyperacute hematoma (0-6 hours) Acute hematoma (6-72 hours) Early subacute hematoma (3 days - 1 week) Late subacute (1 week - months) Chronic hematoma ```

Answer 197

<6 hours Intracellular oxyhemoglobin Primarily intact RBCs containing oxygenated hemoglobin, which is diamagnetic Center of the hematoma will be isointense on T1 and iso to slightly hyperintense on T2. Key is peripheral rim of hypointensity on T2 due to deoxygenation of the most peripheral red cells.

Answer 198

T1 isointense; T2 iso to hyperintense with dark rim.

Answer 199

6-72 hours Intracellular deoxyhemoglobin RBCs desaturate (lose oxygen), entire hematoma becomes hypointense on T2 and iso to mildly hypointense on T1

Answer 200

3 days to 1 week Intracellular methemoglobin Characterized by methemoglobin, which is paramagnetic and undergoes proton-electron dipole-dipole interactions (PEDDI) with water. PEDDI shortens T1 to cause hyperintensity on T1 images. Intracellular and extracellular methemoglobin and both hyperintense on T1. In early subacute, blood remains hypointense on T2 images due to the paramgnetic effects of methemoglobin, which remains trapped in the red cells.

Answer 201

``` 1 week to months Extracellular methemoglobin (after RBC lysis) ``` Methemoglobin PEDDI effec persists are cell lysis- continued hyperintensity on T1. Paramagnetic effects of methemoglobin lessens. Signal intensity on T2 images increases to that of CSF, due to RBC lysis and decrease in protein concentration. May be peripheral enhancement of subacute to chronic infarct.

Answer 202

T2 isointense | T2 iso to hyperintense with dark rim.

Answer 203

T1 iso or hypointense | T2 hypointense

Answer 204

T1 hyperintense | T2 hypointense

Answer 205

T1 hyperintense | T2 hyperintense

Answer 206

T1 iso or hypointense | T2 hypointense

Answer 207

Arteriolar smooth muscle hyperplasia, which eventually leads to smooth muscle death and replacement with collagen. The resultant vascular ectasia predisposes to hemorrhage.

Answer 208

Normotensive elderly adult

Answer 209

Location of hematoma - almost always lobar or cortical - usually in the parietal or occipital lobes.

Answer 210

Glioblastoma

Answer 211

``` Choriocarcinoma Melanoma Thyroid Carcinoma RCC Breast cancer - maybe ```

Answer 212

Bevacizumab - Avastin, Genentech

Answer 213

More than expected edema surrounding a hyperacute hematoma and heterogeneous blood product signal, suggesting varying breakdown stages of hemoglobin. Presence of multiple enhancing masses. If unclear- follow-up MRI once initial hemorrhage improves. May show a delay in the expected evolution of blood products, persistent edema, and enhancement of the underlying tumor.

Answer 214

Cavernous malformation - vascular hamartoma that consists of low-flow endothelial-lined blood vessels w/o intervening normal brain. Angiographically occult.

Answer 215

MC presentation is cerebral ischemia. Less commonly, may present with frank hemorrhage. Multiple foci of T2 prolongation in the basal ganglia and subcortical white matter.

Answer 216

Non-atherosclerotic vasculopathy characterized by progresive stenosis of the intracranial ICA and their proximal branches, which leads to proliferation of fragile lenticulostriate collateral vessels. Angio- enlarged basal perforating arteries gives a puff of smoke appearance. Ivy Sign - FLAIR MRI shows tubular branching hyperintense structures within the sulci, representing cortical arterial branches that appear hyperintense due to slow collateral flow. Susceptible to aneurysm, especially in the posterior circulation.

Answer 217

FLAIR tubular branching hyperintense structures within the sulci, representing cortical arterial branches that appear hyperintense due to slow collateral flow.

Answer 218

Aneurysm formation, especially in the posterior circulation.

Answer 219

Hypertensive hemorrhage

Answer 220

Amyloid angiopathy

Answer 221

Aneurysmal hemorrhage

Answer 222

Cavernous malformation

Answer 223

Venous thrombosis

Answer 224

Hemorrhagic neoplasm

Answer 225

Hemorrhagic infarct

Answer 226

CNS Vasculitis

Answer 227

Minimal mass effect relative to lesion size.

Answer 228

Mucopolysaccharidoses.

Answer 229

Frontal horn periventricular hyperintensity on T2-weighted images due to interstitial CSF backup. Despite "-itis", ependymitis granularis is not associated with inflammation.

Answer 230

Relapsing-remitting (most common): partial or complete resolution of each acute attack. Progressive: No resolution or incomplete resolution between attacks. - Primary progessive: slow onset without discrete exacerbations - Secondary progressive: Similar to relapsing-remitting but with less complete resolution between attacks, leading to progressive disability.

Answer 231

Lymphocytes attacking oligodendrocytes (which make CNS myelin).

Answer 232

Lesions separated in space (different areas of CNS) and time (new lesions across scans).

Answer 233

Decreased NAA, Increased choline, Increased lipids, and increased lactate.

Answer 234

Usually short-segment and unilateral.

Answer 235

Very rare variant of MS with pathognomonic alternating concentric bands of normal and abnormal myelin. More often seen in younger patients.

Answer 236

Alternating concentric bands of normal and abnormal myelin.

Answer 237

Fulminant manifestation of MS, leading to death within months.

Answer 238

Demyelinating disease, distinct from MS, which involves both the optic nerves and spinal cord. Worse prognosis than MS. NMO-IgG, an antibody to aquaporin 4, is highly specific for Devic disease. NMO-IgG activates the complement cascade and induces demyelination. Imaging shows MS-type lesions with involvement of the optic tracts and spinal cord. Brain lesions, if present, tend to be periventricular.

Answer 239

NMO-IgG, an antibody for aquaporin 4. Activates the complement cascade and induces demyelination.

Answer 240

MS-type lesions with involvement of the optic tracts and spinal cord. Brain lesions, if present, tend to be periventricular.

Answer 241

Caused by rapid change in extracellular osmolality, typically after aggressive correction of hyponatremia. Quick osmotic gradient change causes endothelial damage, BBB breakdown, and release of extracellular toxins, which damage myelin. Typically in the pons, but may occur elsewhere in the brainstem and deep gray nuclei. Bilateral central T2 prolongation in the affected region.

Answer 242

Fulminant demyelinating disease of the corpus callosum seen in male alcoholics.

Answer 243

Marchiafava-Bignami

Answer 244

Ataxia, confusion, and oculomotor dysfunction - caused by alcoholism or generalized metabolic disturbances, such as bariatric surgery. T2 prolongation and possible enhancement within the mamillary bodies and medial thalamus. Non-alcoholic form may also affect the cortex.

Answer 245

Acute HTN, eclampsia, sepsis, autoimmune disorders, multidrug chemotherapy, and solid or stem cell transplantation.

Answer 246

Demyelinating disease of immunocompromised patients caused by reactivation of the JC virus. Progressive demyelination with lack of inflammatory response. AIDS defining illness, but also in patients with malignancy, s/p organ transplant, or autoimmune disorders. Asymmetric multifocal white matter lesions that may become confluent. Rarely mass effect or enhancement. The arcuate (subcortical U) fibers are typically involved.

Answer 247

Asymmetric multifocal white matter lesions that may become confluent. Rarely mass effect or enhancement. The arcuate (subcortical U) fibers are typically involved.

Answer 248

PML and HIV encephalitis PML is asymmetric that may become confluent. Involves subcortical white matter and lack of atrophy. HIV encephalitis is usually bilateral (and symmetric), spares the subcortical white matter, and is associated with cerebral atrophy.

Answer 249

Subacute sclerosing panencephalitis (SSPE) is a demyelinating disease caused by reactivation of measles virus, usually after a long latent period Periventricular white matter lesions, but SSPE lesions tend to have surrounding edema and mass effect.

Answer 250

Periventricular white matter lesions, but SSPE lesions tend to have surrounding edema and mass effect.

Answer 251

Subacute sclerosing panencephalitis (SSPE)

Answer 252

Monophasic demyelinating disoder seen primarily in children that typically occurs after viral infection or vaccination. Majority make full recovery. Imaging can be identical to MS- brain, brainstem, and spinal cord.

Answer 253

Acute (during therapy): Edema due to endothelial injury Early delayed (several weeks to 6 months): Demyelination ``` Late delayed (months to years): White matter injury or focal radiation necrosis - Mass effect, edema, and enhancement - ring-enhancing. ``` Other complications - development of meningiomas, capillary telangectasias, cavernous malformations, and/or moyamoya.

Answer 254

Hematogenous dissemination, direct spread from paranasal sinusitis or mastoiditis, or a complication of bacterial meningitis.

Answer 255

Rim-enhancing lesion - thin and smooth. Hypointense rim on T2-weighted images.

Answer 256

Localized tuberculosis granuloma. Not always possible to differentiate a tuberculoma from a pyogenic abscess. Tends to have central hypointensity on T2-weighted image (in contrast to pyogenic abscess, which is hyperintense). A cystic tuberculoma, however, may mimic a pyogenic abscess. Similar to pyogenic abscess, tuberculomas tend to show restricted diffusion.

