Hyperacute Venous Stroke: MR T1-W Sequences

History

Recent neurologic changes, often not focal.

Exam

Head MR T1-w sequence(s) with and/or without contrast

Purpose

1. Assess the noncontrast T1-w MR for hyperintense thrombus in one or more dural sinuses (i.e. the delta sign).

2. Assess the noncontrast T1-w MR for hyperintense thrombus in one or more pial or deep central veins.

3. Assess the noncontrast T1-w MR for blood products (SAH, hemorrhagic conversion).
Note: acute thrombus may be hyperintense on T1-w MR, just as it is hyperdense on CT, but it depends on the presence of met hemoglobin. Therefore, thrombi become hyperintense later than hyperdensity on CT. Hyperacute intraluminal thrombus on noncontrast T1 is more often isodense relative to brain but the isodense clot removes the expected flow void (actually a technical saturation effect).

4. Assess noncontrast T1 MR for venous congestion within the expanded medullary veins due to distal venous egress block.

5. Assess post contrast T1 sequences for intraluminal dural sinus thrombosis. T1-w post contrast exams, especially with multiplanar reconstruction, can discriminate enhancement in the dural sinus wall collateral from intraluminal (non enhancing) thrombus (i.e. the empty delta sign), when viewed in cross-section .

6. Assess post contrast T1 sequence for evidence of pial venous collaterals (typically appear serpiginous, hyperemic, drain the wrong way, the vein size changes from being larger next to the dural sinus to being larger at their inception site).

7. Assess the post-contrast T1 sequence for post ischemic contrast leak (i.e. venous post ischemic dysautoregulation).

8. Assess the post-contrast T1 sequence for unexpected exaggerated filling of atypical venous egress routes (i.e. filling into the orbits or posterior fossa veins or the nasopharyngeal venous plexus (evidence of re-routing of intracranial venous egress).

9. Assess for evidence of raised intracranial pressure, which includes evidence of brain swelling from venous congestion, optic hydrops/retroglobal edema, early hydrocephalus, effaced sulci, and possibly mass effects with herniation. These findings fall under the umbrella of CVT related pseudotumor.

10. Assess for nasopharyngeal/retropharyngeal infection/tumor with skull base extension and possible dural or cavernous sinus thrombosis.

Prior Study

CT Head
CTA/MRA Head and Neck
CTA Venocapillary Pool Analysis

Findings

MR T1-W Sequence with and/or without contrast

There is luminal abnormal isointensity (lack of flow void) or hyperintensity within one or more dural sinuses (delta sign) indicative of acute thrombus on the noncontrast T1. [Yes/No]

There is evidence of hyperintense or hypointensity within one or more cortical or central veins on noncontrast T1. [Yes/No]

There is evidence of dilatation of the intraorbital veins, and optic hydrops (dilated CSF space around the optic nerves) on pre or post contrast T1 MR. [Yes/No]

There is evidence of abnormal ventriculomegaly consistent with early hydrocephalus. [Yes/No]

There is evidence of dural sinus filling defect (empty delta sign) indicating thrombosis within one or more dural sinuses on the post contrast T1. [Yes/No]

There is evidence of dural sinus filling defect indicating thrombosis within the cavernous sinus and either its' afferent input or efferent egress veins on the post contrast T1. [Yes/No]

There is evidence of mural enhancement or actual luminal filling defect within a cortical or central vein indicating acute thrombus on post contrast T1. [Yes/No]

There is evidence of mural enhancement or intraluminal filling defect indicating thrombosis in an ophthalmic vein on post contrast T1. [Yes/No]

There is evidence of parenchymal contrast enhancement in the region of the affected venous zone on post contrast T1 indicative of vascular leak. [Yes/No]

There is evidence of pial venous collateral veins (typically appear serpiginous, enlarged size, draining the reversed directiong, with the size changed from being larger next to the dural sinus to being larger at there inception site on the post constrast T1 MR). [Yes/No]

There is prominence of any of the pial/dural anastomotic sites (i.e. vertex venous lacunae, tenorial confluences, or cavernous sinus/retropharyngeal venous plexus) on the post contrast T1-w sequence. [Yes/No]

There is evidence of unexpected regional cortical vein enlargement (arterialization of othersise NL veins), consistent with the combination of a dural AV fistula plus dural sinus stenosis/thrombosis on post contrast T1. [Yes/No]

There is evidence of skull base destruction (infection/tumor) leading to cavernous or dural sinus thrombosis. [Yes/No]

There is evidence of hemorrhagic conversion. [Yes/No]