Neuroradiology Part II Flashcards
What are the most common areas in the cortex and cerebellum for parenchymal hemorrhage secondary to hypertension?
Basal ganglia, thalamus, dentate nucleus of cerebellum (distal branches of SCA and PICA)
What are the most common sites for contusions?
Inferior frontal lobes
Anterior temporal lobes
Where does axonal injury during shearing usually occur?
Gray-white junctions of cortex, corpus callosum (splenium and body), dorsal brainstem
How can a small intraparenchymal cortical hemorrhage be differentiated from a subarachnoid hemorrhage?
Intraparenchymal hemorrhages are usually surrounded by a small mount of vasogenic edema in the brain
Subarachnoid hemorrhages are not actually in the brain but are around it, and the areas of enhancement in the CT will be in the sulci and cisterns
What does dense artery sign + loss of gray/white distinction + gyral swelling and sulcal effacement mean and what do these indicate when taken together?
Dense artery sign - intraluminal thrombus -> area enhances on CT due to thrombous
Gray-weight distinction loss -> increased water content of cortex making it more hypodense -> seen in first few hours of infarct
Gyral swelling / sulcal effacement - late manifestations of acute infarct (12-24 hours) from brain swelling
What is the hallmark of acute infarct diagnosis? When can this be seen radiologically?
Restricted diffusion -> water normally diffuses freely in equilibrium in brain, but when cytotoxic edema occurs due to loss of Na/K pump, diffusion is restricted
-> can be seen within minutes with MRI diffusion weighted imaging (DWI) -> T2-type image where CSF appears black
Will T2 MRI become positive very quickly in acute infarct?
No -> there is no significant net increase in water content following infarction, and thus normal T2 will appear unchanged until about 6-8 hours post infarct when enough water has actually gotten into the brain to make it appear bright
Early restricted diffusion makes cells swell as water enters them from the interstitium, but there is no major increase in brain water
What is the radiologic hallmark of multiple sclerosis?
Periventricular plaques which are areas of oligodendrocyte loss and reactive gliosis. Lesions may also exist in corpus callosum. Will appear hypointense on T1 and hyperintense on T2
Will lesions in MS enhance with contrast? How else can they be seen?
These WILL enhance with contrast if they are actively inflamed and thus the BBB is damaged at those spots (vasogenic edema), but not all lesions will enhance
They can also be seen on T2 DWI because active plaques demonstrate restricted diffusion
What are the most common spots to find lesions of MS?
Corpus callosum, callosal / septum pellucidum interface, periventricular white matter, middle cerebellar peduncles
How does metastatic disease present in brain imaging?
Focal, solid, or ring-enhancing masses with surrounding vasogenic edema / mass effect (vasogenic edema spreads with finger-like extensions)
Where in the brain does metastatic cancer typically spread to, and what are the most common types of cancer to spread there?
80% will spread to gray / white junction of cerebrum
15% will spread to cerebellum
Lung, breast, and melanoma are most common cancers to spread there
How many metastases will be seen in brain cancer metastasis?
50% will have solitary metastasis
20% have 2 metastases
30% will have >=3 metastases
What is the differential diagnosis for chronic thoracic back pain and mild leg weakness in a middle-aged female?
- Spondylitis / degenerative arthritis
- Injury / fracture
- Tumor causing cord or nerve root compression
Order MRI of spine
What is the DDx for a mass found outside of spinal cord but inside of dura (intradural / etrameduullary)?
- Meningioma
- Nerve sheath tumor - Schwannoma or neurofibroma
- CNS primary drop-metastasis
- Hematogenous metastasis
