Near-infrared Fluorescence Angiography Research Articles

Quantitative analysis of intestinal perfusion with indocyanine green (ICG) and methylene blue (MB) using a single clinically approved fluorescence imaging system: a demonstration in a porcine model.

Near-infrared fluorescence (NIRF) angiography with intraoperative administration of indocyanine green (ICG) has rapidly disseminated in clinical practice. Another clinically approved, and widely available dye, methylene blue (MB), has up to now not been used for this purpose. Recently, we demonstrated promising results for the real-time evaluation of intestinal perfusion using this dye. The primary aim of this study was to perform a quantitative analysis of bowel perfusion assessment for both ICG and MB. Four mature female Landrace pigs underwent laparotomy under general anesthesia. An ischemic bowel loop with five regions of interest (ROIs) with varying levels of perfusion was created in each animal. An intravenous (IV) injection of 0.25mg/kg-0.50mg/kg MB was administered after 10min, followed by NIRF imaging in MB mode and measurement of local lactate levels in all corresponding ROIs. This procedure was repeated in ICG mode (IV dose of 0.2mg/kg) after 60min. The quest spectrum fluorescence camera (Quest Medical Imaging, Middenmeer, The Netherlands) was used for NIRF imaging of both MB and ICG. Intraoperative NIRF imaging of bowel perfusion assessment with MB and ICG was successful in all studied animals. Ingress (i/s) levels were calculated and correlated with local lactate levels. Both MB and ICG ingress values showed a significant negative correlation (r = -0.7709; p = < 0.001; r = -0.5367, p = 0.015, respectively) with local lactate levels. This correlation was stronger for MB compared to ICG, although ICG analysis showed higher absolute ingress values. Our fluorescence quantification analysis validates the potential to use MB for bowel perfusion assessment besides the well-known and widely used ICG. Further human studies are necessary to translate our findings to clinical applications.

An overview of current assessment techniques for evaluating cutaneous perfusion in reconstructive surgery.

This article provides a comprehensive analysis of modern techniques used in the assessment of cutaneous flaps in reconstructive surgery. It emphasizes the importance of preoperative planning and intra- and perioperative assessment of flap perfusion to ensure successful outcomes. Despite technological advancements, direct clinical assessment remains the gold standard. We categorized assessment techniques into non-invasive and invasive modalities, discussing their strengths and weaknesses. Non-invasive methods, such as acoustic Doppler sonography, near-infrared spectroscopy, hyperspectral imaging thermal imaging, and remote-photoplethysmography, offer accessibility and safety but may sacrifice specificity. Invasive techniques, including contrast-enhanced ultrasound, computed tomography angiography, near-infrared fluorescence angiography with indocyanine green, and implantable Doppler probe, provide high accuracy but introduce additional risks. We emphasize the need for a tailored decision-making process based on specific clinical scenarios, patient characteristics, procedural requirements, and surgeon expertise. It also discusses potential future advancements in flap assessment, including the integration of artificial intelligence and emerging technologies.

NIR ICG-Enhanced Fluorescence: A Quantitative Evaluation of Bowel Microperfusion and Its Relation to Central Perfusion in Colorectal Surgery

Background: To date, no standardized protocols nor a quantitative assessment of the near-infrared fluorescence angiography with indocyanine green (NIR-ICG) are available. The aim of this study was to evaluate the timing of fluorescence as a reproducible parameter and its efficacy in predicting anastomotic leakage (AL) in colorectal surgery. Methods: A consecutive cohort of 108 patients undergoing minimally invasive elective procedures for colorectal cancer was prospectively enrolled. The difference between macro and microperfusion (ΔT) was obtained by calculating the timing of fluorescence at the level of iliac artery division and colonic wall, respectively. Results: Subjects with a ΔT ≥ 15.5± 0.5 s had a higher tendency to develop an AL (p &lt; 0.01). The ΔT/heart rate interaction was found to predict AL with an odds ratio of 1.02 (p &lt; 0.01); a cut-off threshold of 832 was identified (sensitivity 0.86, specificity 0.77). Perfusion parameters were also associated with a faster bowel motility resumption and a reduced length of hospital stay. Conclusions: The analysis of the timing of fluorescence provides a quantitative, easy evaluation of tissue perfusion. A ΔT/HR interaction ≥832 may be used as a real-time parameter to guide surgical decision making in colorectal surgery.

