Near-infrared (NIR) perfusion angiography in minimally invasive colorectal surgery

One-pot synthesis of water-soluble near-infrared fluorescence RNase A capped CuInS2 quantum dots for in vivo imaging

Near-infrared (NIR) quantum dots (QDs) have been treated as a promising candidate of imaging agents for NIR fluorescence-guided surgery. Here, the RNase A-CuInS₂ QDs is good candidate, which performers well in gastrointestinal system imaging.

A collaborative review of the current concepts and challenges of anastomotic leaks in colorectal surgery

The reduction of the incidence, detection and treatment of anastomotic leakage (AL) continues to challenge the colorectal surgical community. AL is not consistently defined and reported in clinical studies, its occurrence is variably reported and its impact on longterm morbidity and health-care resources has received relatively little attention. Controversy continues regarding the best strategies to reduce the risk. Diagnostic tests lack sensitivity and specificity, resulting in delayed diagnosis and increased morbidity. Intra-operative fluorescence angiography has recently been introduced as a means of real-time assessment of anastomotic perfusion and preliminary evidence suggests that it may reduce the rate of AL. In addition, concepts are emerging about the role of the rectal mucosal microbiome in AL and the possible role of new prophylactic therapies. In January 2016 a meeting of expert colorectal surgeons and pathologists was held in London, UK, to identify the ongoing controversies surrounding AL in colorectal surgery. The outcome of the meeting is presented in the form of research challenges that need to be addressed.

Clinical role of fluorescence imaging in colorectal surgery - a review

INTRODUCTION

Anastomotic leak (AL) after colorectal surgery is a devastating complication; decreased blood perfusion is an important risk factor. Surgeons rely on subjective measures to assess bowel perfusion. Fluorescence imaging (FI) with indocyanine green (ICG) provides a real-time objective assessment of intestinal perfusion. Areas covered: A PubMed search using the terms 'fluorescence imaging', 'indocyanine green', 'colon and rectal surgery' was undertaken. Sixteen articles between 2010 to present were identified. Main outcomes were leak rate reduction, change in surgical plan, and technical feasibility. Change in surgical strategy due to FI was recorded in 11 studies. Two case control studies showed overall reduction of 4% and 12% in AL rate and one showed no change in AL rate between groups. Expert commentary: According to the available literature, FI is technically feasible and alters surgical strategy in a non-negligible number of patients possibly effecting AL rates.

Emerging Trends in the Etiology, Prevention, and Treatment of Gastrointestinal Anastomotic Leakage

Anastomotic leaks represent one of the most alarming complications following any gastrointestinal anastomosis due to the substantial effects on post-operative morbidity and mortality of the patient with long-lasting effects on the functional and oncologic outcomes. There is a lack of consensus related to the definition of an anastomotic leak, with a variety of options for prevention and management. A number of patient-related and technical risk factors have been found to be associated with the development of an anastomotic leak and have inspired the development of various preventative measures and technologies. The International Multispecialty Anastomotic Leak Global Improvement Exchange group was convened to establish a consensus on the definition of an anastomotic leak as well as to discuss the various diagnostic, preventative, and management measures currently available.

Intraoperative ICG fluorescence contrast imaging of the main artery watershed area in colorectal cancer surgery: Report of a case

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We have reported the case that underwent colorectal resection with intraoperative indocyanine green (ICG) fluorescence angiography from the resection-side of the superior rectal artery.

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Watershed area of the SRA fluoresced 33 s after the intra-arterial injection of ICG.

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PINPOINT, a brightfield color fluorescence camera was used for ICG fluorescence.

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This method can be expected to provide useful information for maintaining the blood flow at the anastomotic site.

Introduction

Visualization of the main artery watershed area may be useful for determining the area that should be resected in colorectal cancer surgery. Resection of the main artery watershed area may result in complete resection of lymph nodes along the main artery and area of potential ischemia.

