Neuroradiology: Head and Brain Imagin

Question 1

lacunar infarct (lacune)

Answer 1

• small cerebral infarcts.
• areas of hypoattenuation (low density), favors basal ganglia, pons, internal capsule
• common with HTN, atherosclerosis, DM

Question 2

epidural hematoma

Answer 2

• hemorrhage between the dura and skull table
• lens shape, biconvex
• hyperattenuation
• midline shift common
• skull fractures common
• does not cross suture lines
• ARTERIAL

Question 3

stroke - considerations

Answer 3

• initial study = CT noncon
• is it hemorrhagic or ischemic?
• <6hrs sxs, CT often falsely negative if ischemic
• MRI more sensitive early on if ischemic
• types of CVA: hemorrhagic, ischemic, lacunar infarcts
• if hemorrhagic, keep pt stable and call neurosurgery
• if ischemic, call neurologist and see if we can fix

Question 4

Imaging for a suspected stroke

Answer 4

• if the stroke score is very high, you run noncon CT first and then you push contrast and get CTA (angiogram) of head and neck
• contrast makes everything look white and blood is white - you dont want to confuse ischemic from hemorrhagic - THIS IS WHY YOU GET NONCON FIRST

Question 5

subdural hematoma

Answer 5

• Hemorrhage between dura and anarchnoid
• Bridging vein damage
• Crescent shaped, concave
• Acute: hyperattenuation
• Chronic: less dense, hypoattenuation
• Midline shift common
• Does not cross midline
• May cross suture lines
• VENOUS

Question 6

CT Head/Brain

Answer 6

• axial cuts and bone windows are standard
• pathology: symmetry, densities, lucencies, blood (new, old, hemorrhage), ischemia, infarction, edema, tumors, mets, hydrocephalus, bony windows (skull fractures)
• it is standard and customary to only get axial slices of the brain

Question 7

Special hydrocephalus

Answer 7

• normal pressure hydrocephalus (communicating type) - classic presentation = >50yo, gait disturbance, dementia, urinary incontinence
• dilated ventricles out of proportion to atrophy, sulci normal

-THIS CAN BE FIXED

Question 8

subdural - avute vs. subacute

Answer 8

• acute blood is white
• subacute - after about 1 week - blood is more isodense
• chronic - after about 2 weeks - blood alppears hypodense

Question 9

Approach to head CT interpretation

Answer 9

• check name, date, study, rotation (contrast?)
• check symmetry (midline shift, effacement)
• hyperattenuation (acute bleed, calcifications, FBs)
• hypoattenuation (edema, ischemia, old blood, tumor, air)
• cisterns, CSF spaces
• ventricle size, symmetry
• gyri, sulci symmetric, edema, atrophy
• soft tissue, sinuses, mastoids
• bone windows
• always interpret with attending physician, confirm with radiologist
• Blood Can Be Very Bad (blood, cisterns, brain, ventricles, bone)

Question 10

Cerebral edema

Answer 10

• Effacement of gyri and sulci
• Loss of grey-white differentiation
• Ventricular compression
• Global or local response
• Herniation may result
• Increased intracraininal pressure:
• Headache, vomiting, papilledema, possibly ALOC

-Psuedotumor Cerebri (BIH), trauma, infection, tox, metabolic

Question 11

CT white things with IV contrast

Answer 11

• abnormal = blood, tumor/mass/infection

- normal = vasculature, choroid plexus, pituitary

Question 12

How CTs are taken

Answer 12

• 15-20 degree axial “cuts”
• 3mm-5mm wide
• skull base to vertes
• scout film
• grey matter appears grey
• white matter appears darker

Question 13

Hydrocephalus

Answer 13

-dilated ventricles, temporal horns visible

Obstructive hydrocephalus: 2 types

• communicating - extraventricular cause (decreased reabsorption of CSF, acute/chronic, entire ventricular system, normal pressure hydrocephalus; 4TH VENTRICLE ENLARGED)
• non-communicating - intraventricular cause (obstruction of outflowof CSF - tumor, mass; narrow site - 3rd or 4th ventricle, foramena of monroe, aqueduct sylvius; 4TH VENTRICLE NORMAL SIZED, SULCI NORMAL)

-prominent temporal horns of the lateral ventricles is one of the first signs of hydrocephalus

Question 14

Tumors, masses on CT

Answer 14

• tumors: intraaxial = w/in brain parenchyma (glioma, astrocytoma, etc.), extraaxial = outside of brain itself (meningioma, acoustic neuroma), metastases (round, multiple, enhance w/ contrast)
• masses (parasites, fungal)

Question 15

indications for non-contrast head CT

Answer 15

• head trauma - clinically significant
• suspected acute CVA/TIA, focal neuro deficit
• HA - atypical worst of life
• delirium (if there is an obvious cause, CT may not be needed)
• HA + fever: meningitis/abscess/encephalitis
• seizure - first one
• cancer hx with new HA, ALOC, focal neuro finding
• consider in: vomiting w/o abdominal sxs, suspected child abuse

Question 16

Cytotoxic cerebral edema

Answer 16

• hypoattenuation from encephalomalacia
• cell death after cerebral ischemia (infarct)
• possible midline shift, herniation
• affects both white and grey matter

