Quantitative fluorescence angiography versus hyperspectral imaging to assess bowel ischemia: A comparative study in enhanced reality

Abstract

BackgroundFLuorescence-based Enhanced Reality (FLER) is a software providing quantitative fluorescence angiography (FA), by computing the fluorescence intensity time-to-peak (TTP), after intravenous injection of indocyanine green (ICG). HSI is a contrast-free optical imaging modality, which measures tissue oxygenation (StO 2 ). MethodsIn 8 pigs, an ischemic bowel segment was created by dividing the arcade branches and imaged using HSI and FLER. StO 2 values were acquired through a hyperspectral imaging (HSI) system. Subsequently, FA was performed using a nearinfrared laparoscopic camera, after intravenous injection of 0.2mg/kg of ICG. The TTP fluorescence signal was analyzed through a proprietary software to realize a perfusion map. This was overlaid onto real-time images to obtain FLER. Simultaneously, nine adjacent regions of interest (ROIs) were selected and superimposed onto the real-time video obtaining HYperspectral-based Enhanced Reality (HYPER). FLER and HYPER were superimposed allowing a comparison of both imaging modalities. Local capillary lactates (LCL) were sampled at the ROIs. Two LCL prediction models were extrapolated based on both imaging. ResultsFor all ROIs mean LCL measured 4.67 ± 4.34 mmol/L, mean StO 2 45.92 ± 18.59%, and mean TTP 10.33 ± 9.36 sec. Pearson's test between FLER-TTP and HSI-StO2 at the corresponding ROIs gave an R=-0.66 (p<0.0001). The HSI lactate prediction model proved significantly more accurate than the FLER-based one (p<0.0001). Powered by Editorial Manager® and ProduXion Manager® from Aries Systems Corporation ConclusionBowel perfusion was clearly quantified using HSI and FA. HSI yielded more accurate results than FA. HYPER might become a useful intraoperative tool to quantify bowel ischemia in a contrast-free fashion.

Hyperspectral evaluation of hepatic oxygenation in a model of total vs. arterial liver ischaemia

“…In addition, HSI has been successfully applied as a tool to discriminate healthy from pathological tissue and for the quantification of organ perfusion level in both preclinical and clinical settings 12 – 14 . The ability of the HSI system to evaluate the liver oxygenation was already assessed and applied by our group in an intraoperative setting to create hyperspectral enhanced reality (HYPER) in liver anatomical resection 15 – 17 . However, doubts remained as to whether or not the system could discriminate different types of hepatic vascular occlusions.…”

“…Correlation between capillary lactate and StO 2 % HSI preset parameters was used as a primary outcome to compute sample size. The calculation was based on previous publications on bowel ischaemia, which showed a ρ correlation coefficient of − 0.7 16 , 32 . The required paired values were 4, considering α = 0.05 with a power (1 − β) = 0.9.…”

A Novel Technique to Improve Anastomotic Perfusion Prior to Esophageal Surgery: Hybrid Ischemic Preconditioning of the Stomach. Preclinical Efficacy Proof in a Porcine Survival Model

“…Similarly, the results of the present study unequivocally demonstrate that IGP, applied 3 weeks prior to gastric tubulation, improves mucosal and serosal perfusion at the GCF, assessed by means of quantitative optical imaging technologies. These findings are supported by LCL levels, which are a robust surrogate of perfusion in the porcine digestive tract [ 19 , 20 , 21 , 22 , 24 , 26 , 31 ]. Additionally, the presence of incremented vessels and inflammatory cells (eosinophils) in both IGP groups represents an indirect sign of neovascularization [ 32 , 33 ].…”

“…Successively, an intravenous injection of 0.2 mg/kg of indocyanine green (ICG) (Infracyanine ® , Serb, Paris, France) was administered, and a fluorescence angiography was performed, using a full HD 30-degree near-infrared (NIR) laparoscope (D-Light P, KARL STORZ, Tuttlingen, Germany). The fluorescent signal was quantified using the previously described ER-PERFUSION software (IRCAD, Strasbourg, France), which allows to compute perfusion as time-to-peak (TTP) of the signal evolution pixel-by-pixel [ 20 , 22 , 46 ]. TTP results from the velocity of the fluorescence signal until it reaches its maximal intensity peak within the first 40 s following fluorophore injection, and it is expressed in seconds.…”

“…Hyperspectral imaging (HSI) is another intraoperative optical imaging modality, which allows for contrast-free tissue oxygen quantification. HSI has proven accurate in assessing intestinal perfusion intraoperatively [ 21 , 22 ]. However, both FLER and HSI allow blood flow estimation exclusively at the serosal side.…”