Presentation of case

A man in his 60 s with a chief complaint of hematochezia visited our hospital, was diagnosed with colorectal cancer and underwent surgery. A case that underwent colorectal resection with intraoperative indocyanine green (ICG) fluorescence angiography from the resection-side of the superior rectal artery (SRA) in order to confirm the watershed area is reported. Observation was performed using a PINPOINT^® bright-field, color, near-infrared fluorescence camera, and the watershed area of the SRA fluoresced 33 s after the intra-arterial injection of ICG. After observation resection and anastomosis was performed. The patient’s postoperative course was good.

Discussion

The method is simple and can be performed within a short time, and it enables visual evaluation of the blood flow in the intestinal tract before anastomosis.

Conclusion

This method can be expected to provide useful information for complete resection of lymph nodes along the main artery and area of potential ischemia.

Intraoperative Identification of a Normal Pituitary Gland and an Adenoma Using Near-Infrared Fluorescence Imaging and Low-Dose Indocyanine Green

BACKGROUND

The intraoperative distinction between normal and abnormal pituitary tissue is crucial during pituitary adenoma surgery to obtain a complete tumor resection while preserving endocrine function. Near-infrared (NIR) fluorescence imaging is a technique to intraoperatively visualize tumors by using indocyanine green (ICG), a contrast agent allowing visualization of differences in tissue vascularization. Although NIR fluorescence imaging has been described in pituitary surgery, it has, in contrast to other surgical areas, never become widely used.

OBJECTIVE

To evaluate NIR fluorescence imaging in pituitary surgery, both qualitatively and quantitatively, and to assess the additional value of resecting adenoma tissue under NIR fluorescence guidance.

METHODS

We included 10 patients planned to undergo transnasal transsphenoidal selective adenomectomy. Patients received multiple intravenous administrations of 5 mg ICG, up to a maximum of 15 mg per patient. Endoscopic NIR fluorescence imaging was performed at multiple points in time. The NIR fluorescent signal in both the adenoma and pituitary gland was obtained, and the fluorescence contrast ratio was assessed.

RESULTS

Four patients had Cushing disease, 1 had acromegaly, and 1 had a prolactinoma. Four patients had a nonfunctioning macroadenoma. In 9 of 10 patients with a histologically proven pituitary adenoma, the normal pituitary gland showed a stronger fluorescent signal than the adenoma. A fluorescence contrast ratio of normal pituitary gland to adenoma of 1.5 ± 0.2 was obtained. In 2 patients; adenoma resection was actually performed under NIR fluorescence guidance instead of under white light.

CONCLUSION

NIR fluorescence imaging can easily and safely be implemented in pituitary surgery. The timing of ICG administration is important for optimal results and warrants further study. It appears that injection of ICG can best be postponed until some part of the normal pituitary gland is identified. Subsequent repeated low-dose ICG administrations improved the distinction between adenoma and gland.

Management of Colorectal Anastomotic Leak

The aim of this article is to present strategies for preventing and managing the failure of the surgical restoration of intestinal continuity. Despite improvements in surgical technique and perioperative care, anastomotic leaks still occur, and with them occur increased morbidity, mortality, length of stay, and costs. Due to the devastating consequences for patients with failed anastomoses, there have been a myriad of materials and techniques used by surgeons to create better intestinal anastomoses. We will also discuss the management strategies for anastomotic leak when they do inevitably occur.

Near-Infrared Illumination of Native Tissues for Image-Guided Surgery

Our initial efforts to prepare tissue-specific near-infrared (NIR) fluorescent compounds generated successful correlation between physicochemical properties and global uptake in major organs after systemic circulation and biodistribution. Herein, we focus on the effects on biodistribution based on modulating electronic influencing moieties from donating to withdrawing moieties at both the heterocyclic site and through meso-substitution of pentamethine cyanine fluorophores. These selected modifications harnessed innate biodistribution pathways through the structure-inherent targeting, resulting in effective imaging of the adrenal glands, pituitary gland, lymph nodes, pancreas, and thyroid and salivary glands. These native-tissue contrast agents will arm surgeons with a powerful and versatile arsenal for intraoperative NIR imaging in real time.

