Predicting the survival of experimental ischaemic small bowel using intraoperative near-infrared fluorescence angiography

Use of real-time near-infrared fluorescence to assess gastric viability in dogs with gastric dilatation volvulus: A case-control study

OBJECTIVE

To describe near-infrared fluorescence (NIRF) for assessment of gastric viability and describe NIRF's influence on the surgeon's operative strategy in dogs with gastric dilatation and volvulus (GDV).

STUDY DESIGN

Prospective clinical trial.

ANIMALS

Twenty dogs with GDV and 20 systemically healthy dogs.

METHODS

Following gastric derotation, the surgeon's subjective assessment of gastric viability was recorded prior to near-infrared imaging. Changes in the surgeon's initial assessment of viability based on the visual pattern of gastric fluorescence was recorded. If nonviable (lack of defined vessels), a partial gastrectomy was performed and submitted for histopathology. The stapled gastrectomy line was imaged. Viable (defined vessels) and nonviable fluorescence intensities were compared with healthy dogs undergoing surgery for nongastrointestinal disease.

RESULTS

Subjective assessment diagnosed 17 viable and three nonviable GDVs (2 fundi; 1 cardia). Near-infrared imaging demonstrated nonviable gastric fluorescence in 4 dogs (3 fundi/cardia; 1 fundus). The surgeon's margins for resection were altered in 3/20 dogs. Fluorescence intensity (cardia, fundus, body, pylorus) was lower in GDV viable (30.59%, p = .04; 38.17%, p < .01; 51.18%, p < .01; 44.12%, p= .01) and nonviable (11.00%, p < .01; 4.33%, p < .01; 57.67%, p = .22; 54.33%, p = .72) dogs compared to healthy controls (44.7%, 70.05%, 84.00%, 63.95%). Fundic fluorescence was less in nonviable gastric tissue in comparison with viable gastric tissue (p = .03). Fluorescence of the gastrectomy staple line approximated that of viable tissue.

CONCLUSION

Near-infrared fluorescence can identify histologically confirmed nonviable gastric tissue.

CLINICAL SIGNIFICANCE

These results provide enough evidence to support the implementation of NIRF as an adjunct to gross examination of the gastric wall in dogs with GDV.

Outcomes of nonrejection in weakly fluorescent intestine detected by indocyanine green fluorescence angiography: a case series of infants

BACKGROUND

Indocyanine green fluorescence angiography, a validated noninvasive imaging technique, is used to assess tissue vascularization. Here, we report three infant patients who underwent intraoperative indocyanine green fluorescence angiography and suffered from postoperative complications caused by the lack of weak fluorescent intestinal resection and assessed residual intestinal perfusion.

CASE PRESENTATION

We observed the clinical characteristics and operative findings of patients treated from January 2022 to December 2022. Indocyanine green (0.5 mg/kg) was intravenously injected. The first patient was a 29-day-old girl with surgical necrotizing enterocolitis who underwent intraoperative indocyanine green fluorescence angiography at the first- and second-look operations. The proximal jejunum was difficult to diagnose to detect blood flow during the second-look operation. The second patient was a 32-day-old boy with surgical necrotizing enterocolitis. A part of the antimesenteric mucosa of the patient that exhibited weak fluorescence was preserved; however, it formed postoperative hematomas. The third patient was a 30-day-old boy with midgut volvulus. Weak fluorescence in the intestinal wall was observed 5 cm of the small intestine from the ileocecal valve was preserved, but it formed a stricture, and the patient underwent ileocecal resection after 30 days.

CONCLUSIONS

Weak fluorescence in the intestine in infants by performing indocyanine green fluorescence angiography is associated with a high risk of non-recovering ischemic lesions and postoperative complications.

Assessment of jejunal interposition perfusion using indocyanine green

INTRODUCTION

Jejunal interposition (JI) is an option for oesophageal replacement in children; ensuring good graft perfusion is essential. We report three cases where Indocyanine Green (ICG) with Near-Infrared Fluorescence (NIRF) was used to assess perfusion during graft selection, passage into the chest and anastomotic assessment. This extra assessment may reduce risk of anastomotic leak and/or stricture.

METHODS

We describe the technique and salient features of all patients who have undergone ICG/NIRF-assisted JI in our centre. Patient demographics, indications for surgery, intra-operative plan, video of NIR perfusion assessment, complications and outcomes were reviewed.

RESULTS

ICG/NIRF was used in three patients (2M:1F) at a dose of 0.2 mg/kg. ICG/NIRF imaging helped select the jejunal graft and confirmed perfusion after division of segmental arteries. Perfusion was assessed before and after passing the graft through the diaphragmatic hiatus and before and after making the oesophago-jejunal anastomosis. Intrathoracic assessment at the end of the procedure confirmed good perfusion of mesentery and intrathoracic bowel. In two patients, the reassurance contributed to successful procedures. In the third patient, graft selection was satisfactory, but borderline perfusion on clinical assessment after passing the graft to the chest, confirmed by ICG/NIRF meant the graft was abandoned.

CONCLUSIONS

ICG/NIRF imaging was feasible and augmented our subjective assessment of graft perfusion, giving greater confidence during graft preparation, movement, and anastomosis. In addition, the imaging helped us abandon one graft. This series demonstrates the feasibility and benefit of ICG/NIR use in JI surgery. Further studies are required to optimise ICG use in this setting.

Unsupervised and quantitative intestinal ischemia detection using conditional adversarial network in multimodal optical imaging

Purpose

Intraoperative evaluation of bowel perfusion is currently dependent upon subjective assessment. Thus, quantitative and objective methods of bowel viability in intestinal anastomosis are scarce. To address this clinical need, a conditional adversarial network is used to analyze the data from laser speckle contrast imaging (LSCI) paired with a visible-light camera to identify abnormal tissue perfusion regions.

Approach

Our vision platform was based on a dual-modality bench-top imaging system with red-green-blue (RGB) and dye-free LSCI channels. Swine model studies were conducted to collect data on bowel mesenteric vascular structures with normal/abnormal microvascular perfusion to construct the control or experimental group. Subsequently, a deep-learning model based on a conditional generative adversarial network (cGAN) was utilized to perform dual-modality image alignment and learn the distribution of normal datasets for training. Thereafter, abnormal datasets were fed into the predictive model for testing. Ischemic bowel regions could be detected by monitoring the erroneous reconstruction from the latent space. The main advantage is that it is unsupervised and does not require subjective manual annotations. Compared with the conventional qualitative LSCI technique, it provides well-defined segmentation results for different levels of ischemia.

