Intracranial infection

Question 1

Imaging appearance of cerebral abscess

Answer 1

Cerebritis - inc T2/FLAIR signal
Abscess - ring enhancing, central diffusion restriction, can cause ventriculitis if ruptures
Satellite lesions also more suggestive of infection

Question 2

Neuro lyme disease imaging findings

Answer 2

Subcortical and periventricular foci of high T2 signal

CRANIAL NERVE ENHANCEMENT

Question 3

Imaging findings in cryptococcocus

Answer 3

Most common fungal infection in AIDS
Spreads along basal ganglia perivascular spaces - gelatinous pseudocyst formation
Cryptococcomas - immune competent patients
Basal meningitis**

Question 4

Imaging findings neurocysticercosis

Answer 4

Most common parasitic CNS infection affecting IMMUNOCOMPETENT patients (pig parasite)

Varied appearances, depending on stage of disease, including: vesicles (tiny cysts), colloidal (ring enhancing with ++edema), granular (involuting cysts), calcified (small parenchymal calcifications)
May have intraventricular involvement in 20% of cases or racemose form which looks like bunch of grapes in basal brain (similar to gelatinous pseudocysts)

Question 5

Imaging findings toxoplasmosis

Answer 5

Most common opportunistic CNS infection in AIDS

Ring enhancing lesions with ++edema (eccentric nodule)
NB: may not diffusion restrict due to necrotic centre compared to pyogenic abscess, COLD thallium (versus lymphoma which is hot)

Pediatric: scattered periventricular/BG calcs, profound hydro, chorioretinitis

Question 6

Imaging findings HSV

Answer 6

HSV 1 - adults - limbic system, mesial temporal lobes, diffusion restriction (first finding), high T2 signal
DDx: limbic encephalitis, post-ictal, infarct, low grade astrocytoma

HSV 2 - children - hemorrhagic infarcts, more diffuse involvement (cerebral cortex, deep white matter, thalamus)

Question 7

Imaging findings HIV encephalopathy

Answer 7

Diffuse atrophy
Symmetric T2 inc signal in periventricular and deep WM
Spares subcortical U fibres (differentiating feature with PML)

Question 8

Imaging findings CMV

Answer 8

Most common TORCH infx in neonates (#2 = toxo)
Periventricular calcs, cortical malformations** (polymicrogyria), hydrocephalus, small cerebellum, temporal lobe cysts

Adults: immunocompromised - ventriculitis (enhancement), periventricular T2/FLAIR abnormality

Question 9

Imaging findings CJD

Answer 9

Progressive atrophy + dementia
Cortical ribboning!! (on DWI)
Basal ganglia and thalamic involvement (Pulvinar & hockey stick sign)

Question 10

Imaging findings PML

Answer 10

JC virus
Asymmetric T2 white matter signal, low T1, INVOLVES subcortical U fibres, often parieto-occipital, enhances in certain scenarios - HAART, IRIS

**lack of significant mass effect, does not enhance

Question 11

Imaging findings TB meningitis

Answer 11

Basal meningitis (basal enhancement) + hydrocephalus

Question 12

Cause of limbic encephalitis

Answer 12

Lung ca

Question 13

Meningitis complications (6)

Answer 13

Abscess
Ventriculitis
Empyema
Venous thrombosis
Vasospasm
Hydrocephalus 
(sterile subdural in kids)