First prototype of a near infrared tomograph for mapping the myocardial oxygenation in small animal isolated hearts

Over the past decade near infrared spectroscopy (NIRS) and imaging are rapidly evolving for a large number of new clinical applications. These techniques, based upon near-infrared light transmission through biological tissues, aim to monitor the hemoglobin and myoglobin concentration changes due to particular physiological state. Clinical applications regard, for instance, the monitoring of muscles and cerebral oxygenation, functional brain activation studies and heart perfusion research. Recently, some works presented tissue oxygenation studies in beating or arrested isolated small animal hearts. Lately, diffuse optical tomography (DOT) has been developed: it employs tissue arrays of infrared sources and detectors to obtain maps of optical properties of illuminated tissues. In this paper we present the design and realization of a first prototype of a near infrared tomograph for the myocardial perfusion analysis of isolated small animal hearts. Preliminary tests have been performed using some phantoms with different NIR absorption coefficients and an isolated rat heart. The device is able to distinguish objects with different absorption coefficients in the imaging area and to provide 2D map of small animals heart IR light absorption.