Results

We demonstrated that our model could accurately segment the ischemic intestine images, with a Dice coefficient and accuracy of 90.77% and 93.06%, respectively, in 2560 RGB/LSCI image pairs. The ground truth was labeled by multiple and independent estimations, combining the surgeons' annotations with fastest gradient descent in suspicious areas of vascular images. The total processing time was 0.05 s for an image size of 256 × 256 .

Conclusions

The proposed cGAN can provide pixel-wise and dye-free quantitative analysis of intestinal perfusion, which is an ideal supplement to the traditional LSCI technique. It has potential to help surgeons increase the accuracy of intraoperative diagnosis and improve clinical outcomes of mesenteric ischemia and other gastrointestinal surgeries.

Quantitative Analysis of Colonic Perfusion Using ICG Fluorescence Angiography and Its Consequences for Anastomotic Healing in a Rat Model

Forty-three rats were randomly assigned to the following four groups: non-ischemic group (Control Group), 1 cm-long ischemic group (Group 1), 2 cm-long ischemic group (Group 2), and 3 cm-long ischemic group (Group 3). The rates of AL were 0% (0/10) in the Control Group, 22.2% (2/9) in Group 1, 25% (2/8) in Group 2, and 50% (4/8) in Group 3. The bursting pressure of the Control Group was significantly higher than that of the other groups (p < 0.01). Regarding the pathological findings, the granulation thickness and the number of blood vessels at the anastomosed site were significantly higher in the Control Group than in Group 3 (p < 0.05). Receiver operating characteristics analysis revealed that Slope was the most significant predictor of AL, with an area under the curve of 0.861. When the cutoff value of Slope was 0.4, the sensitivity and specificity for the prediction of AL were 75% and 81.4%, respectively. Quantitative analysis of ICG fluorescence angiography could predict AL in a rat model.

Usefulness of blood flow evaluation with indocyanine green fluorescence imaging during laparoscopic surgery for strangulated bowel obstruction: A cohort study

INTRODUCTION

Intestinal blood flow evaluation during strangulated bowel obstruction is often based on the subjective assessment of the operator. Therefore, we aimed to comprehensively determine the presence or absence of intestinal blood flow based on normal light and indocyanine green (ICG) fluorescence imaging. Moreover, we ascertained whether the chosen surgical plan was appropriate, based on the patients' postoperative course and pathological findings.

METHODS

All 14 patients diagnosed with strangulated bowel obstruction at our hospital who underwent laparoscopic surgery between July 2019 and January 2021 were enrolled. Surgical plans were chosen based on normal light imaging combined with near-infrared imaging after intravenous ICG injection. Intestinal resection was performed via a small laparotomy if resection was considered necessary. In the intestinal resection group, the presence of intestinal necrosis was examined based on the pathological findings of the resected specimens. In the intestinal preservation group, postoperative complications, such as delayed intestinal perforation and intestinal stricture, were examined.

RESULTS

Intestinal resection was performed in 4 cases. The pathological findings of the resected specimens showed necrosis of the small intestine in all cases. No intra-abdominal complication occurred any of the cases, and the median postoperative hospital stay was 9.9 days.

CONCLUSIONS

The selection of a surgical plan in conjunction with ICG fluorescence findings was valid in all 14 cases. ICG fluorescence imaging is useful in laparoscopic surgery for strangulated bowel obstruction and may be a novel method for evaluating intestinal blood flow during surgery.

Intraoperative quality assessment of tissue perfusion with indocyanine green (ICG) in a porcine model of mesenteric ischemia

Background

Mesenteric ischemia is a severe and potentially lethal event. Assessment of intestine perfusion is eminently depending on the skills, and the experience of the surgeon. Thus, the therapy is biased by the right evaluation. Aim of this study is to determine the applicability, and the usefulness of fluorescent-imaging (FI) with indocyanine green (ICG) in a porcine model of mesenteric ischemia. Second end-point is the verification of a visual and quantitative assessment tool of the intestinal perfusion.

Methods

In 18 pigs (54,2 ±2,9kg) an occlusion of a side-branch of the mesenteric artery was performed for 3 (group I, n = 7), 6 (group II, n = 7), and 10 hours (group III, n = 4). After reperfusion a 60 minutes observation period was carried out. 3 regions of interest were defined: ischemic bowel (D1), transitional zone (D2), and non-ischemic bowel (D3). ICG-FI was performed during baseline (T0), occlusion (T1), reperfusion (T2) and after an observation period of 60 minutes (T4).

Results

All experiments could be finished successfully. ICG-FI was assessed using assessment of background-subtracted peak fluorescence intensity (BSFI), slope of fluorescence intensity (SFI), and a baseline adjusted ratio of both parameters. ICG-FI confirmed loss of perfusion in D1, decreased perfusion in D2, and increased perfusion in D3. After reperfusion ICG-FI increased in group 2 due to a severe tissue damage resulting in a capillary leakage. In group I ICG-FI was equal to baseline values indicating the totally reversible loss of perfusion.

Conclusion

Using ICG-FI to estimate intestine perfusion after different durations of ischemia is viable using a porcine model of mesenteric ischemia. Even small differences in perfusion can be reliably determined by ICG-FI. Thus, ICG-FI is an encouraging method to evaluate intestine perfusion intraoperatively.

Predictive and Diagnostic Biomarkers of Anastomotic Leakage: A Precision Medicine Approach for Colorectal Cancer Patients

Development of an anastomotic leak (AL) following intestinal surgery for the treatment of colorectal cancers is a life-threatening complication. Failure of the anastomosis to heal correctly can lead to contamination of the abdomen with intestinal contents and the development of peritonitis. The additional care that these patients require is associated with longer hospitalisation stays and increased economic costs. Patients also have higher morbidity and mortality rates and poorer oncological prognosis. Unfortunately, current practices for AL diagnosis are non-specific, which may delay diagnosis and have a negative impact on patient outcome. To overcome these issues, research is continuing to identify AL diagnostic or predictive biomarkers. In this review, we highlight promising candidate biomarkers including ischaemic metabolites, inflammatory markers and bacteria. Although research has focused on the use of blood or peritoneal fluid samples, we describe the use of implantable medical devices that have been designed to measure biomarkers in peri-anastomotic tissue. Biomarkers that can be used in conjunction with clinical status, routine haematological and biochemical analysis and imaging have the potential to help to deliver a precision medicine package that could significantly enhance a patient's post-operative care and improve outcomes. Although no AL biomarker has yet been validated in large-scale clinical trials, there is confidence that personalised medicine, through biomarker analysis, could be realised for colorectal cancer intestinal resection and anastomosis patients in the years to come.