Applications of Near-Infrared Fluorescence Imaging and Angiography of Inferior Vesical Artery in Laparoscopic Lateral Lymph Node Dissection: A Prospective Nonrandomized Controlled Study

BACKGROUND: Near-infrared imaging with indocyanine green has been used to guide lateral lymph node dissection, yet its efficacy and benefits need further investigation. OBJECTIVE: To investigate the efficacy and feasibility of near-infrared fluorescence imaging and angiography of the inferior vesical artery in laparoscopic lateral lymph node dissection. DESIGN: A prospective nonrandomized controlled study. SETTINGS: Single-center study. PATIENTS: Patients with lower rectal cancer who underwent total mesorectal excision plus lateral lymph node dissection. MAIN OUTCOME MEASURES: A cohort of 108 patients was enrolled. After propensity score matching, 29 patients in the near-infrared group and 50 patients in the non–near-infrared group were matched. The total number of harvested lateral lymph nodes, positive lateral lymph nodes, inferior vesical artery preservation, and postoperative urinary function were compared. RESULTS: After propensity score matching, both groups had similar baseline characteristics. The total number of harvested lateral lymph nodes in the near-infrared group was significantly higher (12 vs 9, p = 0.013), but positive lateral lymph nodes were similar between the 2 groups (1 vs 1, p = 0.439). The inferior vesical artery preservation ratio was significantly increased with the aid of indocyanine green angiography (93.1% vs 56.0%, p &lt; 0.001). The non–near-infrared group required more days for urinary catheter removal than the near-infrared group (5 vs 4, p = 0.046). Urinary recatheterization tended to occur more frequently in the non–near-infrared group, with a marginally significant trend (16% vs 0%, p = 0.059). The non–near-infrared group tended to have more cases with residual urine volume ≥50 mL than the near-infrared group (20.0% vs 3.4%, p = 0.087), especially in the bilateral dissection subgroup (41.2% vs 0%, p = 0.041). LIMITATIONS: Small sample size. CONCLUSIONS: Near-infrared imaging increased the number of harvested lateral lymph nodes, whereas real-time indocyanine green fluorescence angiography ensured the preservation of the inferior vesical artery and tended to improve postoperative urinary function.

Near-infrared fluorescence angiography with indocyanine green for perfusion assessment of DIEP and msTRAM flaps: A Dutch multicenter randomized controlled trial

BackgroundA common complication after a DIEP flap reconstruction is the occurrence of fat necrosis due to inadequate flap perfusion zones. Intraoperative identification of ischemic zones in the DIEP flap could be optimized using indocyanine green near-infrared fluorescence angiography (ICG-NIR-FA). This randomized controlled trial aims to determine whether intraoperative ICG-NIR-FA for the assessment of DIEP flap perfusion decreases the occurrence of fat necrosis. Design/methodsThis article describes the protocol of a Dutch multicenter randomized controlled clinical trial: the FAFI-trial. Females who are electively scheduled for autologous breast reconstruction using DIEP or muscle-sparing transverse rectus abdominis muscle (msTRAM) flaps are included. A total of 280 patients will be included in a 1:1 ratio between both study arms. In the intervention arm, the intraoperative assessment of flap perfusion will be based on both regular clinical parameters and ICG-NIR-FA. The control arm consists of flap perfusion evaluation only through the regular clinical parameters, while ICG-NIR-FA images are obtained during surgery for which the surgeon is blinded. The main study endpoint is the difference in percentage of clinically relevant fat necrosis between both study arms, evaluated two weeks and three months after reconstruction. ConclusionThe FAFI-trial, a Dutch multicenter randomized controlled clinical trial, aims to investigate the clinical added value of intraoperative use of standardized ICG-NIR-FA for assessment of DIEP/msTRAM flap perfusion in the reduction of fat necrosis. Clinical trial registration numberNCT05507710; NL 68623.058.18.