Answer 257

Can cause white matter disease with nonspecific imaging appearance of T2 prolongation predominantly in the frontal subcortical white matter. Associated enhancement of multiple cranial nerves or meningeal enhancement may suggest the diagnosis.

Answer 258

Cryptococcus - Cryptococcus neoformans Cryptococcus Third MC CNS infection in AIDS overall, after HIV encephalopathy and toxoplasmosis. CD4 count less than 100, similar to toxoplasmosis. MC clinical presentation is chronic basilar meningnitis. MC imaging finding is hydrocephalus, which is nonspecific. Spreads along the basal ganglia periventricular spaces, leaving behind gelatinous pseudocysts, which appear as round water-signal lesions on T2 and T2 weighted MRI. Prediliction for spread to the choroid plexus, producing ring-enhancing granulomas (called cryptococcomas) within the ventricles. Treatment with antifungal agents including fluconazole and amphotericin B.

Answer 259

HIV encephalopathy Toxoplasmosis Cryptococcus

Answer 260

Chronic basilar meningnitis. MC imaging finding is hydrocephalus, which is nonspecific. Spreads along the basal ganglia periventricular spaces, leaving behind gelatinous pseudocysts, which appear as round water-signal lesions on T2 and T2 weighted MRI. Prediliction for spread to the choroid plexus, producing ring-enhancing granulomas (called cryptococcomas) within the ventricles.

Answer 261

Neurocysticercosis

Answer 262

MC parasitic CNS infection of immunocompetent patients. Caused by tapeworm Taenia solium and clinically presents with seizures. Four stages: 1. Viable/vesicular - several CSF-intensity cysts, without enahncement. Many of these cystic lesions may demonstrate an eccentric "dot" representing the scolex. 2. Colloidal - Least specific imaging findingns, ring enhancing lesions. In contrast to pyogenic abscess, the lesions feature increased diffusivity. 3. Nodular/granular - Edema decreases as the cyst involutes and the cyst wall thickens. 4. Calcified - Imaging showed small parenchymal calcifications (on CT) and small foci of susceptibility (GRE)

Answer 263

Four stages: 1. Viable/vesicular - several CSF-intensity cysts, without enahncement. Many of these cystic lesions may demonstrate an eccentric "dot" representing the scolex. 2. Colloidal - Least specific imaging findingns, ring enhancing lesions. In contrast to pyogenic abscess, the lesions feature increased diffusivity. 3. Nodular/granular - Edema decreases as the cyst involutes and the cyst wall thickens. 4. Calcified - Imaging showed small parenchymal calcifications (on CT) and small foci of susceptibility (GRE)

Answer 264

Toxoplasmosis Toxoplasma gondii Second most common CNS infection in AIDS patients, with HIV encephalitis being the most common.

Answer 265

Single or multiple ring-enhancing lesions in the basal ganglia. Asymmetric target sign - not frequently seen, but relatively specific - eccentric nodule of enhancement along the enhancing wall of the toxoplasmosis lesion. Primary DDx of a basal ganglia mass in immunocompromised patient is CNS lymphoma. Toxo does not demonstrate reduced diffusivity and does not demonstrate increased relative cerebral blood volume on perfusion. Will be hypometabolic on PET and not avid on thallium scintigraphy.

Answer 266

Toxoplasmosis vs CNS lymphoma. Toxo does not demonstrate reduced diffusivity and does not demonstrate increased relative cerebral blood volume on perfusion. Toxo is hypometabolic on PET and not avid on thallium scintigraphy.

