The intraoperative assessment of intestinal tissue viability with modern optical technologies

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Abstract
Purpose . To improve the accuracy of diagnosing microcirculation disorders in the intestinal wall tissues in small laboratory animals by introducing hyperspectral imaging in combination with a controlled polychrome LED light source. Materials and methods. 10 clinically healthy Wistar rats were used in the study. Intestinal ischemia was modeled by the ligation of mesenteric vessels after laparotomy under inhalation anesthesia. Relaparotomy was performed in 1, 6 and 12 hours. The viability of intestinal tissues and the identifi cation of secondary pathological changes were assessed with the visual Kerte method and a polychrome LED light source providing contrast visualization of biological tissues. Intestinal wall perfusion was assessed by the hyperspectral imaging system. Intestinal resection followed by the sampling for morphological examination was made according to time intervals established by the examination protocol. Results. Spectral composition of the light source, which reliably detects the intestinal wall necrosis, includes two spectral lines with maxima of λpeak = 503 nm and λpeak = 594 nm at 2:1 intensity ratio. Hyperspectral imaging allowed to get two-dimensional maps of tissue saturation with the following values: 66 ± 2 % (intact tissue), 42 ± 5 % (1 hour), 26 ± 3 % (6 hours) and 21 ± 3 % (12 hours). The performed morphological analysis revealed three key ischemic intervals: 1 hour (ischemia onset), 6 hours (reversible ischemia) and 12 hours (irreversible necrosis). The obtained data confi rm the signifi cant decrease in saturation which correlates with morphological changes, and the effectiveness of the discussed technique for assessing the viability of intestinal tissues. Conclusion . In the course of the study, the authors have developed a technology for optimizing the lighting during surgery so as to improve contrast imaging of ischemic and necrotic tissue changes. Hyperspectral imaging promotes non-invasive and objective intraoperative assessment of the ischemic damage in the intestinal wall without any exogenous fl uorescent drugs. The obtained results also demonstrate the prospects of introducing optimized lighting and hyperspectral imaging into clinical practice so as to improve diagnosis and surgical treatment of ischemic intestinal lesions.

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