Intraoperative assessment of kidney allograft perfusion by laser-assisted indocyanine green fluorescence videography

Indocyanine green: A novel marker for assessment of graft quality during ex situ normothermic machine perfusion of human livers

BACKGROUND

Ex situ machine perfusion facilitates the assessment of livers prior to transplantation. However, currently available markers of liver function poorly predict long-term graft function. Indocyanine green (ICG) is a liver-specific dye which, although common in vivo, has never been comprehensively evaluated for the assessment of graft quality during ex situ machine perfusion. This study aimed to assess the utility of ICG in the ex situ setting.

METHODS

Using a customized long-term perfusion system, human livers that were not suitable for transplantation were perfused using a red cell-based perfusate. ICG was delivered into the perfusate on days 0, 1, and 4 to assess ICG clearance (spectrophotometric absorbance at 805 nm) and ICG fluorescence (near-infrared camera).

RESULTS

Sixteen partial livers were perfused for a median duration of 172 h (7.2 days). On day 0, the median ICG perfusate disappearance rate (PDR) was 7.5%/min and the median ICG retention at 15 min was 9.9%. Grafts that survived ≥7 days had a significantly higher median ICG PDR on day 0 (14.5%/min vs. 6.5%/min, p = 0.005) but not on days 1 or 4. ICG perfusion demonstrated that long-surviving grafts had a significantly lower median red-value (89.8 vs. 118.6, p = 0.011) and a significantly lower median blue-value (12.9 vs. 22.6, p = 0.045) than short-surviving grafts.

CONCLUSION

ICG is a novel marker for the assessment of liver function during ex situ normothermic machine perfusion. ICG PDR and quantitative ICG perfusion can distinguish between long- and short-surviving grafts and demonstrate the utility of ICG in the assessment of graft quality prior to transplant.

Perfusate Proteomes Provide Biological Insight Into Oxygenated Versus Standard Hypothermic Machine Perfusion in Kidney Transplantation

OBJECTIVE

To provide mechanistic insight into key biological alterations in donation after circulatory death kidneys during continuous pefusion we performed mass spectrometry profiling of perfusate samples collected during a phase 3 randomized double-blind paired clinical trial of hypothermic machine perfusion with and without oxygen (COMPARE).

BACKGROUND

Despite the clinical benefits of novel perfusion technologies aiming to better preserve donor organs, biological processes that may be altered during perfusion have remained largely unexplored. The collection of serial perfusate samples during the COMPARE clinical trial provided a unique resource to study perfusate proteomic profiles, with the hypothesis that in-depth profiling may reveal biologically meaningful information on how donor kidneys benefit from this intervention.

METHODS

Multiplexed liquid chromatography-tandem mass spectrometry was used to obtain a proteome profile of 210 perfusate samples. Partial least squares discriminant analysis and multivariate analysis involving clinical and perfusion parameters were used to identify associations between profiles and clinical outcomes.

RESULTS

Identification and quantitation of 1716 proteins indicated that proteins released during perfusion originate from the kidney tissue and blood, with blood-based proteins being the majority. Data show that the overall hypothermic machine perfusion duration is associated with increasing levels of a subgroup of proteins. Notably, high-density lipoprotein and complement cascade proteins are associated with 12-month outcomes, and blood-derived proteins are enriched in the perfusate of kidneys that developed acute rejection.

CONCLUSIONS

Perfusate profiling by mass spectrometry was informative and revealed proteomic changes that are biologically meaningful and, in part, explain the clinical observations of the COMPARE trial.

Exploring the Applications of Indocyanine Green in Robot-Assisted Urological Surgery: A Comprehensive Review of Fluorescence-Guided Techniques

This comprehensive review aims to explore the applications of indocyanine green (ICG) in robot-assisted urological surgery through a detailed examination of fluorescence-guided techniques. An extensive literature search was conducted in PubMed/MEDLINE, EMBASE and Scopus, using keywords such as "indocyanine green," "ICG", "NIRF", "Near Infrared Fluorescence", "robot-assisted", and "urology". Additional suitable articles were collected by manually cross-referencing the bibliography of previously selected papers. The integration of the Firefly^® technology in the Da Vinci^® robotic system has opened new avenues for the advancement and exploration of different urological procedures. ICG is a fluorophore widely used in near-infrared fluorescence-guided techniques. The synergistic combination of intraoperative support, safety profiles and widespread availability comprises an additional asset that empowers ICG-guided robotic surgery. This overview of the current state of the art illustrates the potential advantages and broad applications of combining ICG-fluorescence guidance with robotic-assisted urological surgery.

