Computational Aspects of Endoscopic (Trans-rectal) Near-infrared Optical Tomography: Initial Investigations

Endoscopic near-infrared (NIR) optical tomography is a novel approach that allows the blood-based high intrinsic optical contrast to be imaged for the detection of cancer in internal organs. In endoscopic NIR tomography, the imaging array is arranged within the interior of the medium as opposed to the exterior as seen in conventional NIR tomography approaches. The source illuminates outward from the circular NIR probe, and the detector collects the diffused light from the medium surrounding the NIR probe. This new imaging geometry may involve forward and inverse approaches that are significantly different from those used in conventional NIR tomography. The implementation of a hollowcentered forward mesh within the context of conventional NIR tomography reconstruction has already led to the first demonstration of endoscopic NIR optical tomography. This paper presents some fundamental computational aspects regarding the performance and sensitivity of this endoscopic NIR tomography configuration. The NIRFAST modeling and image reconstruction package developed for conventional circular NIR geometry is used for endoscopic NIR tomography, and initial quantitative analysis has been conducted to investigate the “effective” imaging depth, required mesh resolution, and limit in contrast resolution, among other parameters. This study will define the performance expected and may provide insights into hardware requirements needed for revision of NIRFAST for the endoscopic NIR tomography geometry.