Ultrasound localization microscopy assessment of intraoperative subcortical brain microvasculature in patients undergoing cerebral revascularization

Background Alterations in cerebral microcirculation during revascularization surgery may be associated with neurological outcomes, but methods for assessing subcortical microvasculature remain limited. Ultrasound localization microscopy (ULM) enables microvascular imaging beyond the conventional diffraction limit. We investigated its feasibility during surgery and examined whether measured microvascular changes are associated with clinical outcomes. Methods In this prospective observational study, we analyzed 37 patients with Moyamoya disease who underwent cerebral revascularization at three centers. ULM images were reconstructed from contrast-enhanced ultrasound data acquired before and after bypass surgery. Vessel density, velocity, diameter, tortuosity and length were quantified. Associations between perioperative changes in ULM parameters and complications or neurological outcomes were assessed using multivariable logistic regression, correlation analysis, receiver operating characteristic analysis, and generalized estimating equations. Results Here, we show that intraoperative ULM enables visualization and quantitative assessment of subcortical cerebral microvasculature. Greater increases in vessel density and greater reductions in vessel velocity are independently associated with perioperative complications after adjustment for clinical covariates (adjusted odds ratios, 1.24 and 0.58, respectively). Both parameters show good discrimination for perioperative complications, with optimism-corrected areas under the curve of 0.93 and 0.90, respectively. Greater reductions in vessel velocity are also associated with poorer functional outcomes over 6-24 months of follow-up (adjusted odds ratio, 0.966). Conclusions Intraoperative ULM enables quantitative assessment of subcortical cerebral microcirculation and may provide clinically relevant information for perioperative risk stratification and long-term prognostic assessment.