Automatic Ischemic Core Estimation Based on Noncontrast-Enhanced Computed Tomography.

BACKGROUND: Evaluating the extent of ischemic change is an important step in deciding whether to use thrombolysis or mechanical thrombectomy, but the current standard method, Alberta Stroke Program Early CT Score, is semiquantitative and has low consistency among raters. We aim to create and test a fully automated machine learning-based ischemic core segmentation model using only noncontrast-enhanced computed tomography images. METHODS: In this multicenter retrospective study, patients with anterior circulation acute ischemic stroke who received both computed tomography (CT) and magnetic resonance imaging before thrombolysis or recanalization treatment between 2013 and 2019 were included. On CT, the ischemic core was manually delineated using the diffusion-weighted image and apparent diffusion coefficient maps. A deep learning-based ischemic core segmentation model (DL model) was developed using data from 3 institutions (n=272), and the model performance was validated using data from 3 institutions (n=106 Results: The median time ).between CT and magnetic resonance imaging in the validation cohort was 18 min. The DL model calculated ischemic core volume was significantly correlated with the reference standard (intraclass correlation coefficient, 0.90, P<0.01). Both the early time window (≤4.5 hours from onset; intraclass correlation coefficient, 0.90, P<0.01) and the late time window (>4.5 hours from onset; intraclass correlation coefficient, 0.93, P<0.01) had significant correlations. The median difference in ivolume between the model and the reference standard was 4.7 mL (interquartile range, 0.8-12.4 mL). The DL model performed well in distinguishing large ischemic cores (>70 mL), with a sensitivity of 84.2%, specificity of 97.7%, and area under the curve of 0.91. CONCLUSIONS: The deep learning-based ischemic core segmentation model, which was based on noncontrast-enhanced CT, demonstrated high accuracy in assessing ischemic core volume in patients with anterior circulation acute ischemic stroke.

Bioresorbable Poly (L-Lactic Acid) Flow Diverter Versus Cobalt-Chromium Flow Diverter: In Vitro and In Vivo Analysis.

BACKGROUND: Permanent metallic flow diverter (FD) implantation for treatment of intracranial aneurysms requires antiplatelet therapy for an unclear duration and restricts postprocedural endovascular access. Bioresorbable FDs are being developed as a solution to these issues, but the biological reactions and phenomena induced by bioresorbable FDs have not been compared with those of metallic FDs. METHODS: We have developed a bioresorbable poly (L-lactic acid) FD (PLLA-FD) and compared it with an FD composed of cobalt-chromium and platinum-tungsten (CoCr-FD). FD mechanical performance and in vitro degradation of the PLLA-FD were evaluated. For in vivo testing in a rabbit aneurysm model, FDs were implanted at the aneurysm site and the abdominal aorta in the PLLA-FD group (n=21) and CoCr-FD group (n=15). Aneurysm occlusion rate, branch patency, and thrombus formation within the FD were evaluated at 3, 6, and 12 months. Local inflammation and neointima structure were also evaluated. RESULTS: Mean strut, porosity, and pore density for the PLLA-FD were 41.7 µm, 60%, and 20 pores per mm2, respectively. The proportion of aneurysms exhibiting a neck remnant or complete occlusion did not significantly differ between the groups; however, the complete occlusion rate was significantly higher in the PLLA-FD group (48% versus 13%; P=0.0399). Branch occlusion and thrombus formation within the FD were not observed in either group. In the PLLA-FD group, CD68 immunoreactivity was significantly higher, but neointimal thickness decreased over time and did not significantly differ from that of the CoCr-FD at 12 months. Collagen fibers significantly predominated over elastic fibers in the neointima in the PLLA-FD group. The opposite was observed in the CoCr-FD group. CONCLUSIONS: The PLLA-FD was as effective as the CoCr-FD in this study and is feasible for aneurysm treatment. No morphological or pathological problems were observed with PLLA-FD over a 1-year period.

Cerebral amyloid angiopathy in a young man with a history of traumatic brain injury: a case report and review of the literature.

Cerebral amyloid angiopathy (CAA), a cause of recurrent and multiple lobar hemorrhages, characteristically occurs in persons aged ≥55 years. We report a case of a 32-year-old male who had recurrent hemorrhage in the left multiple lobes, with a history of traumatic brain injury and hematoma evacuation at the age of 1 year. He underwent surgical treatment and was histopathologically diagnosed as having CAA. The literature review yielded six CAA cases, including ours, aged less than 55 years. All were male and four had histories of severe TBI, suggesting that male sex and TBI may be associated with CAA in young persons.

Partially thrombosed giant basilar artery aneurysm with attenuated contrast enhancement of the intraluminal thrombus on vessel wall MRI after flow diversion treatment: illustrative case.

