Noninvasive observation of vascular leakage induced by focused ultrasound with optical coherence tomography

Focused ultrasound (FUS) is a recently discovered noninvasive technique for local and temporal enhancement of vascular permeability, which facilitates drug delivery from the vessels into the surrounding tissue. However, exposure to FUS at a high intensity may cause permanent damage. In this study, to investigate the effects of the FUS treatment on blood vessels, we proposed to use optical coherence tomography (OCT) for real-time observation. OCT can be implemented for the reconstruction of tissue microstructures. To quantitatively evaluate the morphological changes of the vessels after the FUS exposure with OCT, a new algorithm was proposed to estimate the vessel area, based on the comparison of backscattering properties resulting from the tissue and vascular structures. Results showed that the vessel area increased as the exposed power increased, and the area became significantly larger at a higher FUS exposure power of 10W. In conclusion, OCT observation can be potentially effective for monitoring the outcome and investigating effects of FUS treatment.