Intraoperative indocyanine green angiography for the objective measurement of blood flow

PURPOSE

Intraoperative assessment of tissue perfusion is important to predict wound healing or improvement of symptoms in patients with peripheral arterial disease (PAD) or vascular trauma. There is no widely accepted standard for intraoperative measurement of tissue perfusion. Here, we report the use of indocyanine green (ICG)-based angiography to determine the blood flow in patients with PAD and vascular trauma.

METHODS

The SPY fluorescent imaging system was utilized. A dose of 3-5 mL of ICG (2.5 mg/mL) was injected intravenously followed by a 10 mL normal saline flush. The SPY imaging system was used to quantitatively assess perfusion. During the study period, the SPY imaging system was applied in 4 patients with PAD and one patient with vascular trauma.

RESULTS

In 3 patients with PAD associated with an ischemic wound, complete wound healing was achieved with the indication of viable tissue by the SPY system. In one patient with severe claudication in both lower extremities, the ICG angiography was used to determine the increased blood flow after revascularization. In the case of vascular trauma, this imaging system enabled the delineation of viability of the injured tissue.

CONCLUSION

ICG angiography can determine the surface tissue viability in PAD patients. In cases of severe vascular trauma,the SPY system can be used to determine tissue perfusion. Further study is warranted to define the definite utility of this technology to assess perfusion, response to revascularization, and potentially, to predict the likelihood of wound healing.

Indocyanine green fluorescence angiography for intraoperative assessment of gastrointestinal anastomotic perfusion: a systematic review of clinical trials

PURPOSE

Anastomotic leakage following gastrointestinal surgery remains a frequent and serious complication associated with a high morbidity and mortality. Indocyanine green fluorescence angiography (ICG-FA) is a newly developed technique to measure perfusion intraoperatively. The aim of this paper was to systematically review the literature concerning ICG-FA to assess perfusion during the construction of a primary gastrointestinal anastomosis in order to predict anastomotic leakage.

METHODS

The following four databases PubMed, Scopus, Embase, and Cochrane were independently searched by two authors. Studies were included in the review if they assessed anastomotic perfusion intraoperatively with ICG-FA in order to predict anastomotic leakage in humans.

RESULTS

Of 790 screened papers 14 studies were included in this review. Ten studies (n = 916) involved patients with colorectal anastomoses and four studies (n = 214) patients with esophageal anastomoses. All the included studies were cohort studies. Intraoperative ICG-FA assessment of colorectal anastomoses was associated with a reduced risk of anastomotic leakage (n = 23/693; 3.3 % (95 % CI 1.97-4.63 %) compared with no ICG-FA assessment (n = 19/223; 8.5 %; 95 % CI 4.8-12.2 %). The anastomotic leakage rate in patients with esophageal anastomoses and intraoperative ICG-FA assessment was 14 % (n = 30/214). None of the studies involving esophageal anastomoses had a control group without ICG-FA assessment.

CONCLUSION

No randomized controlled trials have been published. ICG-FA seems like a promising method to assess perfusion at the site intended for anastomosis. However, we do not have the sufficient evidence to determine that the method can reduce the leak rate.

Sidestream dark field imaging of the serosal microcirculation during gastrointestinal surgery

AIM

The study aimed to describe the serosal microcirculation of the human bowel using sidestream dark field imaging, a microscopic technique using polarized light to visualize erythrocytes through capillaries. We also compared its feasibility to the current practice of sublingual microcirculatory assessment.

METHOD

In 17 patients sidestream dark field measurements were performed during gastrointestinal surgery. Microcirculatory parameters like microvascular flow index (MFI), proportion of perfused vessels (PPV), perfused vessel density (PVD) and total vessel density (TVD) were determined for every patient, sublingually and on the bowel serosa.

