detection of light images by simple tissues as visualized by photosensitized magnetic resonance imaging检测光的图像通过简单的组织由光敏磁共振成像可视化.pdfVIP

Detection of Light Images by Simple Tissues as Visualized by Photosensitized Magnetic Resonance Imaging 1 2 2 1 Catherine Tempel-Brami , Iddo Pinkas , Avigdor Scherz , Yoram Salomon * 1 Department of Biological Regulation, The Weizmann Institute of Science, Rehovot Israel, 2 Department of Plant Sciences, The Weizmann Institute of Science, Rehovot, Israel In this study, we show how light can be absorbed by the body of a living rat due to an injected pigment circulating in the blood stream. This process is then physiologically translated in the tissue into a chemical signature that can be perceived as an image by magnetic resonance imaging (MRI). We previously reported that illumination of an injected photosynthetic bacteriochlorophyll-derived pigment leads to a generation of reactive oxygen species, upon oxygen consumption in the blood stream. Consequently, paramagnetic deoxyhemoglobin accumulating in the illuminated area induces changes in image contrast, detectable by a Blood Oxygen Level Dependent (BOLD)-MRI protocol, termed photosensitized (ps)MRI. Here, we show that laser beam pulses synchronously trigger BOLD-contrast transients in the tissue, allowing representation of the luminous spatiotemporal profile, as a contrast map, on the MR monitor. Regions with enhanced BOLD-contrast (7-61 fold) were deduced as illuminated, and were found to overlap with the anatomical location of the incident light. Thus, we conclude that luminous information can be captured and translated by typical oxygen exchange processes in the blood of ordinary tissues, and made visible by psMRI (Fig. 1). This process represents a new channel for communicating environmental light into the body in certain analogy to light absorption by visual pigments in the retina where image perception takes place in the central nervous system. Potent