Frequency, Spatial Distribution And Associations To Clinical Characteristics Of Multiple Lesions In A Large Multi-center Dataset Of Acute Ischemic Stroke Patients

Introduction: About ~10% of acute ischemic stroke (AIS) patients experience multiple acute lesions (MAL). However, the spatial distribution and clinical implications of such MAL are incompletely understood. Here, we scrutinized MAL in a large, radiologically deep-phenotyped cohort of AIS patients. Methods: We analyzed imaging and clinical data of 2.485 AIS patients [age: 63.3±14.8, 39%women] of the multi-site MRI-GENIE study. We computed occurrences of (i) MAL within one and, (ii) MAL in several vascular supply territories (with single or multiple lesions within single territories). We furthermore evaluated associations between the presence of MAL in multiple territories and stroke severity, white matter hyperintensity (WMH) and stroke lesion volumes, etiology, age and sex. Results: Half of all patients, i.e., 49.7%, presented with a single lesion. Another 37.3% experienced MAL in a single vascular territory, while 13% featured lesions in multiple vascular territories. For most vascular territories (anterior, middle and posterior cerebral artery, cerebellum) the ratio between single to multiple lesions in that territory equaled ~52%, only the brainstem region comprised fewer multiple compared to single lesions (19%). Combinations of anterior and posterior circulation lesions occurred in 5.6% of all patients, bilateral stroke in the anterior circulation in 3.4%. When comparing patients with lesions in only one compared to in more than one territory, there were no significant differences in WMH or lesion volume, stroke severity, age or sex ( p FDR-corrected >0.05). Patients with lesions in multiple territories had a significantly lower frequency of small vessel occlusions, but a significantly higher frequency of stroke of undetermined etiology. Differences in cardioembolic stroke frequency were only significant before correction for multiple comparisons ( p uncorrected =0.025). Frequencies of large vessel occlusions did not differ between the groups. Conclusions: Multiple lesions, especially those within one vascular territory, occurred frequently. Overall, there were no significant associations between MAL and stroke severity or cardioembolic stroke. Future studies are warranted to explore these findings in greater detail.