RESULTS

Sixty measurements were done on the bowel of which eight (13%) were excluded, five owing to too much bowel peristalsis and three because of pressure artefacts. Image stability was in favour of sublingual measurements [pixel loss per image, bowel 145 (95% CI 126-164) vs sublingual 55 (95% CI 41-68); P < 0.001] and time to acquire a stable image [bowel 96 s (95% CI 63-129) vs. sublingual 46 s (95% CI 29-64); P = 0.013]. No difference in the MFI was observed [bowel 2.9 (interquartile range 2.87-2.95) vs sublingual 3.0 (interquartile range 2.91-3.0); P = 0.081]. There was a difference in the PPV [bowel 95% (95% CI 94-96) vs sublingual 97% (95% CI 97-99); P < 0.001], PVD [bowel 12.9 mm/mm2 (95% CI 11.1-14.8) vs sublingual 17.4 mm/mm2 (95% CI 15.6-19.1); P = 0.003] and the TVD [bowel 13.6 mm/mm2 (95% CI 11.6-15.6) vs sublingual 17.7 mm/mm2 (95% CI 16.0-19.4); P = 0.008].

CONCLUSION

Sidestream dark field imaging is a very promising technique for bowel microcirculatory visualization and assessment. It is comparable to sublingual assessment and the analysis produces a similar outcome with slightly differing anatomical features.

Fluorescence Angiography in Colorectal Resection

BACKGROUND

Intraoperative laser fluorescence angiography is a relatively new tool that can be used by colorectal surgeons to ensure adequate perfusion to bowel that remains after resection. It has been used mostly to determine an appropriate point of transection of the proximal bowel, as well as to ensure perfusion after the anastomosis has been constructed. We propose a different use of the technology in complex cases to ensure the ability to safely transect a major vascular pedicle and to ensure that perfusion will remain adequate.

OBJECTIVE

The purpose of this article is to describe a new use for fluorescence angiography technology.

DESIGN

This is a technical note.

SETTINGS

The work was conducted at a tertiary care military medical center.

PATIENTS

Patients included individuals requiring oncologic colorectal resection where the status of 1 major vascular pedicle was unknown or impaired.

MAIN OUTCOME MEASURES

We assessed perfusion after occlusion of a major vascular pedicle for the short term in hospital outcomes.

RESULTS

Adequate studies were obtained, and perfusion was maintained in both patients. Oncologic resections were performed, and short-term outcomes were comparable with any individual undergoing these procedures.

LIMITATIONS

This study was limited because it is early experience that was not performed in the setting of a scientific investigation.

CONCLUSIONS

Application of intraoperative fluorescence angiography in this setting appears to be safe and may assist the surgeon in estimating reliable vascular perfusion in patients such as these who require oncologic colorectal resection.

Anastomotic leakage in rectal cancer surgery: The role of blood perfusion

Anastomotic leakage after anterior resection for rectal cancer remains a common and often devastating complication. Preoperative risk factors for anastomotic leakage have been studied extensively and are used for patient selection, especially whether to perform a diverting stoma or not. From the current literature, data suggest that perfusion in the rectal stump rather than in the colonic limb may be more important for the integrity of the colorectal anastomosis. Moreover, available research suggests that the mid and upper rectum is considerably more vascularized than the lower part, in which the posterior compartment seems most vulnerable. These data fit neatly with the observation that anastomotic leaks are far more frequent in patients undergoing total compared to partial mesorectal excision, and also that most leaks occur dorsally. Clinical judgment has been shown to ineffectively assess anastomotic viability, while promising methods to measure blood perfusion are evolving. Much interest has recently been turned to near-infrared light technology, enhanced with fluorescent agents, which enables intraoperative perfusion assessment. Preliminary data are promising, but large-scale controlled trials are lacking. With maturation of such technology, perfusion measurements may in the future inform the surgeon whether anastomoses are at risk. In high colorectal anastomoses, anastomotic revision might be feasible, while a diverting stoma could be fashioned selectively instead of routinely for low anastomoses.