Using Laser Speckle Contrast Imaging to Quantify Perfusion Quality in Kidney and Pancreas Grafts on Vascular Reperfusion: A Proof-of-Principle Study

The accuracy of intraoperative graft perfusion assessment still remains subjective, with doppler examination being the only objective adjunct. Laser speckle contrast imaging (LSCI) has been used to assess intraoperative blood flow in neurosurgery and in various surgical specialties. Despite its ability to accurately quantify perfusion at the microvascular level, it has not been clinically evaluated in kidney/kidney-pancreas transplantation for perfusion characterization. We aimed to evaluate the utility of LSCI and identify objective parameters that can be quantified at reperfusion.

Methods

This study was registered in ClinicalTrials.gov (NCT04202237). The Moor FLPI-2 blood flow imager was used in 4 patients (1 Simultaneous Pancreas and Kidney, 2 deceased, and 1 living donor kidney transplants) during reperfusion to capture reperfusion data. The following parameters were measured: flux (average speed × concentration of moving red blood cells in the sample volume), doppler centroid, total and valid pixels, valid rate, and total and valid area. Flux data were analyzed with Moor FLPI analysis software.

Results

The perfusion characteristics and flux images correlated with initial graft function.

Conclusions

LSCI is a safe, noncontact imaging modality that provides real-time, accurate, high-resolution, full field blood flow images and a wide range of flux data to objectively quantify organ reperfusion intraoperatively in kidney/kidney-pancreas transplantation. This modality could be used to develop a robust numerical quantification system for the evaluation and reporting of intraoperative organ perfusion, and aid intraoperative decision-making. Perfusion data could be combined with biomarkers and immunological parameters to more accurately predict graft outcomes.

Enhanced photodynamic therapy/photothermotherapy for nasopharyngeal carcinoma via a tumour microenvironment-responsive self-oxygenated drug delivery system

The hypoxic nature of tumours limits the efficiency of oxygen-dependent photodynamic therapy (PDT). Hence, in this study, indocyanine green (ICG)-loaded lipid-coated zinc peroxide (ZnO₂) nanoparticles (ZnO₂@Lip-ICG) was constructed to realize tumour microenvironment (TME)-responsive self-oxygen supply. Near infrared light irradiation (808 nm), the lipid outer layer of ICG acquires sufficient energy to produce heat, thereby elevating the localised temperature, which results in accelerated ZnO₂ release and apoptosis of tumour cells. The ZnO₂ rapidly generates O₂ in the TME (pH 6.5), which alleviates tumour hypoxia and then enhances the PDT effect of ICG. These results demonstrate that ZnO₂@Lip-ICG NPs display good oxygen self-supported properties and outstanding PDT/PTT characteristics, and thus, achieve good tumour proliferation suppression.

Near-infrared fluorescence imaging with indocyanine green for assessment of donor livers in a rat model of ischemia-reperfusion

BACKGROUND

Although marginal donor livers expand the donor pool, an ideal method for quantitatively evaluating the quality of donor livers has not been developed. This study aimed to explore the feasibility of indocyanine green (ICG) fluorescence imaging for estimating liver function in an ischemia-reperfusion model.

METHODS

Forty-eight rats were randomly and evenly divided into 8 groups: the control group and the experimental groups (I-VII). The portal vein blocking period was 0 min, 10 min, 20 min, 30 min, 40 min, 50 min and 60 min. After blood flow was reestablished and the hemodynamics stabilized, ICG was injected through the dorsal penile vein as a bolus, and the fluorescence signal was recorded for 30 min in real time. The fluorescence intensity (FI) curve of the liver was fitted with an asymptotic regression model. Fresh liver tissues and serum were obtained from the middle lobe of the liver on postoperative day (POD) 1 and POD 7 for histopathological evaluation and liver function tests.

