Laser speckle contrast imaging and quantitative fluorescence angiography for perfusion assessment

Dye-less quantification of tissue perfusion by laser speckle contrast imaging is equivalent to quantified indocyanine green in a porcine model

INTRODUCTION

Subjective surgeon interpretation of near-infrared perfusion video is limited by low inter-observer agreement and poor correlation to clinical outcomes. In contrast, quantification of indocyanine green fluorescence video (Q-ICG) correlates with histologic level of perfusion as well as clinical outcomes. Measuring dye volume over time, however, has limitations, such as it is not on-demand, has poor spatial resolution, and is not easily repeatable. Laser speckle contrast imaging quantification (Q-LSCI) is a real-time, dye-free alternative, but further validation is needed. We hypothesize that Q-LSCI will distinguish ischemic tissue and correlate over a range of perfusion levels equivalent to Q-ICG.

METHODS

Nine sections of intestine in three swine were devascularized. Pairs of indocyanine green fluorescence imaging and laser speckle contrast imaging video were quantified within perfused, watershed, and ischemic regions. Q-ICG used normalized peak inflow slope. Q-LSCI methods were laser speckle perfusion units (LSPU), the base unit of laser speckle imaging, relative perfusion units (RPU), a previously described methodology which utilizes an internal control, and zero-lag normalized cross-correlation (X-Corr), to investigate if the signal deviations convey accurate perfusion information. We determine the ability to distinguish ischemic regions and correlation to Q-ICG over a perfusion gradient.

RESULTS

All modalities distinguished ischemic from perfused regions of interest; Q-ICG values of 0.028 and 0.155 (p < 0.001); RPU values of 0.15 and 0.68 (p < 0.001); and X-corr values of 0.73 and 0.24 (p < 0.001). Over a range of perfusion levels, RPU had the best correlation with Q-ICG (r = 0.79, p < 0.001) compared with LSPU (r = 0.74, p < 0.001) and X-Corr (r = 0.46, p < 0.001).

CONCLUSION

These results demonstrate that Q-LSCI discriminates ischemic from perfused tissue and represents similar perfusion information over a broad range of perfusion levels comparable to clinically validated Q-ICG. This suggests that Q-LSCI might offer clinically predictive real-time dye-free quantification of tissue perfusion. Further work should include validation in histologic studies and human clinical trials.

Real-time quantification of laser speckle contrast imaging during intestinal laparoscopic surgery: successful demonstration in a porcine intestinal ischemia model

BACKGROUND

Anastomotic leakage (AL) is a dreaded complication following colorectal cancer surgery, impacting patient outcome and leads to increasing healthcare consumption as well as economic burden. Bowel perfusion is a significant modifiable factor for anastomotic healing and thus crucial for reducing AL.

AIMS

The study aimed to calculate a cut-off value for quantified laser speckle perfusion units (LSPUs) in order to differentiate between ischemic and well-perfused tissue and to assess inter-observer reliability.

METHODS

LSCI was performed using a porcine ischemic small bowel loop model with the PerfusiX-Imaging® system. An ischemic area, a well-perfused area, and watershed areas, were selected based on the LSCI colormap. Subsequently, local capillary lactate (LCL) levels were measured. A logarithmic curve estimation tested the correlation between LSPU and LCL levels. A cut-off value for LSPU and lactate was calculated, based on anatomically ischemic and well-perfused tissue. Inter-observer variability analysis was performed with 10 observers.

RESULTS

Directly after ligation of the mesenteric arteries, differences in LSPU values between ischemic and well-perfused tissue were significant (p < 0.001) and increased significantly throughout all following measurements. LCL levels were significantly different (p < 0.001) at both 60 and 120 min. Logarithmic curve estimation showed an R2 value of 0.56 between LSPU and LCL values. A LSPU cut-off value was determined at 69, with a sensitivity of 0.94 and specificity of 0.87. A LCL cut-off value of 3.8 mmol/L was found, with a sensitivity and specificity of 0.97 and 1.0, respectively. There was no difference in assessment between experienced and unexperienced observers. Cohen's Kappa values were moderate to good (0.52-0.66).

CONCLUSION

Real-time quantification of LSPUs may be a feasible intraoperative method to assess tissue perfusion and a cut-off value could be determined with high sensitivity and specificity. Inter-observer variability was moderate to good, irrespective of prior experience with the technique.

Intraoperative evaluation of local cerebral hemodynamic change by laser speckle contrast imaging for predicting postoperative cerebral hyperperfusion during STA-MCA bypass in adult patients with moyamoya disease

Cerebral hyperperfusion (CHP) occurred frequently after direct superficial temporal artery-middle cerebral artery (STA-MCA) bypass surgery for moyamoya disease (MMD). We analyzed cortical microvascular density (CMD) and the change of cerebral blood flow (LΔCBF) using intraoperative laser speckle contrast imaging (LSCI) on 130 hemispheres of 95 consecutive adult patients with MMD. The demographic characteristics, cortical hemodynamic sources, bypass methods, intraoperative blood flow data, and relative CBF changes on single-photon emission computed tomography (SPECT) examination (SΔrCBF) were compared between the groups with and without CHP. The median values for CMD, LΔCBF, and SΔrCBF were significantly higher in the CHP group than in the non-CHP group (CMD 0.240 vs 0.206, P = 0.004; LΔCBF 2.285 vs 1.870, P < 0.001; SΔCBF 1.535 vs 1.260, P < 0.001). Multivariate analysis revealed that hemodynamic sources of recipient parasylvian cortical arteries from MCA (M-PSCAs), end-to-side (E-S) bypass method, CMD ≥ 0.217, and LΔCBF ≥ 1.985 were the risk factors for CHP. Intraoperative LSCI was useful for evaluating hemodynamics and predicting CHP in patients with MMD.

Perfusion Mapping of Flaps Using Indocyanine Green Fluorescence Angiography and Laser Speckle Contrast Imaging

Background

Indocyanine green fluorescence angiography (ICG-FA) is often used for assessing tissue circulation in reconstructive surgery. Indocyanine green (ICG) is injected intravenously and visualized in the tissue with an infrared camera. The information is used to plan the surgery, for example, in free flap breast reconstructions. Laser speckle contrast imaging (LSCI) is another method that uses laser to assess tissue perfusion in the skin. Unlike ICG-FA, LSCI is noninvasive and may therefore have an advantaged compared with ICG-FA. The aim of this study was to evaluate the correlation between information obtained from these two techniques.