Answer 267

``` Herpes encephalitis MCA infarction Infiltrating glioma Limbic encephalitis Seizure-related changes. ``` Fever is typically absent in infarction and glioma.

Answer 268

HIV encephalopathy Progressive neurodegenerative disease caused by direct infection of CNS lymphocytes and microglial cells (CNS macrophages) by the HIV virus.

Answer 269

Diffuse cerebral atrophy and symmetric T2 prolongation in the periventricular and deep white matter. In contrast to PML, HIV encephalitis spares the subcortical U-fibers and tends to be symmetric.

Answer 270

Only affects the immunosuppressed, typically when CD4 cell count is less than 50.

Answer 271

Ventriculitis or meningoencephalitis. Subependymal FLAIR hyperintensity and enhancement throughout the ventricular system. In neonates, CMV is one of the most common TORCH infections and causes atrophy, encephalomalacia, ventricular enlargement, and periventricular calcification.

Answer 272

Cortical ribboning - ribbonlike FLAIR hyperintensity and restricted diffusion of the cerebral cortex. The basal ganglia and thalami are also involved. Often sparing the motor cortex. Pulvinar sign - bright DWI and FLAIR signal within the pulvinar nucleus of the thalamus. Hockey stick sign - bright DWI and FLAIR signal within the doromedial thalamus.

Answer 273

Hyperintense signal on T1 in the globus pallidus and substantia nigra, thought to be due to manganese deposition.

Answer 274

Bilateral T2 prolongation in the gray matter, including the cerebral cortex, hippocampi, and basal ganglia.

Answer 275

FLAIR and/or DWI hyperintensity of the affected regions - usually gray matter, including the cerebral cortex, hippocampi, and basal ganglia. Distribution tends to be similar to that of severe hypoglycemia. Involvement of basal ganglia portends a worse prognosis.

Answer 276

Can present as optic neuritis as first symptom. Hemorrhagic necrosis of the putamen and white matter edema may follow.

Answer 277

Symmetric T2 prolongation and restricted diffusion of the globus pallidus.

Answer 278

Potential space located posterior to the pharynx, separated from the pharynx by the pharyngobasilar fascia. Extends from the base of the skull to the upper mediastinum. Directly lateral to the retropharyngeal space are the carotid and parapharyngeal spaces.

Answer 279

Pharyngobasilar fascia.

Answer 280

Alar fascia

Answer 281

Anterior compartment of the perivertebral space in the suprahyoid neck - located just anterior to the vertebral body and is bounded anteriorly by the prevertebral fascia.

Answer 282

Potential space located at base of the tongue - nestled between the genioglossus and geniohyoid muscles medially and the sling of the mylohyoid muscle inferiorly and laterally.

Answer 283

Between the genioglossus and geniohyoid muscles medially. Sling of the mylohyoid muscle inferiorly and laterally.

Answer 284

Cellulitis of the floor of the mouth. Can involve the submental, sublingual, and submandiular spaces. Tongue can become posteriorly displaced.

Answer 285

Children- Spread of an upper respiratory tract infection, such as pharyngitis. Enlargement of retropharyngeal lymph nodes that drain the pharynx may lead to subsequent suppuration and rupture. Adults- Most often due to penetrating injury, such as fish bone ingestion or instrumentation.

Answer 286

Venous thrombophlebitis of the tonsillar and peritonsillar veins, often with spread to the internal jugular vein. Immunocompetent adolescents and young adults are typically affected. MC is anaerobe Fusoacterium necrophorum, which is part of the normal mouth flora. Imaging - enlargement, thrombosis, and mural enhancement of the affected veins. Metastatic pulmonary abscesses may be present.

Answer 287

Complication of otomastoiditis where there is necrosis of the mastoid tip and resultant spread of infection into the adjacent soft tissue. Imaging- opacification of the middle ear and mastoid air cells, often with bony erosion of the mastoid.

Answer 288

Mucus retention cyst that arises from the sublingual gland as a sequella of inflammation. Plunging ranula extends from the sublingual space into the submandibular space by protruding posteriorly over the free edge of the mylohyoid or by extending directly through a defect in the mylohyoid.

Answer 289

Dermoid is a teratomatous lesion that contains at least two germ cell layers, while an epidermoid contains only ectoderm. Both appear as fluid-attenuation lesion, most commonly in the midline of the floor of the mouth. Pathognomonic MRI finding of dermoid is the sack of marbles appearance from floating fat globules. In absence - epidermoid and dermoid can be indistinguishable in this location on MRI.

Answer 290

Persistence of the thyroglossal duct - follows the midline descent of the embryonic thyroid gland from the base of the tongue (foramen cecum) to its normal position of in the neck. Present in childhood as an enlarging neck mass that elevates with tongue protrusion. Majority are infrahyoid- the rest found at the level of the hyoid or above. Most midline, but may be slightly off midline, especially when infrahyoid.

Answer 291

Near the parotid or the external auditory canal

Answer 292

Second - Most occur near the angle of the mandible, anterior to the SCM, posterior to the submandibular gland, and closely associated with the carotid bifurcation.

Answer 293

Can occur at any point along the path extending from the palatine tonsil to the supraclavicular region- most near the angle of the mandible, anterior to the SCM, posterior to the submandibular gland, and closely associated with the carotid bifurcation.

Answer 294

Submandibular abscess is usually due to dental disease and is typically located immediately inferior to the mandible.

Answer 295

Cystic hygroma (MC) Cavernous lymphangioma Capillary Lymphangioma - smallest cystic spaces

Answer 296

MC type of lymphatic malformation. Majority being present at birth and associated with chromosomal anomalies including Turner and Down syndromes. Large lymphatic spaces. MC location is the posterior triangle of the neck.

Answer 297

Present at birth and associated with chromosomal anomalies including Turner and Down syndromes.

Answer 298

Posterior triangle of the neck.

Answer 299

Notochordal remnant that is usually asymptomatic, but may be a cause of halitosis. Typically in the midline nasopharynx.

Answer 300

Epiglotis, thyroid cartilage, cricoid cartilage, and arytenoids.

Answer 301

Extension of the mucosa covering the epiglottis and mark the entrance to the larynx. Connect the epiglottis anteriorly to the arytenoids posteriorly.

Answer 302

Aryepiglottic folds

Answer 303

Mucosal infoldings superior to the laryngeal ventricle. Can be identified by the presence of the paraglottic fat laterally.

Answer 304

Extends from the epiglottis to the ventricle. Contains the false vocal cords, the aryepiglottic folds, and the arytenoid cartilages.

Answer 305

False vocal cords, the aryepiglottic folds, and the arytenoid cartilages.

Answer 306

Includes the true vocal cords and the thyroarytenoid muscle. The medial fibers of the thyroarytenoid muscle comprise the vocalis muscle. True vocal cords are identified in the axial plane on CT or MRI by identifying the transition of paraglottic fat to muscle (thyroarytenoid muscle) within the wall of the larynx.

Answer 307

The medial fibers of the thyroarytenoid muscle comprise the vocalis muscle.

Answer 308

True vocal cords are identified in the axial plane on CT or MRI by identifying the transition of paraglottic fat to muscle (thyroarytenoid muscle) within the wall of the larynx.

Answer 309

Begins 1 cm inferior to the apex of the laryngeal ventricle and extends to the first tracheal ring.

Answer 310

Mediastinal or thoracic mass. Can have enlargement of the left atrium or pulmonary arteries may cause cardiovocal syndrome due to recurrent laryngeal nerve compression. MC cause is iatrogenic trauma from neck surgery.

Answer 311

Recurrent laryngeal nerve innervates all laryngeal musculature except the cricothyroid muscle which is innervated by the superior laryngeal nerve.

Answer 312

Dilation of the laryngeal ventricle- may be caused by high laryngeal pressures. Trumpet players, glassblowers, and patients with COPD have increased risk of developing a laryngocele. May be filled with air or fluid. Can get ventricular obstruction by neoplasm (MC is SCC), which typically causes a fluid-filled laryngocele.

Answer 313

Common drainage pathway for the maxillary, frontal, and anterior ethmoid sinuses - all drain into the middle meatus. Made up of the maxillary sinus ostium, infundibulum, uncinate process, hiatus semilunaris, ethmoid bulla, and middle meatus.

Answer 314

Ostiomeatal unit to the middle meatus.

Answer 315

Obstruction of maxillary sinus ostium or infundibulum.

Answer 316

Obstruction of the hiatus semilunaris

Answer 317

Basal lamella

Answer 318

Via the frontal recess into the middle meatus (via the ostiomeatal unit)

Answer 319

Via tiny ostia underneath the superior turbinate into the superior meatus.

Answer 320

Drains into the ethmoid infundibulum via the frontal recess. The frontal sinus is absent at birth and represents an enlarged anterior ethmoid cell.

Answer 321

Drains into the ethmoid air cells via the sphenoethmoidal recess - then the posterior ethmoids drain into the superior meatus via individual unnamed ostia.

Answer 322

Posterior ethmoids and sphenoid sinus (via the sphenoethmoidal recess)

Answer 323

Common drainage pathway of the maxillary, frontal, and anterior ethmoid sinuses via the ostiomeatal unit.

Answer 324

Drainage pathway of the lacrimal duct.

Answer 325

The most anterior ethmoid air cell. Large agger nasi cell may cause obstruction of the frontal recess.

Answer 326

Ethmoid cell located inferior to the orbit, which may compromise the maxillary ostium if the Haller cell becomes large or inflamed.

Answer 327

The most posterosuperior ethmoid air cell, which is located directly inferomedial to the optic nerve. May be mistaken for a sphenoid sinus endoscopically, potentially placing the optic nerve at risk.

Answer 328

Formed when the inferior bulbous portion of the middle turbinate is pneumatized. Usually incidental, but may cause septal deviation and narrowing of the infundibulum when large.

Answer 329

Agger nasi cell

Answer 330

Onodi Cell

Answer 331

Concha Bullosa

Answer 332

Osteomyelitis of the frontal bone which may cause a subgaleal abscess with associated soft tissue edema.

Answer 333

Affected sinus is expanded and airless, with thin deossified walls. The sinus contents are typically mixed attenuation with heterogeneous curvilinear high attenuation.

Answer 334

Aggressive infection that occurs in immunosuppressed patients. Aspergillus and Zygomycetes are the MC organisms. Aspergillus can cause acute fulminant disease.

Answer 335

Nonspecific sinus mucosal thickening. Later in disease process there is often local invasion, bony destruction, and intracranial and intraorbital spread. Unlike chronic allergic fungal sinusitis, invasive fungal sinusitis is not hyperdense on CT.

Answer 336

Benign polyp extending from the maxillary sinus into the nasal cavity with characteristic widening of the involved ostium. It may erode bone and extend into the nasopharynx.

Answer 337

Benign lobulated epithelial tumor of the sinus mucosa - can be associated with SCC 10-20% of the time. Classic imaging finding on an enhanced study is a cerebriform pattern of enhancement - curvilinear, gyriform enhancement. In contrast to a mucocele or obstructed secretions, the entire solid tumor will enhance. Tends to remodel bone.

Answer 338

Surgeons use facial nerve Radiologists use the retromandibular vein

Answer 339

Stensen's Duct

Answer 340

Parotid - last major salivary gland to become encapsulated.

Answer 341

Exits the stylomastoid foramen and subsequently passes anterior to the posterior belly of the digastric and lateral to the styloid process before entering the parotid gland.

Answer 342

Posterior margin of the mylohyoid muscle.

Answer 343

Benign pleomorphic adenoma. Tumor of a minor salivary gland origin is much more likely to be malignant than submandibular or parotid.

Answer 344

Pleomorphic adenoma Small firm mass in a middle-aged patient. 2nd MC is Warthin tumor

Answer 345

Can transform into carcinoma ex pleomorphic adenoma. Can't distinguish between benign pleomorphic adenoma and malignant mucoepidermoid carcinoma by imaging.

Answer 346

Similar to water, but enhancement is typical.

Answer 347

2nd MC benign parotid tumor. No risk of malignant transformation. Generally appear as a cystic neoplasm, but unlike pleomorphic adenoma, Warthin tumors do not enhance.

Answer 348

Pleomorphic adenoma and Warthin tumor

Answer 349

Mucoepidermoid Carcinoma Adenoid Cystic Carcinoma Carcinoma ex pleomorphic adenoma SCC

Answer 350

MC primary parotid malignancy Appears as an enhancing mass that is hyperintense on T2. Indistinguishable from benign pleomorphic adenoma on MRI.

Answer 351

Mucoepidermoid carcinoma Adenoid cystic carcinoma is 2nd

Answer 352

MC submandibular and sublingual gland malignancy - 2nd MC parotid gland malignancy. Tends to spread along the nerves (perineural spread) and often presents with cranial nerve palsy or paresthesia. Key imaging feature is an enhancing mass with perineural spread

Answer 353

Adenoid cystic carcinoma

Answer 354

Adenoid cystic carcinoma

Answer 355

Adenoid cystic carcinoma

Answer 356

Malignant degeneration of a benign pleomorphic adenoma Elderly with rapid enlargement of an existing mass. Hypointense on both T1 and T2

Answer 357

Hypointense on both T1 and T2

Answer 358

Submandibular - 80-90%

Answer 359

Bilateral uveitis, parotid enlargement, and facial nerve palsy - pathognomonic for sarcoidosis

Answer 360

Atrophy and fatty replacement of the salivary glandular tissue with multiple nodules, abnormal enhancement, numerous small cystic foci and punctate calcification. Risk of lymphoma is increased.

Answer 361

Parotid manifestations of lymphoid dysfunction in patients with HIV - multiple bilateral lymphepithelial cysts and solid masses. Only parotid glands affected b/c only salivary glands to contain lymphoid tissue.

Answer 362

Face and brain - is an important potential pathway for the spread of tumor or infection.

Answer 363

Posterior to the maxillary sinus and inferior to the inferior orbital fissure. 3D box with each of the six sides leading to important structures in the face.

Answer 364

Pterygopalatine ganglion and branches of the internal maxillary artery.

Answer 365

Pterygomaxillary fissure - lateral exit of the pterygopalatine fossa - leads to the masticator space. Sphenopalatine Foramen - Medial exit of the pterygopalatine fossa - leads to the nasopharynx via the superior meatus. The nasal margin of the spheopalatine foramen is though to the the site of origin of juvenile nasopharyngeal angiofibroma. Foramen Rotundum - posterior opening to the middle cranial fossa. CN V2 travels through. Inferior Orbital Fissure - the "roof" of the pterygopalatine fossa and opens anteriorly into the orbit. The infraorbital nerve and artery travel through the inferior orbital fissure. Vidian Canal - located directly below the foramen rotundum. Contains the vidian canal and artery, also known as the nerve and artery of the pterygoid canal. Pterygopalatine Canal - the "floor" of the pterygopalatine fossa - leads to the oral cavity via the greater and lesser palatine foramina. The pterygopalatine canal transmits the descending palatine nerve and artery.

Answer 366

lateral exit of the pterygopalatine fossa - leads to the masticator space

Answer 367

Pterygomaxillary fissure

Answer 368

Medial exit of the pterygopalatine fossa - leads to the nasopharynx via the superior meatus. The nasal margin of the spheopalatine foramen is though to the the site of origin of juvenile nasopharyngeal angiofibroma.

Answer 369

Posterior opening of the pterygopalatine fossa to the middle cranial fossa. CN V2 travels through.

Answer 370

The "roof" of the pterygopalatine fossa and opens anteriorly into the orbit. The infraorbital nerve and artery travel through the inferior orbital fissure.

Answer 371

Infraorbital nerve and artery

Answer 372

Part of the pterygopalatine fossa. Located directly below the foramen rotundum. Contains the vidian canal and artery, also known as the nerve and artery of the pterygoid canal.

Answer 373

Vidian canal is located directly below the foramen rotundum.

Answer 374

the "floor" of the pterygopalatine fossa - leads to the oral cavity via the greater and lesser palatine foramina. The pterygopalatine canal transmits the descending palatine nerve and artery.

Answer 375

Pterygopalatine Canal - leads to the oral cavity via the greater and lesser palatine foramina. The pterygopalatine canal transmits the descending palatine nerve and artery.

Answer 376

Middle meningeal artery

Answer 377

Benign, highly vascular tumor seen in adolescent males. MC presentation is nasal obstruction and epistaxis. Lack of metastatic behavior, is very locally aggresive and insinuates through adjacent skull base foramina. Arises from within the nasal aspect of the sphenopalatine foramen, which is the medial boundary of the pterygopalatine fossa. Enhances very avidly and is centered in the nasopharynx. Can extend into the pterygopalatine fossa or orbits as it continues to grow. Classic findings: Nasopharyngeal mass, expansion of the pterygopalatine fossa and anterior bowing or displacement of the posterior maxillary sinus wall. Usually embolized prior to resection.

Answer 378

Arises from within the nasal aspect of the sphenopalatine foramen, which is the medial boundary of the pterygopalatine fossa.

Answer 379

Nasopharyngeal mass, expansion of the pterygopalatine fossa and anterior bowing or displacement of the posterior maxillary sinus wall.

Answer 380

Arachnoid villi rests

Answer 381

Presence of bony destruction, invasion into the brain parenchyma, and extension into the orbit and cavernous sinus.

Answer 382

Olfactory Neuroblastoma - malignant neural crest tumor that arises from specialized olfactory epithelium. Histology similar to other neural crest tumors, such as small cell lung cancer and neuroblastoma Bimodal age distribition - peak in the teenage years and middle age. Aggressive mass that is slightly hyperattenuating on CT and indeterminate intensity on both T1 and T2 images due to high cellularity. Calcification is often present. Presence of peripheral tumor cysts that occur at the margins of the intracranial portion of the mass is classic

Answer 383

Olfactory Neuroblastoma - malignant neural crest tumor that arises from specialized olfactory epithelium. Histology similar to other neural crest tumors, such as small cell lung cancer and neuroblastoma

Answer 384

Aggressive mass that is slightly hyperattenuating on CT and indeterminate intensity on both T1 and T2 images due to high cellularity. Calcification is often present. Presence of peripheral tumor cysts that occur at the margins of the intracranial portion of the mass is classic

Answer 385

SCC. Maxillary antrum is MC primary site. Enhancement is the key differentiating feature from benign inflammatory processes such as sinonasal polyposis or mucocele.

Answer 386

May arise from minor salivary glands in the sinonasal cavity. Lymphatic spread is rare, distant metastases are seen commonly. Demonstrates water signal on T1 and T2 images, but unlike a cyst, enhancement is characteristic. Adenoid cystic carcinoma arising in the region of the anterior skull base has a high rate of trigeminal nerve perineural spread. Post-contrast evaluation of the cranial nerves offers the highest sensitivity to evaluate for subtle perineural spread.

Answer 387

Rhabdomyosarcoma

Answer 388

External auditory canal (EAC)

Answer 389

Tympanic membrane Ossicles (malleus, incus, stapes) Stapedius Muscle Facial Nerve

Answer 390