RESULTS

The growth rate of the FI curve, parameter b3, decreased from groups I to VII. According to the two sudden changes in b3 (20 min, 50 min), the experimental groups could be classified into 3 groups (A, B and C). Hepatocytes in groups I-II showed slight edema, group III began to show obvious hepatocyte edema and vacuolar degeneration, and in groups VI-VII, severe hepatocyte degeneration, necrosis and large inflammatory cell infiltration were observed. Suzuki's scores in the 3 groups were also significantly different (P < 0.01). At the same time, the serum liver function in the experimental groups showed a significant increase on POD 1 and a decrease on POD 7. The alanine aminotransferase (ALT), aspartate aminotransferase (AST), and total bilirubin (TB) levels of groups A, B, and C were significantly different on POD 1 (P < 0.05), and the ALT and direct bilirubin (DB) levels were significantly different on POD 7 (P < 0.05); the lactic dehydrogenase (LDH) level of the group C was significantly higher than that of the groups A and B on POD 1 and POD 7. Meanwhile, the 7-day survival rate of the rats in group C was poor compared to that of the rats in groups A and B (58.3% vs. 100% vs. 100%).

CONCLUSION

ICG fluorescence imaging is effective for estimating the degree of liver damage and grading in an ischemia-reperfusion model. It probably has the potential for use in assessing the quality of the donor liver in liver transplantation.

Indocyanine Green Angiography for Quality Assessment of the Kidney During Transplantation: An Outcome Predictor Prospective Study

BACKGROUND

Microvascular damage is the main cause of delayed graft function (DGF) after kidney transplant. Assessing its extent may be helpful in predicting DGF to achieve better postoperative management, especially in terms of an immunosuppressive regimen. Our aim was to explore the capability of intraoperative indocyanine green (ICG) angiography to examine the microvasculature of the kidney.

METHODS

We conducted a prospective cohort study on 37 kidney transplant recipients in a high-volume kidney transplant center. During surgery, after graft implant, an ICG angiography was performed through a high-definition Storz camera system (Karl Storz GmbH, Tuttlingen, Germany) with successive quantitative assessment of fluorescence using Icy bioimage analysis.

RESULTS

All transplanted kidneys that showed immediate recovery of their function had a fluorescent intensity ≥49.953 with a mean of 96.930 ± 21. The fluorescence intensity for kidneys that showed a delayed recovery of their function never exceeded 55.648, and the mean was 37.718 ± 13. The difference between the 2 groups was statistically significant with a P value < .001. The only kidney that never recovered showed a fluorescence intensity consistently <25.220, the lowest detected.

CONCLUSIONS

This study demonstrates that intraoperative ICG angiography may be used to assess the microvasculature of the graft. A statistically significant difference in terms of fluorescent intensity can be highlighted between kidneys that immediately recover their function and those with delayed recovery. Further larger studies are needed to confirm the capability of the technique to predict DGF to optimize the transplanted patients' management.

Real-Time Fluorescence Imaging Using Indocyanine Green to Assess Therapeutic Effects of Near-Infrared Photoimmunotherapy in Tumor Model Mice

Background:

Near-infrared photoimmunotherapy (NIR-PIT) is a cancer therapy that causes an increase in tumor perfusion, a phenomenon termed the super-enhanced permeability and retention effect. Currently, in vivo treatment efficacy of NIR-PIT is observable days after treatment, but monitoring would be improved by more acute detection of intratumor change. Fluorescence imaging may detect increased tumor perfusion immediately after treatment.

Methods:

In the first experiment, athymic nude mouse models bearing unilateral subcutaneous flank tumors were treated with either NIR-PIT or laser therapy only. In the second experiment, mice bearing bilateral flank tumors were treated with NIR-PIT only on the left-sided tumor. In both groups, immediately after treatment, indocyanine green was injected at different doses intravenously, and mice were monitored with the Shimadzu LIGHTVISION fluorescence imaging system for 1 hour.

Results:

Tumor-to-background ratio of fluorescence intensity increased over the 60 minutes of monitoring in treated mice but did not vary significantly in control mice. Tumor-to-background ratio was highest in the 1 mg kg⁻¹ and 0.3 mg kg⁻¹ doses. In mice with bilateral tumors, tumor-to-untreated tumor ratio increased similarly.

Conclusions:

Acute changes in tumor perfusion after NIR-PIT can be detected by real-time fluorescence imaging.

Intraoperative assessment of ureter perfusion after revascularization of transplanted kidneys using intravenous indocyanine green fluorescence imaging

Background

Kidney transplantation is the most valuable renal replacement therapy. One of the most common urologic complications following kidney transplantation is ureter anastomosis leakage, which leads to high morbidity along with kidney graft loss. We hypothesized that indocyanine green (ICG) fluorescence videography can assess ureter perfusion after revascularization of transplanted kidneys.