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.

Defining indocyanine green fluorescence to assess anastomotic perfusion during gastrointestinal surgery: systematic review

Background

The aim of this systematic review was to identify all methods to quantify intraoperative fluorescence angiography (FA) of the gastrointestinal anastomosis, and to find potential thresholds to predict patient outcomes, including anastomotic leakage and necrosis.

Methods

This systematic review adhered to the PRISMA guidelines. A PubMed and Embase literature search was performed. Articles were included when FA with indocyanine green was performed to assess gastrointestinal perfusion in human or animals, and the fluorescence signal was analysed using quantitative parameters. A parameter was defined as quantitative when a diagnostic numeral threshold for patient outcomes could potentially be produced.

Results

Some 1317 articles were identified, of which 23 were included. Fourteen studies were done in patients and nine in animals. Eight studies applied FA during upper and 15 during lower gastrointestinal surgery. The quantitative parameters were divided into four categories: time to fluorescence (20 studies); contrast‐to‐background ratio (3); pixel intensity (2); and numeric classification score (2). The first category was subdivided into manually assessed time (7 studies) and software‐derived fluorescence–time curves (13). Cut‐off values were derived for manually assessed time (speed in gastric conduit wall) and derivatives of the fluorescence–time curves (F_max, T_1/2, TR and slope) to predict patient outcomes.

Conclusion

Time to fluorescence seems the most promising category for quantitation of FA. Future research might focus on fluorescence–time curves, as many different parameters can be derived and the fluorescence intensity can be bypassed. However, consensus on study set‐up, calibration of fluorescence imaging systems, and validation of software programs is mandatory to allow future data comparison.

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.

Effect of indocyanine green fluorescence angiography on preventing anastomotic leakage after colorectal surgery: a meta-analysis

Anastomotic leakage (AL) is a serious but not uncommon complication after colorectal surgery. We conducted this study to evaluate the effect of routine indocyanine green fluorescence angiography (ICG-FA) on reducing the AL rate after colorectal surgery. We identified all research articles about colorectal surgery using ICG-FA, published in the PubMed, EMBASE, and Cochrane Library databases from the date of database establishment to May 2020. Revman 5.3 was used for statistical analysis. We analyzed 22 controlled studies and 7 non-controlled studies on ICG-FA, including 6312 patients. The controlled studies included 2354 patients in the ICG group and 3522 patients in the non-ICG group. Meta-analysis showed that ICG-FA reduced the AL rate after colorectal surgery significantly (RR = 0.39; 95% CI 0.30-0.50; P < 0.00001). However, patients whose resection line was changed based on the fluorescence angiography had a higher AL rate than those whose resection line was not changed (OR = 5.37; 95% CI 2.67-10.81; P < 0.00001). The overall complication rate, severe complication rate, and reoperation rate in the ICG group were significantly lower than those in the non-ICG group (RR = 0.79, 95% CI 0.67-0.92, P = 0.002; RR = 0.67, 95% CI 0.47-0.96, P = 0.03; RR = 0.53, 95% CI 0.29-0.96, P = 0.04, respectively), whereas the postoperative ileus rate was significantly higher in the ICG group than in the non-ICG group (RR = 1.65; 95% CI 1.09-2.50; P = 0.02), especially in Western countries (RR = 1.6; 95% CI 1.04-2.47; P = 0.03).ICG-FA may reduce the AL rate after colorectal surgery, but ICG-FA group patients with transection line change for insufficient blood perfusion to the anastomotic stoma after evaluation had a higher AL rate than those without transection line change. Therefore, ICG-FA can help to identify patients at high risk of AL and intercept its occurrence. Moreover, ICG-FA may reduce the overall complication rate, severe complication rate, and reoperation rate, but induce postoperative ileus. High-quality randomized-controlled trials with a placebo control are needed to further evaluate the effectiveness and safety of ICG-FA.

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.

Intraoperative fluorescence perfusion assessment should be corrected by a measured subject-specific arterial input function

SIGNIFICANCE

The effects of varying the indocyanine green injection dose, injection rate, physiologic dispersion of dye, and intravenous tubing volume propagate into the shape and magnitude of the arterial input function (AIF) during intraoperative fluorescence perfusion assessment, thereby altering the observed kinetics of the fluorescence images in vivo.

AIM

Numerical simulations are used to demonstrate the effect of AIF on metrics derived from tissue concentration curves such as peak fluorescence, time-to-peak (TTP), and egress slope.

APPROACH

Forward models of tissue concentration were produced by convolving simulated AIFs with the adiabatic approximation to the tissue homogeneity model using input parameters representing six different tissue examples (normal brain, glioma, normal skin, ischemic skin, normal bone, and osteonecrosis).

RESULTS

The results show that AIF perturbations result in variations in estimates of total intensity of up to 80% and TTP error of up to 200%, with the errors more dominant in brain, less in skin, and less in bone. Interestingly, error in ingress slope was as high as 60% across all tissue types. These are key observable parameters used in fluorescence imaging either implicitly by viewing the image or explicitly through intensity fitting algorithms. Correcting by deconvolving the image with a measured subject-specific AIF provides an intuitive means of visualizing the data while also removing the source of variance and allowing intra- and intersubject comparisons.

CONCLUSIONS

These results suggest that intraoperative fluorescence perfusion assessment should be corrected by patient-specific AIFs measured by pulse dye densitometry.

Assessment of foot perfusion: Overview of modalities, review of evidence, and identification of evidence gaps

Patients with critical limb ischemia have nonhealing wounds and/or ischemic rest pain and are at high risk for amputation and mortality. Accurate evaluation of foot perfusion should help avoid unnecessary amputation, guide revascularization strategies, and offer efficient surveillance for patency. Our aim is to review current modalities of assessing foot perfusion in the context of the practical clinical management of patients with critical limb ischemia.