Question 17

Increased Intracranial Pressure

Answer 17

• Mass effect - midline shift; From blood or space occupying lesion
• Cerebral edema - Increase in brain volume (swelling) (May lose normal definition of gyri/sulci, Infection, reactive, malignancy, toxic, anoxic), Vasogenic, Cytotoxic
• Hydrocephalus - Increase in ventricle size

Question 18

Vasogenic Cerebral edema

Answer 18

• hypoattenuation
• local edema around infection, malignancy
• vasogenic edema around acute hemorrhage
• possible midline shift, herniation
• predominantly affects white matter
• INTRACEREBRAL BLEED, not subdural, epidural, subarachnoid

Question 19

subtle CVA signs

Answer 19

• hyperdense vessel sign
• loss of insular ribbon - grey matter stripe or interface with white matter
• lentiform nucleus and caudate nucleus not distinctly visible
• effacement of sulci
• dont need to recognize on CT, but know the list of signs

Question 20

Plain x-rays - skull

Answer 20

• Rarely obtained - replaced by CT
• AP, Lateral(s), Towne views standard
• Indications: Child abuse survey, Foreign Body, Metastatic or Metabolic bone survey, If CT not available

Question 21

indications for contrast CT

Answer 21

• with IV contrast = “contrast enhanced”
• CVA - non-contrast first in all, then if a significant deficit: CTA (CT angiogram of head and neck, CTA useful for intervention (stent))
• vascular lesions (AVM, aneurysm)
• tumors
• brain abscess, encephalitis
• MRI now often utilized in these conditions (except CVA)

Question 22

CT white things without IV contrast

Answer 22

• abnormal = blood (acute), calcified masses (i.e. tumor)

- normal = bone, TYPICAL calcifications (pineal gland, choroid plexus, falx, basal ganglia)

Question 23

hemorrhagic CVA

Answer 23

• acute: hyperattenuation: collections of blood
• favor basal ganglia, thalamus, pons, cerebellum
• local vasogenic edema
• effacement of gyri/sulci and midline shift common
• risks: HTN, coagulopathy, stimulants (cocaine, meth)
• less common than ischemic; more morbidity/mortality
• call a neurosurgeon

Question 24

neurocysticercosis

Answer 24

• pork tapework parasite, common in mexico, latin americ

- often asymptomatic, often presents with first seizure

Question 25

how do you know cerebral atrophy is not chronic subdural hemorrhage?

Answer 25

-IT CROSSES THE MIDLINE!!

Question 26

CT dark things

Answer 26

-abnormal = air, edema, ischemia, encephalomalacia

Question 27

Cerebral atrophy

Answer 27

- diffuse prominence of sulci, ventricles - space between edges of brain and skull table - normal CSF production, absorption - incidental finding, chronic, normal changes with aging - dementia (alzheimer's) alcoholism (cerebellar)

Question 28

MRI of the brain

Answer 28

- excellent for CVA, tumor, patchy neuro deficits - more sensitive than CT for cerebellar lesions, central vertigo, multiple sclerosis, diffuse axonal injury, tumors - multi plane projections - you get axial, coronal, sagittal (weighting: T1, T2; contrast = gadolinium) - no ionizing radiation - radiologist reads ALL - VERTIGO = MRI!! looking for MS or tumors

Question 29

Subarachnoid hemorrhage

Answer 29

- Hyperattenuation (non-con CT scan) - Suprasellar cisterns (Circle of Willis) or other basilar cisterns - Sulci white, effacement - “Worst HA of my life” - Aneurysm, AV malform tumors, trauma

Question 30

traumatic intracerebral hematoma, hemorrhage

Answer 30

- Coup, contrecoup (brain rocks back and forth, boxing); bridging veins are at high risk for hemorrhage - Areas of hyperattenuation in brain parynchema - Edema surronding blood common - Shift, intraventricular blood also possible

Question 31

Indications for CT in HA

Answer 31

- Focal neuro findings + HA - ALOC + HA - Fever + HA - Vomiting (atypical) + HA - HA + vomiting after head trauma - Severe, persistent, new HA - Headache in young, obese female with vision changes, n/v: BIH/Pseudotumor - “Worst HA of my life”

Question 32

ischemic CVA

Answer 32

- thromboembolic event - vascular watershed distribution of ischemia - cytotoxic edema - CT often initially negative if <6 hrs sxs - hypoattnuation in 12-24hrs on CT - low attenuation >4wks - big CVA? Get CTA head and neck - call neurologist - if you dont see anything on CT in first 6 hrs, its ischemic!

Question 33

Pterion

Answer 33

- intersection of the frontal, parietal, temporal and sphenoid bones. - thinnest part of the skull - middle meningeal artery courses through this area - trauma here may cause epidural hematoma

Question 34

CT in head trauma, looking for, and indications

Answer 34

- head trauma: CT noncon first, readily available, great for acute intracranial bleeding, great for fractures, pt must be stabilized - looking for: subdural hematoma, epidural hematoma, intracerebral hemorrhage, cerebral contusion - indications: focal neuro finding, GCS <8, loss of consciousness, altered level of consciousness, skull penetration, worsening HA, vomiting after head trauma, post-traumatic seizure, suspected child abuse, coagulopathy + trauma, significant mechanism