Methods

We conducted a prospective cross-sectional study in end-stage renal disease patients who underwent deceased donor kidney transplantation at Ramathibodi Hospital from September 2019 to January 2020. The segments of transplanted ureters were categorized as having good or poor perfusion based on the percentage from ICG fluorescence videography images. Then the results from ICG fluorescence videography were compared with histopathology which is considered the gold standard.

Results

Thirty-one sections of dissected ureters were evaluated from 10 patients. Compared with pathological diagnosis of ureteral ischemia, ICG videography had sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and positive likelihood ratio of 100%, 92.6%, 66.7%, 100%, and 14, respectively. Accuracy was 93.6%. The area under the curve of ICG fluorescence videography was 0.96. The average ureter length that maintained good perfusion was 14 cm from the ureteropelvic junction. Adverse events from ICG were not observed in this study.

Conclusions

We conclude that ICG fluorescence videography is beneficial for detection of early ureteral ischemia in kidney transplantation patients, with negligible adverse events. However, further studies with larger numbers of patients are necessary to confirm our results and clinical outcomes regarding complication rates.

Real-time visualization of renal microperfusion using laser speckle contrast imaging

SIGNIFICANCE

Intraoperative parameters of renal cortical microperfusion (RCM) have been associated with postoperative ischemia/reperfusion injury. Laser speckle contrast imaging (LSCI) could provide valuable information in this regard with the advantage over the current standard of care of being a non-contact and full-field imaging technique.

AIM

Our study aims to validate the use of LSCI for the visualization of RCM on ex vivo perfused human-sized porcine kidneys in various models of hemodynamic changes.

APPROACH

A comparison was made between three renal perfusion measures: LSCI, the total arterial renal blood flow (RBF), and sidestream dark-field (SDF) imaging in different settings of ischemia/reperfusion.

RESULTS

LSCI showed a good correlation with RBF for the reperfusion experiment (0.94  ±  0.02; p  <  0.0001) and short- and long-lasting local ischemia (0.90  ±  0.03; p  <  0.0001 and 0.81  ±  0.08; p  <  0.0001, respectively). The correlation decreased for low flow situations due to RBF redistribution. The correlation between LSCI and SDF (0.81  ±  0.10; p  <  0.0001) showed superiority over RBF (0.54  ±  0.22; p  <  0.0001).

CONCLUSIONS

LSCI is capable of imaging RCM with high spatial and temporal resolutions. It can instantaneously detect local perfusion deficits, which is not possible with the current standard of care. Further development of LSCI in transplant surgery could help with clinical decision making.

Quantitative Assessment of Intraoperative Laser Fluorescence Angiography with Indocyanine Green Predicts Early Graft Function after Kidney Transplantation

Objective:

This study was designed to demonstrate the predictive ability of quantitative indocyanine green (ICG) fluorescence angiography for the short-term postoperative outcome, the occurrence of delayed graft function (DGF), and long-term graft survival.

Summary Background Data:

DGF is a relevant problem after kidney transplantation; sufficient microperfusion of the allograft is crucial for postoperative organ function. Fluorescence angiography with ICG can serve as an intraoperative quality control of microperfusion.

Methods:

This prospective diagnostic study, conducted in 2 German transplantation centers from November 2015 to October 2018, included 128 consecutive kidney transplantations. Intraoperative assessment of the allograft microperfusion was performed by near-infrared fluorescence angiography with ICG; a software was used for quantitative analysis. The associations between perfusion parameters (eg, ICG Ingress) and donor, recipient, peri-procedural, and postoperative characteristics were evaluated.

Results:

DGF occurred in 23 (24%) kidney recipients from deceased donors. ICG Ingress (P = 0.0027), donor age (P = 0.0452), recipient age (P = 0.0139), and recipient body mass index (P = 0.0017) were associated with DGF. ICG Ingress correlated significantly with recipient age (r = −0.27662, P = 0.0016), cold and warm ischemia time (r = −0.25204, P = 0.0082; r = −0.19778, P = 0.0283), operating time (r = −0.32208, P = 0.0002), eGFR on postoperative days 1 (r =+0.22674, P = 0.0104) and 7 (r = +0.33189, P = 0.0001). The cutoff value for ICG Ingress was 106.23 AU with sensitivity of 78.3% and specificity of 80.8% (P < 0.0001) for the prediction of DGF.