``` Cochlea Semicircular Canals Vestibule Utricle Saccule Vestibular Aqueduct Cochlear Aqueduct ```

Answer 391

Cochlea, vestibule, and semicircular canals Balance and position sense.

Answer 392

Congenital EAC stenosis, hypoplasia and atresia Acute external otitis EAC exostosis (surfer's ear) Necrotizing external otitis (malignant otitis externa) Keratosis Obturans Cholesteatoma EAC Malignancy

Answer 393

EAC and inner ear have different embryologic origins, so it is uncommon for both an EAC and inner ear abnormality to be present.

Answer 394

Malleus and incus - 1st branchial cleft structures.

Answer 395

AKA surfer's ear - bony exostosis of the EAC seen in those who swim/surf in cold waters.

Answer 396

AKA malignant otitis externa - severe complication of external otitis seen in elderly diabetic or immunocompromised patients. Pseudomonas aeruginosa in diabetics and Aspergillus fumigatus in immunocompromised. Fast spreading and aggressive with potential involvement of the middle or inner ear structures, or skull base extension. Extensive enhancement centered around the external ear with bony erosion.

Answer 397

Pseudomonas aeruginosa in diabetics and Aspergillus fumigatus in immunocompromised.

Answer 398

Keratin plugs w/in an enlarged EAC. Typically seen in young patients with sinusitis and bronchiectasis - usually bilateral.

Answer 399

Tensor tympani and stapedius

Answer 400

The oval window.

Answer 401

The oval window.

Answer 402

Extra-adrenal pheochromocytoma (paraganglioma) isolated to the middle ear. MC primary middle ear tumor. Pulsatile tinnitus or conductive hearing loss.

Answer 403

Glomus Tympanicum

Answer 404

Labrynthine Segment - courses from the IAC to the geniculate ganglion, which is located superior to the cochlea. Greater superficial petrosal nerve innervates salivation. Tympanic (horizontal) segment - Courses under the lateral semicircular canal. Mastoid (descending) segment - Courses inferiority, then exits the temporal bone at the stylomastoid foramen. Nerve to stapedius and Chorda Tympani (taste to anterior 2/3 of tongue)

Answer 405

Courses from the IAC to the geniculate ganglion, which is located superior to the cochlea. Greater superficial petrosal nerve innervates salivation.

Answer 406

Courses under the lateral semicircular canal.

Answer 407

Courses inferiority, then exits the temporal bone at the stylomastoid foramen. Nerve to stapedius and Chorda Tympani (taste to anterior 2/3 of tongue)

Answer 408

Chorda Tympani - branch of the mastoid (descending) segment of the facial nerve

Answer 409

Geniculate ganglion, followed by the labyrinthine and tympanic segments.

Answer 410

AKA a cholesterol cyst - MC benign petrous apex lesion, but may occur in the middle ear. Caused by giant cell reaction to cholesterol crystals thought to be intially incited by an obstructed air cell. Blue mass behind the tympanic membrane. Cholesterol granuloma and cholesteatoma are often considered together in the DDx of a soft tissue middle ear mass with bony erosion. Cholesteatoma will show restricted diffusion and will appear as a white mass on otoscopic examination. Cholesterol granuloma is typically hyperintense on T1.

Answer 411

Cholesterol granuloma and cholesteatoma Cholesteatoma will show restricted diffusion and will appear as a white mass on otoscopic examination. Cholesterol granuloma is typically hyperintense on T1.

Answer 412

Non-neoplastic lesion of the temporal bone - skin in the wrong place. Does not contain fat and is not neoplastic - despite it's name. An intracranial, extra-axial "cholesteatoma" is an epidermoid cyst.

Answer 413

Epidermoid cyst

Answer 414

Lateral semicircular canal, the tegmen tympani (bony roof separating the mastoids from the brain), and the facial nerve.

Answer 415

Well-circumscribed soft-tissue mass with adjacent bony erosion, blunting of the scutum, and erosion of the ossicles. CT can't tell the difference between cholesteatoma and cholesterol granuloma.

Answer 416

Diffusion- hyperintense - combination of T2 shine through and restricted diffusion. Post-contrast - do not enhance. Intermediate to slightly hyperintense on T2 and of variable signal intensity on T1.