Methods

Five deep inferior epigastric perforator patients were included. The flaps were assessed with LSCI and ICG-FA. For LSCI, the perfusion was calculated in 32 regions of interest. For ICG-FA, the maximum slope and area under curve (AUC) were calculated based on average pixel intensity data.

Results

Large variations in maximum slope values could be seen between flaps, whereas AUC had lower variability within the same flap and between flaps. Pearson rank correlation comparing average perfusion (LSCI) and AUC (ICG-FA) showed a correlation between the values (r = 0.55, P < 0.0001). No significant correlation was observed between perfusion and maximum slope (r = 0.11, P = 0.18).

Conclusions

There is a significant correlation between data obtained using LSCI and ICG-FA, when ICG-FA data are presented as AUC of the ICG-FA intensity curve. Maximum slope lacks significant correlation with flap data obtained with LSCI. The study indicates that LSCI may be used in reconstructive surgery to assess tissue circulation in a way similar to ICG-FA.

Blinded Intraoperative Quantitative Indocyanine Green Metrics Associate With Intestinal Margin Acceptance in Colorectal Surgery

BACKGROUND

Indocyanine green is a useful tool in colorectal surgery. Quantitative values may enhance and standardize its application.

OBJECTIVE

To determine whether quantitative indocyanine green metrics correlate with standard subjective indocyanine green perfusion assessment in acceptance or rejection of anastomotic margins.

DESIGN

Prospective single-arm, single-institution cohort study. Surgeons viewed subjective indocyanine green images but were blinded to quantitative indocyanine green metrics.

SETTING

Tertiary academic center.

PATIENTS

Adults undergoing planned intestinal resection.

MAIN OUTCOME MEASURES

Accepted perfusion and rejected perfusion of the intestinal margin were defined by the absence or presence of ischemia by subjective indocyanine green and gross inspection. The primary outcomes included quantitative indocyanine green values, maximum fluorescence, and time-to-maximum fluorescence in accepted compared to rejected perfusion. Secondary outcomes included maximum fluorescence and time-to-maximum fluorescence values in anastomotic leak.

RESULTS

There were 89 perfusion assessments comprising 156 intestinal segments. Nine segments were subjectively assessed to have poor perfusion by visual inspection and subjective indocyanine green. Maximum fluorescence (% intensity) exhibited higher intensity in accepted perfusion (accepted perfusion 161% [82%-351%] vs rejected perfusion 63% [10%-76%]; p = 0.03). Similarly, time-to-maximum fluorescence (seconds) was earlier in accepted perfusion compared to rejected perfusion (10 seconds [1-40] vs 120 seconds [90-120]; p < 0.01). Increased BMI was associated with higher maximum fluorescence. Anastomotic leak did not correlate with maximum fluorescence or time-to-maximum fluorescence.

LIMITATIONS

Small cohort study, not powered to measure the association between quantitative indocyanine green metrics and anastomotic leak.

CONCLUSIONS

We demonstrated that blinded quantitative values reliably correlate with subjective indocyanine green perfusion assessment. Time-to-maximum intensity is an important metric in perfusion evaluation. Quantitative indocyanine green metrics may enhance intraoperative intestinal perfusion assessment. Future studies may attempt to correlate quantitative indocyanine green values with anastomotic leak. See Video Abstract .

LAS MTRICAS CUANTITATIVAS INTRAOPERATORIAS CIEGAS DEL VERDE DE INDOCIANINA SE ASOCIAN CON LA ACEPTACIN DEL MARGEN INTESTINAL EN LA CIRUGA COLORRECTAL

ANTECEDENTES:El verde de indocianina es una herramienta útil en la cirugía colorrectal. Los valores cuantitativos pueden mejorar y estandarizar su aplicación.OBJETIVO:Determinar si las métricas cuantitativas de verde de indocianina se correlacionan con la evaluación subjetiva estándar de perfusión de verde de indocianina en la aceptación o rechazo de los márgenes anastomóticos.DISEÑO:Estudio de cohorte prospectivo de un solo brazo y de una sola institución. Los cirujanos vieron imágenes subjetivas de verde de indocianina, pero no conocían las métricas cuantitativas de verde de indocianina.AJUSTE:Centro académico terciario.PACIENTES:Adultos sometidos a resección intestinal planificada.PRINCIPALES MEDIDAS DE RESULTADO:La perfusión aceptada y la perfusión rechazada del margen intestinal se definieron por la ausencia o presencia de isquemia mediante verde de indocianina subjetiva y la inspección macroscópica. Los resultados primarios fueron los valores cuantitativos de verde de indocianina, la fluorescencia máxima y el tiempo hasta la fluorescencia máxima en la perfusión aceptada en comparación con la rechazada. Los resultados secundarios incluyeron la fluorescencia máxima y el tiempo hasta alcanzar los valores máximos de fluorescencia en la fuga anastomótica.RESULTADOS:Se realizaron 89 evaluaciones de perfusión, comprendiendo 156 segmentos intestinales. Se evaluó subjetivamente que 9 segmentos tenían mala perfusión mediante inspección visual y verde de indocianina subjetiva. La fluorescencia máxima (% de intensidad) mostró una mayor intensidad en la perfusión aceptada [Perfusión aceptada 161% (82-351) vs Perfusión rechazada 63% (10-76); p = 0,03]. De manera similar, el tiempo hasta la fluorescencia máxima (segundos) fue más temprano en la perfusión aceptada en comparación con la rechazada [10 s (1-40) frente a 120 s (90-120); p < 0,01]. Aumento del índice de masa corporal asociado con una fluorescencia máxima más alta. La fuga anastomótica no se correlacionó con la fluorescencia máxima ni con el tiempo hasta la fluorescencia máxima.LIMITACIONES:Estudio de cohorte pequeño, sin poder para medir la asociación entre las mediciones cuantitativas del verde de indocianina y la fuga anastomótica.CONCLUSIÓN:Demostramos que los valores cuantitativos ciegos se correlacionan de manera confiable con la evaluación subjetiva de la perfusión de verde de indocianina. El tiempo hasta la intensidad máxima es una métrica importante en la evaluación de la perfusión. Las métricas cuantitativas de verde de indocianina pueden mejorar la evaluación de la perfusión intestinal intraoperatoria. Los estudios futuros pueden intentar correlacionar los valores cuantitativos de verde de indocianina con la fuga anastomótica. (Traducción-Dr. Yolanda Colorado).

Dye-free visualisation of intestinal perfusion using laser speckle contrast imaging in laparoscopic surgery: a prospective, observational multi-centre study

INTRODUCTION

Intraoperative perfusion imaging may help the surgeon in creating the intestinal anastomoses in optimally perfused tissue. Laser speckle contrast imaging (LSCI) is such a perfusion visualisation technique that is characterized by dye-free, real-time and continuous imaging. Our aim is to validate the use of a novel, dye-free visualization tool to detect perfusion deficits using laparoscopic LSCI.