A quantitative assessment of perfusion of the gastric conduit after oesophagectomy using near-infrared fluorescence with indocyanine green

IntroductionAnastomotic leakage is a severe complication after oesophageal resection with gastric conduit reconstruction. Poor perfusion of the gastric conduit plays an important role in the development of anastomotic leakage. Quantitative near-infrared (NIR) fluorescence angiography with indocyanine green (ICG-FA) is an objective technique that can be used for perfusion assessment. This study aims to assess perfusion patterns of the gastric conduit with quantitative ICG-FA. MethodsIn this exploratory study, 20 patients undergoing oesophagectomy with gastric conduit reconstruction were included. A standardized NIR ICG-FA video of the gastric conduit was recorded. Postoperatively, the videos were quantified. Primary outcomes were the time-intensity curves and nine perfusion parameters from contiguous regions of interest on the gastric conduit. A secondary outcome was the inter-observer agreement of subjective interpretation of the ICG-FA videos between six surgeons. The inter-observer agreement was tested with an intraclass correlation coefficient (ICC). ResultsIn a total of 427 curves, three distinct perfusion patterns were recognized: pattern 1 (steep inflow, steep outflow); pattern 2 (steep inflow, minor outflow); and pattern 3 (slow inflow, no outflow). All perfusion parameters were significantly different between the perfusion patterns. The inter-observer agreement was poor – moderate (ICC:0.345,95%CI:0.164–0.584). DiscussionThis was the first study to describe perfusion patterns of the complete gastric conduit after oesophagectomy. Three distinct perfusion patterns were observed. The poor inter-observer agreement of the subjective assessment underlines the need for quantification of ICG-FA of the gastric conduit. Further studies should evaluate the predictive value of perfusion patterns and parameters on anastomotic leakage.

Ureterovesical Anastomosis Complications in Kidney Transplantation: Definition, Risk Factor Analysis, and Prediction by Quantitative Fluorescence Angiography with Indocyanine Green.

Ureteral stenosis and urinary leakage are relevant problems after kidney transplantation. A standardized definition of ureterovesical anastomosis complications after kidney transplantation has not yet been established. This study was designed to demonstrate the predictive power of quantitative indocyanine green (ICG) fluorescence angiography. This bicentric historic cohort study, conducted between November 2015 and December 2019, included 196 kidney transplantations. The associations between quantitative perfusion parameters of near-infrared fluorescence angiography with ICG and the occurrence of different grades of ureterovesical anastomosis complications in the context of donor, recipient, periprocedural, and postoperative characteristics were evaluated. Post-transplant ureterovesical anastomosis complications occurred in 18%. Complications were defined and graded into three categories. They were associated with the time on dialysis (p = 0.0025), the type of donation (p = 0.0404), and the number of postoperative dialysis sessions (p = 0.0173). Median ICG ingress at the proximal ureteral third was 14.00 (5.00-33.00) AU in patients with and 23.50 (4.00-117.00) AU in patients without complications (p = 0.0001, cutoff: 16 AU, sensitivity 70%, specificity 70%, AUC = 0.725, p = 0.0011). The proposed definition and grading of post-transplant ureterovesical anastomosis complications is intended to enable valid comparisons between studies. ICG Fluorescence angiography allows intraoperative quantitative assessment of ureteral microperfusion during kidney transplantation and is able to predict the incidence of ureterovesical anastomosis complications. Registration number: NCT-02775838.

Ex Vivo Thrombolysis to Salvage Free Flaps Using Machine Perfusion: A Pilot Study in a Porcine Model