Techniques for intraoperative evaluation of bowel viability in mesenteric ischemia: A review

Acute mesenteric ischemia (AMI) is a deadly and common surgical emergency. While several imaging modalities aid in the diagnosis of AMI preoperatively, there are limited intraoperative tools for surgeon decision making regarding bowel viability. Here we offer a review of the utility and limitations of the many extensively studied techniques. We classify each of these modalities into three hallmarks of healthy bowel: oxygenation, myoelectric activity and perfusion. Finally, we offer a brief discussion of emerging and promising techniques to assist surgeons in intraoperative decision making for patients with mesenteric ischemia.

Remote computer-assisted analysis of ICG fluorescence signal for evaluation of small intestinal anastomotic perfusion: a blinded, randomized, experimental trial

BACKGROUND

Indocyanine green fluorescence imaging (ICG-FI) may be used to visualize intestinal perfusion prior to anastomosis. Methods for quantification of the fluorescence signal are required to ensure an objective evaluation. The aim of this study was to evaluate a method for quantification of relative perfusion and to investigate the correlation between the perfusion level and the anastomotic strength.

METHOD

This blinded, randomized, experimental trial included twenty pigs. Each pig received three small intestinal anastomoses with 30%, 60%, or 100% perfusion, respectively. The perfusion levels were determined relative to healthy intestine using ICG-FI. Ischemia was induced by mesenteric ligation and the perfusion level of each anastomosis was determined using a software-based analysis of the fluorescence signal. On postoperative day 5, the anastomoses were subjected to tensile strength test and histopathological assessment.

RESULTS

No anastomotic leakage occurred. The tensile strength of the 30% perfusion group was 9.09 N, which was significantly lower than the 60% perfusion group (11.5 N) and the 100% perfusion group (12.9 N). The difference between the 60% perfusion group and the 100% perfusion group was not significant. The histopathological assessment showed no significant differences between perfusion groups.

CONCLUSIONS

A reduction in blood supply to 30%, as determined by ICG-FI, in small intestinal anastomoses was necessary to demonstrate a decrease in tensile strength.

HYPerspectral Enhanced Reality (HYPER): a physiology-based surgical guidance tool

BACKGROUND

HSI is an optical technology allowing for a real-time, contrast-free snapshot of physiological tissue properties, including oxygenation. Hyperspectral imaging (HSI) has the potential to quantify the gastrointestinal perfusion intraoperatively. This experimental study evaluates the accuracy of HSI, in order to quantify bowel perfusion, and to obtain a superposition of the hyperspectral information onto real-time images.

METHODS

In 6 pigs, 4 ischemic bowel loops were created (A, B, C, D) and imaged at set time points (from 5 to 360 min). A commercially available HSI system provided pseudo-color maps of the perfusion status (StO2, Near-InfraRed perfusion) and the tissue water index. An ad hoc software was developed to superimpose HSI information onto the live video, creating the HYPerspectral-based Enhanced Reality (HYPER). Seven regions of interest (ROIs) were identified in each bowel loop according to StO2 ranges, i.e., vascular (VASC proximal and distal), marginal vascular (MV proximal and distal), marginal ischemic (MI proximal and distal), and ischemic (ISCH). Local capillary lactates (LCL), reactive oxygen species (ROS), and histopathology were measured at the ROIs. A machine-learning-based prediction algorithm of LCL, based on the HSI-StO2%, was trained in the 6 pigs and tested on 5 additional animals.

RESULTS

HSI parameters (StO2 and NIR) were congruent with LCL levels, ROS production, and histopathology damage scores at the ROIs discriminated by HYPER. The global mean error of LCL prediction was 1.18 ± 1.35 mmol/L. For StO2 values > 30%, the mean error was 0.3 ± 0.33.

CONCLUSIONS

HYPER imaging could precisely quantify the overtime perfusion changes in this bowel ischemia model.

Intraoperative biophotonic imaging systems for image-guided interventions

Biophotonic imaging has revolutionized the operation room by providing surgeons intraoperative image-guidance to diagnose tumors more efficiently and to resect tumors with real-time image navigation. Among many medical imaging modalities, near-infrared (NIR) light is ideal for image-guided surgery because it penetrates relatively deeply into living tissue, while nuclear imaging provides quantitative and unlimited depth information. It is therefore ideal to develop an integrated imaging system by combining NIR fluorescence and gamma-positron imaging to provide surgeons with highly sensitive and quantitative detection of diseases, such as cancer, in real-time without changing the look of the surgical field. The focus of this review is to provide recent progress in intraoperative biophotonic imaging systems, NIR fluorescence imaging and intraoperative nuclear imaging devices, and their future perspectives for image-guided interventions.

Dual-display laparoscopic laser speckle contrast imaging for real-time surgical assistance

Laser speckle contrast imaging (LSCI) utilizes the speckle pattern of a laser to determine the blood flow in tissues. The current approaches for its use in a clinical setting require a camera system with a laser source on a separate optical axis making it unsuitable for minimally invasive surgery (MIS). With blood flow visualization, bowel viability, for example, can be determined. Thus, LSCI can be a valuable tool in gastrointestinal surgery. In this work, we develop the first-of-its-kind dual-display laparoscopic vision system integrating LSCI with a commercially available 10mm rigid laparoscope where the laser has the same optical axis as the laparoscope. Designed for MIS, our system permits standard color RGB, label-free vasculature imaging, and fused display modes. A graphics processing unit accelerated algorithm enables the real-time display of three different modes at the surgical site. We demonstrate the capability of our system for imaging relative flow rates in a microfluidic phantom with channels as small as 200 μm at a working distance of 1-5 cm from the laparoscope tip to the phantom surface. Using our system, we reveal early changes in bowel perfusion, which are invisible to standard color vision using a rat bowel occlusion model. Furthermore, we apply our system for the first time for imaging intestinal vasculature during MIS in a swine.

Quantitative perfusion assessment of intestinal anastomoses in pigs treated with glucagon-like peptide 2

PURPOSE

Despite exhaustive research and improvement of techniques, anastomotic leakage remains a frequent complication in gastrointestinal surgery. As leakage is associated with poor perfusion, reliable objective methods to assess anastomotic perfusion are highly demanded. In addition, such methods enable evaluation of interventions that may improve anastomotic perfusion. Glucagon-like peptide 2 (GLP-2) is an enteroendocrine hormone that regulates mid-gut perfusion. In the present study, we aimed to explore if quantitative perfusion assessment with indocyanine green (q-ICG) could detect an increase in porcine anastomotic perfusion after treatment with GLP-2.

