Noninvasive monitoring of vascular alterations in mice with acute lower limb ischemia using multimodal photoacoustic imaging.

Acute limb ischemia (ALI), especially acute lower limb ischemia (ALLI), is a common clinical vascular emergency with high amputation and mortality rates. However, major challenges exist in rapidly diagnosing and assessing collateral vascular compensatory capacity, leading to appropriate clinical treatment strategies to improve limb preservation and reduce recurrence rates. Traditional imaging methods, such as digital subtraction angiography (DSA) and ultrasound, have high demands on patient kidney function and operator maneuvers and are unable to monitor the temporal and spatial variability of collateral circulation establishment in the limb. In this study, we report the first combined use of real-time and wide-field laser speckle imaging (RFLSI), near-infrared two-zone imaging (NIR-II), duplex ultrasound (DUS), and optical coherence tomography angiography (OCTA) for the diagnosis and monitoring of ALLI in male C57 and ICR mice. The RFLSI assesses overall perfusion, the NIR-II allows rapid diagnosis and monitoring of the establishment of collateral circulation, DUS monitors muscle tenderness and stiffness, and OCTA detects microcirculation in the skin of the limb, which is confirmed by histopathological testing. Overall, the results of this study demonstrate the ability to accurately diagnose and detect ALLI with the help of a variety of optical and acoustic imaging devices, with significant clinical translational implications for intervention in clinical decision-making preoperatively and prognostic assessment postoperatively.