METHODS

In this multi-centre study, a total of 64 patients were imaged using the laparoscopic laser speckle contrast imager. Post-operatively, surgeons were questioned if the additional visual feedback would have led to a change in clinical decision-making.

RESULTS

This study suggests that the laparoscopic laser speckle contrast imager PerfusiX-Imaging is able to image colonic perfusion. All images were clear and easy to interpret for the surgeon. The device is non-disruptive of the surgical procedure with an average added surgical time of 2.5 min and no change in surgical equipment. The potential added clinical value is accentuated by the 17% of operating surgeons indicating a change in anastomosis location. Further assessment and analysis of both white light and PerfusiX perfusion images by non-involved, non-operating surgeons showed an overall agreement of 80%.

CONCLUSION

PerfusiX-Imaging is a suitable laparoscopic perfusion imaging system for colon surgery that can visualize perfusion in real-time with no change in surgical equipment. The additional visual feedback could help guide the surgeons in placing the anastomosis at the most optimal site.

Correlation between Indocyanine Green Fluorescence Angiography and Laser Speckle Contrast Imaging in a Flap Model

Background

Indocyanine green fluorescence angiography (ICG-FA) is used to assess tissue intraoperatively in reconstructive surgery. This requires an intra-venous dye injection for each assessment. This is not necessary in laser speckle contrast imaging (LSCI); therefore, this method may be better suited for tissue evaluation. To determine this, we compared the two methods in a porcine flap model.

Methods

One random and one pedicled flap were raised on each buttock of six animals. They were assessed with LSCI at baseline, when raised (T0), at 30 minutes (T30) and with ICG-FA at T0 and T30. Regions of interest (ROI) were chosen along the flap axis. Perfusion, measured as perfusion units (PU) in the LSCI assessment and pixel-intensity for the ICG-FA video uptake, was calculated in the ROI. Correlation was calculated between PU and pixel-intensity measured as time to peak (TTP) and area under curve for 60 seconds (AUC60).

Results

Correlation between LSCI and AUC60 for the ICG-FA in corresponding ROI could be seen in all flaps at all time points. The correlation was higher for T0 (r=0.7 for random flap and r=0.6 for pedicled flap) than for T30 (r=0.57 for random flap and r=0.59 for pedicled flap). Even higher correlation could be seen PU and TTP (T0: random flap r=-0.8 and pedicled flap r=0.76. T30: random flap r=-0.8 and pedicled flap r=0.71).

Conclusion

There is a correlation between PU from LSCI and TTP and AUC60 for ICG-FA, indicating that LSCI could be considered for intraoperative tissue assessment.

Real-time quantification of bowel perfusion using Laparoscopic Laser Speckle Contrast Imaging (LSCI) in a porcine model

BACKGROUND/PURPOSE

Real-time quantification of tissue perfusion can improve intraoperative surgical decision making. Here we demonstrate the utility of Laser Speckle Contrast Imaging as an intra-operative tool that quantifies real-time regional differences in intestinal perfusion and distinguishes ischemic changes resulting from arterial/venous obstruction.

METHODS

Porcine models (n = 3) consisted of selectively devascularized small bowel loops that were used to measure the perfusion responses under conditions of control/no vascular occlusion, arterial inflow occlusion, and venous outflow occlusion using laser speckle imaging and indocyanine green fluoroscopy. Laser Speckle was also used to assess perfusion differences between small bowel antimesenteric-antimesenteric and mesenteric-mesenteric anastomoses. Perfusion quantification was measured in relative perfusion units calculated from the laser speckle perfusion heatmap.

RESULTS

Laser Speckle distinguished between visually identified perfused, watershed, and ischemic intestinal segments with both color heatmap and quantification (p < .00001). It detected a continuous gradient of relative intestinal perfusion as a function of distance from the stapled ischemic bowel edge. Strong positive linear correlation between relative perfusion units and changes in mean arterial pressure resulting from both arterial (R2 = .96/.79) and venous pressure changes (R2 = .86/.96) was observed. Furthermore, Laser Speckle showed that the antimesenteric anastomosis had a higher perfusion than mesenteric anastomosis (p < 0.01).

CONCLUSIONS

Laser Speckle Contrast Imaging provides objective, quantifiable tissue perfusion information in both color heatmap and relative numerical units. Laser Speckle can detect spatial/temporal differences in perfusion between antimesenteric and mesenteric borders of a bowel segment and precisely detect perfusion changes induced by progressive arterial/venous occlusions in real-time.

Indocyanine Green (ICG) and Colorectal Surgery: A Literature Review on Qualitative and Quantitative Methods of Usage

Background: Due to its many benefits, indocyanine green (ICG) has gained progressive popularity in operating rooms (ORs) globally. This literature review examines its qualitative and quantitative usage in surgical treatment. Method: Relevant terms were searched in five international databases (1. Pubmed, 2. Sciencedirect, 3. Scopus, 4. Oxfordjournals, 5. Reaxys) for a comprehensive literature review. The main benefits of using ICG in colorectal surgery are: intraoperative fluorescence angiography; fluorescence-guided lymph node involvement detection and the sentinel technique; the fluorescent emphasis of a minute liver tumour, counting just 200 tumour cells; facilitation of fistula diagnosis; and tumour tattooing. This methodology can also be used with quantitative characteristics such as maximum intensity, relative maximum intensity, and in-flow parameters such as time-to-peak, slope, and t1/2max. This article concludes that fluorescence surgery with ICG and near-infrared (NIR) light is a relatively new technology that improves anatomical and functional information, allowing more comprehensive and safer tumour removal and the preservation of important structures.

Real-time quantification of intestinal perfusion and arterial versus venous occlusion using laser speckle contrast imaging in porcine model

PURPOSE

Real-time intraoperative perfusion assessment may reduce anastomotic leaks. Laser speckle contrast imaging (LSCI) provides dye-free visualization of perfusion by capturing coherent laser light scatter from red blood cells and displays perfusion as a colormap. Herein, we report a novel method to precisely quantify intestinal perfusion using LSCI.

METHODS

ActivSight™ is an FDA-cleared multi-modal visualization system that can detect and display perfusion via both indocyanine green imaging (ICG) and LSCI in minimally invasive surgery. An experimental prototype LSCI perfusion quantification algorithm was evaluated in porcine models. Porcine small bowel was selectively devascularized to create regions of perfused/watershed/ischemic bowel, and progressive aortic inflow/portal vein outflow clamping was performed to study arterial vs. venous ischemia. Continuous arterial pressure was monitored via femoral line.

