Page 16 Flashcards by mkb drs

5 corners of the pentagon of the suprasellar cistern?

interhemispheric fissure - anteriorly 2-3. sylvian cisterns - anterolaterally 4-5. ambient cisterns - posterolaterally

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6th point of the Jewish star or Hindu Shatkona of the supracellar cistern?

interpeduncular fossa

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What does a small lucency frequently seen in the midbrain tegmentum represent?

decussation of the superior cerebellar peduncle

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What is the most posterior projection of the dorsal medulla?

obex

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The cerebellar tonsils should project no more than __ mm below a line drawing between the anterior and posterior lips of the foramen magnum.

5 mm

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Follow-up question: Histologic grade correlates with choline-to-creatine ratio but there are exceptions. What disease should you think of if the choline peak is sky high?

there are exceptions. What disease should you think of if the choline peak is sky high?
meningioma (**also, demyelinating processes can present with elevated choline peaks)

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-marker for cellular turnover?

choline (since it is a marker for cell membranes; it may be considered a tumor marker)

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In what conditions do you see focally decreased NAA?

mesial temporal sclerosis and infarcts

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-marker of neuronal density?

NAA (found only in neurons)

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-marker of anaerobic metabolism?

lactate - ??? di ko alam kung interchangeable iyong lactate at lipid?

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In what conditions do you see global depletion of NAA?

MS and dementia

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Since they tend to infiltrate rather than replace brain, which conditions will have
lower NAA-to-creatine rations compared to primary brain tumors?

abscesses and mets

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-serves as a “reference standard” metabolite since it is evenly distributed in many cell types?

creatine

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NAA (found only in neurons)NAA (found only in neurons)

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-Follow-up question: A characteristic doublet peak of lactic acid can help make the diagnosis of?

ischemia

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Ulrich’s (older) classification of temporal bone fractures according to their orientation to the long axis of the petrous bone:

longitudinal (MC), transverse, mixed

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Which conditions show nonspecific lipid necrosis peak?

malignant tumors, infections, and some ACTIVE DEMYELINATING lesions

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-marker of necrosis?

lipids

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How do you differentiate radiation necrosis from recurrent tumor on MRS?

radiation necrosis - elevated lactate; tumors - elevated choline and depressed NAA (which are not seen in radiation necrosis

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What is the most reliable sign of an extra-axial mass in the posterior fossa?

widening of the ipsilateral subarachnoid space

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Compare the hearing loss seen as a complication in longitudinal and in transverse temporal bone fractures

longitudinal - conductive (sensorineural is uncommon); transverse - sensorineural

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What findings on cranial CT for trauma should raise suspicion for temporal bone
fracture?

Opacification of mastoid air cells, fluid in middle ear cavity, pneumocephalus, pneumolabyrinth

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What are some signs that can point to an isodense subacute SDH (instead of atrophy)?

Sulcal effacement, white matter buckling, thick gray matter mantle, distorted ventricles, midline shift

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How can you differentiate convexal SAH from SDH?

SAH extends into adjacent sulci, may also have sulcal effacement

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What biochemical state of Hb is responsible for the MRI appearance of a subacute hematoma?

methemoglobin (intracellular pag early, extracellular pag subacute)

What artery may be infarcted in tonsillar herniation?

PICA

What is the peak time for hemorrhagic transformation?

1-2 weeks post infarction (same sa gyral enhancement)

What normal variant pertains to one pericallosal branch of ACA supplying both hemispheres?

azygous ACA (occlusion will affect both hemispheres)

Most sensitive places to look for SAH on CT

interpeduncular fossa, posterior Sylvian fissure, far posterior aspects of the occipital horns

What gyrus is displaced in subfalcine herniation?

cingulate gyrus (another term for subfalcine is cingulate herniation)

Le Fort fractures (fractures of the midface):

Le Fort I - floating palate - horizontal fracture through the maxillary sinuses, extending throught the nasal septum and walls of the maxillary sinuses into the inferior aspect of the pterygoid plates Le Fort II - pyramidal - fracture beginning at the bridge of the nose and extending in a pyramidal fashion through the nasal septum, frontal process of the maxillar, medial wall of the orbit, inferior orbital rim, superior, latera and posterior walls of the maxillary antrum, and midportion of the pterygoid plates Le Fort III - craniofacial dysjunction - horizontally oriented fracture through the orbits

What injury demonstrates association of subdural hematomas and retinal hemorrhages in chiildren with metaphyseal long bone fractures?

whiplash skaken injur

When does intravascular enhancement on MR resolve?

10 days

What term represents injury causing coma, subdural hematomas, and primary brain injury in child abuse?

shaken impact injury

When does gyral enhancement resolve?

3 months

Common locations of perivascular spaces

medial temporal lobes, inferior 1/3 of the putamen, thalamus

Rule of 3s regarding MR parenchymal enhancement:

peaks at 3 days to 3 weeks and resolves by 3 months

What size does an intracranial aneurysm pose risk for rupture?

3-5mm

Osborn: What size of saccular aneurysm poses increased risk of rupture?

> or = 5mm

What is the hallmark of uncal herniation?

effacement of the ambient cistern and contralateral hydrocephalus

How far is a significant general midline shift?

