Encephaloduroarteriosynangiosis (EDAS) treatment of moyamoya syndrome: evaluation by computed tomography perfusion imaging

Longitudinal evaluation of cerebral perfusion evolution after revascularization surgery in moyamoya disease by CT perfusion

OBJECTIVE

To assess the longitudinal evolution of cerebral perfusion after revascularization surgery in patients with moyamoya disease (MMD) by CT perfusion (CTP).

MATERIALS AND METHODS

Thirty-one clinically confirmed MMD patients (12 males and 19 females, average age: 33.26 y, Suzuki stages 3 and 4: 19 and 11, respectively) who underwent revascularization surgery (bilateral (n=13) or unilateral (n=18)) were studied retrospectively. All patients underwent CTP examinations before and in the week after surgery and long-term (>3 months). CTP metrics (CBF, CBV, MTT, TTP, and delay TTP) were derived. The corresponding CTP metric values of the ROIs, which were manually drawn in the white matter (WM) and gray matter (GM), were recorded.

RESULTS

Six patients developed a new or progressive cerebral infarction/hemorrhage. In all patients, compared with the preoperative level, the TTP of GM and WM decreased in the short term after the surgery (P ≤ 0.005). Concurrently, the WM CBF increased significantly a week after surgery (P =0.02). However, in the long-term follow-up, the CBV and CBF in the GM and WM decreased to equal to or lower than the preoperative level, especially for CBV in the WM (P =0.012). Furthermore, cerebral perfusion began to decrease in the sixth month, and a continuous decline was observed over the next two months. It returned to the presurgical level after one year. In addition, the improvement in postsurgical perfusion was greater in Suzuki stage 3 patients than stage 4 patients.

CONCLUSION

Cerebral perfusion in patients with MMD improved shortly after surgery. However, in the long-term, brain perfusion decreased, most seriously in 6-8 months postoperatively, which might indicate that patients with MMD need timely follow-up and long-term intervention.

Future of Endovascular and Surgical Treatments of Atherosclerotic Intracranial Stenosis

Intracranial atherosclerotic disease and resultant intracranial stenosis is a global leading cause of stroke, and poses an ongoing treatment challenge. Among patients with intracranial stenosis, those with hemodynamic compromise are at high risk for recurrent stroke despite medical therapy and risk factor modification. Revascularization of the hypoperfused territory is the most plausible treatment strategy for these high-risk patients, yet surgical and endovascular therapies have not yet shown to be sufficiently safe and effective in randomized controlled trials. Advances in diagnostic and therapeutic technologies have led to a resurgence of interest in surgical and endovascular treatment strategies, with a growing body of evidence to support their further evaluation in the treatment of select patient populations. This review outlines the current and emerging endovascular and surgical treatments and highlights promising future management strategies.

Evaluation of surgical revascularization procedure outcomes for adult Moyamoya disease: a computed tomography perfusion-based study

BACKGROUND

The effectiveness of surgical interventions, whether direct or indirect, for Moyamoya disease (MMD) remains controversial. This study aims to investigate CT perfusion (CTP) as an objective method to evaluate the outcomes of different surgical modalities for adult MMD.

METHODS

The clinical and imaging data of 41 patients who underwent superficial temporal artery-middle cerebral artery (STA-MCA) bypass and 43 who received encephaloduroarteriosynangiosis (EDAS) were retrospectively analyzed. Intra- and intergroup differences in the Modified Rankin Scale (mRS) score, the change in clinical symptoms, collateral grade, and CTP parameters pre- and postoperatively were compared.

RESULTS

The overall level of the change in clinical symptoms in the STA-MCA group was higher than in the EDAS group (p < 0.05). In the operative area, the relative cerebral blood flow (rCBF) was significantly higher whereas the relative time to peak (rTTP) and the relative mean transit time (rMTT) were significantly lower in the STA-MCA and EDAS groups postoperatively than preoperatively (all p < 0.05). In the ipsilateral frontal lobe and basal ganglia, the postoperative rCBF was significantly higher, and the rTTP was significantly lower than the preoperative in the STA-MCA group (all p < 0.05). The postoperative rCBF improvement was higher in each brain area for STA-MCA than in the EDAS group (all p < 0.05).

