Search

Background and Purpose: Endovascular thrombectomy is of benefit to most patients with acute ischemic stroke caused by major intracranial vessel occlusion. Reperfusion injury is, however, one of the critical complications after successful recanalization, which has not been fully evaluated. The aim of this prospective study was to assess the impact of hyper-intensity signal on postoperative arterial spin labeling (ASL) MR imaging on hemorrhagic complications and clinical outcome after endovascular treatment. Methods: Consecutive patients showing acute stroke with major intracranial vessel occlusion were prospectively analyzed. All the patients underwent endovascular thrombectomy, and MR imaging including ASL was performed at pre-, postoperative day 1 and day 7. Clinical and radiological outcomes were evaluated especially focusing on arterial spin labeling findings. Results: Of 81 patients, 21/81 (25.9%) showed hyper-intensity signal on ASL (ASL+) at postoperative day 1. There were no significant differences in baseline characteristics between the groups with and without ASL+, including preoperative NIH stroke scale, door to puncture time, occlusion vessel and TICI score. Interestingly, 15/21 (71.4%) patients developed minor bleeding or hemorrhagic changes in ASL+ group, which was detected only in 3/60 (5.0%) in ASL- group. Modified Rankin Scale was not different between the groups at postoperative day 90 under strict control of blood pressure. Multivariate regression analysis showed that ASL+ is significantly related to postoperative hemorrhagic complications (Adjusted OR: 21.68, P=0.004). Conclusions: Postoperative hyper-intensity signal on ASL MRI indicates vasoparalysis and luxury perfusion even successful recanalization after endovascular thrombectomy, which has a risk for hemorrhagic complications.

Background and Purpose: Thrombus composition has been suggested to have a decisive impact on the outcome of patients treated by mechanical thrombectomy because of embolic stroke. The aim of this prospective study was to assess the impact of a mechanical thrombectomy device (Penumbra aspiration catheter vs. Stent retriever) on thrombus composition, which could affect flow impairment after reperfusion. Methods: Thrombi of consecutive stroke patients with large vessel occlusion were collected during intracranial mechanical recanalization. Mechanical thrombectomy device was used either Penumbra aspiration catheter or Stent retriever. The hematoxylin and eosin-stained specimens were quantitatively analyzed in terms of the relative fractions of the main constituents (red blood cells and fibrin/platelets). Results: Of 65 cardio-embolic patients, Penumbra aspiration catheter was used in 27 patients, and Stent retriever was used in 38 patients. There was no significance in age, sex, occlusion vessel, NIH stroke scale, and onset to reperfusion time. The volume of thrombi was significantly larger in Penumbra group compared with that in Stent group (3.68 cm3 vs. 0.95 cm3, P Conclusions: Stent retriever could crush thrombus and reduce its size, which induce distal migration of the red blood cell component. However, it did not affect the final infarct lesion and outcome.

Background and purpose: T2 star weighted MR angiography (SWAN) can detect hemodynamic insufficiency as hypointensity areas in the medullary or cortical veins. In this study, we investigate whether SWAN in 1.5T MRI can help to detect ischemic penumbra-like lesions in acute ischemic stroke (AIS) patients. Materials and methods: Patients showing acute major vessel occlusion (ICA and MCA) within 4.5 hours from onset were consecutively analyzed with MRI including SWAN, DWI, and MRA. To evaluate ischemic area in SWAN and DWI, modified ASPECT (mASPECTS) were used. SWAN- and DWI- based mASPECTS was calculated, and correlation between DWI-SWAN mismatch and final infarct lesion or outcome was evaluated. Results: Thirty-five patients were included in this study. Of the 35 patients (mean age: 73.5 ± 13.5 years), cardioembolic stroke was confirmed in 26 patients, atherothrombotic stroke was in 4 patients, and the others had unknown etiology. Overall, recanalization was achieved in 23 patients (65%), showing higher mASPECTS in follow up DWI and lower mRS at 90 days than patients with no recanalization ( P =0.037 and P P =0.016 and P =0.042). Of 12 patients showing no recanalization, DWI-SWAN mismatch was significantly correlated with infarct growth (R 2 =0.6160, P =0.0025). On the other hand, there was no such correlation for patients showing recanalization. Interestingly, initial SWAN-based mASPECTS was significantly correlated with mRS at 90 days (R=-0.38, P =0.037) regardless of recanalization. Conclusions: DWI-SWAN mismatch in 1.5T MRI could show penumbra-like lesions in AIS patients with major vessel occlusion. Low mASPECTS in initial SWAN might predict unfavorable outcome. Assessment of ischemic penumbra from venous side using SWAN can visualize a lesion’s viable tissue and is quite useful without contrast media.

