Dural metasases
Breast
Prostate
Lung
H+N cancer
Pachymeningeal enahcnement
- Infection – skull base osteomyelitis, paranasal sinuses.
- Tumour – meningioma (dural tail); metastasis (especially breast);
lymphoma. - Postoperative.
- Following LP
- IIH – also often subdural effusions, dural
sinus engorgement and brainstem descent. - Venous thrombosis.
- Neurosarcoid
Leptomeningeal enhancement
- Infection –
- Tumour – metastases, leukaemia, lymphoma, meningeal seeding
of primary brain tumours, LCH - Infarcts – surface enhancement often seen.
- SAH
- Sarcoidosis.
- Rheumatoid arthritis.
- Neurocutaneous syndromes, especially Sturge–Weber.
Wenickes encephalopathy
Increased FLAIR/ DWI
Medial thalami, mamillary bodies, hypothalamus, periaqueductal grey matter
Causes- alcohol/ fasting/ post gastrectomy
Hepatic encephaloathy
Acute- High FLAIR/ DWI
Insula/ thalamus/ posterior limb/ internal capsule/ cingulate gyrus (high ammonia)
Chronic- High T1 GP (manganese)
Uraemic encephaloapthy
- High T2/ FLAIR basal ganglia
- Lentiform nucleus sign > hyperintense external and internal capsule
HIE
High FLAIR/ DWI grey matter
Cerebral cortex, hippocampi, BG
Ethanol poisoning
Hemorrhage in putamen
INCREASED RESTRICTED DIFFUSION (ACUTE) +/- ENHANCEMENT
CO poisoning
- Bilateral necrosis GP
Increased FLAIR, decreased rim
Osmotic demyelination
high T2 pons
causes: rapid electrolye correction, chronic alcohol use, transplant patients
Toxo vs lymhpoma
MR DWI: Lymphoma tends to restrict diffusion more
MR perfusion: Lymphoma has higher rCBV
MR spectroscopy: Lymphoma shows elevated choline
FDG PET: Lymphoma has higher glucose metabolism
Thallium SPECT: Lymphoma more avidly takes up thallium
Primary vs secondary lymphoma
primary- homongenously enhances
secondary- ring enhancement
HIV encephalitis
Atrophy
High T2 periventricular and deep white matter.
Spares the subcortical U-fibers and tends to be symmetric.
CMV encephalitis
CD4<50
subependymal high FLAIR + enhancement throughout the ventricular system
Cryptococcus
AIDS, CD4 <100
spreads along basal ganglia perivascular spaces> behind gelatinous pseudocysts,
choroid plexus> ring-enhancing granulomas within the ventricles.
Toxo
Commonest atypical infection in AIDS
(CD4<100)
Single/ multiple ring enhancing lesion
Less cellular than lymphoma (less restricted diffusion)
basal ganglia, thalami, corticomedullary junction
NO THALLIUM UPTAKE
Neuromyelitis optica spectrum disorder
- Optic nerve myelitis (extends back to chiasm)
- White matter lesions (subependymal, around ventricles, smooth)
- Transverse myelitis (central cord, > 3 vertebral bodies)
- AQP4-IgG-positive
ADEM
- Young adults
- Subcortical high T2
- Involves grey matter/ thalami / brainstem
- open ring of enahncement
> Hurst variant- acute hemorrhagic
MS
LOCATION:
Brain: periventricular white matter, spinal cord, infratentorial brain, juxtacortical white matter or cerebral cortex
Spinal cord- < 3 VB, peripheral
MRI: Callososepal interface, thinned corpus callosum
T1 black holes
Dawson fingers
Open ring enhancement
Ependymal dot dash sign (FLAIR)
PML
Risk factors- malignancy, status post-organ transplant, autoimmune disorders
ASYMMETRIC white matter lesions
Involves subcortical U fibres (frontal + parieto occipital)
No enhancement/ mass effect
Peripheral patchy restricted diffusion
Diagnosis: PCR for JC virus DNA from CSF
HIV encephalitis
Diffuse bilateral involvement- SYMMETRIC
Sparing of subcortical white matter
cerebral atrophy
Spares subcortical white matter + posterior fossa structures
No enhancement
CADASIL
ANTERIOR DISTRIBUTION
Involves deep white matter
Anterior temporal lobe + external capsule
Can involve basal ganglia, thalamus, pons
MELAS
KIDS
- multiple infarcts, multiple vascular territories
- symmetrical or asymmetrical
- parieto-occipital and parieto-temporal
- basal ganglia calcification
Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS)
GIST
FDG Avid
Central necrosis
Large round/ lobulated
Big extraluminal component
Does not cause obstruction
cAN CAUSE ULCERATION
NO CALC
Small lesions- strong arterial enhancement
Low T1/ High T2
ddx- gastric leiomyoma