Conclusion:

Fluorescence angiography with ICG allows intraoperative quantitative assessment of microperfusion during kidney transplantation. The parameter ICG Ingress reflects recipient and procedure characteristics and is able to predict the incidence of DGF.

Trial registration:

Clinicaltrials.gov: NCT-02775838

Advances in image enhancement for sarcoma surgery

The recurrence rate of soft tissue and bone sarcomas strongly correlates to the status of the surgical margin after excision, yet excessive removal of tissue may lead to distinct, otherwise avoidable morbidity. Therefore, adequate margination of sarcomas both pre- and intra-operatively is a clinical necessity that has not yet fully been met. Current guidance for soft-tissue sarcomas recommends an ultrasound scan followed by magnetic resonance imaging (MRI). For bone sarcomas, two plane radiographs are required, followed similarly by an MRI scan. The introduction of more precise imaging modalities may reduce the morbidity associated with sarcoma surgery; the PET-CT and PET-MRI approaches in particular demonstrating high clinical efficacy. Despite advancements in the accuracy in pre-operative imaging, translation of an image to surgical margins is difficult, regularly resulting in wider resection margins than required. For soft tissue sarcomas there is currently no standard technique for image guided resections, while for bone sarcomas fluoroscopy may be used, however margins are not easily discernible during the surgical procedure. Near infra-red (NIR) fluorescence guided surgery offers an intra-operative modality through which complete tumour resection with adequate tumour-free margins may be achieved, while simultaneously minimising surgical morbidity. NIR imaging presents a potentially valuable adjunct to sarcoma surgery. Early reports indicate that it may be able to provide the surgeon with helpful information on anatomy, perfusion, lymphatic drainage, tumour margins and metastases. The use of NIR fluorochromes have also been demonstrated to be well tolerated by patients. However, prior to widespread implementation, studies related to cost-effectiveness and the development of protocols are essential. Nevertheless, NIR imaging may become ubiquitous in the future, carrying the potential to transform the surgical management of sarcoma.

Microcirculatory assessment of vascular diseases

The term "microcirculation" refers to the terminal vascular network of the body, which includes arterioles, capillaries, venules as well as initial lymphatic vessels. Additionally, it insinuates to their unique function in thermoregulation, fluid balance, maintenance of cellular exchange, and metabolism. Disturbances of microvascular function were identified to precede macrovascular involvement in the presence of cardiovascular risk factors and is the hallmark of terminal disease stages like critical limb or acral ischemia. Nevertheless, despite its obvious significance in vascular medicine assessment of microvascular function became increasingly neglected in the clinical institutions during the last decades and seems to play a subordinary role in medical education. We therefore provide an overview over relevant and clinically practicable methods to assess microcirculation in vascular medicine with critical estimations of their pros and cons and their perspectives in the future.

Monitoring kidney optical properties during cold storage preservation with spatial frequency domain imaging

Transplantation of kidneys results in delayed graft function in as many as 40% of cases. During the organ transplantation process, donor kidneys undergo a period of cold ischemic time (CIT), where the organ is preserved with a cold storage solution to maintain tissue viability. Some complications observed after grafting may be due to damage sustained to the kidney during CIT. However, the effects due to this damage are not apparent until well after transplant surgery has concluded. To this end, we have used spatial frequency domain imaging (SFDI) to measure spatially resolved optical properties of porcine kidneys over the course of 80-h CIT. During this time, we observed an increase in both reduced scattering (μ s& ' ) and absorption (μa) coefficients. The measured scattering b parameter increased until 24 h of CIT, then returned toward baseline during the remaining duration of the imaging sequence. These results show that the optical properties of kidney tissue change with increasing CIT and suggest that continued investigation into the application of SFDI to kidneys under CIT may lead to the development of a noninvasive method for assessing graft viability.

Quantitative assessment of microperfusion by indocyanine green angiography in kidney transplantation resembles chronic morphological changes in kidney specimens

OBJECTIVE

ICG fluorescence angiography enables a quantitative real-time perfusion assessment in kidney transplantation. The results of intraoperative microperfusion of the kidney allograft were compared to the renal chronicity score in pre-transplantation kidney biopsy specimens. The intrarenal resistance index was calculated by duplex sonography as a method of reference.