Answer 417

Otic capsule - densest bone in the body.

Answer 418

Cochlea - allows us to hear - two-and-a-half turn spiral containing numerous neuroepithelial hair cells of the organ of Corti - send electrical impulses to the spiral ganglia of the cochlea in response to mechanical bending.

Answer 419

Contains numerous neuroepithelial hair cells of the organ of Corti - send electrical impulses to the spiral ganglia of the cochlea in response to mechanical bending. Hydralic pressure created in the perilymph by the vibrations of the stapes against the oval window ascends to the apex of the cochlea by the scala vestibuli. Pressure waves descend back to the basal turn through the scala tympani. Vibrations from the scala tympani are transmitted through the round window, where the energy is dissipated.

Answer 420

Scala Vestibuli

Answer 421

Scala Tympani and out through the round window.

Answer 422

Vestibule and semicircular canals.

Answer 423

Vestibular aqueduct connects the crus common (common channel of the superior and posterior semicircular canals) to the subarachnoid space in the IAC and is thought to be involved in pressure equalization between the CSF and the inner ear.

Answer 424

Mondini Deformity - MC form of congenital cochlear dysplasia - incomplete development of the normal two and a half turns of the cochlea, resulting in confluence of the apical and middle turns and preservation of a distinct basilar turn Strong association between cochlear dysplasia and enlarged vestibular aqueduct.

Answer 425

Very rare complete lack of development of the entire inner ear.

Answer 426

Spectrum of congenital hearing loss associated with an enlarged vestibular aqueduct - the vestibular aqueduct does not have a direct function in the physiology of hearing. Clinically, enlarged vestibular aqueduct syndrome may lead to progressive hearing loss while playing contact sports. The vestibular aqueduct should not be larger than the posterior semicircular canal, which is often seen at the same level in the axial plane.

Answer 427

AKA otosclerosis. A primary bone dysplasia of the otic capsule characterized by replacement of normal endochondral bone by irregular spongy bone - MC in young and middle-aged women - bilateral 85% of the time. Fenesteral - anterior to the oval window Retrofenestral - more severe - involvement of the otic capsule in addition to the lateral wall of the labyrinth.

Answer 428

Fenestral - more common - occurs as the fissula ante fenestrum (located directly anterior to the oval window), and usually affects the oval window. Retrofenestral (cochlear) - thought to represent more severe form with involvement of the otic capsule in addition to the lateral wall of the labyrinth.

Answer 429

Retrofenestral otospongiosis, osteogenesis imperfecta in a child, fibrous dysplasia in a young adult, and Paget disease in an older adult.

Answer 430

Acute Labyrinthitis - pus in the inner ear. Enhancement of the affected inner ear structures. Fibrous Labyrinthitis - Replacement of endolymph and perilymph with fibrous strands that cause decreased signal intensity on T2. May be mild (but decreased) residual post-contrast enhancement of the affected structures. Labyrinthitis Ossificans - final stage - calcified debris replaces the normal endolymph and perilymph. Calcification on CT with decreased signal intensity on T2 with lack of enhancement.

Answer 431

Longitudinal (MC) and Transverse

Answer 432

MC - likely to involve the ossicles and result in conductive hearing loss. 20% associated with facial nerve injury.

Answer 433

More likely to involve the bony labyrinth and result in sensorineural hearing loss. 50% result in facial nerve injury.

Answer 434

Longitudinal

Answer 435

Transverse

Answer 436

Transverse (50%) | Longitudinal (20%)

Answer 437

Most medial portion of the temporal bone Bridge between the suprahyoid neck inferiorly and the intracranial component above. Adjacent to several important structures such as Dorello's canal, Meckel's cave and the petrous portion of the ICA Normally bone marrow and dense bone. Pneumatized in 10% of the population which increases the risk for development of cholesterol cyst or apical petrositis.

Answer 438

Cranial nerve VI

Answer 439

Trigeminal ganglion.

Answer 440

cholesterol cyst or apical petrositis

Answer 441

Cholesterol cyst Can also occur in the mastoid portion of the temporal bone or the middle ear.

Answer 442

Rare complication of infectious otomastoiditis - infection extends medially into a pneumatized petrous apex. Gradenigo Triad - Otomastoiditis, facial pain due to trigeminal neuropathy at Meckel's Cave, and lateral rectus palsy from CN VI palsy at Dorello's canal.

Answer 443

Apical Petrositis Otomastoiditis, facial pain due to trigeminal neuropathy at Meckel's Cave, and lateral rectus palsy from CN VI palsy at Dorello's canal.

Answer 444

Middle ear Congenital - can be located anywhere in the temporal bone, including the petrous apex.

Answer 445

Neoplastic proliferation of eosinophils and Langerhans Cells Temporal bone is MC site of skull base involvement.

Answer 446

Midline from the clivus or slightly off midline from the petroclival synchondrosis.

Answer 447

Apical petrositis

Answer 448

Congenital cholesteatoma

Answer 449

Cholesterol Granuloma

Answer 450

Meningioma

Answer 451

Eosinophilic granuloma

Answer 452

Schwannoma

Answer 453

Mets/Myeloma

Answer 454

Chondrosarcoma/Chordoma

Answer 455

Locally invasive tumor arising in the midline from notochord remnants 50% near the sacrum, 35% near the clivus, and remainder in the vertebral column.

Answer 456

Breast cancer

Answer 457

Glomus Tumors - neoplasms of paraganglionic tissue that arise from sympathetic glomus bodies. Histologically identical to extra-adrenal pheochromocytoma. Occur in a few predictable locations in neck. Associated with MEN 1 and NF1. Highly vascular and enhance avidly. Classic MRI appearance is salt and pepper appearance due to intratumora flow voids.

Answer 458

MEN 1 and NF1.

Answer 459

``` Glomus Jugulare Glomus tympanicum Glomus Jugulotympanicum Carotid Body Tumor (glomus caroticum) Glomus Vagale ```

Answer 460

MC primary neoplasm of the jugular foramen - woman in late middle age presenting with pulsatile tinnitus and conductive hearing loss. Moth-eaten bony destruction typical of paragangliomas centered around the jugular foramen. Schwannoma and meningioma features smooth bony remodeling and meningioma causes hyperostosis.

Answer 461

Paraganglioma isolated to the middle ear Vascular, red, retro-tympanic mass

Answer 462

Glomus tympanicum Aberrant carotid artery Tympanic membrane hemangioma

Answer 463

Glomus jugular that has spread into the middle ear

Answer 464

Glomus Caroticum - paraganglioma of the carotid body Characteristically splays the internal and external carotid arteries.

Answer 465

Paraganglioma of the vagus nerve - typically occuring at the same level of the neck as the carotid body tumor Displaces the carotid artery (both internal and external branches) medially and anteriorly. In contrast, a carotid body tumor splays the internal and external carotids. Schwannoma of the vagus nerve may occur in the same location and will also displace the carotid artery medially and anteriorly. Generally less vascular. May enhance avidly, but would show the flow voids of typical glomus vagale.

Answer 466

Carotid Body Tumor

Answer 467

Glomus Vagale

Answer 468

Frontal, ethmoid, nasal, zygomatic, and maxilla.

Answer 469

Optic nerve | Opthalmic artery

Answer 470

All cranial nerves of the cavernous sinus except V2 (exits via the foramen rotundum and enters the orbit via the inferior orbital fissure). ``` CN III (oculomotor) CN IV (trochlear) CN V1 (opthalmic division of trigeminal nerve) CN VI (abducens) Superior opthalmic vein ```

Answer 471

Oculomotor Nerve - Innervates the superior, medial, and inferior rectus, and the inferior oblique

Answer 472

Trochlear Nerve - Innervates the superior oblique

Answer 473

Opthalmic division of the trigeminal nerve - provides sensory innervation to the upper face

Answer 474

Abducens Nerve - innervates the lateral rectus

Answer 475

Superior orbital fissure

Answer 476

CN V2 | Infraorbital artery

Answer 477

Maxillary division of the trigeminal nerve - provides sensory innervation to the inferior eyelid, upper lip, and nose.

Answer 478

``` Preseptal Postseptal Extraconal Conal Intraconal Globe ```

Answer 479

Orbital septum

Answer 480

Lacrimal gland, fat, and bony orbit.

Answer 481

All the muscles except the inferior oblique muscle arise from a common fibrous ring called the annulus of Zinn - located at the apex of the orbit at the optic foramen and medial superior orbital fissure. The inferior oblique arises from the medial orbital floor.

Answer 482

Optic nerve-sheath complex, sensory and motor nerves of the orbit, lymph nodes, and fat.

