Lightweight Head-Mounted Optical Coherence Tomography Scope for Longitudinal, Intact-Skull Imaging of Ischemic Stroke in Freely Behaving Mouse

Understanding the dynamic progression of an ischemic stroke under physiologically relevant conditions is essential for advancing therapeutic strategies. Here, we present a miniaturized, lightweight (1.5 g), head-mounted Doppler optical coherence tomography system capable of high-resolution, high-speed imaging through the intact skull in freely behaving mice. The system enables real-time monitoring of cerebral vasculature and structural dynamics without the need for invasive cranial window implantation. Using a permanent middle cerebral artery occlusion (pMCAo) model, we conducted longitudinal imaging of stroke progression across multiple time points: baseline, immediately post-surgery within 3 h, and at days 1 and 2 post-pMCAo. Volumetric angiography (OCTA) allowed depth-resolved vascular mapping, and comparative analysis of anesthetized versus freely moving conditions revealed activity-dependent changes in microvascular flow. Moreover, K-means-based segmentation was applied to quantify blood vessel density (BVD) across nine cortical regions of interest for a more accurate and robust analysis compared with that of the traditional method. BVD declined post-pMCAo and showed region-specific recovery trends, with some areas demonstrating reperfusion and new vessel formation by day 2. Structural OCT also revealed cortical shrinkage following a stroke, with partial recovery observed over time. This study represents the first demonstration of OCT imaging in freely moving ischemic stroke models and provides new insights into vascular and structural responses under natural behavior. Our findings underscore the utility of head-mounted OCT systems for studying cerebrovascular diseases in a minimally invasive, longitudinal, and behaviorally relevant contextlaying the foundation for future stroke research and therapeutic evaluation.