Simultaneous white light and laser speckle contrast imaging for in-vivo blood flow imaging during laparoscopic surgery: an alternative to fluorescence-based endoscopy

Real-time intraoperative blood perfusion monitoring is an important aid for avoiding the anastomotic leaks (AL) in laparoscopic ('keyhole') surgery which in turn reduces patients' length of hospitalization and healthcare cost. The occurrence of AL at the rate of 11% to 15% (in rectal surgery, AL also varies with the surgical site) is a burden to patients and the healthcare system. Visualization of intraoperative surgical regions of interest is conducted by intravenous injection of the fluorescent contrast agent - indocyanine green (ICG). However, intravenously ICG administration is limited by non-linear fluorescence intensity with concentration, risk of an allergic reaction, and aggregation in aqueous solution. The fluorescence persists limits the frequency of repeated imaging and real-time assessments. Therefore, an alternative approach allowing label-free visualization would be advantageous. To this end, laser speckle contrast imaging (LSCI) is a potential alternative technique for real-time, label-free, and full-field blood flow monitoring techniques. We have developed a prototype medical device using a commercial rigid endoscope that allowed simultaneous white light imaging as well as blood perfusion monitoring using LSCI. The prototype was assessed for simultaneous white-light endoscopy and flow-monitoring of objects, such as; colored cardboard, a motility standard, occluded fingers, and oral mucosa of the human mouth - all positioned at various distances (e.g., 50mm, 70mm, and 100mm) from endoscope tip. We envision that this bimodal, label-free prototype allowing simultaneous blood flow measurement and white light imaging capability will prove a valuable tool for laparoscopic surgeries.