Answer 483

Direct spread of infection from the paranasal sinuses Can get from trauma, foreign body, and odotogenic

Answer 484

``` Preseptal infection Orbital cellulitis/phlegmon Subperiosteal abscess Orbital abscess Cavernous sinus thrombosis ```

Answer 485

``` Hemangioma Orbital Lymphoma Lymphangioma Schwannoma/Neurofibroma Metastases Lacrimal Gland Lesion ```

Answer 486

Cavernous hemangioma - seen in adults - MC adult orbital mass, typically presents with proptosis. Usually intraconal, but may be extraconal. Ovoid enhancing intra or extraconal mass. Isointense on T1 and hyperintense on T2 with patchy enhanement that progressively fills in. Capillary hemangioma - seen only in the first year of life. Analogous to and often present in conjunction with skin lesions - typically enlarges over first few months of life before spontaneously involuting.

Answer 487

Lacrimal gland- usually associated with systemic disease. Painless downward proptosis. Hypercellular tumor that is hyperdense on CT and hypointense on both T1 and T2. Molds to the globe like orbital pseudotumor, but pseudotumor presents with pain.

Answer 488

Both mold to the globe. | Pseudotumor typically presents with pain.

Answer 489

Benign hamartomatous lesion seen in the pediatric population - low flow lymphatic malformation Most commonly involve the extraconal compartment but may be found anywhere in the orbit. Multilocular cystic mass, often with complex internal contents with fluid levels from prior hemorrhage. Slight peripheral and septal enhancement.

Answer 490

Lymphangioma

Answer 491

Sensory branches of V1 - characteristic location in the superior orbit

Answer 492

Breast, lung, thyroid, renal cell, and melanoma.

Answer 493

Epithelial salivary gland tumors - 50% benign (pleomorphic adenoma) and 50% malignant (adenoid cystic and mucoepidermoid carcinoma) Diseases of lymphoid tissue - sarcoidosis and lymphoma May become enlarged in orbital pseudotumor

Answer 494

Mediated by lymphocytes that produce hyaluronic acid - leads to fibrosis of the extraocular muscles. Can occur with any thyroid disorder, MC with Graves. Initially increase in intra-orbital fat, which may demonstrate stranding due to inflammatory change, then extraocular muscles become enlarged. I'M SLow Inferior rectus --> Medial Rectus --> Superior Rectus --> Lateral rectus

Answer 495

Very uncommon in thyroid opthalmopathy - prompt search for alternative diagnosis such as orbital pseudotumor. Thyroid opthalmopathy tends to be bilateral and spares the muscle tendons.

Answer 496

Idiopathic orbital inflammation mediated by an infiltrate of lymphocytes, plasma cells, and macrophages. Painful proptosis (in contrast to lymphoma which is painless) Dx of exclusion Lacrimal gland is MC involved orbital structure. Several other structures in the orbit may be affected, including the anterior structures (producing uveitis) and the extraocular muscles. Stranding w/in the orbit fat, increased orbital soft tissue, and enlargement of the extrocular muscles. Tx with steroids

Answer 497

Painful proptosis (in contrast to lymphoma which is painless)

Answer 498

Lacrimal gland is MC involved orbital structure. Several other structures in the orbit may be affected, including the anterior structures (producing uveitis) and the extraocular muscles.

Answer 499

Stranding w/in the orbit fat, increased orbital soft tissue, and enlargement of the extrocular muscles.

Answer 500

Same pathologic process as orbital pseudotumor (inflammation mediated by an infiltrate of lymphocytes, plasma cells, and macrophages), but involving the cavernous sinus

Answer 501

MC Tumor to arise from the optic nerve-sheath complex. In children: typically low-grade astrocytoma with indolent course. Associated with NF1 and often bilateral. Variable appearance with fusiform enlargement of optic nerve and variable nehancement. May have a cyst and nodule appearance like low-grade pilocytic astrocytomas of the posterior fossa. Adulthood: usually anaplastic astrocytoma or GBM with poor prognosis. Aggressive enhancing mass, often extends intracranially to involve the optic chiasm. May involve any part of optic tract, including the optic radiations.

Answer 502

Optic nerve glioma

Answer 503

Typically low-grade astrocytoma with indolent course. Associated with NF1 and often bilateral. Variable appearance with fusiform enlargement of optic nerve and variable nehancement. May have a cyst and nodule appearance like low-grade pilocytic astrocytomas of the posterior fossa.

Answer 504

Usually anaplastic astrocytoma or GBM with poor prognosis. Aggressive enhancing mass, often extends intracranially to involve the optic chiasm. May involve any part of optic tract, including the optic radiations.

Answer 505

2nd MC optic nerve-sheath tumor- arising from arachnoid cells within the leptomeninges surrounding the optic nerve Middle aged female with slowly progressive visual impairment, classically with preservation of the central visual field. Nerve-sheath tends to be circumferentially thickened, with uniform contrast enhancement. The enhancing peripheral tumor and the nonenhancing, central optic nerve produce the tram-track sign on axial image.

Answer 506

Optic nerve meningioma

Answer 507

Middle aged female with slowly progressive visual impairment, classically with preservation of the central visual field.

Answer 508

Nerve-sheath tends to be circumferentially thickened, with uniform contrast enhancement. The enhancing peripheral tumor and the nonenhancing, central optic nerve produce the tram-track sign on axial image.