Mechanical evacuation of capillary thrombi in free flaps is difficult, and often requires thrombolytic therapy. Utilizing machine perfusion systems, the possibility rises to salvage free flaps ex vivo by administering high doses of thrombolytic agents. The primary aim of this pilot study in a porcine model is to investigate the feasibility of ex vivo thrombolysis using an extracorporeal perfusion machine. A model of stasis-induced thrombosis was used in 12 free rectus abdominis flaps harvested from six Dutch Landrace pigs. Compromised flaps were ex vivo perfused with University of Wisconsin preservation solution and treated according to the following study groups: (1) 1 mg of tissue plasminogen activator (t-PA) as additive, (2) 3 mg of t-PA as an additive, and (3) no thrombolytic additive. Microcirculation was assessed using near-infrared fluorescence angiography. Pedicled abdominal flaps were created and thrombus formation was successfully induced. Eleven abdominal flaps were perfused using the modified heart-lung machine setup. Near-infrared fluorescence angiography showed delayed or no filling was noted in the control group. In comparison, the flaps which were perfused with 1 mg t-PA or 3 mg t-PA as additive showed increased fluorescence intensity curves. This pilot study in a porcine model presents a reliable and reproductive stasis-induced thrombosis model in free flaps. By adding t-PA to a custom-made extracorporeal perfusion system, the indocyanine green fluorescence intensity curves increased of all flaps that were perfused with different dosages of t-PA as additives, indicating restoration of capillary pressure and microcirculatory inflow.

Ex Vivo Machine Thrombolysis Reduces Rethrombosis Rates in Salvaged Thrombosed Myocutaneous Flaps in Swine.

There is a risk for thrombotic complications (2 to 5 percent) associated with microsurgical reconstruction. Current thrombolytic therapy has a salvage rate between 60 and 70 percent, but it is afflicted by bleeding complications (2 to 6 percent). The use of machine perfusion for delivering thrombolytic agents is a new method that could potentially reduce these complications. In this article, the authors compared flap salvage outcomes comparing machine thrombolysis versus a manual flush with tissue plasminogen activator. Sixteen bilateral flaps (12 × 9 cm) were dissected from eight female Dutch Landrace pigs (70 kg). Thrombosis was induced in free rectus abdominis flaps by clamping the pedicle's veins for 2 hours. Flaps were either thrombolysed with 2 mg tissue plasminogen activator (1 mg/ml) during 2 hours of machine perfusion (perfusion group; n = 8) or injected intraarterially (manual group; n = 8) before replantation. Near-infrared fluorescence angiography was used to confirm thrombus formation and to assess tissue perfusion; muscle biopsy specimens were analyzed for ischemia/reperfusion injury directly after thrombolysis and 15 hours after replantation. A higher incidence of secondary thrombosis was seen in the manual group compared to the perfusion group ( n = 6 versus n = 0, respectively; p < 0.001), resulting in two complete flap failures. Fifteen hours after replantation, mean fluorescence intensities were 13.0 (95 percent CI, 10.1 to 15.8) and 24.6 (95 percent CI, 22.0 to 27.2) in the perfusion and manual group, respectively ( p < 0.001), and mean muscle injury scores were comparable, measuring 7.5 ± 1.5. Two hours of machine thrombolysis of compromised flaps in a porcine model showed higher salvage rates compared to a manual injection with tissue plasminogen activator and reduced the incidence of secondary thrombosis. Using machine perfusion systems for ex vivo thrombolysis provides the benefits of local treatment of a composite tissue without the risk of systemic complications and may improve salvage rates and reduce the incidence of secondary thrombosis.

Folate-targeted co-delivery polymersomes for efficient photo-chemo-antiangiogenic therapy against breast cancer and in vivo evaluation via OCTA/NIRF dual-modal imaging

Intelligent nanoplatform that combines multimodal imaging and therapeutic effects holds great promise for precise and efficient cancer therapy. Herein, folate-targeted polymersomes with stimuli-responsiveness were fabricated and evaluated by near-infrared fluorescence (NIRF) and optical coherence tomography angiography (OCTA) dual-imaging for photo-chemo-antiangiogenic therapy against cancer. The folate-targeted polymersomes (FA-MIT-SIPS) not only integrated ammonium bicarbonate (ABC) and mitoxantrone (MIT) into their hydrophilic cavity but also encapsulated indocyanine green (ICG) and sorafenib (SOR) within their hydrophobic layer. NIRF imaging demonstrated that FA-MIT-SIPS effectively accumulated and retained in the tumors. Upon 808 nm laser irradiation, the ICG produced hyperthermia and reactive oxygen species (ROS) for efficient photothermal and photodynamic therapy. In addition, the decomposition of ABC in responsive to acidic tumor environment and ICG-induced hyperthermia accelerated drug release. The released MIT accumulated in nucleus to inhibit DNA synthesis, while the released SOR destructed tumor vascularization. Notably, OCTA imaging was applied to observe the tumor blood flow upon the combination therapy, demonstrating that FA-MIT-SIPS obviously decreased the vessels area density. Moreover, the synergistic photo-chemo-antiangiogenic therapy of FA-MIT-SIPS achieved excellent antitumor effect with 40% of the 4T1 tumor-bearing mice being completely cured without recurrence. The multifunctional polymersomes provide a promising dual-modal imaging-evaluated synergistic strategy for tumor therapy.