METHODS

Nineteen pigs had two small bowel resections followed by anastomosis. Blinded to all investigators, animals were randomized to receive GLP-2 or placebo. Anastomotic perfusion was assessed at baseline, 30 min after injection of GLP-2/placebo, and after 5 days of treatment. Anastomotic strength and healing were evaluated by bursting pressure and histology.

RESULTS

Q-ICG detected a significantly higher increase in anastomotic perfusion (p < 0.05) in animals treated with GLP-2, compared with placebo. No significant differences in anastomotic strength or healing were found.

CONCLUSIONS

Q-ICG is a promising tool for perfusion assessment in gastrointestinal surgery and opens new opportunities in research of factors that may influence anastomotic healing, but further research is warranted to evaluate the effects of GLP-2 on anastomotic healing.

Utilization of indocynanine green fluorescent imaging (ICG-FI) for the assessment of microperfusion in vascular medicine

Intraoperative valuation of organ and tissue microperfusion is always a current topic in different surgical situations. Although indocyanine green fluorescent imaging (ICG-FI) has turned to be a more and more common technique to evaluate organ perfusion, only few studies tried to quantitatively validate the technique for microperfusion assessment. The aim of the following manuscript is to present the results of our interdisciplinary research confirming additional quantitative assessment tools in different surgical conditions. Thus, we are implementing the background-subtracted peak fluorescent intensity (BSFI), the slope of fluorescence intensity (SFI), and the time to slope (TTS) using ICG-FI in several regions of interest (ROI).

Enhanced anastomotic healing by Daikenchuto (TJ-100) in rats

Daikenchuto (DKT), a traditional Japanese medicine, is widely used to treat various gastrointestinal disorders. This study aimed to investigate whether DKT could promote the anastomotic healing in a rat model. Pedicled colonic segments were made in left colon by ligation of the feeding arteries, and then intestinal continuity was restored. Colonic blood flow was analyzed by using ICG fluorescence imaging: Fmax, Tmax, T1/2, and Slope were calculated. Anastomotic leakage (AL) was found in 6 of 19 rats (31.6%) in the control group, whereas in 1 of 16 rats (6.2%) in the DKT group. The Fmax and Slope of DKT group were significantly higher than those of control group. DKT could promote the anastomotic healing, with the higher bursting pressure on postoperative day (POD) 2 and 5, the larger granulation thickness on POD 5, and neoangiogenesis on POD 5. Histological examination showed DKT exhibited a decreased inflammatory cell infiltration, enhanced fibroblast infiltration, and enhanced collagen density on POD 5. In the DKT group, the levels of TGFβ1 on POD 2 and VEGFα on POD5 were significantly higher, whereas the level of TNFα on POD 2 was significantly lower. Therefore, DKT could be effective for the prevention of AL following colorectal surgery.

Intraoperative Real-Time Assessment of Liver Function with Near-Infrared Fluorescence Imaging

BACKGROUND

Postoperative liver failure is a serious complication after major hepatectomy, and perioperative prediction of its incidence using current technology is still very difficult. Near-infrared (NIR) fluorescence imaging allows quantitative assessment of the fluorescent signal from indocyanine green (ICG) in regions of interest on the liver surface. This method might offer a new promising modality for evaluating regional liver reserve. However, data are lacking regarding the relationship between liver function and fluorescent signals on the liver surface after intravenous ICG injection. This study was conducted to obtain the data necessary to apply NIR fluorescence imaging as a modality for measuring liver function.

MATERIALS AND METHODS

This study included 16 patients who underwent open hepatopancreatobiliary surgery between March 2011 and March 2012. After laparotomy, ICG was injected intravenously at 2.5 mg/L of liver volume, then the fluorescence intensity (FI) and signal-to-background ratio (SBR) in the lateral segment of the liver were assessed for 15 min. Intraoperative blood samples were also obtained to measure the plasma clearance rate of ICG (ICGK). Correlations between ICGK, liver volume, and SBR, as well as between ICGK, liver volume, and rate of change of FI were analyzed.

RESULTS

The experimental procedure was performed in all 16 patients. The FI of the liver increased rapidly after ICG injection, then became more gradual, reaching a near-plateau after 15 min. A significant correlation was seen between ICGK and the rate of change of FI up to 15 min (|rS| = 0.5725, p < 0.05).

CONCLUSION

This is the first report to show a relationship between liver function and fluorescent signals on the liver surface after intravenous ICG injection. Intraoperative NIR fluorescence imaging with ICG may be useful as a new method for assessing liver function.

ICG fluorescence imaging for quantitative evaluation of colonic perfusion in laparoscopic colorectal surgery

BACKGROUND

Fluorescence technology with indocyanine green (ICG) provides a real-time assessment of intestinal perfusion. However, a subjective evaluation of fluorescence intensity based on the surgeon's visual judgement is a major limitation. This study evaluated the quantitative assessment of ICG fluorescence imaging in determining the transection line of the proximal colon during laparoscopic colorectal surgery.

METHODS

This is a retrospective analysis of a prospectively maintained database of 112 patients who underwent laparoscopic surgery for left-sided colorectal cancers. After distal transection of the bowel, the specimen was extracted extracorporeally and then the proximal colon was divided within the well-perfused area based on the ICG fluorescence imaging. We evaluated whether quantitative assessment of intestinal perfusion by measuring ICG intensity could predict postoperative outcomes: F _max, T _max, T _1/2, and Slope were calculated.

RESULTS

Anastomotic leakage (AL) occurred in 5 cases (4.5%). Based on the fluorescence imaging, the surgical team opted for further proximal change of the transection line up to an "adequate" fluorescent portion in 18 cases (16.1%). Among the 18 patients, AL occurred in 4 patients (4/18: 22.2%), whereas it occurred in only 1 case (1/94: 1.0%) in the good perfusion patients who did not need proximal change of the transection line. The F _max of the AL group was less than 52.0 in all 5 cases (5/5), whereas that of the non-AL group was in only 8 cases (8/107): with an F _max cutoff value of 52.0, the sensitivity and specificity for the prediction of AL were 100 and 92.5%, respectively. Regarding postoperative bowel movement recovery, the T _max of the early flatus group or early defecation group was significantly lower than that of the late flatus group or late defecation group, respectively.

CONCLUSIONS

ICG fluorescence imaging is useful for assessing anastomotic perfusion in colorectal surgery, which can result in more precise operative decisions tailored for an individual patient.