Answer 509

``` MS (MC) Viral infection Sarcoidosis Vasculitis Toxin exposure ```

Answer 510

Devic Syndrome

Answer 511

MC primary malignant tumor of the globe Almost always seen in children under 5 and typically presents with leukocoria (white pupillary reflex) Hyperattenuating, enhancing retinal mass with calcification, in normal-sized globe. "Trilateral" retinoblastoma = bilateral retinoblastoma with pineal-gland pineoblastoma "Quadrilateral" retinoblastoma = bilateral retinoblastoma, pineoblastoma, and suprasellar retinoblastoma

Answer 512

Retinoblastoma

Answer 513

Almost always seen in children under 5 and typically presents with leukocoria (white pupillary reflex)

Answer 514

Hyperattenuating, enhancing retinal mass with calcification, in normal-sized globe.

Answer 515

bilateral retinoblastoma with pineal-gland pineoblastoma

Answer 516

bilateral retinoblastoma, pineoblastoma, and suprasellar retinoblastoma

Answer 517

Vascular disease of the retina that affects boys and features lipoproteinaceous subretinal exudates that lead to retinal detachment. Slightly older than those affected by retinoblastoma Globe is normal in size, but features subretinal soft tissue that does not enhance.

Answer 518

Coat Disease

Answer 519

Coat Disease

Answer 520

Seen only premature infants and due to prolonged oxygen therapy. Abnormal vascular development, hemorrhage, and retinal detachment. Both eyes tend to be affected equally. Bilateral microthalmia (small globes), with increased attenuation of the globes due to prior hemorrhage. Intraocular calcifications may be present (similar to retinoblastoma), but distinguished by microphthamia End-stage is phthisis bulbi - shrunken, nonfunctioning globe.

Answer 521

Prolonged oxygen therapy. Abnormal vascular development, hemorrhage, and retinal detachment.

Answer 522

Bilateral microthalmia (small globes), with increased attenuation of the globes due to prior hemorrhage. Intraocular calcifications may be present (similar to retinoblastoma), but distinguished by microphthalmia End-stage is phthisis bulbi - shrunken, nonfunctioning globe.

Answer 523

Retinopathy of prematurity and Retinoblastoma ROP has microphthalmia

Answer 524

Persistent embryonic vasculature w/in the vitreous that leads to loss of vision from hemorrhage, cataracts, and retinal detachment. Affected infants are typically full term. Eye is small (microphthalmia) with increased attenuation of the vitreous Distinguished from retinoblastoma and ROP by absence of calcifications

Answer 525

Persistent Hyperplastic Primary Vitreous (PHPV)

Answer 526

Eye is small (microphthalmia) with increased attenuation of the vitreous Distinguished from retinoblastoma and ROP by absence of calcifications

Answer 527

Calcifications = Retinoblastoma and Retinopathy of prematurity - ROP = small globe Small globe = Retinopathy of Prematurity and Persistent Hyperplastic Primary Vitreous - PHPV = no calcifications

Answer 528

Incomplete fusion of the embryonic introcular fissure, which can result in an elongated or malformed globe. Associated with numerous syndromes - trisomies 13 and 18, and CHARGE and VATER associations Cone-shaped or notch-shaped deformity. Optic nerve colobomas can have outpouchings posteriorly, while iris colobomas are anterior. Colobomas that involve the uvea tend to have microphthalmos and a cyst.

Answer 529

Numerous syndromes - trisomies 13 and 18, and CHARGE and VATER associations

Answer 530

Coloboma Optic nerve colobomas can have outpouchings posteriorly, while iris colobomas are anterior. Colobomas that involve the uvea tend to have microphthalmos and a cyst.

Answer 531

NF 1 Transmission of CSF pulsation through the sphenoid wing defect may classically produce pulsatile exophthalmos.

Answer 532

Optic nerve hypoplasia and agenesis of the septum pellucidum. Often associated with schizencephaly, a full-thickness cleft in the cerebral hemisphere that creates a communication between the ventricles and the extra-axial subarachnoid space.

Answer 533

Septo-optic dysplasia

Answer 534

Schizencephaly, a full-thickness cleft in the cerebral hemisphere that creates a communication between the ventricles and the extra-axial subarachnoid space. Optic nerve hypoplasia and agenesis of the septum pellucidum.

Answer 535

Nasopharynx - Top of the pharynx behind the nasal cavity Oropharynx - From level of the palate to the hyoid bone, behind the oral cavity. The posterior 1/3 of the tongue is part of the oropharynx Oral Cavity - Space defined by the anterior 2/3 of the tongue, bounded superiorly by the palate and inferiorly by the floor of the mouth Hypopharynx - From the hyoid bone to the esophagus (posterior) Larynx - From the hydoid bone to the trachea (anterior)

Answer 536

Top of the pharynx behind the nasal cavity

Answer 537

From level of the palate to the hyoid bone, behind the oral cavity. The posterior 1/3 of the tongue is part of the oropharynx

Answer 538

Space defined by the anterior 2/3 of the tongue, bounded superiorly by the palate and inferiorly by the floor of the mouth

Answer 539

From the hyoid bone to the esophagus (posterior)

Answer 540

From the hydoid bone to the trachea (anterior)

Answer 541

Located directly anterior to the parotid and contains the muscles of mastication, the mandible, and cranial nerve V3. CN V3 (manidbular division) exits the skull through foramen ovale and innervates the muscles of mastication. If lesion is seen in masticator space, need to check for perineural spread along V3.

Answer 542

CN V3 (manidbular division) exits the skull through foramen ovale and innervates the muscles of mastication. If lesion is seen in masticator space, need to check for perineural spread along V3.

Answer 543

Odontogenic Abscess - dental disease is MC masticator space pathology, which can lead to abscess Mandibular Lesion - Osteosarcoma and metastasis are the two MC malignant mandibular lesions. Rhabdomyosarcoma - MC head and neck tumor of childhood.

Answer 544

Osteosarcoma and metastasis

Answer 545

Rhabdomyosarcoma

Answer 546

AKA post-styloid parapharyngeal space. Incomplete fascial ring surrounding the carotid artery and jugular vein. Extends from the skull base to the aortic arch Contents: carotid artery, carotid body, jugular vein, and several cranial nerves. Vagus nerve (CN X) is the only CN that remains w/in the carotid space the entire way into the thorax. CN IX, XI, and XII pass transiently through the carotid space. Lymph nodes are seen surrounding it, but not contained within it.

Answer 547

Carotid artery, carotid body, jugular vein, and several cranial nerves. Vagus nerve (CN X) is the only CN that remains w/in the carotid space the entire way into the thorax. CN IX, XI, and XII pass transiently through the carotid space. Lymph nodes are seen surrounding it, but not contained within it.

Answer 548

Paraganglioma - benign highly vascular neoplasm of neural crest cells - intense enhancement and a characteristic salt and pepper appearance on MRI due to intra-tumoral flow voids. Paraganglioma of the carotid body (carotid body tumor) splays the external and internal carotid arteries at the carotid bifurcation Paraganglioma of the vagal nerve (glomus vagale) displaces the internal and external carotid aarteries anteromedially. Schwannoma - Similar to glomus vagale, schwannoma (MC of the vagus nerve) also displaces the carotid arteries anteromedially. Schwannoma, however, is not nearly as vascular as paraganglioma and usually does not enhance as homogeneously. Neurofibroma - Almost always associated with NF1. Neurofibroma and schwannoma are indistinguishable by MRI.

Answer 549

Paraganglioma - benign highly vascular neoplasm of neural crest cells - intense enhancement and a characteristic salt and pepper appearance on MRI due to intra-tumoral flow voids. Paraganglioma of the carotid body (carotid body tumor) splays the external and internal carotid arteries at the carotid bifurcation Paraganglioma of the vagal nerve (glomus vagale) displaces the internal and external carotid aarteries anteromedially.

Answer 550

Paraganglioma of the carotid body (carotid body tumor) splays the external and internal carotid arteries at the carotid bifurcation Paraganglioma of the vagal nerve (glomus vagale) displaces the internal and external carotid aarteries anteromedially.

Answer 551

Triangular fat-filled space with no significant contents aside from occasional ectopic minor salivary gland tissue. Direction of displacement by a mass lesion in an adjacent compartment is predictable and helpful in determining from which compartment a given mass originates. Masticator space lesions (e.g. masticator abscess) displaces the PPS posteromedially. Parotid lesions (e.g. pleomorphic adenoma) displace the PPS anteromedially. Carotid space lesions (e.g. paraganglioma) displace the PPS anteriorly.

Answer 552

Formed by the deep layer of cervical fascia, which wraps entirely around the prevertebral and paraspinal muscles. Is the anterior component of the perivertebral space. The perivertebral space is in the suprahyoid neck; the paravertebral space is the analgous region in the thoracolumbar spine. Contents include the vertebral arteries, paraspinal muscles, spinal column, and exiting nerves.

Answer 553

Vertebral arteries, paraspinal muscles, spinal column, and exiting nerves

Answer 554

Submental and submandibular nodes, which are superior to the hyoid bone and inferior to the mandible and mylohyoid. * IA nodes are submental, lying between the medial margins of the anterior bellies of the digastrics. * IB nodes are submandibular, lateral to the medial margin of the anterior belly of the digastric and extending to the posterior margin of the submandibular gland.

Answer 555

Submental, lying between the medial margins of the anterior bellies of the digastrics.

Answer 556

Submandibular, lateral to the medial margin of the anterior belly of the digastric and extending to the posterior margin of the submandibular gland.

Answer 557

Upper internal jugular nodes, extending from the skull base to the inferior margin of the hyoid bone. * IIA nodes are anterior to the posterior margin of the internal jugular vein (IJV). * IIB nodes are posterior to the IJV but anterior to the posterior margin of the sternocleidomastoid muscle.

Answer 558

IIA nodes are anterior to the posterior margin of the internal jugular vein (IJV).

Answer 559

IIB nodes are posterior to the IJV but anterior to the posterior margin of the sternocleidomastoid muscle.

Answer 560

Level III lymph nodes are middle jugular nodes, extending craniocaudally from the inferior aspect of the hyoid to the inferior aspect of the cricoid cartilage. The posterior edge of the sternocleidomastoid is the shared posterior margin for both level III and level IIB nodes.

Answer 561

Posterior edge of the sternocleidomastoid

Answer 562

Level IV nodes are inferior jugular nodes, extending from the inferior aspect of the cricoid cartilage to the clavicle. Superiorly, the posterior border is the posterior aspect of the sternocleidomastoid muscle (similar to level III and IIB nodes). Inferiorly, the posterior border is the posterior aspect of the anterior scalene muscle.

Answer 563

Level V lymph nodes are posterior cervical nodes. * VA nodes are superior, extending from the skull base to the inferior cricoid cartilage. * VB nodes are inferior, extending from the inferior cricoid cartilage to the clavicle.

Answer 564

VA nodes are superior, extending from the skull base to the inferior cricoid cartilage.

Answer 565

VB nodes are inferior, extending from the inferior cricoid cartilage to the clavicle.

Answer 566

Level VI nodes are pretracheal nodes, which are often simply called “pretracheal.” They are located anteromedially in the lower neck and bounded laterally by the carotid sheaths. Level VI extends craniocaudally from the inferior aspect of the hyoid bone to the top of the manubrium.

Answer 567

Pretracheal

Answer 568

Level VII nodes are superior mediastinal nodes, which are also commonly described by their location. They are inferior to level VI and medial to the carotid sheaths, extending craniocaudally from the superior aspect of the manubrium to the brachiocephalic vein.

Answer 569

Intramedullary Intradural Extramedullary Extradural

Answer 570

ependymoma astrocytoma hemangioblastoma demyelinating lesion

Answer 571

``` schwannoma neurobroma meningioma myxopapillary ependymoma epidermoid/dermoid arachnoiditis ```