CONCLUSION

Highlighting the utility of CTP, this study demonstrates its effectiveness in assessing postoperative cerebral hemodynamic changes in adult MMD patients. STA-MCA yielded a larger postoperative perfusion area and greater improvement compared to EDAS, suggesting CTP's potential to elucidate symptom variation between two surgical revascularization procedures.

CRITICAL RELEVANCE STATEMENT

We analyzed computed tomography perfusion parameters in pre- and postoperative adult Moyamoya disease patients undergoing superficial temporal artery-middle cerebral artery bypass and encephaloduroarteriosynangiosis. Our findings suggest computed tomography perfusion's potential in objectively elucidating symptom variations between these surgical revascularization approaches for MMD.

KEY POINTS

• Postoperative perfusion improvement is only confined to the operative area after EDAS. • Besides the operative area, postoperative perfusion in the ipsilateral frontal lobe and basal ganglia was also improved after STA-MCA. • The degree of perfusion improvement in each brain area in the STA-MCA group was generally greater than that in the EDAS group.

Influence of Patient and Technical Variables on Combined Direct and Indirect Cerebral Revascularization: Case Series

BACKGROUND

Cerebral bypass for flow augmentation is an important technique for selected neurosurgical patients, with multiple techniques used (direct, indirect, or combined).

OBJECTIVE

To assess the impact of patient and technical variables on direct and indirect bypass flow after combined revascularization.

METHODS

This was a retrospective, single-institution review of patients undergoing direct superficial temporal artery-to-middle cerebral artery bypass with indirect encephaloduro-myosynangiosis for moyamoya disease and steno-occlusive cerebrovascular disease over a 2-year period. We evaluated the effect of baseline patient characteristics, preoperative imaging characteristics, and operative variables on direct and indirect patency grades.

RESULTS

Twenty-six hemispheres (8 moyamoya disease and 18 steno-occlusive cerebrovascular disease) in 23 patients were treated with combined revascularization. The mean patient age was 53.4 ± 19.1 years. Direct bypass patency was 96%. Over a mean follow-up of 8.3 ± 5.4 months, there were 3 strokes in the treated hemispheres (11.5%). The mean modified Rankin Scale score improved from 1.3 ± 1.1 preoperatively to 0.7 ± 0.8 postoperatively. Preservation of the nondonor superficial temporal artery branch was associated with a lower direct bypass grade ( P < .01), whereas greater mean time to maximum perfusion (Tmax)> 4 and >6 seconds and mismatch volumes were associated with higher direct bypass grades ( P < .05). Tmax >4-second volume inversely predicted indirect bypass patency.

CONCLUSION

Patient and technical variables may influence the relative contributions of the direct and indirect components of combined revascularizations.

Longitudinal angiographic characterization of the efficacy of combined cerebral revascularization using minimally invasive encephalodurosynangiosis in patients with moyamoya angiopathy

Moyamoya angiopathy (MMA) can be treated using direct, indirect, or combined revascularization procedures. We perform combined revascularization using the STA-MCA bypass and minimally invasive encephalodurosynangiosis (MIS-EDS). Due to lack of systematic analyses to date it remains unclear whether and to which extent this limited EDS serves as a growth source for extracerebral blood vessels into the brain. The objective of the current study is to characterize the extent of angiographic filling of MIS-EDS and STA-MCA bypass development over time and to determine possible predictors of EDS development in adult MMA patients. Single-center retrospective analysis of 81 MMA patients (139 hemispheres) treated with a MIS-EDS and STA-MCA bypass was performed. Angiographic images and clinical/operative data were reviewed and scored. Uni-/ and multivariate Cox regression analyses identified preoperative predictors of good EDS vascularization. At 3-6 months after surgery EDS showed moderate and high angiographic filling in 40% and 5% of hemispheres, respectively. After 12 months moderate and high filling was found in 57% and 4% of hemispheres, respectively. STA-MCA bypass filling was moderate in 47% and high in 7% of hemispheres at 3-6 months and 45% moderate and 9% high after 12 months. High STA-MCA bypass filling on angiography was a negative predictor of EDS development. MIS-EDS is a simple technique and serves as a source of vessel growth into the brain. EDS development lags behind that of STA-MCA bypass and can be recommended as an additive revascularization source when combined with a direct bypass.

