Radiology Flashcards
What is the most common cause of stroke?
thromboembolic infarct
What is the most sensitive examination for acute ischemia?
MRI diffusion weighted imaging (DWI)
Noncontrast head CT shows imaging features of infarcts at what time after stroke symptoms?
6-12 hours
What is the insular ribbon sign?
swelling of insular cortex on CT sensitive to ischemia - sign of acute MCA infarct
Ischemia/infarct appears ___ on CT.
hypodense
___ test can detect acute ischemia within 15-30 min of symptoms.
DWI on MRI
What is the most sensitive test for finding mass lesions in the brain?
MRI with and without gadolinium contrast
also best for distinguishing different mass lesions common to HIV patients
What are MRI findings that indicate toxoplasmosis?
multiple lesions, edema, hyperintense center on T2, deep gray matter involvement, T1 hyperintensity, target pattern of enhancement
What are MRI findings that indicate Primary CNS lymphoma?
solitary lesion, subependymal enhancement, encasement of ventricles, hypointensity of core on T2
In malignancy, the ____ ratio is increased, and the ___ ratio is decreased on MR spectroscopy.
increased - choline/creatine
decreased - N-acetyl-aspartate/creatine
A lipid/lactate peak on MR spectroscopy indicates what?
anaerobic metabolism - infection and necrotic tumor
What is the most sensitive scan for hemorrhage?
CT scan
What size aneurysm can be seen on CT?
more than 5 mm
What would you expect to see on imaging of a patient with Huntington’s Disease?
caudate atrophy
What would you expect to see on imaging of a patient with Alzheimer’s disease?
diffuse atrophy of the cerebral cortex