RESULTS

LSCI perfusion colormaps and quantification distinguished between perfused, watershed, and ischemic bowel in all vascular control settings: no vascular occlusion (p < 0.001), aortic occlusion (p < 0.001), and portal venous occlusion (p < 0.001). LSCI quantification demonstrated similar levels of ischemia induced both by states of arterial inflow and venous outflow occlusion. LSCI-quantified perfusion values correlated positively with higher mean arterial pressure and with increasing distance from ischemic bowel.

CONCLUSION

LSCI relative perfusion quantification may provide more objective real-time assessment of intestinal perfusion compared to conventional naked eye assessment by quantifying currently subjective gradients of bowel ischemia and identifying both arterial/venous etiologies of ischemia.

Quantitative perfusion assessment using indocyanine green during surgery - current applications and recommendations for future use

PURPOSE

Incorrect assessment of tissue perfusion carries a significant risk of complications in surgery. The use of near-infrared (NIR) fluorescence imaging with Indocyanine Green (ICG) presents a possible solution. However, only through quantification of the fluorescence signal can an objective and reproducible evaluation of tissue perfusion be obtained. This narrative review aims to provide an overview of the available quantification methods for perfusion assessment using ICG NIR fluorescence imaging and to present an overview of current clinically utilized software implementations.

METHODS

PubMed was searched for clinical studies on the quantification of ICG NIR fluorescence imaging to assess tissue perfusion. Data on the utilized camera systems and performed methods of quantification were collected.

RESULTS

Eleven software programs for quantifying tissue perfusion using ICG NIR fluorescence imaging were identified. Five of the 11 programs have been described in three or more clinical studies, including Flow® 800, ROIs Software, IC Calc, SPY-Q™, and the Quest Research Framework®. In addition, applying normalization to fluorescence intensity analysis was described for two software programs.

CONCLUSION

Several systems or software solutions provide a quantification of ICG fluorescence; however, intraoperative applications are scarce and quantification methods vary abundantly. In the widespread search for reliable quantification of perfusion with ICG NIR fluorescence imaging, standardization of quantification methods and data acquisition is essential.

Anastomotic perfusion assessment with indocyanine green in robot-assisted low-anterior resection, a multicenter study of interobserver variation

BACKGROUND

Securing sufficient blood perfusion to the anastomotic area after low-anterior resection is a crucial factor in preventing anastomotic leakage (AL). Intra-operative indocyanine green fluorescent imaging (ICG-FI) has been suggested as a tool to assess perfusion. However, knowledge of inter-observer variation among surgeons in the interpretation of ICG-FI is sparse. Our primary objective was to evaluate inter-observer variation among surgeons in the interpretation of bowel blood-perfusion assessed visually by ICG-FI. Our secondary objective was to compare the results both from the visual assessment of ICG and from computer-based quantitative analyses of ICG-FI between patients with and without the development of AL.

METHOD

A multicenter study, including patients undergoing robot-assisted low anterior resection with stapled anastomosis. ICG-FI was evaluated visually by the surgeon intra-operatively. Postoperatively, recorded videos were anonymized and exchanged between centers for inter-observer evaluation. Time to visibility (TTV), time to maximum visibility (TMV), and time to wash-out (TWO) were visually assessed. In addition, the ICG-FI video-recordings were analyzed using validated pixel analysis software to quantify blood perfusion.

RESULTS

Fifty-five patients were included, and five developed clinical AL. Bland-Altman plots (BA plots) demonstrated wide inter-observer variation for visually assessed fluorescence on all parameters (TTV, TMV, and TWO). Comparing leak-group with no-leak group, we found no significant differences for TTV: Hazard Ratio; HR = 0.82 (CI 0.32; 2.08), TMV: HR = 0.62 (CI 0.24; 1.59), or TWO: HR = 1.11 (CI 0.40; 3.11). In the quantitative pixel analysis, a lower slope of the fluorescence time-curve was found in patients with a subsequent leak: median 0.08 (0.07;0.10) compared with non-leak patients: median 0.13 (0.10;0.17) (p = 0.04).

CONCLUSION

The surgeon's visual assessment of the ICG-FI demonstrated wide inter-observer variation, there were no differences between patients with and without AL. However, quantitative pixel analysis showed a significant difference between groups.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04766060.

Effects of glepaglutide, a long-acting glucagon-like peptide-2 analog, on intestinal morphology and perfusion in patients with short bowel syndrome: Findings from a randomized phase 2 trial

BACKGROUND

The proadaptive effects of glucagon-like peptide-2 (GLP-2) include stimulation of intestinal mucosal growth as well as intestinal blood flow and angiogenesis. We have recently reported that daily subcutaneous injections of glepaglutide, a long-acting GLP-2 analog, improved intestinal absorptive function in patients with short bowel syndrome (SBS). As secondary and exploratory end points, the effects of glepaglutide on intestinal morphology and perfusion are reported.

METHODS

The following assessments were done in 18 patients with SBS in a randomized, crossover, dose-finding, phase 2 trial before and after three weeks of treatment with glepaglutide: plasma citrulline and mucosa biopsies to assess changes in (1) intestinal morphology by immunohistochemistry and (2) gene expressions associated with absorption, proliferation, and markers of tight-junction integrity by quantitative polymerase chain reaction. Intestinal perfusion was assessed in stoma nipples by laser speckle contrast imaging and quantitative fluorescence angiography with indocyanine green.

RESULTS

In the 1- and 10-mg dose groups, glepaglutide significantly increased plasma citrulline by 15.3 µmol/L (P = 0.001) and 15.6 µmol/L (P = 0.001), respectively. Trends toward an increase in villus height, crypt depth, and epithelium height were seen in the same groups. No significant changes were seen in gene expressions or intestinal perfusion.

CONCLUSION

The increase in plasma citrulline and the morphological improvements may partly account for improvement in the intestinal absorptive function. However, the finding of a stability in perfusion after three weeks of treatment with glepaglutide may have been preceded by a more profound acute-phase increase in intestinal perfusion at treatment initiation.