3mm or >

What neoplasms that metastasize to the brain often bleed?

bronchogenic, thyroid, melanoma, choriocarcinoma, RCC

pilocytic astrocytoma

Grade I

diffuse astrocytoma (Osborn)

Grade II

oligodendroglioma

Grade II

-subependymal giant cell astrocytoma

Grade I

-fibrillary astrocytoma

Grade II

-pleomorphic xanthoastrocytoma (located along meningocerebral interface)

Grade II

germistocytic astrocytoma and protoplasmic astrocytroma (rare variants of fibrillary)

anaplastic astrocytomas

III

dysembryoplastic neuroepithelial tumor

Grade I

GBM

-ependymoma

Grade II

medulloblastoma

-atypical teratoid/rhabdoid tumor (ATRT)

choroid plexus papilloma

Grade I

subependymoma

Grade I

-choroid plexus ca

III

-central neurocytoma

III (sa Osborn, II)

What are the 2 entities that commonly have bihemispheric spread through the corpus callosum with involvemenet of both frontal lobes?

GBM and CNS lymphoma

-pineoblastoma

Usual hyperdense neoplasms?

lymphoma, pineablastoma, neuroblastoma, medulloblastoma

What are the calcified glial tumors in order of frequency?

oligodendroglioma, ependymoma, astrocytoma, GBM (Old Elephants Age Gracefully)

How can you differentiate medulloblastoma from astrocytoma on noncontrast CT?

astrocytoma - usually hypodense; medulloblastoma - almost never hypodense

Which malignancy is linked with the combination of falcine calcification and medulloblastoma?

nevoid basal cell ca

Which malignancy has a predilection to metastasize to the posterior fossa?

RCC

(Osborn) What syndrome should the patient be evaluated for if dense tentorial or falcine calcifications are present together with medulloblastoma?

basal cell nevus (Gorlin) syndrome

Causative agent of subacute sclerosing panencephalitis (SSPE)?

measles

What is the likely diagnosis if a calcified pineal mass is seen in a female? male?

female - pineocytoma; male - germinoma

What is the size of microadenomas?

1 cm or less

What is the size of a pathologic pineal calcification?

1 cm

What viruses are associated with acute necrotizing encephalitis in children?

Influenza A and B

CD4 count in AIDS patients with toxoplasmosis?

<200

Causative agent of PML?

JC polyomavirus (reactivation)

CD4 count in AIDS patients with progressive multifocal leukoencephalopathy (PML)?

<200

diseases What are the areas of predilection of HSV type 1?

temporal lobes (hippocampus), insular cortex, subfrontal area, and cingulate gyri; spares the putamen

What disease refers to supraclinoid obliterative arteriopathy?

moyamoya disease

Characteristic locations of CSF obstruction in the following neoplasms:

What structure connects the third and fourth ventricles?

cerebral aqueduct

-colloid cyst

anterior third ventricle

-pineal tumors and tectal gliomas

aqueduct

ependymoma and medulloblastoma

fourth

Classic clinical triad of normal pressure hydroceph?

dementia, gait disturbance, urinary incontinence

What toxin may result in signal abnormalities in the globus pallidus?

What toxin may result in signal abnormalities in the putamen?

methanol

Radiation leukoencephalitis usually follows a cumulative dose in excess of __ Gy delivered to the brain and occurs 6 to 9 months after treatment.

What age does T1 demonstrate an adult pattern?

8 mos (so sa 1st yr of life, best ang T1 for evaluating myelination)

What age is the adult gyral pattern established?

38 weeks

corpus callosum anatomy and development

1) rostrum, 2) genu, 3) body, and 4) splenium (development: 2->4 and then 1)

What age does T2 demonstrate an adult pattern?

18 mos (8-18 mos, most useful ang T2 for myelination)

What conditions do typically cause hemorrhages at gray-white matter interface?

mets, septic emboli, and fungal

T1 myelination milestones

3 months anterior limb of the internal capsule 4 months splenium 6 months genu

Most severe malformation resulting from an arrest of neuronal migration

lissencephalies

Which lobes are usually most severely affected in type 1 classic licencephalies/agyria-pachygyria complex?

parieto-occipital lobes

What has probably the highest rate of infiltration of the meninges among the non-CNS tumors?

leukemia

What size should a saccular aneurysm be for it to be called a giant aneurysm

2.5 cm or > (sa table 2 cm)

Direction of vermian development?

from top to bottom (so pag hypogenetic iyong vermis, may mga kulang na folia sa inferior vermis)

What intracranial hemorrhage is a common association with intracranial hypotension?

subdural hematoma

How many components do the the circle of Willis have?

What artifact is the major imaging mimic of classic superficial siderosis?

bounce point artifact

What Zabramski type is the classic CCM appearing as a popcorn ball?

Zabramski type II (pag multiple microhemorrhages iyong appearance, type IV)

What is the size of a giant cerebral cavernous malformation (CCM)?

>6 cm

What is the only CN that lies inside the cavernous sinus itself?

abducens (CN VI)

2010 McDonald criteria for MS:

Dissemination in space - >or= 1 T2 hyperiontense lesion(s) in at least 2 of these 4 areas (periventricular, juxtacortical, infratentorial, spinal cord Dissemination in time - new lesion on follow-up; or simultaneous presence of asymptomatic enhancing and non-enhancing lesions at any time

In MS lesions especially large tumefactive lesions, where does the "open" nonenhancing segment of the horseshoe enhancement face?

face the cortex

Page 16 Flashcards

(108 cards)