2025年1月19日 · Aging ischemic strokes can be important in a number of clinical and medicolegal settings. Both CT and MRI can help in determining when a stroke occurred as imaging features evolve in a reasonably predictable fashion. There is substantial heterogeneity in the terminology denoting time from onset.

Subacute cerebral infarction is an important differential to always consider and depending on the timing, the appearances can be quite bizarre and mimic tumor.

Acute infarcts demonstrate high-signal on DWI within a few minutes after the stroke and leasts for at least 2 weeks. Restricted diffusion without a bright signal on FLAIR should make you think hyperacute (< 6 hours).

Detection of different patterns of contrast enhancement can help in determining the age of infarct. There are two patterns of MR contrast enhancement in the acute phase of ischemic stroke-intravascular enhancement and cortical enhancement.

This case beautifully demonstrates how similar a primary brain neoplasm and subacute infarction can be on imaging. Follow up can make things clearer before getting surgical knives involved!

2025年1月17日 · Diffusion-weighted imaging (DWI) is a commonly performed MRI sequence for the evaluation of acute ischemic stroke and is very sensitive in the detection of small and early infarcts. Conventional MRI sequences (T1WI, T2WI) may not demonstrate an infarct for 6 hours, and small infarcts may be hard to appreciate on CT for days, especially without ...

On CT, contrast enhancement following infarct occurs in the subacute stage, and generally starts towards the end of the first week. Peak enhancement occurs at week 2 and 3, and gradually fades over the following weeks. On MRI, enhancement can be seen as early as day 1 following ictus, although available data is not as extensive as for CT.

Missed cerebral infarcts, those where the first imaging is in the subacute phase, can sometimes appear unusual and mimic tumors or infections. Identifying that the abnormality is confined to a vascular territory is the most useful clue.

On vessel wall MRI (VM-MRI), eccentric wall thickening of the proximal M1 segment of the right middle cerebral artery is noted, with strong post-contrast enhancement, causing moderate luminal stenosis. Differential diagnoses include atherosclerotic plaque and vasculitis.

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