Indocyanine green fluorescence angiography for quantitative evaluation of in situ parathyroid gland perfusion and function after total thyroidectomy

BACKGROUND

Because the fluorescent light intensity on an indocyanine green fluorescence angiography reflects the blood perfusion within a focused area, the fluorescent light intensity in the remaining in situ parathyroid glands may predict postoperative hypocalcemia risk after total thyroidectomy.

METHODS

Seventy patients underwent intraoperative indocyanine green fluorescence angiography after total thyroidectomy. Any parathyroid glands with a vascular pedicle was left in situ while any parathyroid glands without pedicle or inadvertently removed was autotransplanted. After total thyroidectomy, an intravenous 2.5 mg indocyanine green fluorescence angiography was given and real-time fluorescent images of the thyroid bed were recorded using the SPY imaging system (Novadaq, Ontario, Canada). The fluorescent light intensity of each indocyanine green fluorescence angiography as well as the average and greatest fluorescent light intensity in each patient were calculated. Postoperative hypocalcemia was defined as adjusted calcium <2.00 mmol/L within 24 hours.

RESULTS

The fluorescent light intensity between discolored and normal-looking indocyanine green fluorescence angiographies was similar (P = .479). No patients with a greatest fluorescent light intensity >150% developed postoperative hypocalcemia while 9 (81.8%) patients with a greatest fluorescent light intensity ≤150% did. Similarly, no patients with an average fluorescent light intensity >109% developed PH while 9 (30%) with an average fluorescent light intensity ≤109% did. The greatest fluorescent light intensity was more predictive than day-0 postoperative hypocalcemia (P = .027) and % PTH drop day-0 to 1 (P < .001).

CONCLUSION

Indocyanine green fluorescence angiography is a promising operative adjunct in determining residual parathyroid glands function and predicting postoperative hypocalcemia risk after total thyroidectomy.

SPY technology as an adjunctive measure for lower extremity perfusion

OBJECTIVE

Lack of a reliable outcome measure often leads to excessive or insufficient interventions for critical limb ischemia (CLI). SPY technology (Novadaq Technologies Inc, Bonita Springs, Fla), widely adapted by plastic and general surgeons, uses laser-assisted fluorescence angiography (LAFA) to assess tissue perfusion. We sought to determine the role of SPY as an alternative, perhaps more reliable outcome measure for vascular interventions.

METHODS

All patients undergoing elective or urgent revascularization for claudication and CLI were prospectively recruited from June 2012 to August 2014. LAFA using SPY technology was performed before and after revascularization procedures under a standard Institutional Review Board-approved protocol. Quantitative measures of perfusion at plantar surfaces were analyzed and compared with ankle-brachial index.

RESULTS

A total of 93 patients with claudication or CLI underwent LAFA before and after a revascularization procedure in the study period. The mean preoperative ankle-brachial index increased from 0.60 to 0.84 (P < .001) after a revascularization procedure. Plantar perfusion as measured by LAFA also improved significantly after intervention. Ingress, defined as the rate at which fluorescence intensity increases on the plantar surface during LAFA, increased from 7.1 to 12.4 units/s (P < .001). Peak perfusion, defined as the difference between the baseline and the peak of fluorescence intensity, increased from 97.1 and 143.9 units (P < .001). Egress, defined as the rate at which intensity diminishes after reaching peak perfusion, increased from 1.0 to 1.9 units/s (P = .035). Procedure-related digital embolization was also observed in several patients despite lack of an angiographic finding.

CONCLUSIONS

This is the largest prospective study evaluating SPY technology in peripheral vascular interventions. Our study shows that SPY is a valuable tool in visualizing real-time procedural outcomes and providing additionally useful information on regional tissue perfusion. Further investigation is warranted to standardize outpatient use and to determine threshold values that predict wound healing.

Intraoperative measurement of bowel oxygen saturation using a multispectral imaging laparoscope

Intraoperative monitoring of tissue oxygen saturation (StO2 ) has potentially important applications in procedures such as organ transplantation or colorectal surgery, where successful reperfusion affects the viability and integrity of repaired tissues. In this paper a liquid crystal tuneable filter-based multispectral imaging (MSI) laparoscope is described. Motion-induced image misalignments are reduced, using feature-based registration, before regression of the tissue reflectance spectra to calculate relative quantities of oxy- and deoxyhaemoglobin. The laparoscope was validated in vivo, during porcine abdominal surgery, by making parallel MSI and blood gas measurements of the small bowel vasculature. Ischaemic conditions were induced by local occlusion of the mesenteric arcade and monitored using the system. The MSI laparoscope was capable of measuring StO2 over a wide range (30-100%) with a temporal error of ± 7.5%. The imager showed sensitivity to spatial changes in StO2 during dynamic local occlusions, as well as tracking the recovery of tissues post-occlusion.

Indocyanine Green: Historical Context, Current Applications, and Future Considerations

BACKGROUND

Indocyanine green (ICG) is a dye used in medicine since the mid-1950s for a variety of applications in in cardiology, ophthalmology, and neurosurgery; however, its fluorescent properties have only recently been used in the intraoperative evaluation of tissue perfusion.

METHOD

A literature review was conducted on the characterization and employment of ICG within the medical field. Historical and current context of ICG was examined while also considering implications for its future use.

RESULTS

ICG is a relatively nontoxic, unstable compound bound by albumin in the intravascular space until rapid clearance by the liver. It has widespread uses in hepatic, cardiac, and ophthalmologic studies, and its use in analyzing tissue perfusion and identifying sentinel lymph nodes in cancer staging is gaining popularity.

CONCLUSIONS

ICG has myriad applications and poses low risk to the patient. Its historical uses have contributed to medical knowledge, and it is now undergoing investigation for quantifying tissue perfusion, providing targeted therapies, and intraoperative identification of neurovascular anatomy, ophthalmic structures, and sentinel lymph nodes. New applications of ICG may lead to reduction in postoperative wound-related complications, more effective ophthalmologic procedures, and better detection and treatment of cancer cells.

Application of fluorescence in robotic general surgery: review of the literature and state of the art

The initial use of the indocyanine green fluorescence imaging system was for sentinel lymph node biopsy in patients with breast or colorectal cancer. Since then, application of this method has received wide acceptance in various fields of surgical oncology, and it has become a valid diagnostic tool for guiding cancer treatment. It has also been employed in numerous conventional surgical procedures with much success and benefit to the patient. The advent of minimally invasive surgery brought with it a new use for fluorescence in helping to improve the safety of these procedures, particularly for single-site procedures. In 2010, a near-infrared camera was integrated into the da Vinci Si System, creating a combination of technical and minimally invasive advantages that have been embraced by several experienced surgeons. The use of fluorescence, although useful, is considered challenging. Only a few studies are currently available on the use of fluorescence in robotic general surgery, whereas many articles have focused on its application in open and laparoscopic surgery. Many of these reports describe promising and satisfactory results, although with some shortcomings. The purpose of this article is to review the current status of the use of fluorescence in general surgery and particularly its role in robotic surgery. We also review potential uses in the future.