CT perfusion-based delta-radiomics models to identify collateral vessel formation after revascularization in patients with moyamoya disease

Purpose

To build CT perfusion (CTP)-based delta-radiomics models to identify collateral vessel formation after revascularization in patients with moyamoya disease (MMD).

Methods

Fifty-three MMD patients who underwent CTP and digital subtraction angiography (DSA) examination were retrospectively enrolled. Patients were divided into good and poor groups based on postoperative DSA. CTP parameters, such as mean transit time (MTT), time to drain (TTD), time to maximal plasma concentration (Tmax), and flow extraction product (FE), were obtained. CTP efficacy in evaluating surgical treatment were compared between the good and poor groups. The changes in the relative CTP parameters (ΔrMTT, ΔrTTD, ΔrTmax, and ΔrFE) were calculated to evaluate the differences between pre- and postoperative CTP values. CTP parameters were selected to build delta-radiomics models for identifying collateral vessel formation. The identification performance of machine learning classifiers was assessed using area under the receiver operating characteristic curve (AUC).

Results

Of the 53 patients, 36 (67.9%) and 17 (32.1%) were divided into the good and poor groups, respectively. The postoperative changes of ΔrMTT, ΔrTTD, ΔrTmax, and ΔrFE in the good group were significantly better than the poor group (p < 0.05). Among all CTP parameters in the perfusion improvement evaluation, the ΔrTTD had the largest AUC (0.873). Eleven features were selected from the TTD parameter to build the delta-radiomics model. The classifiers of the support vector machine and k-nearest neighbors showed good diagnostic performance with AUC values of 0.933 and 0.867, respectively.

Conclusion

The TTD-based delta-radiomics model has the potential to identify collateral vessel formation after the operation.

Radiomics models for preoperative prediction of microvascular invasion in hepatocellular carcinoma: a systematic review and meta-analysis

PURPOSE

To assess the methodological quality and to evaluate the predictive performance of radiomics studies for preoperative prediction of microvascular invasion (MVI) in hepatocellular carcinoma (HCC).

METHODS

Publications between 2017 and 2021 on radiomic MVI prediction in HCC based on CT, MR, ultrasound, and PET/CT were included. The risk of bias was assessed using the prediction model risk of bias assessment tool (PROBAST). Methodological quality was assessed through the radiomics quality score (RQS). Fourteen studies classified as TRIPOD Type 2a or above were used for meta-analysis using random-effects model. Further analyses were performed to investigate the technical factors influencing the predictive performance of radiomics models.

RESULTS

Twenty-three studies including 4947 patients were included. The risk of bias was mainly related to analysis domain. The RQS reached an average of (37.7 ± 11.4)% with main methodological insufficiencies of scientific study design, external validation, and open science. The pooled areas under the receiver operating curve (AUC) were 0.85 (95% CI 0.82-0.89), 0.87 (95% CI 0.83-0.92), and 0.74 (95% CI 0.67-0.80), respectively, for CT, MR, and ultrasound radiomics models. The pooled AUC of ultrasound radiomics model was significantly lower than that of CT (p = 0.002) and MR (p < 0.001). Portal venous phase for CT and hepatobiliary phase for MR were superior to other imaging sequences for radiomic MVI prediction. Segmentation of both tumor and peritumor regions showed better performance than tumor region.

CONCLUSION

Radiomics models show promising prediction performance for predicting MVI in HCC. However, improvements in standardization of methodology are required for feasibility confirmation and clinical translation.