3) CNS disorders, brain infection, tumours Flashcards Preview

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Flashcards in 3) CNS disorders, brain infection, tumours Deck (11):

Pyogenic meningitis (CT, MRI)

- Bacterial infectious infiltration of meninges
- CT: usually normal in uncomplicated PM, but CT is useful for detecting complications such as hydrocephalus
- MRI: High SI, meningeal enhancement in C+


Tuberculous meningitis (CT, MRI)

- CNS involvement is seen in 5% of TB cases
- CT: obliteration of basal cisterns by isodense or slightly hyperdense exudates. Multiple "ring" like appearance. Sometimes hydrocephalus
- MRI: more sensitive than CT for above signs


Tuberculous granuloma/tuberculoma (CT, T1, T2, T1+con)

- Benign tumour
- CT: small rounded lesion which are isodense or hyperdense to brain, variable surrounding oedema, homogeneous enhancement in solid lesions, rim enhancement in lesions w/ central caseation or liquefaction
- MRI: Ring enhancement seen w/ caseation
T1) low SI
T2) high SI, low SI with caseation
T1+gad) solid lesions have homogeneous enhancement


Herpes encephalitis (CT, T2)

- Viral infection of brain tissue (usually glial cells)
- drowsiness, fever, chills, vomiting
- CT: normal in first 3-5 days, followed by low attenuation in ateromedial lobe
- MRI: T2) high SI w/ in the anteromedial lobe in first 2 days of onset


Brain abscess (CT, T1, T2)

- Encapsulated accumulation of puss within brain resulting from cranial infection, penetrating head wound or infection spreading through blood stream
- fever, headache, nausea, vomiting
Radiological features
- usually subcortical or periventricular
- Rim enhancing mass is non-specific finding
- CT: Central low attenuation puss. Following contrast, rim enhancement corresponds to abscess capsule
- T1: hypointense mass with isointense capsule (hyperintense capsule with contrast)
- T2: Hyperintensity in mass and surrounding oedema


Multiple sclerosis (T1, T2, T1+con)

Radiological features
- MS lesions are located in subependymal periventricular white matter, typically ovoid lesions
- Dawson fingers are radiographic feature depicting demyelinating plaques
- MRI:
T1) isointense or hypointense plaque
T2) Hyperintense signal plaques
T1 + con) solid or ring enhancement of acute lesions


Alzheimers disease (CT, MRI, T2)

CT: usually normal, sometimes cerebral atrophy and ventricular enlargement
MRI: similar to CT. Periventricular high intensity on T2


Tumour classification

Intra-axial tumours
- tumours arising from within the brain parenchyma
- glioma: broad category which includes tumours that arise from astrocytes, oligodendrocytes, ependymal cells, mostly malignant

Extra-axial tumours
- Tumours arising from tissues covering brain
- more frequent in adults than children
- Meningioma: usually slow growing and benign


Intra-axial and extra-axial differentiation

Extra-axial tumour
- meningioma often has a bone reaction
- grey/white matter junction preserved

Intra-axial tumour
- Rarely has bony changes
- grey/white matter junction destroyed


Glioma/glioblastoma (T1, T2, CT)

T1) masses of low SI (or isointensity)
T2) masses of high SI
-CT: thick heterogeneous hyperdense margins, hypodense centre


Meningioma (T1 & T2, T1 & T2 w/ con, CT)

T1 & T2) isointense
T1 & T2 + con) hyperintense
- CT: rounded, well circumscribed, hyperdense