A Class of Biocompatible Dye-Protein Complex Optical Nanoprobes.

Molecular organic dyes are classic fluorescent nanoprobes finding tremendous uses in biological and life sciences. Yet, they suffer from low brightness, poor photostability, and lack of functional groups for bioconjugation. Here, we describe a class of biocompatible dye-protein optical nanoprobes, which show long-time photostability, superbrightness, and enriched functional groups. These nanoprobes utilize apoferritin (an intracellular protein for iron stores and release) to encase appropriate molecular organic dyes to produce on-demand fluorescence in aqueous solution. A pH-driven dissociation-reconstitution process of apoferritin subunits allows substantial incorporation of hydrophilic (aggregation caused quenching, ACQ) or hydrophobic (aggregation induced enhancement, AIE) dye molecules into the protein nanocavity (8 nm), producing monodispersed dye-apoferritin nanoparticles (apo-dye-NPs, ∼12 nm). As compared with single dye monomer, single apo-dye-NPs possess hundreds of times larger molar extinction coefficient and 2 orders of magnitude higher absolute luminescence quantum yield (up to 45-fold), multiplying fluorescence brightness up to 2778-fold. We show that varying the type of incorporated dyes entails a precise control over nanoprobe emission profile tunable in a broad spectral range of 370-1300 nm. Mechanical investigations indicate that the diversified microstructures of nanocavity inner surface are able to conform ACQ dyes at reasonable space interval while providing protein-guided-stacking for AIE dyes, thus enhancing fluorescence quantum yield through confining intermolecular quenching and intramolecular rotation. Moreover, apo-dye-NPs are able to emit stable fluorescence (over 13 min) without quenching in confocal imaging of HepG2 cancer cell under ultrahigh laser irradiance (1.3 × 106 W/cm2). These superb properties make them suitable, as demonstrated in this work, for long-term super-resolved structured illumination microscopic cell imaging (spatial resolution, 117 nm) over 48 h, near-infrared (NIR) fluorescence angiography imaging of whole-body blood vessels (spatial resolution, 380 μm), and NIR photoacoustic imaging of liver in vivo.

Use of indocyanine green fluorescence guidance in redo ileocolic resection for Crohn's disease.

Redo ileocolic resection in patients with Crohn's disease (CD) is associated with significant technical challenges that may be associated with high complication rates. The aim of this study was to evaluate the feasibility of near-infrared fluorescence angiography with indocyanine green (ICG), often used to evaluate blood supply to the anastomosis in CD patients undergoing repeat ileocolic resection. This study was a retrospective analysis of patients who underwent redo ileocolic resection using ICG bowel perfusion assessment between 2015 and 2021. Patients were matched and compared on a 1:2 basis with a control group undergoing the same procedure without perfusion assessment. Twelve patients underwent redo ileocolic resection with ICG perfusion assessment (ICG group). These were compared with 24 patients who underwent the procedure without ICG (control group). Both groups were similar in demographics and operative characteristics including median operating time (255 vs. 255.5min, p=0.39) and conversion rate (22% vs. 36.8%, p=0.68). Median estimated blood loss was significantly higher in the ICG group [150 (50-400) vs. 100ml (20-125)]. Successful ICG perfusion assessment was seen in all patients in the ICG group and did not change management in any case. Overall postoperative complication rates were comparable between the groups (58.3% vs. 54.1%, p=0.72). No anastomotic leaks occurred in the ICG group compared with one (1/24, 4.2%) in the control group (p=0.99). Fluorescence ICG perfusion assessment is feasible and safe in redo ileocolic resection in patients with CD. Larger studies are needed to evaluate whether this technique should be routinely used in these complex surgical interventions.