Evaluation of inter-user variability in indocyanine green fluorescence angiography to assess gastric conduit perfusion in esophageal cancer surgery

Indocyanine Green Fluorescence Angiography (ICGFA) has been deployed to tackle malperfusion-related anastomotic complications. This study assesses variations in operator interpretation of pre-anastomotic ICGFA inflow in the gastric conduit. Utilizing an innovative online interactive multimedia platform (Mindstamp), esophageal surgeons completed a baseline opinion-practice questionnaire and proceeded to interpret, and then digitally assign, a distal transection point on 8 ICGFA videos of esophageal resections (6 Ivor Lewis, 2 McKeown). Annotations regarding gastric conduit transection by ICGFA were compared between expert users versus non-expert participants using ImageJ to delineate longitudinal distances with Shapiro Wilk and t-tests to ascertain significance. Expert versus non-expert correlation was assessed via Intraclass Correlation Coefficients (ICC). Thirty participants (13 consultants, 6 ICGFA experts) completed the study in all aspects. Of these, a high majority (29 participants) stated ICGFA should be used routinely with most (21, including 5/6 experts) stating that 11-50 cases were needed for competency in interpretation. Among users, there were wide variations in dosing (0.05-3 mg/kg) and practice impact. Agreement regarding ICGFA video interpretation concerning transection level among experts was 'moderate' (ICC = 0.717) overall but 'good' (ICC = 0.871) among seven videos with Leave One Out (LOO) exclusion of the video with highest disagreement. Agreement among non-experts was moderate (ICC = 0.641) overall and in every subgroup including among consultants (ICC = 0.626). Experts choose levels that preserved more gastric conduit length versus non-experts in all but one video (P = 0.02). Considerable variability exists with ICGFA interpretation and indeed impact. Even adept users may be challenged in specific cases. Standardized training and/or computerized quantitative fluorescence may help better usage.

The effect of intracorporeal versus extracorporeal anastomosis in robotic right colectomy on perianastomotic perfusion: a substudy to a multicenter RCT

PURPOSE

Previous studies have shown that intracorporeal anastomosis (ICA) in minimally invasive right colectomy may improve postoperative recovery compared with extracorporeal anastomosis (ECA). It has been hypothesized that creating the anastomosis extracorporeally may cause mesenteric traction and compromised intestinal perfusion. The purpose of this study was to investigate the effect of either ICA or ECA on intestinal perfusion.

METHOD

This was a substudy to a multicenter, triple-blind randomized clinical trial comparing ICA with ECA in patients undergoing robotic right colectomy for colonic cancer. Videos from intraoperative Indocyanine Green (ICG) fluorescence imaging were analyzed with quantitative ICG perfusion assessment (q-ICG). q-ICG was performed by extracting perfusion metrics from a time-intensity curve generated from an image analysis software: F_MAX: maximal fluorescence intensity, T_MAX: time until maximal fluorescent signal, T_1/2MAX: time until half-maximal fluorescent signal, time ratio (T_1/2MAX/T_MAX) and slope.

RESULTS

A total of 68 patients (33 ICA and 35 ECA) were available for analysis. Demographics were similar between the groups, except for mean arterial blood pressure at the time of ICG infusion, which was significantly lower in the ICA group. We found a significantly steeper slope in the ICA group compared to the ECA group (6.3 vs. 4.7 AU/sec, P = .048). There were no significant differences in F_MAX, T_MAX, T_1/2MAX, and time ratio.

CONCLUSION

We found evidence of an improved intestinal perfusion following ICA compared with ECA. This finding may be related to patient outcomes and should be explored further in the future.

TRIAL REGISTRATION

CLINICALTRIALS

gov NCT03130166.

Utility and usability of laser speckle contrast imaging (LSCI) for displaying real-time tissue perfusion/blood flow in robot-assisted surgery (RAS): comparison to indocyanine green (ICG) and use in laparoscopic surgery

Background

Utility and usability of laser speckle contrast imaging (LSCI) in detecting real-time tissue perfusion in robot-assisted surgery (RAS) and laparoscopic surgery are not known. LSCI displays a color heatmap of real-time tissue blood flow by capturing the interference of coherent laser light on red blood cells. LSCI has advantages in perfusion visualization over indocyanine green imaging (ICG) including repeat use on demand, no need for dye, and no latency between injection and display. Herein, we report the first-in-human clinical comparison of a novel device combining proprietary LSCI processing and ICG for real-time perfusion assessment during RAS and laparoscopic surgeries.

Methods

ActivSight™ imaging module is integrated between a standard laparoscopic camera and scope, capable of detecting tissue blood flow via LSCI and ICG in laparoscopic surgery. From November 2020 to July 2021, we studied its use during elective robotic-assisted and laparoscopic cholecystectomies, colorectal, and bariatric surgeries (NCT# 04633512). For RAS, an ancillary laparoscope with ActivSight imaging module was used for LSCI/ICG visualization. We determined safety, usability, and utility of LSCI in RAS vs. laparoscopic surgery using end-user/surgeon human factor testing (Likert scale 1–5) and compared results with two-tailed t tests.

Results

67 patients were included in the study—40 (60%) RAS vs. 27 (40%) laparoscopic surgeries. Patient demographics were similar in both groups. No adverse events to patients and surgeons were observed in both laparoscopic and RAS groups. Use of an ancillary laparoscopic system for LSCI/ICG visualization had minimal impact on usability in RAS as evidenced by surgeon ratings of device usability (set-up 4.2/5 and form-factor 3.8/5). LSCI ability to detect perfusion (97.5% in RAS vs 100% in laparoscopic cases) was comparable in both RAS and laparoscopic cases.

Conclusions

LSCI demonstrates comparable utility and usability in detecting real-time tissue perfusion/blood flow in RAS and laparoscopic surgery.

Graphical abstract

Normalization of Time-Intensity Curves for Quantification of Foot Perfusion Using Near-Infrared Fluorescence Imaging With Indocyanine Green

PURPOSE

Near-infrared (NIR) fluorescence imaging using indocyanine green (ICG) is gaining popularity for the quantification of tissue perfusion, including foot perfusion in patients with lower extremity arterial disease (LEAD). However, the absolute fluorescence intensity is influenced by patient-and system-related factors limiting reliable and valid quantification. To enhance the quality of quantitative perfusion assessment using ICG NIR fluorescence imaging, normalization of the measured time-intensity curves seems useful.

MATERIALS AND METHODS

In this cohort study, the effect of normalization on 2 aspects of ICG NIR fluorescence imaging in assessment of foot perfusion was measured: the repeatability and the region selection. Following intravenous administration of ICG, the NIR fluorescence intensity in both feet was recorded for 10 mins using the Quest Spectrum platform^®. The effect of normalization on repeatability was measured in the nontreated foot in patients undergoing unilateral revascularization preprocedural and postprocedural (repeatability group). The effect of normalization on region selection was performed in patients without LEAD (region selection group). Absolute and normalized time-intensity curves were compared.

