Stroke Imaging & Diagnostics Flashcards
7 cards from real ASC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Stroke Imaging & Diagnostics flashcards as text
On CT perfusion imaging, which map best identifies the ischemic penumbra (tissue at risk but potentially salvageable)?
Answer: Mean transit time (MTT) or Tmax map showing perfusion delay
Tmax or MTT maps highlight areas with prolonged transit time representing the ischemic penumbra, which differs from the core infarct seen on CBF maps.
Which MRI sequence is most sensitive for detecting hyperacute subarachnoid hemorrhage within the first few hours?
Answer: Gradient echo (GRE) T2*
GRE/T2* sequences are highly sensitive to blood products due to susceptibility effects of deoxyhemoglobin, making them superior to FLAIR in the hyperacute phase.
A patient's CTA reveals a hyperdense basilar artery sign. What does this finding indicate?
Answer: Acute thrombus within the basilar artery
A hyperdense basilar artery on non-contrast CT indicates acute thrombus and is associated with basilar artery occlusion requiring urgent intervention.
In CT perfusion imaging, the ischemic core is best represented by which parameter threshold?
Answer: CBF < 30% of contralateral normal tissue
A CBF reduction to less than 30% of normal contralateral tissue is the widely accepted threshold for identifying irreversibly infarcted core tissue.
Which artifact on diffusion-weighted MRI can mimic acute ischemic stroke and must be recognized?
Answer: T2 shine-through effect
T2 shine-through occurs when subacute lesions with long T2 relaxation times appear bright on DWI without true diffusion restriction, mimicking acute infarct.
What is the primary advantage of flat-panel detector CT (DynaCT) used in the angiography suite?
Answer: Real-time imaging during endovascular procedures to detect hemorrhage
DynaCT in the angiography suite allows rapid detection of intracranial hemorrhage during endovascular stroke treatment without transferring the patient.
On non-contrast CT, the 'insular ribbon sign' in acute MCA stroke indicates loss of distinction between which structures?
Answer: Gray matter and white matter in the insular cortex
The insular ribbon sign refers to loss of the normal gray-white differentiation in the insular cortex, an early CT sign of MCA territory ischemia.