Fluorescent angiography in colorectal surgery, the influence of augmented reality in the operating room on the anastomotic leakage after low rectal resection

Near-infrared (NIR) fluorescence angiography (FA) is an augmented reality (AR) technique. When used in the operating room, it allows colorectal surgeons to visualize and evaluate intestinal blood flow in real time, identify lymph nodes, ureters, or peritoneal metastases. Evaluation of perfusion with FA in augmented reality mode has an impact on reducing the ALR (anastomotic leakage rate) in rectal resections. Data analysis of patients after minimally invasive surgery (MIS) for middle and lower rectal adenocarcinoma with total mesorectal excision (TME) using fluorescent angiography (FA) with indocyanine green (ICG) (100 patients, 20152019) were subsequently compared with a historical control group (100 patients) operated on for the same diagnosis before the introduction of the FA-ICG method (20122015) using minimally invasive approach (MIS). The patients were operated on consequently at one workplace. In fifteen patients (15%), the resection line was shifted due to insufficient perfusion detected by FA-ICG. The incidence of AL was lower in the group with FA compared to the group without FA (9% vs. 19%, p=0.042, &#967; test). A retrospective analysis of the group revealed a significant risk factor (RF) for the anastomotic leak, namely diabetes (p=0.036) and, among others, a protective factor, application of the transanal drain (NoCoil) (p=0.032). The introduction of new procedures and the use of new technologies, such as the use of the FA method in the AR mode in resections of the rectum with TME for cancer can lead to a reduction in the incidence of anastomotic leakage.

The impact of the quantitative assessment procedure for coronary artery bypass graft evaluations using high-resolution near-infrared fluorescence angiography.

Near-infrared angiography (NIR) is used for on-site graft assessment during coronary artery bypass grafting. This study evaluated the results of a quantitative NIR assessment using a new high-resolution NIR device (h-NIR) for graft assessment. Forty-three patients were enrolled in our study. Internal thoracic artery (ITA) grafts anastomosed to the left anterior descending artery and examined intraoperatively using h-NIR were included. The ITA grafts were divided into 2 groups for a comparative analysis: patent grafts (P group; n = 37) and failed grafts (F group; n = 6). The graft flow was evaluated by a "quantitative NIR assessment", and the fluorescence luminance intensity (FLI) was measured. Direct observation of the graft and anastomosis with h-NIR was also performed. The FLI was higher in the P group than in the F group. The receiver operating characteristic analysis revealed the following cut-off values for FLIs depending on imaging duration: 21.1% at 1s, 35.5% at 2s, 58.4% at 3s, and 83.3% at 4s. The sensitivity and specificity for detecting graft failure were 83.3% and 69.8-80.6%, respectively. Furthermore, h-NIR was also able to visualize arterial dissection in ITA grafts. A quantitative NIR assessment with an h-NIR device can improve the detectability of anastomotic stenosis, and h-NIR successfully detected arterial dissection of grafts.

Fluorescence imaging in evaluating the revascularization of heterotopically transplanted primate trachea segment

