Deep tiny flow voids along middle cerebral artery atherosclerotic occlusions: A high-resolution MR imaging study

Abstract

Background and purposeWe aim to report the “deep tiny flow voids” (DTFV), a unique HR-MRI finding suggestive of deep collateral vessels along middle cerebral artery (MCA) occlusions. MethodsWe retrospectively reviewed the HR-MRI data of 60 patients with unilateral MCA occlusion (32 symptomatic and 28 asymptomatic) and 205 control subjects with normal MCA on magnetic resonance angiography. The presence or absence of DTFV, defined as three or more flow voids along the occluded MCA on at least two consecutive T2-weighted image slices, was observed. The relationships among DTFV, clinical presentations, and infarct sizes were analyzed. ResultsDTFV were identified in 20/28 (71%) patients with asymptomatic MCA occlusions, much more frequently than in the patients with symptomatic occlusions (5/32, 16%) (P<0.001). There were 9 patients with a large territorial infarction (≥1/3 MCA distribution), none of whom had DTFV on HR-MRI. DTFV was not observed in any control subject. ConclusionsDTFV are pathological conditions and associated with relatively good imaging outcomes and asymptomatic MCA occlusions. The function and clinical implications of DTFV warrant further investigations.