Transmission Laser Speckle Contrast Imaging Combined With Optical Clearing Using Magnetic Resonance Contrast Agents

Advances in improving existing noninvasive optical diagnostic methods and creating new criteria for assessing the effects of diabetes on tissues and the vascular system are highly demanded. One of the promising, noninvasive and contactless methods for visualizing the vascular system is laser speckle contrast imaging. This study studies the possibility of using magnetic resonance contrast agents in laser speckle contrast imaging and optical coherence tomography, for the first time, on rat ears, under conditions of alloxan-induced type 1 diabetes. By combining diagnostic techniques, the study investigated the ability to differentiate between healthy rat tissue and diabetic rat tissue based on dynamic and structural changes caused by local application of magnetic resonance agents.

This study explores the possibility of using magnetic resonance contrast agents for laser speckle-contrast imaging and optical coherence tomography of rat ears under conditions where alloxan-induced type 1 diabetes mellitus is developing was studied for the first time.

Kinetics of scattering coefficient (µ_s) for healthy and diabetic rats during optical clearing were evaluated. The most significant reduction is seen with the Gadovist solution, showing decreases of 18.6% and 16.1% for healthy and diabetic rats, respectively. Magnevist induced a smaller reduction in the µ_s, with decreases of 12.6% and 6.8%, respectively. Data on the flow rate in the vessels of the ears of laboratory rats obtained in the diabetic group demonstrate reduced indicators, relative to the healthy group of animals.

These results confirm the effectiveness of magnetic resonance contrast agents as optical clearing agents for both optical coherence tomography and laser speckle contrast imaging. For the first time, the nature of the change in the contrast of the static part with a change in scattering was studied. This is an additional application for studying the efficiency of optical clearing, and contributes to the multimodal application of speckle imaging methods.