Enhanced-reality video fluorescence: a real-time assessment of intestinal viability

OBJECTIVE

Our aim was to evaluate a fluorescence-based enhanced-reality system to assess intestinal viability in a laparoscopic mesenteric ischemia model.

MATERIALS AND METHODS

A small bowel loop was exposed, and 3 to 4 mesenteric vessels were clipped in 6 pigs. Indocyanine green (ICG) was administered intravenously 15 minutes later. The bowel was illuminated with an incoherent light source laparoscope (D-light-P, KarlStorz). The ICG fluorescence signal was analyzed with Ad Hoc imaging software (VR-RENDER), which provides a digital perfusion cartography that was superimposed to the intraoperative laparoscopic image [augmented reality (AR) synthesis]. Five regions of interest (ROIs) were marked under AR guidance (1, 2a-2b, 3a-3b corresponding to the ischemic, marginal, and vascularized zones, respectively). One hour later, capillary blood samples were obtained by puncturing the bowel serosa at the identified ROIs and lactates were measured using the EDGE analyzer. A surgical biopsy of each intestinal ROI was sent for mitochondrial respiratory rate assessment and for metabolites quantification.

RESULTS

Mean capillary lactate levels were 3.98 (SD = 1.91) versus 1.05 (SD = 0.46) versus 0.74 (SD = 0.34) mmol/L at ROI 1 versus 2a-2b (P = 0.0001) versus 3a-3b (P = 0.0001), respectively. Mean maximal mitochondrial respiratory rate was 104.4 (±21.58) pmolO2/second/mg at the ROI 1 versus 191.1 ± 14.48 (2b, P = 0.03) versus 180.4 ± 16.71 (3a, P = 0.02) versus 199.2 ± 25.21 (3b, P = 0.02). Alanine, choline, ethanolamine, glucose, lactate, myoinositol, phosphocholine, sylloinositol, and valine showed statistically significant different concentrations between ischemic and nonischemic segments.

CONCLUSIONS

Fluorescence-based AR may effectively detect the boundary between the ischemic and the vascularized zones in this experimental model.

Investigating viability of intestine using spectroscopy: a pilot study

BACKGROUND

The differentiation of "viable" from "nonviable" bowel remains a challenge in the treatment of acute mesenteric ischemia. In this study, diffuse reflectance spectroscopy (DRS) was used to investigate the viability of bowel tissue after ischemia and reperfusion in an animal model in vivo and in real time.

METHODS

A total of 25 females Sprague-Dawley rats were divided into five groups based on different bowel ischemia times. In each study group for four of them, the superior mesenteric artery was occluded using a vascular clamp for a different period (i.e., 30, 45, 60, and 90 min; n = 5 for each group). Intestinal reperfusion was accomplished by releasing the clamps after the given occlusion period for each group. Spectra were acquired by gently touching the optical fiber probe to the bowel tissue before the induce ischemia, at the end of the induced ischemia, and after the reperfusion. The data acquired before the ischemia were used as a control group. Without occluding the superior mesenteric artery, the spectra were acquired on the bowel with the same time intervals of the experiments were used as a sham group (n = 5). Subsequently, the same bowel segments were sent for histopathologic examination.

RESULTS

Based on the correlation between the spectra acquired from the bowel segments and the results from the histopathologic investigation, DRS is able to differentiate the histopathologic grading that appears when the Chiu/Park score ≥5 (i.e., high-level ischemic injury) than Chiu/Park score <5. Eight out of nine low-level ischemic injury tissue samples were correctly defined using the spectroscopic classification system. All eleven high-level ischemic injury tissues that were histopathologically assigned grade 5 and above were correctly defined using the spectroscopic classification system in the ischemia-reperfusion groups.

CONCLUSIONS

DRS could potentially be used intraoperatively for the assessment of bowel viability in real time. These preliminary findings suggest that DRS has the potential to reduce unnecessary resection of viable tissue or insufficient resection of nonviable tissues may reduce the mortality and morbidity rates of intestinal ischemia-reperfusion as acute mesenteric ischemia.

Systematic review of methods to predict and detect anastomotic leakage in colorectal surgery

AIM

Anastomotic leakage is a serious complication of gastrointestinal surgery resulting in increased morbidity and mortality, poor function and predisposing to cancer recurrence. Earlier diagnosis and intervention can minimize systemic complications but is hindered by current diagnostic methods that are non-specific and often uninformative. The purpose of this paper is to review current developments in the field and to identify strategies for early detection and treatment of anastomotic leakage.

METHOD

A systematic literature search was performed using the MEDLINE, Embase, PubMed and Cochrane Library databases. Search terms included 'anastomosis' and 'leak' and 'diagnosis' or 'detection' and 'gastrointestinal' or 'colorectal'. Papers concentrating on the diagnosis of gastrointestinal anastomotic leak were identified and further searches were performed by cross-referencing.

RESULTS

Computerized tomography CT scanning and water-soluble contrast studies are the current preferred techniques for diagnosing anastomotic leakage but suffer from variable sensitivity and specificity, have logistical constraints and may delay timely intervention. Intra-operative endoscopy and imaging may offer certain advantages, but the ability to predict anastomotic leakage is unproven. Newer techniques involve measurement of biomarkers for anastomotic leakage and have the potential advantage of providing cheap real-time monitoring for postoperative complications.

CONCLUSION

Current diagnostic tests often fail to diagnose anastomotic leak at an early stage that enables timely intervention and minimizes serious morbidity and mortality. Emerging technologies, based on detection of local biomarkers, have achieved proof of concept status but require further evaluation to determine whether they translate into improved patient outcomes. Further research is needed to address this important, yet relatively unrecognized, area of unmet clinical need.