Discriminatory influence of Pinpoint perfusion imaging on diversion ileostomy after laparoscopic low anterior resection

While still debated, it was advised to perform a protective temporary ileostomy after a low anterior resection (LAR). This might help to decrease the leak rate and therefore offers the patient better outcomes. Anastomotic leak can occur in many situations after a LAR and the control of the risk factors helps to adapt the need of an ileostomy. Near infrared technology allows assessing the microvascularisation of the anastomosis at the time of surgery and therefore might be an important tool to avoid a stoma in given situation. This article reviews the evidences with the use of this technology.

Impact of intraoperative microperfusion assessment with Pinpoint Perfusion Imaging on surgical management of laparoscopic low rectal and anorectal anastomoses

AIM

Inadequate intestinal blood flow may contribute to anastomotic leakage accounting for substantial morbidity and mortality in colorectal surgery. Precise intraoperative assessment of microperfusion may have an impact on the surgeons intraoperative management and leakage rate.

METHOD

In this single center observational study we implemented and integrated intraoperative indocyanin green (ICG) based microperfusion assessment of anastomosis with Pinpoint Perfusion Imaging in a series of consecutive rectal cancer patients who underwent laparoscopic anterior and lower anterior resection with primary anastomosis during a 5-months period.

RESULTS

We could demonstrate the feasibility and safety of intraoperative fluorescence angiography for colorectal microperfusion assessment. Technology implementation was immediately successful. No adverse effects have been documented related to fluorescent dye. Microperfusion angiography of the colon succeeded in all cases and assessment of perfusion imaging influenced surgical decision making in 28% of the patients, of which all patients showed primary healing of the anastomosis. We found a leakage rate of 6% with one leakage of a coloanal anastomosis in all patients.

CONCLUSION

Fluorescence angiography is an accurate tool for assessing microperfusion and is most likely associated with improved outcomes with regard to anastomotic healing.

Ischemic and injured bowel evaluation by Fluorescence imaging

AIM

Although fluorescence has been proposed for estimation of bowel perfusion decades ago it is still not widely used. In emergency situations like mesenteric ischemia, fluorescence might give objective criteria to evaluate the perfusion and guide the decisions of surgeons.

METHOD

The use of near-inrafrared angiography by PinPoint (Novadaq) in a serial of four emergency situations of acute mesenteric ischemia has been evaluated in a university hospital setting.

RESULTS

The use of the near-infrared tool is in emergency situations easy to handle and little time-consuming. The angiography showed clearly the perfusion in regions that were not estimated as recoverable by the surgeons. In one of the cases a significant amount of bowel could be spared by use of the system.

CONCLUSION

Although the assessment of the perfusion with the applied system is comprehensible, it would be desirable to evaluate a threshold level in order to further objectify it. While the surgeons who used the tool were subjectively assured by the expressiveness it would need a randomized and maybe experimental setting to evaluate objectively the amount of spared bowel length.

Fluorescence angiography in laparoscopic low rectal and anorectal anastomoses with pinpoint perfusion imaging--a critical appraisal with specific focus on leak risk reduction

BACKGROUND AND AIMS

Anastomotic dehiscence is one of the most feared complications in colorectal surgery leading to significant morbidity and mortality. Progressively lower anastomoses are associated with a greater leak rate. One of the key factors is the perfusion of the bowel to be joined. Presently, surgeons rely on a variety subjective measures to determine anastomotic perfusion and mechanical integrity however these have shortcomings. The aim of this paper is to appraise the literature on the use of fluorescence angiography (FA) in laparoscopic rectal surgery.

MATERIALS AND METHODS

A Pubmed search was undertaken using terms 'fluorescence angiography' and 'rectal surgery'. The search was expanded using the related articles function. Studies were included if they used FA specifically for rectal surgery. Outcomes of interest including anastomotic leak rate, change of operative strategy and time taken for FA were recorded.

