Investigation of temporal vascular effects induced by focused ultrasound treatment with speckle-variance optical coherence tomography

Abstract

Focused ultrasound (FUS) can be used to locally and temporally enhance vascular permeability, improving the efficiency of drug delivery from the blood vessels into the surrounding tissue. However, it is difficult to evaluate in real time the effect induced by FUS and to noninvasively observe the permeability enhancement. In this study, speckle-variance optical coherence tomography (SVOCT) was implemented for the investigation of temporal effects on vessels induced by FUS treatment. With OCT scanning, the dynamic change in vessels during FUS exposure can be observed and studied. Moreover, the vascular effects induced by FUS treatment with and without the presence of microbubbles were investigated and quantitatively compared. Additionally, 2D and 3D specklevariance images were used for quantitative observation of blood leakage from vessels due to the permeability enhancement caused by FUS, which could be an indicator that can be used to determine the influence of FUS power exposure. In conclusion, SVOCT can be a useful tool for monitoring FUS treatment in real time, facilitating the dynamic observation of temporal effects and helping to determine the optimal FUS power. Yasufumi, and R. Morishita, "Local delivery of plasmid DNA into rat carotid artery using ultrasound," Circulation 105(10), 1233-1239 (2002

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

“…During this BBB-opened process, transient vessel/capillary dilation has been observed previously via two-photon microscopy, and also contributes to this ultrasound-microbubble interacted mechanical-stress localized amplification on capillary lumen [8,9]. Previously, it has been pointed out that the morphological change was resulted from the mechanical stress due to FUS exposure and the results revealed that such deformation can be identified with OCT [19,20]. Therefore, we proposed to use OCT as a potential tool to in-vivo monitor and evaluate the induced cerebral effects.…”

“…ICR mice (male, 7-8 weeks old) were employed. The experimental procedures are similar to our previous studies [19,20]. Prior to FUS exposure, animals received anesthesia (10% isoflurane); then craniotomy was performed (the cranial bone of 5 mm dimension was removed) in order to eliminate the issue of focal beam aberration and energy distortion caused by skull bone, as well as optical attenuation.…”

Microvascular contrast enhancement in optical coherence tomography using microbubbles

“…These smallest microvessels are difficult to detect otherwise, yet are important of early pathology detection and treatment response monitoring. 31 Further, as MB-based OCT contrast appears to decrease with flow velocity, this methodology may potentially help visualize stationary (no blood flow) conditions as blocked/stagnant microvessels amongst the flowing microvascular network, thus isolating dysfunctional perfusion foci that are otherwise difficult to detect. These findings warrant further investigations in utilizing MB for tissue hemodynamic investigations and for microvasculature contrast enhancement in OCT angiography.…”

Binary dose level classification of tumour microvascular response to radiotherapy using artificial intelligence analysis of optical coherence tomography images

“…The extent of these image pre-processing steps was fairly modest and direct, compared to the more extensive and more subjective set of operations and transformations (e.g., binarization, skeletonization, etc.) that are needed for analytical metrics derivations 9 , 13 – 16 . The resultant microvascular images were then grouped for AI analysis.…”