Objective:to assess the potentials of using indocyanine green fluorescence angiography in evaluating revascularization of tissue-engineered construct that was obtained from the decellularized biological matrix of primate trachea, including using mesenchymal stem cells, after heterotopic tracheal allotransplantation.Material and methods.Tracheas were obtained from two male hamadryas baboons. After decellularization, 4 cm segments of tracheas were implanted under the lateral part of the latissimus dorsi in two healthy primates, one after recellularization with mesenchymal stem cells (animal 1), and the second without recellularization (animal 2). Immunosuppressive therapy was not performed. Blood flow in the transplanted segment of the trachea was evaluated 60 days after transplantation by surgical isolation of the flap of the latissimus dorsi with the transplanted segment of the trachea, while maintaining blood flow through the thoracodorsal artery. Indocyanine green near-infrared fluorescence angiography was visualized using a FLUM-808 multispectral fluorescence organoscope.Results.Sixty days after implantation, the tracheal cartilaginous framework macroscopically appeared to be intact in both animals, tightly integrated into the muscle tissue. The framework retained its natural color. After intravenous injection of indocyanine green, the tracheal vessels were visualized in both animals. Intercartilaginous vessels and portions of the cartilaginous semi-rings devoid of vessels were clearly distinguished. The entire implanted segment was almost uniformly vascularized. No local disruptions in blood supply were observed. The fluorescence brightness of the tracheal vessels was 193 ± 17 cu and 198 ± 10 cu in animals 1 and 2, respectively. The average muscle brightness in the implantation zone was 159 ± 9 cu and 116 ± 8 cu in animals 1 and 2, respectively.Conclusion. Indocyanine green fluorescence angiography is characterized by high-contrast images and high sensitivity. This facilitates vascular patency visualization and allows to assess the degree of neoangiogenesis after experimental transplantation of the tracheal segment, at different stages of experiment, without euthanizing the animal.

Bowel viability assessment during surgery (review of the literature)

The problem of bowel viability assessment during surgery is still opened. High value predictive and economically available technique is thought to decrease postoperative morbidity and mortality during elective and urgent abdominal surgery. To evaluate the available techniques for intraoperative bowel viability assessment, the search of Russian and foreign up-to-date literature was performed. Parameters of techniques are analyzed: intraoperative clinical application, invasiveness, objectivity and quantification of viability parameters, predictive value for necrosis and anastomotic leakage. There is still no standardised and available for every operative theatre method for bowel viability assessment during surgery. Numerous of techniques such as near-infrared fluorescence (NIR) angiography, using indocyanine green (ICG), optical coherence tomography (OCT), laser doppler flowmetry (LDF) are proposed to be more evaluated and perspective. Autofluorescence spectroscopy for NADH and flavoproteins seems to be a promising tool for early detection of nonviable bowel segments.

Near-infrared fluorescence angiography for colorectal surgery is associated with a reduction of anastomotic leak rate.

Decreased blood perfusion at the anastomotic site increases the risk of anastomotic leakage (AL) following colorectal surgery. Indocyanine green near-infrared fluoroangiography (NIRF/ICG) is a technique that allows for the assessment of intestinal perfusion before and after the formation of an anastomosis. We aimed to compare the rate of AL after colorectal surgery conducted with NIRF/ICG assessing vascular anastomotic perfusion and without this support. The data of patients who underwent colorectal surgery from November 2014 to February 2019 were reviewed retrospectively. Left-sided hemicolectomy, sigmoid resection, and anterior rectal resection were included. Emergency resections were excluded. Procedures conducted with NIRF/ICG and without NIRF/ICG (no-NIRF/ICG) support were compared using Fisher's and Mann-Whitney U test. Overall, 196 procedures were included, 98 were carried out with no-NIRF/ICG and 98 with NIRF/ICG. Patients' clinical and intraoperative characteristics were similar in the two groups. In the NIRF/ICG, fluorescence was detected in 100% of the cases; following NIRF/ICG the planned site of transection was changed in eight cases, whereas in one case the anastomosis was re-performed. Overall, six patients (3%) developed an AL, 0% in the NIRF/ICG and 6% (n = 6) in the no-NIRF/ICG group (p = 0.029). Median hospital length of stay was shorter in the NIRF/ICG group [6days (IQR 6-7) vs. 7days (IQR 6-9), p < 0.001]. The results of this study suggest that the use of the NIRF/ICG was safe for colorectal surgery and decreases the risk of anastomotic leak. A randomized trial is required to confirm these preliminary data.

