Background: Concentric vessel-wall contrast enhancement (VW-CE) of the terminal carotid artery and its proximal branches may be linked to ischemic strokes, disease activity and progression in Moyamoya disease (MMD). The objective of this retrospective cohort study is to analyze the association between VW-CE and perioperative acute ischemic stroke (PAIS) occurring within 24 h after revascularization. Methods: All previously untreated MMD patients who required revascularization and who had undergone preoperative MRI with VW-CE-sequences were included. PAIS was detected by CT and/or diffusion-weighted MRI sequences within 24 h postoperatively. Results: Of the 110 patients included (female-to-male ratio: 2.7:1, median age: 45.1 (16.6–69.2); n = 247 revascularizations), a priori VW-CE was present in 67.3% (mean time from MRI to first surgery: 86 days ± 82 days). PAIS occurred in five patients undergoing primary revascularization (PAIS rate per revascularization: 2.1%), all of whom had a preoperative pathological VW-CE in the vascular segment corresponding to the stroke area. Two (40%) incidents of PAIS occurred in revascularized territory, while three (60%) occurred in non-revascularized vascular territory. In each case, the supplying artery exhibited VW-CE, indicating disease activity. No additional PAIS occurred during subsequent revascularizations in cases of multistage procedures (n = 38), such as ACA or PCA revascularization as a second step. Conclusions: Preoperative VW-CE in one or more vascular segments may be a marker for postoperative stroke in the respective vascular territory at the time of revascularization. VW-CE imaging should be routinely performed when planning revascularization in MMD. If VW-CE is found, strict perioperative monitoring of these high-risk patients should be performed to achieve the best results possible.

Objective : In moyamoya disease (MMD), the internal carotid and proximal cerebral arteries narrow, potentially leading to stroke or hemorrhage from fragile collaterals. Disease activity and progression may be detected by contrast-enhanced (CE) high-resolution (HR) vessel wall imaging (CE-VWI) on T1-weighted MRI. However, this imaging approach needs standardization for the evaluation of signal intensity and longitudinal reproducibility. Methods: MMD patients with at least two separate CE-VWI examinations on the same and on different scanners were included. Signal intensity of the vessel wall, pituitary stalk, and temporal lobe white matter were measured and normalized using manually selected regions of interest. Intraindividual longitudinal reproducibility of MRI was analyzed and the clinical course was correlated with vessel wall enhancement data. Results: Eighty-seven patients were analyzed. Primary analysis included 60 patients with two or more CE-VWI measurements (n = 129) with median 14.8 months between examinations (range: 2–36 months) on the same scanner. Intraindividual variation in pituitary stalk enhancement (positive control) and temporal lobe white matter enhancement (negative control) showed median signal variability of 20.5% and 17.5%, respectively. The pituitary-to-temporal lobe signal intensity ratio remained stable over time (p = 0.843) with 9.4% median variability. Correlation analysis revealed a significant positive association between pituitary and temporal lobe signal changes (ρ = 0.717, p < 0.001). A total of 75% of patients showed vessel wall contrast enhancement with fluctuating signal intensity over approximately 15.9 months, likely depicting disease activity. Conclusions: CE-VWI is important for screening disease activity in moyamoya patients. Our findings demonstrate longitudinal intraindividual reproducibility when normalized to pituitary stalk, enabling quantified evaluation of disease progression through longitudinal vessel wall contrast-enhancement changes.

Background: Assessment of cerebrovascular reserve capacity (CVRC) is central to treatment planning in adult Moyamoya disease. [¹⁵O]-water-PET with acetazolamide challenge (PET-ACZ) serves as the reference standard but is resource-intensive and not universally available, whereas breathhold BOLD MRI (bh-fMRI) may offer a practical noninvasive alternative for screening and triage. Methods: This retrospective diagnostic accuracy study compared bh-fMRI and PET-ACZ in 67 adult MMD patients (1072 ROIs across 402 supratentorial vascular territories) to determine correlation and clinically useful MRI thresholds for impaired cerebrovascular reserve. Data were analyzed using Pearson’s correlation and ROC curves (STARD-compliant). Cerebellum-normalized percent signal change (CN-PSC) was referenced against PET-ACZ < 66% for pathological CVRC. Results: Supratentorial territories showed strong correlation (r = 0.71, 95%CI 0.62–0.80). Optimal diagnostic threshold was <28.2% CN-PSC on bh-fMRI (Youden index; sensitivity 83.8%, specificity 80.9%, AUROC = 0.87); screening threshold < 60% CN-PSC yielded sensitivity 94.6% and NPV 91.1%. No patient factors (age, Suzuki stage, etc.) influenced agreement (univariate/multivariate analyses). Conclusions: Bh-fMRI supplements PET-ACZ as a screening and diagnostic tool for cerebrovascular reserve impairment in adult MMD. PET remains the reference standard for confirmation, especially in intermediate or discordant cases, and the proposed thresholds (60%: monitor) require prospective validation before routine decision-making use.

Background/Objectives: Contralateral disease progression (CDP) in Moyamoya disease (MMD) is a clinically relevant phenomenon, yet difficult to predict. We investigated the association between vessel wall contrast enhancement (VW-CE) and CDP in a European cohort of adult MMD patients with initially unilateral hemodynamic impairment treated with unilateral revascularization. Methods: In this retrospective single-center study, patients with an indication for only unilateral revascularization (based on BOLD fMRI or H₂¹⁵O-PET) were stratified into three subgroups according to contralateral Suzuki grade (0, 1, or ≥2). CDP was defined as secondary contralateral disease progression on imaging with hemodynamic worsening requiring contralateral revascularization during follow-up. Results: Of 158 screened patients, 38 with adequate follow-up were included. CDP occurred in 31.6% (n = 12; 13.6%, 71.4%, and 44.4% in groups 1–3; mean follow-up 2.71 years). In time-to-event analysis, CDP occurred earlier in groups 2 and 3 than in group 1, without reaching significance (log-rank p = 0.078). Patients who later developed CDP more often showed preoperative VW-CE in either hemisphere (90.0% vs. 43.5%, p = 0.021), with consistent but non-significant trends for each hemisphere separately. De novo contralateral VW-CE occurred exclusively in CDP(+) patients (n = 4); contralateral VW-CE overall was significantly more common in CDP(+) than stable patients at the time of CDP (70% vs. 4.3%, p < 0.001). Conclusions: In this exploratory study, contralateral angiographic involvement and preoperative VW-CE were associated with CDP in unilaterally treated MMD patients. De novo contralateral VW-CE may represent a candidate imaging marker of active CDP. Larger multicenter studies are needed to confirm these hypothesis-generating findings.