Magnetic Resonance Imaging Evaluation of Photodynamic Therapy with Indocyanine Green in Atherosclerosis Plaques Before and After Gadovist Administration

Background: Singlet oxygen (1O2) generation in biological samples remains a significant challenge. Studying the mechanism of 1O2 action during photodynamic therapy (PDT) in atherosclerotic plaques in vitro represents an innovative cardiological approach. Atherosclerosis, a chronic and progressive disease, is characterized by plaque buildup inside arterial walls. Objectives: This study focused on the use of spin–lattice (T1) and spin–spin (T2) relaxation times measured by Magnetic Resonance Imaging (MRI) before and after the administration of indocyanine green-mediated PDT (ICG-PDT). Methods: To enhance visualization of morphological changes in atherosclerotic plaques, the clinically approved MRI contrast agent Gadovist was utilized. A total of 12 atherosclerotic plaque samples were collected from six patients undergoing endarterectomy. The generation of 1O2 in these plaques was assessed using quantitative MRI measurements and microscopic imaging, which visualized structural changes induced by PDT. Results: This research explores the potential of T1 and T2 relaxation times as indicators of PDT efficacy, while Gadovist helped provide evidence of 1O2 diffusion within the samples. Conclusions: Considering advancements in modern treatment, PDT may offer a novel approach for targeting atherosclerosis.