Which is the Pivotal Vessel in Vascular Supercharging? An Assessment of Three Forms of Vascular Supercharging Models Using Indocyanine Green Fluorescence Angiography

BackgroundThe study aimed to perform continuous and dynamic observation on the blood flow changes in a rat abdominal model of supercharged flaps to examine the roles of arterial and venous supercharging in preventing distal flap necrosis. Materials and methodsEighteen rats were divided into three experimental groups. The left-sided flaps in all groups were used as controls such that the subxiphoid perforator vessels served as the only pedicle. Experimental groups I, II, and III consisted of supercharged right-sided flaps. Group I, the arteriovenous supercharging group, had flaps supercharged by the suprapubic perforator arteries and veins. Group II, the arterial supercharging group, had flaps supercharged by the suprapubic perforator arteries. Group III, the venous supercharging group, had flaps supercharged by the suprapubic perforator veins. Laser-induced near-infrared fluorescence angiography was performed before and after surgery. ResultsAs revealed by near-infrared fluorescence angiography, the control group and venous supercharging group exhibited rapid reductions in blood supply and loss of arterial perfusion in distal areas. The distal flap necrosis was much smaller in the venous supercharging group than in the control group. Both the arteriovenous supercharging group and the arterial supercharging group exhibited adequate perfusion and resulted in full postoperative survival of the flaps. ConclusionsThese findings indicated that the distal arterial hypoperfusion is the major cause of the distal venous stasis and necrosis in the flaps. Sufficient arterial supercharging ensures the distal arterial perfusion and therefore diminishes the occurrence of distal flap necrosis.

Near-infrared fluorescence angiography for intra-operative assessment of pedicled omentoplasty for filling of a pelvic cavity: a pilot study

BackgroundDuring creation of a pedicled omentoplasty, blood flow to segments of the omentum might become compromised. If unrecognized, this can lead to omental necrosis. The purpose of this study was to investigate the potential added intra-operative value of the use of fluorescence angiography (FA) with indocyanine green (ICG) to assess omental perfusion.MethodsAll consecutive patients undergoing a pedicled omentoplasty in a 6-month period (April 1 2018–October 1 2018) in a University hospital were included. The primary outcome was change in management due to FA. Secondary outcomes included the amount of additionally resected omentum, added surgical time, and quantitative fluorescent values (time to fluorescent enhancement, contrast quantification).ResultsFifteen patients had pelvic surgery with omentoplasty and FA. Change in management occurred in 12 patients (80%) and consisted of resecting a median of 44 g (range 12–198 g) of poorly perfused omental areas that were not visible by conventional white light. The median added surgical time for the use of FA and subsequent management was 8 min (range 3–39 min). The first fluorescent signal in the omental tissue appeared after a median of 20 s (range 9–37 s) after injection of ICG. The median signal-to-baseline ratio was 23.7 (interquartile range 12.2–29.7) in well perfused and 2.5 (interquartile range 1.7–4.0) in poorly perfused tissue.ConclusionsFA of a pedicled omentoplasty allows a real-time assessment of omental perfusion and leads to change in management in 80% of the cases in this pilot study. These findings support the conduct of larger studies to determine the impact on patient outcome in this setting.

Influence of residual coronary flow on bypass graft flow for graft assessment using near-infrared fluorescence angiography.

Near-infrared fluorescence angiography (NIR) detects the attenuation of fluorescence luminance intensity (FLI) through coronary artery bypass grafts affected by anastomotic stenosis. This study investigates the influence of residual blood flow of the host coronary artery (Ho) on bypass graft (Gr) FLI using a coronary artery bypass (CABG) model. A mock circuit system was created using artificial vessels and artificial blood was supplied to the Gr and the Ho. We used NIR to examine the changes in FLI through the Gr. The Gr FLI was significantly attenuated according to the degree of Gr stenosis. The Gr FLI did not differ significantly among all degrees of Ho stenosis. High FLI grafts included grafts with degrees of Gr stenosis ≤ 75%, regardless of the severity of Ho stenosis. Moderate and low FLI grafts had 90 or 99% Gr stenosis, regardless of the severity of Ho stenosis. Gr FLI with 99% Gr stenosis was higher in 99% Ho stenosis than in ≤ 90% Ho stenosis. A high Gr FLI indicated the absence of ≥ 90% stenosis in the anastomosis and a low Gr FLI indicated severe stenosis in the anastomosis despite Ho stenosis. High Ho stenosis may prevent the attenuation of Gr FLI in severely stenosed grafts.