Background and Purpose: The ivy sign on fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI) is a specific finding in moyamoya disease (MMD). This sign indicates decreased cerebral perfusion, dilated pial vasculature, and slow leptomeningeal collateral flow. This study aimed to clarify the characteristics of perioperative changes in the ivy sign in relation to cerebral hyperperfusion (HP), which frequently occurs in MMD of unknown etiology. Methods: This prospective study included patients with MMD who underwent superior temporal artery-middle cerebral artery single bypass. FLAIR MRI was performed to evaluate the appearance of the ivy sign in the ipsilateral hemisphere preoperatively and on postoperative days 2 and 30. The ivy sign was assessed in combination with perioperative symptoms and cerebral hemodynamics using single-photon emission computed tomography (SPECT). Results: Of 42 consecutive patients (55 sides) who underwent bypass surgery, 32 (58.2%) showed an increase in the ivy sign (de novo ivy sign) on postoperative day 2; this had disappeared by day 30. Interestingly, these 32 patients had a significantly higher incidence of HP on SPECT and HP syndrome, and there was no correlation between the de novo ivy sign and a preoperative ivy sign or the preoperative cerebral hemodynamics. In multivariate analysis, a de novo ivy sign was significantly correlated with postoperative HP. Conclusions: In MMD, a de novo ivy sign could indicate postoperative HP after bypass, which is not always correlated with preoperative hemodynamic impairment. Additional factors other than preoperative cerebral hemodynamics might be involved in postoperative HP in MMD.

Background and Purpose: Neovascularization of carotid plaques is associated with plaque vulnerability. However, the role of neovascularization in the development of intraplaque hemorrhage (IPH) and the clinical contribution of neovascularization to IPH and symptomatic presentation remain undetermined. Methods: Consecutive patients with moderate to severe carotid atherosclerosis who underwent carotid endarterectomy were prospectively analyzed from 2010 to 2014. The neovessel appearance was categorized into three groups based on dynamic intraoperative indocyanine green videoangiography: neovessels derived from the endothelium (NVe), neovessels derived from the vasa vasorum (NVv), and no neovessels. Each neovessel pattern was evaluated with respect to clinical, radiological, and pathological findings. Results: Of 57 patients, 13 exhibited NVe, 33 exhibited NVv, and 11 exhibited no neovessels. There were no significant differences in baseline characteristics among the three groups with the exception of a higher percentage of symptomatic presentations among patients with NVe. Moreover, patients with NVe exhibited larger infarctions than did those with NVv (P=0.04). Pathologically, patients with NVe had more severe IPH (P=0.002), hemosiderin spots (P=0.04), neovessels (P=0.11) and inflammation (P=0.26), all of which were correlated with hyperintensity on time-of-flight magnetic resonance imaging. Interestingly, inflammation was significantly correlated with neovessel formation (R=0.43, P=0.008), hemosiderin spots (R=0.62, P Conclusions: Luminal neovascular sprouting with inflammation and lumen communication could clinically contribute to IPH and symptomatic presentation in patients with carotid stenosis. This condition may thus be a key therapeutic target against neovessel formation and inflammation.

Introduction: T2 star weighted MR angiography (SWAN) can detect slight changes of susceptibility caused by microbleeds. It has also been reported that SWAN can detect hemodynamic insufficiency as hypointensity area in the medullary or cortical veins. In this study, we investigate whether SWAN can help to detect ischemic penumbra in the acute stage. Materials and methods: Patients showing acute major vessel occlusion (internal carotid artery and middle cerebral artery) within 4.5 hours from onset were consecutively analyzed with MR imaging including SWAN, diffusion weighted imaging (DWI) and MR angiography. To evaluate ischemic area in SWAN and DWI, modified Alberta Stroke Program Early CT score (mASPECTS) was used as follows; M1~6 and basal ganglion including caudate, insula, lentiform or internal capsule. SWAN based mASPECTS was calculated with DWI based ASPECTS, and correlation between DWI-SWAN mismatch and final infarct area or outcome was evaluated. Result: Of 30 patients (mean age: 72.7 ± 13.3 years). Cardioembolic stroke was confirmed in 24 patients, atherothrombotic stroke was in 3 patients, and others had unknown etiology. Intravenous t-PA was performed in 17 patients, and endovascular therapy was performed in 17 patients. Overall, recanalization was achieved in 70% (21 patients) with lower modified Rankin Scale at 90 days compared with no recanalization (P=0.0004). Interestingly, SWAN based mASPECTS was significantly correlated with mRS at 90 days (R=-0.4382, P=0.02) regardless of recanalization. Of 9 patients showing no recanalization, DWI-SWAN mismatch was significantly correlated with new infarction (R=0.8221, P=0.0065). On the other hand, patients showing recanalization showed no correlation between mismatch and new infarct. Conclusion: DWI-SWAN mismatch could simply predict ischemic penumbra requiring immediate reperfusion. Assessment of ischemic penumbra from venous side using SWAN is quite useful without contrast media.