RESULTS

Successful ICG NIR fluorescence imaging was performed in 54 patients (repeatability group, n = 38; region selection group, n = 16). For the repeatability group, normalization of the time-intensity curves displayed a comparable inflow pattern for repeated measurements. For the region selection group, the maximum fluorescence intensity (Imax) demonstrated significant differences between the 3 measured regions of the foot (P = .002). Following normalization, the time-intensity curves in both feet were comparable for all 3 regions.

CONCLUSION

This study shows the effect of normalization of time-intensity curves on both the repeatability and region selection in ICG NIR fluorescence imaging. The significant difference between absolute parameters in various regions of the foot demonstrates the limitation of absolute intensity in interpreting tissue perfusion. Therefore, normalization and standardization of camera settings are essential steps toward reliable and valid quantification of tissue perfusion using ICG NIR fluorescence imaging.

Segmental branches emanating from saphenous nerve morphing into sympathetic trunks for innervation of saphenous artery and its clinical implication for arterial sympathectomy

Sympathectomy of arteries has been adopted for the treatment of peripheral arterial disease and Raynaud's disease. However, the exact route for sympathetic axons to reach peripheral arteries awaits further investigation that could pave the way for development of new surgical strategies. In this study, saphenous neurovascular bundles from 10 neonatal Sprague-Dawley rats first were harvested for whole-mount immunostaining to show sympathetic innervation pattern of the artery. Secondly, 40 Sprague-Dawley male rats weighing 350 to 400 g were assigned to five groups, receiving either sham, perivascular sympathectomy, nerve-artery separation, nerve transection in the saphenous neurovascular bundle, or lumbar sympathectomy surgery that removes the lumbar sympathetic trunks. Immediately after surgery, the arterial perfusion and diameter were measured using laser speckling contrast imaging, and 1 week later the saphenous neurovascular bundles were harvested for immunostaining using antibodies against TH, neuron-specific β-tubulin (Tuj 1), and α-SMA to show the presence or absence of the TH-immuopositive staining in the adventitia. The differences among the five groups were determined using one-way analysis of variance (ANOVA). We found that an average of 2.8 ± 0.8 branches with a diameter of 4.8 ± 1.2 μm derived from the saphenous nerve that morphed into a primary and a secondary sympathetic trunk for innervation of the saphenous artery. Nerve-artery separation, nerve transection, and lumbar sympathectomy could eradicate TH-immunopositive staining of the artery, resulting, respectively, in a 12%, 36%, and 59% increase in diameter (P < .05), and a 52%, 63%, and 201% increase in perfusion compared with sham surgery (P < .01). In contrast, perivascular sympathectomy did not have a significant impact on the TH-immunopositive staining, the diameter, and perfusion of the distal part of the artery (P > .05). We conclude that the sympathetic innervation of an artery derives from segmental branches given off from its accompanying nerve. Nerve-artery disconnection is a theoretic option in sympathectomy of an artery.

Perfusion Parameters in Near-Infrared Fluorescence Imaging with Indocyanine Green: A Systematic Review of the Literature

(1) Background: Near-infrared fluorescence imaging is a technique capable of assessing tissue perfusion and has been adopted in various fields including plastic surgery, vascular surgery, coronary arterial disease, and gastrointestinal surgery. While the usefulness of this technique has been broadly explored, there is a large variety in the calculation of perfusion parameters. In this systematic review, we aim to provide a detailed overview of current perfusion parameters, and determine the perfusion parameters with the most potential for application in near-infrared fluorescence imaging. (2) Methods: A comprehensive search of the literature was performed in Pubmed, Embase, Medline, and Cochrane Review. We included all clinical studies referencing near-infrared perfusion parameters. (3) Results: A total of 1511 articles were found, of which, 113 were suitable for review, with a final selection of 59 articles. Near-infrared fluorescence imaging parameters are heterogeneous in their correlation to perfusion. Time-related parameters appear superior to absolute intensity parameters in a clinical setting. (4) Conclusions: This literature review demonstrates the variety of parameters selected for the quantification of perfusion in near-infrared fluorescence imaging.

Quantitative fluorescence angiography aids novice and experienced surgeons in performing intestinal resection in well-perfused tissue

Background

Anastomotic leakage (AL) after gastrointestinal resection is a devastating complication with huge consequences for the patient. As AL is associated with poor blood supply, tools for objective assessment of perfusion are in high demand. Indocyanine green angiography (ICG-FA) and quantitative analysis of ICG-FA (q-ICG) seem promising. This study aimed to investigate whether ICG-FA and q-ICG could improve perfusion assessment performed by surgeons of different experience levels.

Methods

Thirteen small bowel segments with a varying degree of devascularization, including two healthy sham segments, were constructed in a porcine model. We recruited students, residents, and surgeons to perform perfusion assessment of the segments in white light (WL), with ICG-FA, and after q-ICG, all blinded to the degree of devascularization.

Results

Forty-five participants fulfilled the study (18 novices, 12 intermediates, and 15 experienced). ICG and q-ICG helped the novices correctly detect the healthy bowel segments to experienced surgeons’ level. ICG and q-ICG also helped novice surgeons to perform safer resections in healthy tissue compared with normal WL. The relative risk (RR) of leaving ischemic tissue in WL and ICG compared with q-ICG, even for experienced surgeons was substantial, intermediates (RR = 8.9, CI95% [4.0;20] and RR = 6.2, CI95% [2.7;14.1]), and experienced (RR = 4.7, CI95% [2.6;8.7] and RR = 4.0, CI95% [2.1;7.5]).

Conclusion

Q-ICG seems to guide surgeons, regardless of experience level, to safely perform resection in healthy tissue, compared with standard WL. Future research should focus on this novel tool’s clinical impact.

Fluorescence-Based Quantification of Gastrointestinal Perfusion: A Step Towards an Automated Approach

Background: Qualitative fluorescence angiography (FA) provides insights into intestinal tissue perfusion, but today it is not yet accurate in predicting anastomotic leakage. To improve peroperative detection of impaired perfusion, quantified parameters should be investigated using a standardized method. The aim of this study was to develop a (semi)automated algorithm for comprehensive and convenient analysis of FA parameters. Materials and Methods: An analysis tool was developed for the extraction of quantified FA parameters. The start- and endpoint of intensity increase (T₀ and Tmax) were automatically detected in the intensity-time curves. Algorithm performance was measured against manual assignment of T₀ and Tmax by 9 independent observers in 18 in vivo generated test signals, using the intraclass correlation coefficient (ICC). Characteristics of parameter T1∕2 (time to 50% of maximal intensity) were analyzed in normally perfused small intestine of 32 subjects who underwent robotic laparoscopic surgery. Since ethical approval was not required under the Dutch law, the need for informed consent was waived. Results: Automated detection of T₀ and Tmax was successful in all subjects. Output of the algorithm had an excellent agreement with the median of the human observations: ICC = 0.95 (95% confidence interval: 0.86-0.96). Overall, T1∕2 had a median value of 5.1 (interquartile range = 2.4) seconds and a minimal and maximal value of 1.3 and 9.9 seconds, respectively. Conclusions: The presented method provided convenient data analysis in the search for effective FA quantification. Future research should expand the data to find adequate threshold values for peroperatively identifying insufficient perfusion and investigate the influence of physiological conditions.

