Vertebrobasilar Stroke: Association Between Infarction Patterns and Quantitative Magnetic Resonance Angiography Flow State

Abstract

Background Treatment and prognosis of vertebrobasilar atherosclerotic disease differs depending on stroke mechanism, such as artery‐to‐artery embolism, branch atheromatous disease, and hemodynamic ischemia. Our aim was to investigate the relationship between infarction pattern and flow status using quantitative magnetic resonance angiography (QMRA), to determine the validity of using infarction patterns to infer stroke mechanism. Methods and Results This is a retrospective study of patients with ischemic stroke with intra‐ or extracranial vertebrobasilar atherosclerotic stenosis, who underwent magnetic resonance imaging of the brain, neurovascular imaging, and QMRA, between 2009 and 2021. Patients with cerebral infarction predating or following QMRA by ≥1 year, or QMRA studies performed for basilar thrombosis, vertebral dissection, or only postangioplasty/stenting, were excluded. Poststenotic flow (basilar and posterior cerebral arteries) was dichotomized as low‐flow or normal‐flow based on published criteria. Of 1211 consecutive patients who underwent QMRA noninvasive optimal analysis, 69 met inclusion. Mixed patterns were most common (46.4%), followed by perforator (23.2%), borderzone (14.5%), and territorial (15.9%). Patients with low‐flow had a significantly higher rate of borderzone+ patterns (borderzone alone or in mixed pattern) compared with patients with normal‐flow (77.4% low‐flow versus 39.5% normal‐flow, P =0.002). Borderzone+ patterns were associated with 61.5% probability of low‐flow state, while no borderzone (perforator/territorial) patterns were associated with 76.7% probability of normal‐flow state. Conclusions Borderzone infarction pattern (alone or mixed) was associated with low poststenotic posterior circulation flow by QMRA. However, borderzone pattern only moderately predicted low‐flow state, and may be an unreliable flow marker. Therefore, infarct topography may complement, but should not replace hemodynamic studies to establish flow status.

Association between the degree of vertebrobasilar stenosis, location, infarction pattern, and QMRA flow state

“…This is likely due to the inherent limitations of our current imaging (QMRA, perfusion studies, infarction patterns), since none of these unimodal imaging modalities fully reflect the complex hemodynamic environment surrounding atherosclerotic lesions as each imaging modality likely depicts a piece of the complicated hemodynamic picture. Coupling borderzone infarctions with low distal flow states strengthened the association between borderzone infarctions and vertebrobasilar low distal flow states that was previously shown 14 …”

“…A detailed exclusion diagram depicting the screening of the current patient cohort can be referenced in our previous study. 14 Two board-certified neuroradiologists (K.B., P.S.) blinded to distal flow status and clinical history measured the degree of intracranial and extracranial stenosis, using the Warfarin-Aspirin Symptomatic Intracranial Disease 15 and Carotid And Vertebral Artery Transluminal Angioplasty Study 16 methods, respectively, and QMRA distal flow status was dichotomized as low distal flow and normal distal flow based on the VERiTAS criteria.…”

Association Between the Degree of Vertebrobasilar Stenosis, Location, Infarction Pattern and QMRA Flow State

“…Using the same patient cohort of our previous study which assessed the relationship between vertebrobasilar infarction pattern and QMRA distal-flow state, 14 we sought to evaluate the relationship between degree and location of vertebrobasilar stenosis and QMRA distal-flow state. Patients with acute ischemic stroke, neurovascular imaging demonstrating ≥50% stenosis of extracranial or intracranial vertebral or basilar arteries, and QMRA within one year of stroke, between 2009 and 2021 at two comprehensive stroke centers, were included.…”

“…A detailed exclusion diagram depicting the screening of the current patient cohort can be referenced in our previous study. 14 Two board-certified neuroradiologists (K.B., P.S.) blinded to distal-flow status and clinical history measured the degree of intracranial and extracranial stenosis, using the WASID 15 and CAVATAS 16 methods, respectively, and QMRA distal-flow status was dichotomized as low distal-flow and normal distal-flow based on the VERiTAS criteria.…”

“…blinded to distal-flow status and clinical history measured the degree of intracranial and extracranial stenosis, using the WASID 15 and CAVATAS 16 methods, respectively, and QMRA distal-flow status was dichotomized as low distal-flow and normal distal-flow based on the VERiTAS criteria. 13 Infarction patterns were delineated in our previous study 14 by two board-certified neuroradiologists (K.B., P.S.) blinded to distal-flow status, based on published templates, where borderzone infarctions were defined as the territory between the posterior inferior and anterior inferior cerebellar arteries, anterior inferior and superior cerebellar arteries, or posterior cerebral and middle cerebral arteries.…”