METHODS

Seventy-seven patients with end-stage renal disease undergoing kidney transplantation were prospectively included in two centers. Correlation analysis of chronic changes in kidney biopsy specimens and the IN of ICG fluorescence signal were investigated.

RESULTS

The results yielded a significantly negative correlation for the renal chronicity (r = -0.294, P = 0.017) as well as the intestinal fibrosis and tubular atrophy score (r = -0.328, P = 0.007). There was a significant inverse relationship between the IN and the mean RI values of the upper pole of the kidney allograft.

CONCLUSIONS

In summary, fluorescence angiography reflects preexisting morphological changes of the renal cortex. ICG angiography may serve as an alternative method for the assessment of microperfusion of the kidney allograft.

Intraoperative assessment of ureteral and graft reperfusion during robotic kidney transplantation with indocyanine green fluorescence videography

BACKGROUND

The aim of this paper is to report the first preliminary experience with intraoperative indocyanine green (ICG) fluorescence videography (IFV) to assess graft and ureteral reperfusion during robot-assisted kidney transplantation (RAKT).

METHODS

We prospectively collected data from consecutive patients undergoing RAKT and IFV from living-donors at our Institution between January 2017 and April 2018. RAKT was performed following the principles of the Vattikuti-Medanta technique. ICG was injected intravenously after vascular anastomoses to quantitate graft and ureteral fluorescence signal. The signal intensity within selected intraoperative snapshots was evaluated for renal parenchyma, ureter and vascular anastomoses. A systematic review of the English-language literature about the topic was performed according to the PRISMA statement recommendations.

RESULTS

Six patients were included. Neither conversions to open surgery nor major intra- or postoperative complications were recorded. At a median follow-up of 12 months (IQR 8-13), median estimated glomerular filtration rate was 64.2 mL/min/1.73 m2 (IQR 45.3-98.4). Intraoperative quantitative assessment of ICG fluorescence was successful in all patients. Of the five studies selected by our review, mostly prospective studies, all including open KT series. Yet, most studies were limited by lack of quantitative measures of IFV fluorescence.

CONCLUSIONS

IFV during RAKT is feasible and safe and provides a reliable assessment of graft reperfusion. Larger studies are needed to standardize the technique and to evaluate the association between fluorescence signal, ultrasound parameters and postoperative kidney function.

The Utility of Intraoperative Near Infrared Fluorescence (NIR) Imaging with Indocyanine Green (ICG) for the Assessment of Kidney Allograft Perfusion

Background

Near infrared light (NIR) fluorescence imaging with indocyanine green (ICG) has been used in various aspects of surgery, such as in the assessment of vascular anastomosis, tissue perfusion, and the identification of lymph nodes. In this study we evaluated the utility of NIR/ICG fluorescence imaging in kidney transplantation.

Materials and Methods

NIR/ICG imaging was used to assess allograft perfusion in n=1 living donor (LDRT) and n=2 deceased donor (DDRT) renal transplantations, performed in February 2017. The allograft arterial and venous anastomoses were done end-to-side to the corresponding recipient external iliacs, and ureteroneocystostomies were performed for urinary reconstructions. After completion of vascular anastomosis, ICG was given as intravenous bolus at 0.3mg/kg, followed by visual assessment of tissue perfusion and vascular anastomoses at 1-minute interval using fluorescence imaging (KARL STORZ NIR/ICG System).

Results

Homogenous global fluorescence of the allograft and vascular anastomosis was observed in all 3 cases. Immediate postoperative perfusion studies showed patent inflow and outflow vessels and well perfused transplanted kidneys. Immediate graft function was observed in 2 recipients (1 LDRT and 1 DDRT). One session of haemodialysis was performed in 1 DDRT recipient, for high serum potassium in the immediate postoperative setting, who otherwise had good urine output and serially declining serum creatinine.

Conclusions

NIR/ICG fluorescence imaging can be useful in renal transplantation for the intraoperative assessment of allograft perfusion, especially in complex cases with multiple renal arteries and vascular reconstructions.

Indocyanine green-based fluorescent angiography in breast reconstruction

BACKGROUND

Fluorescent angiography (FA) has been useful for assessing blood flow and assessing tissue perfusion in ophthalmology and other surgical disciplines for decades. In plastic surgery, indocyanine green (ICG) dye-based FA is a relatively novel imaging technology with high potential in various applications. We review the various FA detector systems currently available and critically appraise its utility in breast reconstruction.

