Hyperacute Arterial Stroke: MR Susceptibility

History

Acute change in neurologic status; rule out stroke.

Exam

Head MR SWI Sequence

Purpose

MR Susceptibility Sequence:
1. To identify sites of arterial thrombosis based on SWI blooming artifact in the proximal afferent arteries.

2. To assess the presence of venous stasis based on SWI blooming artifact within the deep medullary veins

3. To assess for venous collapse based on SWI blooming artifact in both the deep medullary veins and the draining central & cortical veins.

4. To identify sites of hematoma (blood extravasated into the neuropil) representing actual hemorrhagic conversion.

5. To identify sites of sequestered infarction (stagnant blood within the capillary bed), which implies virtually no transcapillary blood flow. This can be in the cortex (i.e. laminar necrosis), or in the parenchyma (tumefactive stroke).

6. Compare the FLAIR & DWI sequences with the SWI sequence in order to differentiate between hemorrhagic conversion (hematoma formation within the neuropil) versus acutely sequestered completed infarction (non extravasated blood stagnated within the capillary bed).

7. To identify areas of hyperemia with dilated deep medullary veins, which are part of the physiologic hyperemia in the collateral stroke zone, since this is an expected finding and not evidence of venous stasis.

Prior Study

CT Head

CTA Final Impression

MR Diffusion/FLAIR

Findings

Evaluate for evidence of hyperacute ischemic brain event on susceptibility imaging (SWI)

There is abnormal prominence (hyperemia) of the deep medullary veins within the diffusion positive stroke-zone, but without blooming. This implies post ischemic dysautoregulation, not venous stasis. It often is associated with contrast leak on the CTA. [Yes/No]

There is SWI venous prominence with blooming artifact within the deep medullary veins implying significant venous stasis within the dense ischemic core of the stroke-zone. [Yes/No]

There is virtual absence of the medullary veins deep to stroke zone. [Yes/No]

There is SWI blooming artifact in proximal arteries indicating thrombosis. [Yes/No]

There is SWI blooming artifact along major cortical veins indicating thrombosis. [Yes/No]

There is reduction in size of the ipsilateral major deep central veins indicating significant reduction in transcapillary blood flow. This increases the probability of malignant brain swelling. [Yes/No]

There is hyperemia in the collateral zone from physiologic vasodilation. [Yes/No]

There is SWI susceptibility artifact in the parenchyma included within the stroke-zone indicating sequestered infarction. [Yes/No]

There is SWI susceptibility artifact within the stroke-zone to indicate hemorrhagic conversion. [Yes/No]

Other

Other findings are present more consistent with a diagnosis other than stroke. [Yes/No]

Impression

Hyperacute Stroke - Arterial, Diagnostic: MR Susceptibility

There is no evidence of acute stroke.
There is evidence of acute stroke.
There is an abnormality, but it is related to a process other than stroke.