A Novel Approach Combining Ultrasound-Induced Drug-Free Vasodilation and Photoacoustic Monitoring of Vascular Responses.

Pharmacological vasodilators are widely used to treat vascular disorders, but their systemic nature often leads to undesirable side effects. Moreover, conventional techniques for evaluating vascular responses-including ultrasound and wire myography-suffer from limited resolution or require invasive procedures. This study aimed to develop an integrated platform that overcomes both challenges simultaneously. A high-intensity focused ultrasound (HIFU) transducer was attached to the photoacoustic microscopy (PAM) system for integrated operation. Baseline images of murine ear and abdominal vessels were acquired prior to HIFU exposure. During the subsequent scan, HIFU was applied, while PAM captured the vascular response. As a result, HIFU application induced consistent and localized vasodilation in both the ear and abdominal vessels. PAM visualized the vascular changes, showing vessel diameter increases of approximately 9 to 21%. The integration of HIFU and PAM enables drug-free, localized modulation of vascular tone together with high-resolution in vivo vascular imaging. This integrated platform is intended as a preclinical research tool for studying localized vascular physiology and ultrasound-induced vascular responses without pharmacological intervention.