Assessment of temporary cerebral effects induced by focused ultrasound with optical coherence tomography angiography

Abstract

Focused ultrasound (FUS) in combination with microbubbles temporally and locally increases the permeability of the blood-brain barrier (BBB) for facilitating drug delivery. However, the temporary effects of FUS on the brain microstructure and microcirculation need to be addressed. We used label-free optical coherence tomography (OCT) and OCT angiography (OCTA) to investigate the morphological and microcirculation changes in mouse brains due to FUS exposure at different power levels. Additionally, the recovery progress of the induced effects was studied. The results show that FUS exposure causes cerebral vessel dilation and can be identified and quantitatively analyzed via OCT/OCTA. Micro-hemorrhages can be detected when an excessive FUS exposure power is applied, causing the degradation of OCTA signal owing to strong scattering by leaked red blood cells (RBCs) and weaker backscattered intensity from RBCs in vessels. The vessel dilation effect due to FUS exposure was found to abate in several hours. This study demonstrates that the FUS-induced cerebral transiently dilated effects can be differentiated and monitored with OCTA, and shows the feasibility of using OCT/OCTA as a novel tool for long-time monitoring of cerebral vascular dynamics during FUS-BBB opening process.

In vivo detection of UV-induced acute skin effects using optical coherence tomography

“…Then, the measured mouse skin thicknesses at these twenty-one transverse locations in each 2D OCT image were averaged to obtain a mean value of skin thickness. Additionally, the method for estimating the vessel density is similar to that in the previous report [ 27 ]. Three subareas in each OCTA image for each group (as marked by colored squares in Figs.…”

“…C: collimator; DC: dispersion compensator; M: mirror; G: two-axis galvanometer; SL: scanning lens. [ 27 ]. A 1060-nm swept source (SSOCT-1060, AXSUN Technologies Inc., MA, USA) with a scanning bandwidth of 100 nm was utilized, corresponding to a longitudinal resolution of 5 μm in air.…”

Focused Ultrasound Combined with Microbubbles in Central Nervous System Applications

“…Faster dextran accumulation (which occurred instantaneously with BBB disruption) was found to be accompanied with absolute and immediate BBB disruption, whereas slower dextran accumulation (5–15 min postsonication) occurred over a wide range of ultrasound intensities [ 29 , 30 ]. Tsai et al recently used swept-scan optical coherence tomography and real-time 3D angiography to reveal transient cerebral vessel dilation during FUS-BBBO, where the degree of vessel dilation was correlated with the FUS intensity [ 31 ].…”