Introduction: Postoperative cerebral hyperperfusion (HP) is a notable complication that occurs more frequently in moyamoya disease (MMD) than in atherosclerosis of unknown etiology. This study aimed to clarify the characteristics of intraoperative indocyanine green (ICG) videoangiography in MMD and atherosclerotic disease in terms of postoperative HP. Methods: This prospective study included 47 patients with 60 sides that underwent superior temporal artery (STA)-middle cerebral artery (MCA) single bypass. ICG videoangiography was performed after revascularization. The ICG time intensity curve was recorded in the STA, proximal MCA, distal MCA, and superficial Sylvian vein, and the angiographic differences among adult MMD, pediatric MMD, and atherosclerosis were analyzed. Results: Twenty two patients (27 sides) had adult MMD, 14 patients (22 sides) had pediatric MMD, and 11 patients (11 sides) had atherosclerosis. Postoperative HP was significantly higher in adult MMD (40.7%) than in pediatric MMD (18.2%) and atherosclerosis (0%). Adult MMD with HP was associated with a longer ICG peak time (P Conclusions: ICG videoangiography provides different characteristics of bypass flow among adult MMD, pediatric MMD, and atherosclerosis. Poor distribution and run-off of blood flow from the STA might contribute to postoperative HP in MMD. The occurrence of postoperative HP in MMD could depend on two factors: host STA size and recipient MCA integrity.

Background and Purpose— Malignant middle cerebral artery (MCA) infarction is one of the most devastating forms of ischemic stroke, and identification of predictors of a malignant course of the MCA or internal carotid artery (ICA) infarction is exceedingly important. Here, we investigated whether thrombus component defined with MR imaging could predict malignant changes in the acute stage of the cerebral infarction. Methods— We retrospectively analyzed 468 consecutive patients with cerebral infarction in our institute from 2007 to 2011. In all the patients, initial MR imaging including T2 star (T2*), diffusion weighted imaging (DWI), fluid-attenuated inversion recovery (FLAIR) and MR angiography were performed and susceptibility vessel sign (SVS) on T2* was evaluated in relation to the brain swelling on CT 24 hours after the initial imaging. Correlation of the thrombus component between MRI and CT was also evaluated. Results— One hundred and twelve patients showed MCA main trunk or carotid T occlusion. Among them, 38 patients were t-PA failed or did not undergo endovascular treatment. Twenty eight patients had ICA occlusion and 10 patients had MCA main trunk occlusion. SVS was apparent in 17 (45%) patients, and there was no significant difference between SVS positive and SVS negative group in age (75.6 vs. 72.3 years old), time to arrival (84.4 vs. 106.9 min) and NIH stroke scale (19.5 vs. 18.7). On the other hand, DWI area was significantly larger in SVS positive group (189.3 vs. 107.6 ml). DWI area was also significantly correlated with brain swelling 24 hour later regardless of SVS. Most SVS positive patients showed MCA dense sign on CT performed 24 hours later (85.7% vs. 29.4%). Conclusions— Susceptibility vessel sign on MRI, which suggests RBC rich thrombus, indicates early maturation of the infarct in the MCA area, but could not predict following malignant change.

Background and Purpose— Recent studies have investigated plaque morphology to determine patients who are at high risk of carotid atherosclerosis. In this study, we investigated whether a difference in dynamic enhancement pattern in plaque components could be useful to assess plaque stability with multidetector CT angiography. Methods— Fifty-nine lesions with moderate to severe carotid atherosclerosis in 51 patients (33 symptomatic, 18 asymptomatic) were consecutively included. Early- and delayed-phase images were obtained in 3 equivalent axial slices with multidetector CT angiography. Hounsfield units (HU) in the early phase were subtracted from those in the delayed phase in plaques (ΔHU) and compared with clinical features, MRI-based plaque characteristics, and histological findings with 20 surgical specimens acquired from carotid endarterectomy. Results— The ΔHU was significantly higher in asymptomatic than that in symptomatic presentation ( P =0.02). With MRI, a higher ΔHU was negatively correlated with signal intensity on T1-weighted imaging ( r =−0.56, P r =0.67, P =0.001) and negatively correlated with a lipid-rich necrotic core with hemorrhage ( r =−0.70, P Conclusions— Delayed-phase images provide information regarding the dynamic change in contrast media from the early arterial phase. An increase in HU from the early phase on multidetector CT angiography indicates plaque stability with more fibrous tissue and a less lipid-rich necrotic core, intraplaque hemorrhage, and neovascularization.