METHODS

A review of the published English literature dating from 1950 to 2015 using databases, such as PubMed, Medline, Web of Science, and EMBASE was undertaken.

RESULTS

In comparison to the old fluorescein dye, ICG has a superior side effect profile and can be accurately detected by various commercial devices, such as SPY Elite (Novadaq, Canada), FLARE (Curadel LLC, USA), PDE-Neo (Hamamatsu Photonics, Japan), Fluobeam 800 (Fluoptics, France), and IC-View (Pulsion Medical Systems AG, Germany). In breast reconstruction, ICG has established as a safer, more accurate tracer agent, in lieu of the traditional blue dyes, for detection of sentinel lymph nodes with radioactive isotopes ((99m)-Technetium). In prosthesis-based breast reconstruction, intraoperative assessment of the mastectomy skin flap to guide excision of hypoperfused areas translates to improved clinical outcomes. Similarly, in autologous breast reconstructions, FA can be utilized to detect poorly perfused areas of the free flap, evaluate microvascular anastomosis for patency, and assess SIEA vascular territory for use as an alternative free flap with minimal donor site morbidity.

CONCLUSIONS

ICG-based FA is a novel, useful tool for various applications in breast reconstruction. More studies with higher level of evidence are currently lacking to validate this technology.

Fluorescence in robotic surgery

Currently, there are several clinical applications for intraoperative ICG, such as identification of vascular and biliary anatomy, assessment of organ and tissue perfusion, lymph node mapping, and real-time identification of lesions. In this paper we present a review of the available literature related to the use of ICG fluorescence in robotic surgery in order to provide a better understanding of the current applications, show the rapid growth of this technique, and demonstrate the potential future applications.

Intraoperative vascular DIVA surgery reveals angiogenic hotspots in tumor zones of malignant gliomas

Malignant gliomas belong to the most threatening tumor entities and are hallmarked by rapid proliferation, hypervascularization and an invasive growth pattern. The primary obstacle in surgical treatment lies in differentiation between healthy and pathological tissue at the tumor margins, where current visualization methods reach their limits. Here, we report on a novel technique (vascular dual intraoperative visualization approach - vDIVA) enabling visualization of different tumor zones (TZ I–III) on the basis of angiogenic hotspots. We investigated glioblastoma patients who underwent 5-ALA fluorescence-guided surgery with simultaneous intraoperative ICG fluorescence angiography. This vDIVA technique revealed hypervascularized areas which were further histologically investigated. Neuropathological assessments revealed tissue areas at the resection margins corresponding to TZ II, and postoperative CD34- and Map2 immunostaining confirmed these angiogenic hotspots to be occupied by glioma cells. Hence, the vascular architecture in this transitional zone could be well differentiated from both primary tumor bulk and healthy brain parenchyma. These data demonstrate that ICG fluorescence angiography improves state-of-the-art glioma surgery techniques and facilitates the future characterization of polyclonal attributes of malignant gliomas.

Intraoperative fluorescence vascular imaging using indocyanine green for assessment of transplanted kidney perfusion

INTRODUCTION AND OBJECTIVE

Indocyanine green (ICG) emits infrared light with exposure to laser light. When intravenously injected, it binds to plasma proteins and predominantly persists in the vasculature, which is very useful for definition of the vascular network. The HyperEye Medical System (HEMS; Mizuho Ikakogyo Co., LTD, Tokyo, Japan) is a new device able to identify both near-infrared and visible rays "in situ" without needing to dim the operation room lighting. We speculated that intraoperative ICG imaging would be applicable for kidney transplantation, by providing "in situ" determination of successful vascular anastomosis.

MATERIALS AND METHODS

Four patients underwent intraoperative ICG imaging following intravenous administration of 1 mL of a solution containing 0.25% ICG. After performing vascular anastomosis, the allograft was examined using the HEMS light source device. Fluorescent signals were transmitted to a digital video processor connected to a television monitor and evaluated in real time.

RESULTS

In all 4 patients, intraoperative ICG imaging provided excellent resolution of blood flow at each step in real time, namely, coming from the recipient's artery to the allograft renal artery, circulating throughout the whole grafted kidney, and draining through the allograft renal vein to the recipient's vein. HEMS provides ICG fluorescence image in color, allowing surgeons to clearly discriminate the positional relationship between the target tissue and the surrounding tissue. No complications associated with ICG injection were noted.

