Comparison of quantitative laser speckle contrast and indocyanine green imaging for intestinal perfusion measurements in robot assisted surgery

Abstract

Adequate perfusion is essential to prevent anastomotic leakage in intestinal and rectal surgeries. This study compares Laser Speckle Contrast Imaging (LSCI) and Indocyanine Green Fluorescence Angiography (ICG-FA) for assessing blood flow in intestinal anastomoses during robot-assisted surgeries in pigs. Intestinal perfusion was evaluated in three pigs using LSCI and ICG-FA, before and after clamping the main arterial supply, with measurements taken across ten regions of interest (ROIs). Pearson correlation coefficients were used to compare the two techniques. ROIs were normalized for analysis to facilitate direct comparison of the perfusion patterns. The results showed a strong correlation between the maximum fluorescence intensity from ICG-FA and LSCI values after clamping (r = 0.7293), with comparable perfusion patterns observed post-unclamping. LSCI provides continuous monitoring, while ICG-FA captures contrast-enhanced snapshots, explaining weaker correlations for static values. No significant difference was found in normalized measurements between the two methods. This study supports the use of both LSCI and ICG-FA in clinical practice, highlighting their complementary roles in assessing perfusion during surgeries. Further research is needed to explore their combined utility.

Fig. 1

The intestinal segment held by the Carina™ robot system. Two arms (upper left and right) are used to lift the intestinal tissue. A third arm (center bottom) is used to clamp the arteries.

Fig. 2

Images produced at different phases of image acquisition using LSCI (top) and ICG-FA (bottom). A baseline was recorded for 10 s (A), for LSCI before artery clamping and for ICG with the artery clamped. Ischemia was then introduced for a period of 30 s by clamping the feeding artery (B), Lastly, reperfusion was recorded for the following 30 s by releasing the clamped artery (C).

Fig. 3

Assessment setup. The rectum segment was suspended using robotic arms (A) The segments were assessed with LSCI (B) and ICG-FA(C). ROIs were chosen from left to right along the intestine segment (1–10). D, The LSCI curve for this segment. Different colours represent different ROIs. E, The ICG-FA fluorescence intensity curve for this segment, where different colours represent different ROI.

Fig. 4

Example of extracted laser speckle contrast imaging (LSCI) and indocyanine green fluorescence angiography (ICG-FA) curves. The following parameters can be extracted from the ICG-FA curves: Max fluorescence intensity (Fmax) measured in a.f.u., and ICG-FA slope to 90% of Fmax value (ΔF/Δt 90%). For LSCI, laser speckle pattern analysis, measured in laser speckle perfusion units (LSPU) were extracted. Parameters can be measured before clamp release (b.c.r) and after clamp release (a.c.r).

Fig. 5

Plots of Pearson correlations between several laser speckle contrast imaging (LSCI) and Indocyanine green perfusion angiography (ICG-FA) parameters. ICG delta Fmax correlates strongly to Delta LSCI (r = 0.7293) (A), ICG 90% inflow slope correlates weakly to the delta LSCI value (r = 0.3009) (B), ICG Fmax and Average LSCI before and after unclamping show a moderate correlation (r = 0.6169 and r = 0.6556 respectively (C and D).

Fig. 6

Average normalized delta ICG and delta LSPU values with standard deviation per ROI for both intestinal and rectal perfusion measurements (A). The grey arrows from A to B and the green arrows to C illustrate that each point on the graph represents an ROI (only 5 arrows were drawn towards the LSCI and ICG-FA images respectively, however all 10 ROI for both imaging modalities appear in graph A).