Image-guided cancer surgery using near-infrared fluorescence

Paradigm shifts in surgery arise when surgeons are empowered to perform surgery faster, better and less expensively than current standards. Optical imaging that exploits invisible near-infrared (NIR) fluorescent light (700-900 nm) has the potential to improve cancer surgery outcomes, minimize the time patients are under anaesthesia and lower health-care costs largely by way of its improved contrast and depth of tissue penetration relative to visible light. Accordingly, the past few years have witnessed an explosion of proof-of-concept clinical trials in the field. In this Review, we introduce the concept of NIR fluorescence imaging for cancer surgery, examine the clinical trial literature to date and outline the key issues pertaining to imaging system and contrast agent optimization. Although NIR seems to be superior to many traditional imaging techniques, its incorporation into routine care of patients with cancer depends on rigorous clinical trials and validation studies.

Intraoperative near-infrared indocyanine green fluorescence angiography (NIR-ICG AG) can predict delayed small bowel stricture after ischemic intestinal injury: report of a case

We herein report the case of a 15-year-old male who developed delayed intestinal stricture after undergoing massive intestinal resection due to severe small intestinal volvulus. At the time of the initial surgery, the laparotomy findings showed a massive intestinal volvulus without malrotation. Most of the small intestine appeared to be necrotic; therefore, massive necrotic intestinal resection was performed. The residual intestine comprised only the proximal jejunum and short ileum, including the ileocecal valve and entire colon. After the resection, the serosal surface color of the distal part of the residual jejunum (DPRJ) initially showed a slightly darker hue than normal. However, the color improved with time, and the other clinical findings also improved, which were considered to indicate that the perfusion of the DPRJ was preserved. The perfusion of that area was therefore clinically expected to improve with time. On the other hand, repeated intraoperative near-infrared indocyanine green fluorescence angiography (NIR-ICG AG) consistently showed abnormal vascular flow patterns in the same region, which were suspected to indicate the presence of perfusion damage of the DPRJ, in spite of improvements in the clinical findings. Although the necessity of additional resection was discussed at the time of reconstruction, we finally estimated that the perfusion of the DPRJ was preserved, mainly based on the improvement of the clinical findings of the intestine. The primary anastomosis was performed without additional resection, to maximize the lengths of the residual intestine. However, after the initial surgery, the patient developed a delayed partial stricture of the residual intestine, and an additional resection was necessary on the 22nd postoperative day. The stricture segment corresponded to the area that presented abnormal findings by NIR-ICG AG. This case suggests that abnormal NIR-ICG AG findings may predict delayed intestinal ischemic complications. We believe that NIR-ICG AG can intraoperatively provide more useful real time information for the assessment of intestinal perfusion, than conventional clinical assessment methods.

Use of indocyanine green for detecting the sentinel lymph node in breast cancer patients: from preclinical evaluation to clinical validation

Assessment of the sentinel lymph node (SLN) in patients with early stage breast cancer is vital in selecting the appropriate surgical approach. However, the existing methods, including methylene blue and nuclides, possess low efficiency and effectiveness in mapping SLNs, and to a certain extent exert side effects during application. Indocyanine green (ICG), as a fluorescent dye, has been proved reliable usage in SLN detection by several other groups. In this paper, we introduce a novel surgical navigation system to detect SLN with ICG. This system contains two charge-coupled devices (CCD) to simultaneously capture real-time color and fluorescent video images through two different bands. During surgery, surgeons only need to follow the fluorescence display. In addition, the system saves data automatically during surgery enabling surgeons to find the registration point easily according to image recognition algorithms. To test our system, 5 mice and 10 rabbits were used for the preclinical setting and 22 breast cancer patients were utilized for the clinical evaluation in our experiments. The detection rate was 100% and an average of 2.7 SLNs was found in 22 patients. Our results show that the usage of our surgical navigation system with ICG to detect SLNs in breast cancer patients is technically feasible.

Translational optical imaging

OBJECTIVE

Optical imaging is experiencing significant technologic advances. Simultaneously, an array of specific optical imaging agents has brought new capabilities to biomedical research and is edging toward clinical use. We review progress in the translation of macroscopic optical imaging-including fluorescence-guided surgery and endoscopy, intravascular fluorescence imaging, diffuse fluorescence and optical tomography, and multispectral optoacoustics (photoacoustics)-for applications ranging from tumor resection and assessment of atherosclerotic plaques to dermatologic and breast examinations.

CONCLUSION

Optical imaging could play a major role in the move from imaging of structure and morphology to the visualization of the individual biologic processes underlying disease and could, therefore, contribute to more accurate diagnostics and improved treatment efficacy.

Clinical application of fluorescence imaging of liver cancer using indocyanine green

Recently, fluorescence imaging using indocyanine green (ICG) has been applied to hepatobiliary surgery, not only to visualize the bile ducts, but also to identify liver cancer during surgery. In this technique, ICG is administered intravenously at a dose of 0.5 mg/kg body weight for routine liver function testing before surgery. Intraoperatively, liver cancer can be readily identified by fluorescence imaging on the liver surface before resection and on the cut surface of the resected specimen. This is achieved by visualizing fluorescence from the area of impaired bile excretion in hepatocellular cancer tissue and in the liver parenchyma surrounding metastatic liver cancers. Liver cancer navigation surgery, first developed in Japan, is also possible, and it represents one of the few fluorescence imaging techniques for cancer that have reached the stage of clinical application; with further developments in basic research, fluorescence imaging is expected to become an indispensable technique for the diagnosis and treatment of liver cancer.

Nitrite anion stimulates ischemic arteriogenesis involving NO metabolism

Nitric oxide (NO) is a potential regulator of ischemic vascular remodeling, and as such therapies augmenting its bioavailability may be useful for the treatment of ischemic tissue diseases. Here we examine the effect of administering the NO prodrug sodium nitrite on arteriogenesis activity during established tissue ischemia. Chronic hindlimb ischemia was induced by permanent unilateral femoral artery and vein ligation. Five days postligation; animals were randomized to control PBS or sodium nitrite (165 μg/kg) therapy twice daily. In situ vascular remodeling was measured longitudinally using SPY angiography and Microfil vascular casting. Delayed sodium nitrite therapy rapidly increased ischemic limb arterial vessel diameter and branching in a NO-dependent manner. SPY imaging angiography over time showed that nitrite therapy enhanced ischemic gracillis collateral vessel formation from the profunda femoris to the saphenous artery. Immunofluorescent staining of smooth muscle cell actin also confirmed that sodium nitrite therapy increased arteriogenesis in a NO-dependent manner. The NO prodrug sodium nitrite significantly increases arteriogenesis and reperfusion of established severe chronic tissue ischemia.