Background and Purpose-In contrast to platelet-rich white thrombi, red thrombi in the heart are rich in fibrin and trapped erythrocytes. The magnetic susceptibility effect of deoxygenated hemoglobin in red thrombi may result in hypointense signals on T2*-weighted gradient echo imaging (GRE). We tested the hypothesis that a GRE susceptibility vessel sign (SVS) is specific for cardioembolic stroke. Methods-This retrospective study examined data from acute ischemic stroke patients who underwent diffusion-weighted imaging, GRE and magnetic resonance angiography (MRA) within 24 hours of stroke onset and who had symptomatic occlusion of large intracranial arteries in the circle of Willis. Hypointense signals within vascular cisterns on GRE corresponding to symptomatic vascular occlusion were termed "GRE SVS." Recanalization was assessed on follow-up MRA performed within 7 days of onset. The relationships between GRE SVS and stroke subtypes and subsequent recanalization were explored. Results-Of the 95 patients who met the inclusion criteria, GRE SVS was observed in 45 (47.4%). GRE SVS was more commonly associated with cardioembolic stroke patients (31 of

Background and Purpose-Diffusion-weighted imaging (DWI) is superior to conventional MRI in identification of small new ischemic lesions and discrimination of recent infarcts from old ones. Thus, this technique is useful in the detection of acute multiple brain infarcts (AMBI). We sought to determine the frequency and the topographical and etiologic patterns of AMBI detected on DWI. Methods-We studied 329 consecutive ischemic stroke patients who underwent DWI and MRI/MR angiography within 4 days of stroke onset. AMBI was defined as noncontiguous high signal intensities on DWI in Ͼ1 vascular territory. Stroke mechanism was determined according to the criteria of the Trial of Org 10172 in Acute Stroke Treatment (TOAST). Results-We

Previous studies have addressed the differences in risk factors and stroke mechanisms between ICAS and ECAS, 2,3 but the results are inconsistent. Whereas some reported that hypertension, diabetes mellitus, and metabolic syndrome (MetS) are more closely associated with ICAS, 4-8 this was not confirmed by others. 9-11 It also remains unclear whether the risk factors and stroke mechanisms differ between anterior and posterior circulation atherosclerosis. 12Previous studies examined a small number of patients at single hospitals. 6,7,11 Most importantly, prospective studies that used detailed examinations, including advanced brain and vascular imaging, are scarce. The purpose of this study was to elucidate the differences in the risk factors and mechanisms of stroke between ICAS and ECAS, and between anterior and posterior circulation atherosclerosis. We developed a Background and Purpose-The aim of this study was to investigate differences in risk factors and stroke mechanisms between intracranial atherosclerosis (ICAS) and extracranial atherosclerosis (ECAS) and between anterior and posterior circulation atherosclerosis. Methods-A multicenter, prospective, Web-based registry was performed on atherosclerotic strokes using diffusionweighted magnetic resonance imaging and magnetic resonance angiography. Stroke mechanisms were categorized as artery-to-artery embolism, in situ thrombo-occlusion, local branch occlusion, or hemodynamic impairment. Results-One-thousand patients were enrolled from 9 university hospitals. Age (odds ratio [OR]

Background and Purpose-Single small subcortical infarctions (SSSIs), so-called lacunae, are typically caused by lipohyalinosis of a perforator artery. However, SSSIs can be caused by underlying large parent arterial disease or microatheroma of the proximal portion of a perforator artery. We sought to investigate whether indicators for small vessel disease (SVD) and atherosclerosis in patients with SSSI differ according to lesion location and the presence of parent artery disease. Methods-We assessed 449 patients who had an SSSI (lesion diameter Յ20 mm) in the perforator territory of middle cerebral artery (nϭ244), basilar artery (nϭ141), and vertebral artery (nϭ64) on diffusion-weighted imaging performed within 48 hours of stroke onset. We divided SSSI into 3 groups according to lesion location and the presence of parent artery disease: (1) SSSI with parent artery disease (SSSIϩPAD); (2) proximal SSSI without PAD (pSSSI-PAD); and (3) distal SSSI without PAD (dSSSI-PAD). The prevalence of SVD indicators (leukoaraiosis and microbleeds) and atherosclerosis indicators (cerebral atherosclerosis and coronary heart disease) were compared among the groups. Results-SSSIϩPAD had the highest prevalence of atherosclerosis indicators and the lowest prevalence of SVD indicators, whereas dSSSI-PAD had the lowest prevalence of atherosclerosis indicators and the highest prevalence of SVD indicators. pSSSI-PAD showed intermediate features. Atherosclerosis indicators significantly increased and SVD indicators significantly decreased as the vascular territory became lower (from middle cerebral artery, basilar artery to vertebral artery). Conclusion-Differences in SVD and atherosclerosis indicators suggest that SSSI has a heterogeneous pathogenesis according to lesion location and the presence of PAD.

Outcome after ischaemic stroke is adversely influenced by complications, especially ischaemic stroke progression, symptomatic hemorrhagic transformation, pneumonia, extracranial bleeding, and urinary tract infection. Interventions to prevent those complications might improve ischaemic stroke outcome.

Background and Purpose-Patterns and mechanisms of stroke in patients with atherosclerotic middle cerebral artery (MCA) disease remain unclear. We sought to identify lesion patterns and stroke mechanisms associated with MCA disease using early diffusion-weighted imaging (DWI). Methods-We reviewed 185 acute ischemic stroke patients who had (1) symptomatic lesions located in the unilateral MCA territory on DWI performed within 48 hours of symptom onset, and (2) either corresponding MCA disease, internal carotid artery disease, or cardioembolism. Acute DWI lesion patterns were classified as (1) single (small perforator Ͻ2 cm; large perforator Ն2 cm; pial; large territorial; border-zone) and (2) multiple. Results-MCA disease was diagnosed in 63 patients, 32 (50.8%) of whom showed multiple lesions. Concomitant perforator and pial infarcts (14/63, PϽ0.001), concomitant perforator, pial, and border-zone infarcts (9/63, PϽ0.001), and single small perforator infarcts (12/63, Pϭ0.001) were identified more often in patients with MCA disease than in those with cardioembolism or internal carotid artery disease. Small perforator infarcts were more common in patients with milder stenosis than with severe stenosis or occlusion of MCA (PϽ0.001). Whether they occurred singly or in addition to other lesions, pial infarcts were identified more often in patients with severe stenosis or occlusion of MCA (Pϭ0.001). Conclusions-Perforating artery infarcts, whether single or occurring in addition to pial or border-zone infarcts, are lesion patterns specific for MCA disease. This suggests that local branch occlusion and coexisting distal embolization may be a common stroke mechanism in patients with MCA disease.

NILs frequently occur during the acute phase of ICH and are mainly associated with small-vessel pathogenesis. NILs occurring together with ICH may be a useful marker to identify patients at high risk of future clinical cerebrovascular events or vascular death.

Artificial intelligence (AI), a computer system aiming to mimic human intelligence, is gaining increasing interest and is being incorporated into many fields, including medicine. Stroke medicine is one such area of application of AI, for improving the accuracy of diagnosis and the quality of patient care. For stroke management, adequate analysis of stroke imaging is crucial. Recently, AI techniques have been applied to decipher the data from stroke imaging and have demonstrated some promising results. In the very near future, such AI techniques may play a pivotal role in determining the therapeutic methods and predicting the prognosis for stroke patients in an individualized manner. In this review, we offer a glimpse at the use of AI in stroke imaging, specifically focusing on its technical principles, clinical application, and future perspectives.