RESULTS

Eleven papers detailing the use of FA in rectal surgery are outlined demonstrating that this technique may change operative strategy and lead to a reduction in anastomotic leak rate.

CONCLUSION

In this paper, we discuss assessment of colorectal blood supply using FA and how this technique holds great potential to detect insufficiently perfused bowel. In so doing, the operator can adjust their operative strategy to mitigate these affects with the aim of reducing the complications of anastomotic leak and stenosis. However, it is highlighted that there is a clear need for randomised controlled trials in order to determine this definitively.

Laparoscopic deroofing for polycystic liver disease using laparoscopic fusion indocyanine green fluorescence imaging

BACKGROUND

Laparoscopic deroofing is widely used for the treatment of symptomatic polycystic liver disease (PCLD). However, bile leakage is a common complication of surgical management for PCLD. Until now, indocyanine green fluorescence imaging (IGFI) has played an active role in hepatobiliary surgery. Herein, we report the effective application of a laparoscopic fusion IGFI system, known as PINPOINT, for laparoscopic deroofing.

METHODS

In this study, we performed laparoscopic deroofing for PCLD using the laparoscopic fusion IGFI system. We conducted the procedure mainly under the normal view mode, occasionally switching to the fusion IGFI mode. First, we confirmed that the liver cysts did not contain bile using the fusion IGFI mode and then used a percutaneous puncture needle to remove the fluid from some of the giant cysts. Second, using the fusion IGFI mode, we were able to detect thin biliary branches and to adjust the division line of the cyst wall accordingly or, occasionally, to ligate the branches. Finally, we searched for and identified unexpected small bile leakage and then closed it using sutures.

RESULTS

The laparoscopic fusion IGFI system can simultaneously show fluorescent images, such as cholangiography and the liver parenchyma, on the normal color view. In the fusion IGFI mode, the intrahepatic bile duct and liver parenchyma can be easily discriminated in real time throughout the procedure. Accordingly, the laparoscopic fusion IGFI system is useful for the surgical treatment of PCLD, in which the boundary between the liver cysts and the liver parenchyma can otherwise be difficult to identify. This technique also enables the branches of Glisson's capsule to be identified without any other intervention.

CONCLUSION

The novel application of the laparoscopic fusion IGFI system allows reliable navigation for PCLD surgery.

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.

Indocyanine green fluorescence-guided redo parathyroidectomy

Re-operative neck surgery for hyperparathyroidism is a technically difficult operation that requires adjunctive studies to assist with finding the parathyroid tissues. Intraoperative tests help minimise exploration of the neck and decrease injuries to the surrounding structures. Indocyanine green is a near-infrared fluorescent dye that in pre-clinical models was found to be useful in locating the parathyroid glands of dogs. No study has yet reported its use as a tool for parathyroid localisation in humans. We investigated the use of indocyanine green to assist with localisation of a recurrent parathyroid adenoma using a near-infrared imaging system. After exposure of the neck tissues, the parathyroid gland fluoresced brightly and directed our dissection. Exploration of the neck was minimal, and allowed for fast localisation and excision of the adenoma. Overall, use of indocyanine green is a simple and safe technique of intraoperative parathyroid localisation that warrants further investigation.

Single-incision robotic colectomy (SIRC): Current status and future directions

By combining laparo-endoscopic single-site surgery (LESS) techniques with the da Vinci robotic platform, single-incision robotic colectomy (SIRC) aims to further minimize incision-related complications and improve cosmetic outcomes from the current standard of care, laparoscopic colectomy. While there is limited literature on SIRC, all available reports suggest SIRC to be a safe and feasible procedure in terms of perioperative outcomes. Future research should focus on further clarification of proposed benefits of SIRC such as cosmetics, ergonomics, incidence of incision-related complications, and long-term oncologic outcomes.