CONCLUSION

Our preliminary results indicate that HEMS is a feasible and safe ICG imaging system that helps prevent technical failure during vascular anastomosis, and also demonstrates blood supply to the grafted kidney.

Use of invisible near infrared light fluorescence with indocyanine green and methylene blue in urology. Part 2

Introduction

In the second part of this paper, concerning the use of invisible near infrared light (NIR) fluorescence with indocyanine green (ICG) and methylene blue (MB) in urology, other possible uses of this new technique will be presented. In kidney transplantation, this concerns allograft perfusion and real time NIR–guided angiography; moreover, perfusion angiography of tissue flaps, NIRF visualization of ureters, NIR–guided visualization of urinary calcifications, NIRF in male infertility and semen quality assessment. In this part, we have also analysed cancer targeting and imaging fluorophores as well as cost benefits associated with the use of these new techniques.

Material and methods

PubMed and Medline databases were searched for ICG and MB use in urological settings, along with data published in abstracts of urological conferences.

Results

Although NIR–guided ICG and MB are still in their initial phases, there have been significant developments in a few more major domains of urology, including 1) kidney transplantation: kidney allograft perfusion and vessel reconstruction; 2) angiography perfusion of tissue flaps; 3) visualization of ureters; 4) visualization of urinary calcifications; and 5) NIRF in male infertility and semen quality assessment.

Conclusions

Near infrared technology in urology is at its early stages. More studies are needed to assess the true potential and limitations of the technology. Initial studies show that this pioneering tool may influence various aspects of urology.

Vascular fluorescence imaging control for complex renal artery aneurysm repair using laparoscopic nephrectomy and autotransplantation

Intraoperative fluorescent imaging using indocyanine green enables vascular surgeons to confirm the location and states of the reconstructed vessels during surgery. Complex renal artery aneurysm repair involving second order branch vessels has been performed with different techniques. We present a case of ex vivo repair and autotransplantation combining the advantages of minimally invasive surgery and indocyanine green enhanced fluorescence imaging to facilitate vascular anatomy recognition and visualization of organ reperfusion.

The application of indocyanine green to evaluate duodenal perfusion in pancreas transplantation

In cases of suspected duodenal ischemia during pancreas transplantation, surgical decisions severely affect the outcome of the patient and the graft. The use of a nontoxic intravenous tracer, indocyanine green, allows the surgeon to evaluate the perfusion of tissues within seconds of injection. Its application to pancreas transplantation has not been reported previously.

Noninvasive optical measurement of cerebral blood flow in mice using molecular dynamics analysis of indocyanine green

In preclinical studies of ischemic brain disorders, it is crucial to measure cerebral blood flow (CBF); however, this requires radiological techniques with heavy instrumentation or invasive procedures. Here, we propose a noninvasive and easy-to-use optical imaging technique for measuring CBF in experimental small animals. Mice were injected with indocyanine green (ICG) via tail-vein catheterization. Time-series near-infrared fluorescence signals excited by 760 nm light-emitting diodes were imaged overhead by a charge-coupled device coupled with an 830 nm bandpass-filter. We calculated four CBF parameters including arrival time, rising time and mean transit time of a bolus and blood flow index based on time and intensity information of ICG fluorescence dynamics. CBF maps were generated using the parameters to estimate the status of CBF, and they dominantly represented intracerebral blood flows in mice even in the presence of an intact skull and scalp. We demonstrated that this noninvasive optical imaging technique successfully detected reduced local CBF during middle cerebral artery occlusion. We further showed that the proposed method is sufficiently sensitive to detect the differences between CBF status in mice anesthetized with either isoflurane or ketamine–xylazine, and monitor the dynamic changes in CBF after reperfusion during transient middle cerebral artery occlusion. The near-infrared optical imaging of ICG fluorescence combined with a time-series analysis of the molecular dynamics can be a useful noninvasive tool for preclinical studies of brain ischemia.

A review of indocyanine green fluorescent imaging in surgery

The purpose of this paper is to give an overview of the recent surgical intraoperational applications of indocyanine green fluorescence imaging methods, the basics of the technology, and instrumentation used. Well over 200 papers describing this technique in clinical setting are reviewed. In addition to the surgical applications, other recent medical applications of ICG are briefly examined.