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Detecting important anatomic structures including ureters and mesenteric vessels is of utmost importance to preventing unintended injury, facilitating intraoperative decision making, and potentially reducing operative time, in minimally invasive procedures performed in the abdomen. Diffuse reflectance spectroscopy (DRS) has been investigated previously for augmenting surgeon’s knowledge of tissue types intraoperatively. The potential of detecting a hollow structure by DRS is not only bounded by the parametric differences between that hollow structure and peripheral tissues including solid organs, but also determined by the relative scale between the hollow structure and the sampling depth of the probe. We have developed an applicator-probe with a 10mm source-detector distance that can be mounted on an 8mm laparoscopic instrument and passed through a 12mm trocar port for laparoscopic operability. The 10mm source-detector separation of this laparoscopically adaptable applicator probe renders sampling depth of a few millimeters for the potential of better discrimination between a hollow structure and a solid tissue parenchyma. DRS using this applicator-probe was performed on a number of hollow structures and solid organs intraoperatively in pigs. The hollow structures included urinary bladder, ureter, large intestine, small intestine, stomach, gallbladder, and mesenteric vessel. The solid organs or tissues included kidney, liver, and ovary. The ratio between the model-based normalized DRS signals at 700nm and 800nm was used as an index. An index value of 1 separates the hollow structures including ureter, bladder, and stomach (between 1 and 2) from other hollow structures including intestines and mesenteric vessel and solid organs (less than 0.7).
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