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.

Visualization of Lymph/Blood Flow in Laparoscopic Colorectal Cancer Surgery by ICG Fluorescence Imaging (Lap-IGFI)

PURPOSE

In laparoscopic colorectal cancer (Lap-CRC) surgery, determination of a suitable mesentery division line and the appropriate degree of lymphadenectomy by tracing the blood supply is critical. We performed visualization of the lymph and blood flow by laparoscopic indocyanine green (ICG) fluorescence imaging (Lap-IGFI).

METHODS

ICG is injected into the submucosa near the tumor via colonoscopy, and the lymph flow is observed. Intestinal blood flow is evaluated by administering ICG intravenously.

RESULTS

For lymph flow, visualization of the main lymph node basin helped to determine the surgical division line for cases in which the blood flow was not completely visualized. Lap-IGFI changed the surgical plan of the lymphadenectomy in 23.5 %. In our experience, the metastatic rate of ICG-positive nodes was 10.0 %, and the metastatic rate of ICG-negative nodes was 5.3 %. Furthermore, there were no metastatic nodes that were ICG negative more than 5 cm from the tumor. For blood flow, the blood flow distribution of the intestinal wall from the last branch of the vasa recta of the anastomotic site was clearly visualized and proved useful in choosing the extent of intestinal resection. Lap-IGFI changed the surgical plan of the extensive intestinal resection in 16.7 %.

CONCLUSIONS

Lap-IGFI can noninvasively provide detailed lymph and blood flow information and is a useful device to aid in the accurate identification of individual patients' lymph drainage. This helps dictate adequate lymphadenectomy and the extent of intestinal resection in Lap-CRC surgery.

Intraoperative fluorescence-based enhanced reality laparoscopic real-time imaging to assess bowel perfusion at the anastomotic site in an experimental model

BACKGROUND

Fluorescence videography is a promising technique for assessing bowel perfusion. Fluorescence-based enhanced reality (FLER) is a novel concept, in which a dynamic perfusion cartogram, generated by computer analysis, is superimposed on to real-time laparoscopic images. The aim of this experimental study was to assess the accuracy of FLER in detecting differences in perfusion in a small bowel resection-anastomosis model.

METHODS

A small bowel ischaemic segment was created laparoscopically in 13 pigs. Animals were allocated to having anastomoses performed at either low perfusion (25 per cent; n = 7) or high perfusion (75 per cent; n = 6), as determined by FLER analysis. Capillary lactate levels were measured in blood samples obtained by serosal puncturing in the ischaemic area, resection lines and vascularized areas. Pathological inflammation scoring of the anastomosis was carried out.

RESULTS

Lactate levels in the ischaemic area (mean(s.d.) 5·6(2·8) mmol/l) were higher than those in resection lines at 25 per cent perfusion (3·7(1·7) mmol/l; P = 0·010) and 75 per cent perfusion (2·9(1·3) mmol/l; P < 0·001), and higher than levels in vascular zones (2·5(1·0) mmol/l; P < 0·001). Lactate levels in resection lines with 75 per cent perfusion were lower than those in lines with 25 per cent perfusion (P < 0·001), and similar to those in vascular zones (P = 0·188). Levels at resection lines with 25 per cent perfusion were higher than those in vascular zones (P = 0·001). Mean(s.d.) global inflammation scores were higher in the 25 per cent perfusion group compared with the 75 per cent perfusion group for mucosa/submucosa (2·1(0·4) versus 1·2(0·4); P = 0·003) and serosa (1·8(0·4) versus 0·8(0·8); P = 0·014). A ratio of preanastomotic lactate levels in the ischaemic area relative to the resection lines of 2 or less was predictive of a more severe inflammation score.

