Are lacunar infarcts associated with a "susceptibility vessel sign"? A 7-tesla magnetic resonance imaging study

The pathophysiological basis for lacunar stroke is uncertain. The susceptibility vessel sign (SVS) on magnetic resonance imaging (MRI) is associated with thrombotic large vessel occlusion and has been reported in association with lacunar infarcts using T2* imaging. We investigated the presence of a relevant SVS in acute lacunar stroke with susceptibility-weighted imaging (SWI) and time-of-flight MR angiography (TOF-MRA) at 7 Tesla (T).

We performed a single-centre prospective observational study in patients with small subcortical infarct confirmed on 1.5 or 3 T MRI. Additional 7 T MRI was acquired and raters independently reviewed 7 T SWI and TOF-MRA sequences blinded to clinical data. Presence of an SVS and any associated occluded vessels were recorded. A SVS was considered present if reported by two or more raters in the relevant hemisphere with agreement confirmed at consensus review.

Twenty people (10 male, 10 female), with median age 67.5 [interquartile range (IQR) 64-81] years and median National Institutes of Health Stroke Scale 3 (IQR 2-4.75), underwent 7 T MRI. Possible SVS was visualized in 7 of 20 scans (35%) on SWI, with 4 considered highly likely (20%). TOF-MRA review showed an occluded small vessel proximal to the infarct in 1 of 20 patients (5%). This was not associated with a positive SVS on SWI.

A possible SVS was observed in up to 7 of 20 (35%) people with recent small subcortical infarcts, but anatomically related vessel occlusion was not confirmed using TOF-MRA. Diagnosis of small vessel SVS appears subjective and confirmation with 3-dimensional vascular imaging may increase reliability.