Ultrasonographic assessment of bypass capacity after revascularization surgery in moyamoya disease: a systematic review and single-arm meta-analysis
Bibliographic record
Abstract
PURPOSE: Moyamoya disease (MMD) is a chronic cerebrovascular disorder characterized by progressive arterial stenosis and fragile collateral formation, elevating stroke risk. Revascularization is the standard treatment, yet up to 27% of patients experience ischemic events within a year due to bypass insufficiency. While digital subtraction angiography (DSA) remains the gold standard for assessing bypass function, it is invasive and time-consuming. This study evaluates ultrasonography (US) as a noninvasive, cost-effective tool to assess bypass capacity post-revascularization in MMD. METHODS: A systematic search was conducted following PRISMA guidelines. PubMed, Web of Science, and Scopus were searched for studies reporting US parameters with control imaging confirming bypass capacity. Study quality was assessed using the Newcastle-Ottawa Scale. Mean difference (MD) values were calculated using random-effects models. High bypass capacity was defined as good patency or favorable collateral development. RESULTS: Eight cohort studies comprising 264 MMD patients and 301 operated hemispheres were included, with 180 demonstrating high bypass capacity. Within two weeks post-surgery, increased superficial temporal artery (STA) peak systolic velocity (PSV, MD = 28.26, p < 0.0001), mean flow velocity (MFV, MD = 22.97, p = 0.03), end-diastolic velocity (EDV, MD = 33.45, p < 0.0001), and decreased resistance index (RI, MD = -0.09, p = 0.006) were predictive. External carotid artery (ECA) EDV (MD = 13.92, p = 0.04) was also significant. At 3-6 months, elevated EDV in both STA (MD = 8.13, p = 0.006) and ECA (MD = 8.71, p = 0.0002) remained predictive. In the indirect subgroup, lower anterior cerebral artery (ACA) MFV within 0-3 months predicted favorable outcomes (MD = -64.98, p = 0.001). CONCLUSIONS: Changes in STA and ECA US parameters measured following revascularization surgery predict high bypass capacity. Decreased ACA MFV suggests effective revascularization after indirect surgery. Ultrasound modality offers a valuable, noninvasive tool for postoperative assessment in MMD.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.009 | 0.023 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.016 | 0.024 |
| Bibliometrics | 0.005 | 0.006 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".