Mechanically Induced Vasospasm-Evaluation of Spasmolytic Efficacy of 10 Pharmaceutical Agents Using Laser Speckle Contrast Imaging

BACKGROUND AND OBJECTIVES

Vasospasm is a thorny problem often encountered in microvascular surgery that seriously threatens the survival of vascularized tissue transfers. This investigation is dedicated to establishing a model of vasospasm and to evaluating the antispasmodic efficacy of 10 pharmacologic agents.

STUDY DESIGN/MATERIALS AND METHODS

Eighty Sprague-Dawley rats were used. After anesthesia and depilation, the femoral neurovascular bundle was exposed, and a pair of microsurgical forceps were used to trigger vasospasm of the femoral vessels by blunt dissection. Then, 10 pharmacological agents, namely, prostaglandin E1, sodium nitroprusside, magnesium sulfate, papaverine, normal saline, phentolamine, verapamil, 2% lidocaine hydrochloride, amrinone, and 12% lidocaine hydrochloride, were dripped to the femoral vessels, after which laser speckle contrast imaging was used to collect perfusion images, acquiring the perfusion and the inner caliber of the femoral vessels at multiple timepoints. Furthermore, blood perfusion and the time consumed to escape vasospasm and reach hyperperfusion in each group were calculated. The difference of spasmolytic efficacy among the agents was statistically analyzed by one-way analysis of variance.

RESULTS

There was a significant difference in antispasmodic ability among the 10 agents (P < 0.001). 10% magnesium sulfate and 12% lidocaine were distinguished among the 10 agents in resolving the vasospasm. 10% magnesium sulfate demonstrated the best antispasmodic potency, which enabled the shortest time consumed for vessels to escape spasm and reach hyperperfusion. 12% lidocaine ranked second in efficacy, demonstrating a similar effect except that it could not propel the femoral vein to a state of hyperperfusion. For the remaining agents, the time consumed for the artery to escape spasm was all significantly shortened when compared with normal saline (P < 0.001). For the venous spasm, all agents except prostaglandin E1 could significantly shorten the time consumed for the vein to escape spasm (P < 0.001).

CONCLUSIONS

In terms of resolving mechanically induced vasospasm, 10% magnesium sulfate is the best antispasmodic, followed by 12% lidocaine. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

Quantitative fluorescence angiography detects dynamic changes in gastric perfusion

INTRODUCTION

The use of Indocyanine green (ICG) fluorescence angiography (ICG-FA) is an applied method to assess visceral perfusion during surgical procedures worldwide. Further development has entailed quantification of the fluorescence signal; however, whether quantified ICG-FA can detect intraoperative changes in perfusion after hemorrhage has not been investigated previously. In this study, we investigated whether a quantification method, developed and validated in our department (q-ICG), could detect changes in gastric perfusion induced by hemorrhage and resuscitation.

METHODS

Ten pigs were included in the study. Specific regions of interest of the stomach were chosen, and three q-ICG measurements of gastric perfusion obtained: 20 min after completion of the laparoscopic setup (baseline), after reducing the circulating blood volume by 30%, and after reinfusion of the withdrawn blood volume. Hemodynamic variables were recorded, and blood samples were collected every 10 min during the procedure.

RESULTS

The reduction in blood volume generated decreased gastric perfusion (q-ICG) from baseline (p = 0.023), and gastric perfusion subsequently increased (p < 0.001) after the reintroduction of the withdrawn blood volume. Cardiac output (CO) and mean arterial blood pressure (MAP) shifted correspondingly and the gastric perfusion correlated to CO (r = 0.575, p = 0.001) and MAP (r = 0.436, p = 0.018).

CONCLUSION

We present a novel study showing that the q-ICG method can detect dynamic changes in local tissue perfusion induced by hemorrhage and resuscitation. As regional gastrointestinal perfusion may be significantly reduced, while hemodynamic variables such as MAP or heart rate remain stable, q-ICG may provide an objective, non-invasive method for detecting regional early ischemia, strengthening surgical decision making.

Fluorescence guided intraluminal endoscopy in the gastrointestinal tract: A systematic review

BACKGROUND

Conventional endoscopy is based on full spectrum white light. However, different studies have investigated the use of fluorescence based endoscopy systems where the white light has been supplemented by infrared light and the use of relevant fluorophores. Fluorescence endoscopy utilizes the fluorescence emitted from a fluorophore, visualizing what is not visible to the naked eye.

AIM

To explore the feasibility of fluorescence endoscopy and evaluate its use in diagnosing and evaluating gastrointestinal disease.

METHODS

We followed the PRISMA guidelines for this systematic review. The research covered five databases; PubMed, Scopus, Web of Science, Embase, and the Cochrane Collection, including only studies in English and Scandinavian languages. Authors screened title and abstract for inclusion, subsequently full-text for inclusion according to eligibility criteria listed in the protocol. The risk of bias was assessed for all studies according to the Newcastle-Ottawa Scale. The authors extracted the data and reported the results in both text and tables.

RESULTS

We included seven studies in the systematic review after screening a total of 2769 papers. The most prominent fluorophore was indocyanine green (n = 6), and whereas one study (n = 1) used Bevacizumab 800-CW. Three studies investigated fluorescence endoscopy in detecting varices, adenomas in patients with familial adenomatous polyposis and neoplasms in the gastrointestinal tract. Four studies evaluated the usefulness of fluorescence endoscopy in assessing tumor invasion. Three of the four studies reported an exceptional diagnostic accuracy (93%, 89% and 88%) in assessing tumor invasion, thus representing better visualization and more correct diagnosis by fluorescence endoscopy compared with the conventional endoscopy. The relationship between the endoscopic findings, tumor invasion, and tumor vascularity was evaluated in two studies showing a significant correlation (^dP < 0.05 and ^bP < 0.01).

