QS105 - Preclinical Quantification of Laser Speckle Contrast Imaging for Bowel Perfusion Assessment

Purpose/Background:

Introduction: The aim of this study was to assess real time interpretability and validation of laser speckle contrast imaging (LSCI)-derived colormaps for the indication and discrimination between ischemic and well perfused bowel tissue using the PerfusiX-Imaging device (LIMIS Development BV, Leeuwarden, The Netherlands).

Methods/Interventions:

Methods: A total of 15 small bowel loops of 15 cm long were visualized in four Landrace pigs, performed via laparotomy under general anesthesia. In each loop, a minimum of eight adjacent mesenterial arteries were identified and ligated to create a gradual ischemic loop. The LSCI-based PerfusiX-Imaging device (LIMIS Development BV, Leeuwarden, The Netherlands) was attached to an Olympus S190 laparoscopic video system (Olympus, Hamburg, Germany) to create the LSCI-based colormaps. The surgeon indicated and marked ischemic, well perfused and transition areas based on the colormaps. Multiple LSCI recordings were made over a time span of 120 minutes. At each measurement, local and systemic capillary lactate levels were registered to confirm the state of perfusion. Statistical analyses were performed on the correlation between local lactate and LSCI levels and differences between well and poor perfused areas. In addition, cut-off values were calculated for laser speckle perfusion units (LSPU) values.

Results/Outcomes:

Results: Differences in LSPU values between ischemic and well perfused tissue were significant (p < 0.001 (66.8 [A.U.], 95% CI [57.3-76.3] vs 94.7, 95% CI [85.3-103.9]) directly after ligation of the arteries and remained significant throughout all following measurements. Lactate levels were significantly different (p < 0.001) at both 60 minutes (10.2 mmol/L, 95% CI [9.4-11.0] vs 1.9mmol/L, 95% CI [1.7-2.2]) and 120 minutes (8.1 mmol/L, 95% CI [6.7-9.6] vs 2.3 mmol/L 95% CI [1.9-2.8]) measurements. Logarithmic Curve Estimation showed a R2 value of 0.581 between LSPU-values and lactate levels. With ischemic and well perfused areas selected based on the colormap produced by PerfusiX-Imaging, a capillary lactate cut-off value of 3.7 mmol/L was found, with a sensitivity and specificity of 0.97 and 1.0 respectively. LSPU values showed a cut off value of 69 with a sensitivity and specificity of 0.94 and 0.87 respectively (Figure 1).

Conclusion/Discussion:

Conclusion: PerfusiX-Imaging allows for real time visualization of quantitative perfusion measurement during laparoscopic procedures. The system is capable of discriminating between ischemic and well perfused areas. This makes laparoscopic use of LSCI a feasible option for real time perfusion assessment. Lactate cut-off values are in concordance with existing literature, indicating accurate identification of regions using LSCI.