Answer 572

``` degenerative disease vertebral neoplasm epidural metastasis hemangioma epidural lipomatosis ```

Answer 573

Astrocytoma and Ependymoma Astrocytoma - more common in children Ependymoma - more common in adults

Answer 574

Astrocytoma is the most common intramedullary tumor in children. Most spinal astrocytomas are low grade. Usually extends over several vertebral levels and causes fusiform dilation of the spinal cord. Cystic components are seen in approximately 1/3 and a syrinx may be present. Tumors almost always enhance despite being low grade. In contrast to ependymoma, hemorrhage is rare. Astrocytoma cannot be reliably differentiated from ependymoma based on imaging features. Hemorrhage is more commonly seen with ependymoma and may occasionally be a helpful discriminating feature.

Answer 575

Hemorrhage more common with ependymoma.

Answer 576

Ependymoma is the most common intramedullary tumor in adults, arising from ependymal cells that line the central spinal canal. Ependymoma is associated with neurofibromatosis type 2, especially when seen in children. Often hemorrhagic, leading to a heterogeneous MRI appearance. Peripheral hemosiderin deposition causes a dark rim on T2-weighted images. Most ependymomas enhance. Classically, there is extensive formation of both tumoral cysts and nontumoral polar cysts. Tumoral cysts are surrounded by enhancement and must be resected with the mass. A classic radiographic finding of ependymoma is scalloping of the vertebral bodies; however, that finding is associated with advanced disease and is rarely seen today.

Answer 577

Rare intramedullary tumor (distant third most common behind astrocytoma) associated with von Hippel–Lindau (VHL). One third of hemangioblastomas are associated with this syndrome. Marked enhancement, cyst formation, and numerous flow voids. Up to 15% have both intramedullary and intradural–extramedullary components.

Answer 578

VHL. 1/3 of hemangioblastomas are associated with VHL.

Answer 579

Located within the dura but outside the spinal cord. Most of the time, intradural–extramedullary lesions are located in the subarachnoid space. A cleft of CSF can sometimes be seen between the lesion and the spinal cord. Nerve-sheath tumors (neurofibromas and schwannomas) and meningiomas together make up 90%

Answer 580

Encapsulated - can be treated by a nerve-sparing approach, which is accomplished by "shelling out" the tumor. Neurofibroma is associated with NF1, younger patients and lacks a capsule. The complete circumference of the nerve is involved and treatment therefore necessitates nerve resection.

Answer 581

Lacks a capsule. The complete circumference of the nerve is involved and treatment therefore necessitates nerve resection.

Answer 582

Target Sign - Central hypointensity on T2 surrounded by a hyperintense periphery, suggests benignity.

Answer 583

An ependymoma variant that occurs exclusively within the conus medullaris or the filum terminale. It is the most common tumor of the conus and filum and arises from ependymal cells in the filum. Characterized by slow growth, classically leading to vertebral scalloping and spinal canal enlargement. Highly vascular, hemorrhagic tumor, featuring a complex, lobulated MRI appearance with internal hemorrhage. Peripheral hemosiderin is often present, producing hypointensity on T2-weighted images and blooming on GRE.

Answer 584

Myxopapillary Ependymoma

Answer 585

Highly vascular, hemorrhagic tumor, featuring a complex, lobulated MRI appearance with internal hemorrhage. Peripheral hemosiderin is often present, producing hypointensity on T2-weighted images and blooming on GRE.

Answer 586

inflammation of the arachnoid surrounding the nerve roots, which produces a fibrinous exudate and secondary dural adhesions. In the past, tuberculosis and syphilis were common causes of arachnoiditis. Today, lumbar spine surgery is a far more common cause. Arachnoiditis may be a cause of persistent back pain after lumbar surgery.

Answer 587

Group 1: Central conglomerations of nerve roots within the thecal sac. Group 2: Peripheral clumping of nerve roots, causing the empty thecal sacsign. Group 3: Obliteration of the subarachnoid space. Imaging shows increased soft tissue within the thecal sac. This is the most severe form of arachnoiditis.

Answer 588

Breast, lung, and prostate Marrow should always be more hyperintense on T1-weighted images than the intervertebral discs. Focal decrease in intensity on T1-weighted images is concerning for metastasis Diffuse decrease in intensity on T1-weighted images is abnormal but nonspecific. The differential for diffusely decreased T1 marrow signal includes leukemia, lymphoma, myelofibrosis, HIV, and idiopathic causes.

Answer 589

Metastases

Answer 590

Abnormal but nonspecific. Leukemia, lymphoma, myelofibrosis, HIV, and idiopathic causes

Answer 591

Hyperintense on both T1- and T2-weighted images

Answer 592

Chordoma - Malignant tumor of older adults that arises from a notochord remnant. Occurs most commonly in the sacrococcygeal region and second most commonly in the clivus. Up to 15% may occur in the vertebral bodies. Appears as a destructive, hyperintense mass on T2-weighted images. It avidly enhances. Plasmacytoma - Lytic, expansile bony lesion of late adulthood that is thought to be a precursor of multiple myeloma. A plasmacytoma is a solitary lesion. The presence of multiple plasmacytomas implies the diagnosis of multiple myeloma. Chondrosarcoma - low-grade malignancy that appears as a hyperintense mass on T2-weighted images, similar to chordoma. Chondroid rings-and-arcscalcification may be seen

Answer 593

Malignant tumor of older adults that arises from a notochord remnant. Occurs most commonly in the sacrococcygeal region and second most commonly in the clivus. Up to 15% may occur in the vertebral bodies. Appears as a destructive, hyperintense mass on T2-weighted images. It avidly enhances.

Answer 594

Protrusion - focal herniation where the diameter of the neck is greater than the diameter of the dome. Extrusion - Focal herniation where the diameter of the neck is less than the diameter of the dome.

Answer 595

Central Paracentral (adjacent to the subarticular facet joint) Foraminal Far-lateral (extra-foraminal) Medial hernation (central or paracentral) will affect the descending nerve root corresponding to the level below the disc. A lateral herniation (foraminal or far-lateral) will affect the exiting nerve root.

Answer 596

Descending nerve root corresponding to the level below the disc.

Answer 597

The exiting nerve root.

Answer 598

Degenerative changes in the spine are associated with vertebral body endplate and subchondral marrow signal changes that were described and classified by Modic

Answer 599

Hyperintense on T2-weighted images and hypointense on T1-weighted images, reflecting bone marrow edema and inflammation. These changes may be associated with active back pain and their presence predicts a better outcome following lumbar spine surgery.

Answer 600

Hyperintense on both T2- and T1-weighted images and reflect fatty proliferation within the affected marrow, thought to be secondary to chronic marrow ischemia. Modic 2 changes are less likely to be associated with active symptoms.

Answer 601

Hypointense on both T2- and T1-weighted images and are thought to represent sclerosis. Their clinical significance is unclear.

Answer 602

Perineural cyst of the sacrum, formed within the nerve root sheath, usually asymptomatic. Not associated with facet arthropathy, in contrast to a synovial cyst.

Answer 603

Distinguish between recurrent disc disease and scar tissue. Both disc and scar appear hypointense on T2-weighted MRI. In theory, scar tissue should enhance throughout, while recurrent disc demonstrates only peripheral enhancement. If there is recurrent disc herniation, further surgical intervention may be indicated. In general, however, the presence of scar tissue would decrease the chance of successful relief of symptoms.

Answer 604

Typically from a hematogenous source. Staphylococcus aureus is the most common agent. In adults, the vascularized subchondral bone is the initial site of infection, which spreads to the disc. In children, however, the intervertebral disc is initially infected, with subsequent spread to the vertebral endplates.

Answer 605

The key imaging appearance of discitis/osteomyelitis is marrow hypointensity on T1-weighted images centered on both sides of an abnormal intervertebral disc that is hyperintense on T2-weighted images. Loss of adjacent endplate definition is usually present. On radiography, the only initial clue may be loss of disc space height. Later in the course of infection, there may be vertebral collapse. Adjacent soft tissue infection (paraspinal or epidural) is often present

Answer 606

Also called Pott disease, tuberculous osteomyelitis represents infection of the vertebral body with Mycobacterium tuberculosis. Unlike pyogenic discitis/osteomyelitis, the discs are usually spared as M. tuberculosislacks the proteolytic enzymes necessary to break down the disc substance. Classically causes wedge-shaped compression of the anterior aspect of the vertebral body, often leading to a gibbus deformity centered at the infected vertebra. Gibbus deformity is an acutely angled kyphosis. Gibbus deformity may result from a vertebral compression fracture or can be seen in congenital syndromes including achondroplasia and the mucopolysaccharidoses (Hunter and Hurler syndromes)

Answer 607

Unlike pyogenic discitis/osteomyelitis, the discs are usually spared as M. tuberculosislacks the proteolytic enzymes necessary to break down the disc substance.

Answer 608

Classically causes wedge-shaped compression of the anterior aspect of the vertebral body, often leading to a gibbus deformity centered at the infected vertebra. Gibbus deformity is an acutely angled kyphosis. Gibbus deformity may result from a vertebral compression fracture or can be seen in congenital syndromes including achondroplasia and the mucopolysaccharidoses (Hunter and Hurler syndromes)

Answer 609

Gibbus deformity is an acutely angled kyphosis. Gibbus deformity may result from a vertebral compression fracture (can be seen with Tuberculous osteomyelitis) or can be seen in congenital syndromes including achondroplasia and the mucopolysaccharidoses (Hunter and Hurler syndromes)

Answer 610

Dural arteriovenous fistula (dAVF)

Answer 611

MRI of dAVF shows flow voids surrounding the cord. The cord is often swollen, with abnormal intramedullary T2 prolongation. CT myelography shows serpiginous filling defects in the subarachnoid space.

Answer 612

Most common in the upper thoracic or thoracolumbar spine due to more precarious blood supply. The predominant blood supply to the distal cord is the artery of Adamkiewicz.

Answer 613

Imaging of spinal cord infarction shows hyperintensity of the affected cord regions on T2-weighted images. The cord may be enlarged. Diffusion images typically show restricted diffusion. Concomitant vertebral body infarction may be present, which is more common in sickle cell disease and chronic steroid use.

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