CONCLUSION

The use of fluorescence endoscopy is a promising method adding diagnostic value in the detection of neoplasia, adenomas, and assessment of tumor invasion within the gastrointestinal tract. More studies are needed to utilize the feasibility of fluorescence endoscopy compared with other endoscopic methods.

Quantification of ICG fluorescence for the evaluation of intestinal perfusion: comparison between two software-based algorithms for quantification

BACKGROUND

Indocyanine green fluorescence imaging (ICG-FI) can be used to evaluate intestinal perfusion prior to anastomosis. Several software for the quantification of fluorescence have emerged, but these have not previously been compared. The aim of this study was to compare the results from quantitative ICG-FI analysis of relative perfusion in an experimental setting using two different software-based quantification algorithms (FLER and Q-ICG).

METHODS

Twenty pigs received a laparotomy, and ischemic areas were created in three segments of the small intestine of each pig. For each ischemic area, fluorescence imaging was performed and the fluorescence recordings were quantitatively analyzed using FLER and Q-ICG. The quantitative analysis resulted in a set of perfusion lines for each software for either 30%, 60% or 100% relative perfusion. The perfusion lines were compared by registering the normalized slope for each set of perfusion lines, calculating the relative perfusion percentage in the FLER perfusion line according to Q-ICG, and measuring the length of the ischemic area for each analysis.

RESULTS

Fifty-four fluorescence recordings from 18 pigs were included. The ischemic segment for FLER was significantly longer in the 30% perfusion group and significantly shorter in the 100% perfusion group as compared to Q-ICG. The normalized slope for the FLER perfusion lines was significantly higher in the 30% perfusion group and significantly lower in the 100% perfusion group as compared to the Q-ICG perfusion lines. For the perfusion lines defined by FLER as 30%, 60%, and 100%, Q-ICG found 35.2% (p = 0.07), 63.7% (p = 0.31), and 84.1% perfusion (p = 0.003) respectively.

CONCLUSION

The two software demonstrated significant differences in quantitative fluorescence analysis when perfusion was either very high or very low. The clinical relevance of these differences is unclear.

Quantification of fluorescence angiography: Toward a reliable intraoperative assessment of tissue perfusion - A narrative review

BACKGROUND

Accurate intraoperative assessments of tissue perfusion are essential in all forms of surgery. As traditional methods of perfusion assessments are not available during minimally invasive surgery, novel methods are required. Here, fluorescence angiography with indocyanine green has shown promising results. However, to secure objective and reproducible assessments, quantification of the fluorescent signal is essential (Q-ICG). This narrative review aims to provide an overview of the current status and applicability of Q-ICG for intraoperative perfusion assessment.

RESULTS

Both commercial and custom Q-ICG software solutions are available for intraoperative use; however, most studies on Q-ICG have performed post-operative analyses. Q-ICG can be divided into inflow parameters (ttp, t0, slope, and T_1/2max) and intensity parameters (Fmax, PI, and DR). The intensity parameters appear unreliable in clinical settings. In comparison, inflow parameters, mainly slope, and T_1/2max have had superior clinical performance.

CONCLUSION

Intraoperative Q-ICG is clinically available; however, only feasibility studies have been performed, rendering an excellent usability score. Q-ICG in a post-operative setting could detect changes in perfusion following a range of interventions and reflect clinical endpoints, but only if based on inflow parameters. Thus, future studies should include the methodology outlined in this review, emphasizing the use of inflow parameters (slope or T_1/2max), a mass-adjusted ICG dosing, and a fixed camera position.

Noninvasive assessment of bowel blood perfusion using intraoperative laser speckle flowgraphy

PURPOSE

Laser speckle flowgraphy (LSFG) is a noninvasive method for quantitative evaluation of blood flow using the mean blur rate (MBR) as the blood flow index. We investigated whether LSFG can intraoperatively detect the demarcation line after vessel dissection and reduce the incidence of anastomotic leakage (AL).

METHODS

This study included 36 patients who underwent left-sided colorectal surgery. First, we compared the demarcation line (determined by LSFG) with the transection line (TL) at which the marginal vessels were divided. We then measured the MBR on both sides of the TL to determine where the MBR changed significantly. We investigated the presence or absence of significant differences between the MBR on the proximal side and that on the distal side of the TL. Finally, we retrospectively compared the patient characteristics and AL rates in the LSFG group (n = 36) and control group (n = 87).

RESULTS

In total, 58.3% (21/36) of the demarcation lines determined by LSFG matched the TL. The median distance between the demarcation line determined by LSFG and the TL was 0.0 mm (0.0-12.1 mm). The MBR sharply decreased at the TL in 80.6% (29/36) of cases. The median MBR was significantly lower on the distal than proximal side. The AL rate was not significantly lower in the LSFG group than in the control group.

CONCLUSION

LSFG accurately detected the demarcation line during surgery. However, LSFG did not reduce the incidence of AL.

Feasibility and usability of real-time intraoperative quantitative fluorescent-guided perfusion assessment during resection of gastroesophageal junction cancer

PURPOSE

Anastomotic leakage after resection of gastroesophageal junction cancer is a dangerous complication, and leakage rates have remained stable for decades. Perfusion is crucial for anastomotic healing, but traditional perfusion assessment is limited in a minimally invasive environment. New methods as indocyanine green fluorescence angiography (ICG-FA) have proven promising, but quantitative analysis has been challenging. This study aimed to demonstrate the feasibility and usability of real-time intraoperative quantitative fluorescence angiography (q-ICG) with a touchscreen tablet.

METHODS

A software for q-ICG was previously developed and validated. Ten patients underwent perfusion assessment in white light (WL), with ICG-FA, and with q-ICG during Ivor-Lewis esophageal resection. The usability of the tablet-based software was tested with the System Usability Scale (SUS®). Furthermore, we investigated the differences in perfusion assessment as the distance from the conduit margin to a surgeon selected point of sufficient perfusion for anastomosis using the different modalities.

RESULTS

Q-ICG was successful in all patients, with an excellent median SUS® of 82.5 (77.5-93.8). Significant differences in distances from the conduit margin to points of sufficient perfusion selected by the surgeons were found: ICG: WL = 14.1 mm (p = 0.048), q-ICG: WL = 32.08 mm (p < 0.001), and q-ICG: ICG = 17.95 mm (p = 0.002). Furthermore, significant differences of perfusion were found between the points, when q-ICG was performed retrospectively in the surgeon selected areas (p = 0.008-0.013).

CONCLUSION

Real-time intraoperative touchscreen-based q-ICG was feasible with excellent usability, and differences in sufficient perfusion points selected by the surgeons between modalities were found. Further studies should focus on clinical relevance and determine cutoff values associated with anastomotic leakage.