BACKGROUND: The effect of vessel wall magnetic resonance imaging (VW-MRI) enhancement in partially thrombosed aneurysms has previously indicated aneurysmal instability and a rupture risk. However, whether the contrast effect of the wall changes before or after flow diversion treatment is still under investigation. OBSERVATIONS: The authors report a case of a partially thrombosed basilar artery aneurysm that increased in size over a short period, worsened brainstem compression symptoms, and was treated with a flow diverter stent with good results. In this case, VW-MRI after surgery showed a reduced contrast effect on the intraluminal thrombus within the aneurysm. The aneurysm thrombosed and markedly regressed over the next 5 months, with remarkable improvement in the brainstem compression symptoms. LESSONS: This finding on VW-MRI may indicate an attenuation of neovascularization in the thrombus wall and be a sign of aneurysm stabilization.

Predictors of aneurysm shrinkage after flow diversion treatment for internal carotid artery aneurysms: quantitative volume analysis with MRI.

Background and purpose: Although aneurysm shrinkage often occurs after flow diversion treatment for intracranial aneurysms, no reports have addressed the factors associated with aneurysm shrinkage. Materials and methods: This retrospective single-center study was performed to examine patients with unruptured internal carotid artery aneurysms who were treated using flow diversion and followed up by imaging for at least 12 months. The study outcome was aneurysm shrinkage (volume reduction of ≥10%) 12 months after treatment. Aneurysm volume was quantitatively assessed using the MRIcroGL software. Patient and aneurysm characteristics were statistically analyzed. Results: This study involved 81 patients with 88 aneurysms. At the 6 months, 12 months, and last follow-ups, the proportion of aneurysms that had shrunk was 50, 64, and 65%, respectively. No adjunctive coiling (odds ratio, 56.7; 95% confidence interval, 7.03-457.21; p < 0.001) and aneurysm occlusion (odds ratio, 90.7; 95% confidence interval, 8.32-988.66; p < 0.001) were significantly associated with aneurysm shrinkage. In patients treated by flow diversion with adjunctive coiling, only the volume embolization rate was a factor significantly associated with aneurysm shrinkage (p < 0.001). Its cutoff value was 15.5% according to the receiver operating characteristic curve analysis (area under the curve, 0.87; sensitivity, 0.87; specificity, 0.83). Conclusion: The rate of aneurysm shrinkage after flow diversion increased during the first 12 months after treatment, but not thereafter. No adjunctive coiling and aneurysm occlusion were predictors of aneurysm shrinkage, respectively. If adjunctive coiling is required, a volume embolization rate of ≤15.5% may be suggested for aneurysm regression.

Onset-to-treatment time and aneurysmal regression predict improvement of cranial neuropathy after flow diversion treatment in patients with symptomatic internal carotid artery aneurysms.

BACKGROUND: Although flow diversion plays a pivotal role in treating internal carotid artery aneurysms presenting with cranial neuropathy, predictors of symptom improvement have not been established. OBJECTIVE: To investigate improvement of symptoms after flow diversion treatment in patients with internal carotid artery aneurysms causing cranial neuropathy, with sufficient follow-up period. Additionally, to examine factors associated with improvement of symptoms. METHODS: This retrospective multicenter study examined patients with unruptured internal carotid artery aneurysms presenting with cranial neuropathy who were treated using flow diversion and followed up for at least 12 months. Study outcomes were transient worsening of symptoms and symptom status 12 months after treatment. Patient and aneurysm characteristics were statistically analyzed. RESULTS: Seventy-seven patients were included. Data needed for outcome analysis were available for 66 patients. At the 1-, 3-, 6-, 12-month, and last follow-ups, the proportion of patients with resolved or improved symptoms was 26% (20/77), 51% (39/77), 74% (57/77), 83% (64/77), and 79%(62/77), respectively. Symptom onset-to-treatment time <6 months (OR=24.2; 95% CI 3.09 to 188.84; p=0.002) and aneurysmal regression (OR=23.1; 95% CI 1.97 to 271.75; p=0.012) were significantly associated with symptom improvement. Transient symptom worsening and worse symptoms at 12 months occurred in 19/77 (25%) and 2/77 (3%) patients, respectively. CONCLUSIONS: The rate of cranial neuropathy symptom improvement after flow diversion increased over the first 12 months after treatment, but not thereafter. Treatment within 6 months of symptom onset and aneurysmal regression were predictors of symptom improvement.

Ruptured thrombosed vertebral artery dissecting aneurysm treated with staged flow diverter after prediction of the rupture point by vessel wall MRI.

The safety and feasibility of using staged flow diverter (FD) for ruptured cerebral aneurysms, in which coil embolization is performed in the acute phase and FD is deployed in the subacute phase, has recently been reported. This strategy requires assuming the rupture point and performing coil embolization. Although vessel wall magnetic resonance imaging (VW-MRI) has been reported to be useful in predicting the rupture point of aneurysms, its use with staged FD has not yet been reported. We report the first case of staged FD with preoperative contrast-enhanced VW-MRI to predict the rupture point for partially thrombosed vertebral artery dissecting large aneurysm involving posterior inferior cerebellar artery (PICA) origin. This approach achieved a very good outcome, not only completely occluding the aneurysm, but also reconstructing the parent artery while maintaining the patency of the PICA.