CONCLUSION

In an experimental model, FLER appeared accurate in discriminating bowel perfusion levels. Surgical relevance Clinical assessment has limited accuracy in evaluating bowel perfusion before anastomosis. Fluorescence videography estimates intestinal perfusion based on the fluorescence intensity of injected fluorophores, which is proportional to bowel vascularization. However, evaluation of fluorescence intensity remains a static and subjective measure. Fluorescence-based enhanced reality (FLER) is a dynamic fluorescence videography technique integrating near-infrared endoscopy and specific software. The software generates a virtual perfusion cartogram based on time to peak fluorescence, which can be superimposed on to real-time laparoscopic images. This experimental study demonstrates the accuracy of FLER in detecting differences in bowel perfusion in a survival model of laparoscopic small bowel resection-anastomosis, based on biochemical and histopathological data. It is concluded that real-time imaging of bowel perfusion is easy to use and accurate, and should be translated into clinical use.

Photoacoustic tomography of human hepatic malignancies using intraoperative indocyanine green fluorescence imaging

Recently, fluorescence imaging following the preoperative intravenous injection of indocyanine green has been used in clinical settings to identify hepatic malignancies during surgery. The aim of this study was to evaluate the ability of photoacoustic tomography using indocyanine green as a contrast agent to produce representative fluorescence images of hepatic tumors by visualizing the spatial distribution of indocyanine green on ultrasonographic images. Indocyanine green (0.5 mg/kg, intravenous) was preoperatively administered to 9 patients undergoing hepatectomy. Intraoperatively, photoacoustic tomography was performed on the surface of the resected hepatic specimens (n = 10) under excitation with an 800 nm pulse laser. In 4 hepatocellular carcinoma nodules, photoacoustic imaging identified indocyanine green accumulation in the cancerous tissue. In contrast, in one hepatocellular carcinoma nodule and five adenocarcinoma foci (one intrahepatic cholangiocarcinoma and 4 colorectal liver metastases), photoacoustic imaging delineated indocyanine green accumulation not in the cancerous tissue but rather in the peri-cancerous hepatic parenchyma. Although photoacoustic tomography enabled to visualize spatial distribution of ICG on ultrasonographic images, which was consistent with fluorescence images on cut surfaces of the resected specimens, photoacoustic signals of ICG-containing tissues decreased approximately by 40% even at 4 mm depth from liver surfaces. Photoacoustic tomography using indocyanine green also failed to identify any hepatocellular carcinoma nodules from the body surface of model mice with non-alcoholic steatohepatitis. In conclusion, photoacoustic tomography has a potential to enhance cancer detectability and differential diagnosis by ultrasonographic examinations and intraoperative fluorescence imaging through visualization of stasis of bile-excreting imaging agents in and/or around hepatic tumors. However, further technical advances are needed to improve the visibility of photoacoustic signals emitted from deeply-located lesions.

Real-time navigation by fluorescence-based enhanced reality for precise estimation of future anastomotic site in digestive surgery

BACKGROUND

Fluorescence-based enhanced reality (FLER) is a technique to evaluate intestinal perfusion based on the elaboration of the Indocyanine Green fluorescence signal. The aim of the study was to assess FLER's performances in evaluating perfusion in an animal model of long-lasting intestinal ischemia.

MATERIALS AND METHODS

An ischemic segment was created in 18 small bowel loops in 6 pigs. After 2 h (n = 6), 4 h (n = 6), and 6 h (n = 6), loops were evaluated clinically and by FLER to delineate five regions of interest (ROIs): ischemic zone (ROI 1), presumed viable margins (ROI 2a-2b), and vascularized areas (3a-3b). Capillary lactates were measured to compare clinical vs. FLER assessment. Basal (V 0 ) and maximal (V max) mitochondrial respiration rates were determined according to FLER.

RESULTS

Lactates (mmol/L) at clinically identified resection lines were significantly higher when compared to those identified by FLER (2.43 ± 0.95 vs. 1.55 ± 0.33 p = 0.02) after 4 h of ischemia. Lactates at 2 h at ROI 1 were 5.45 ± 2.44 vs. 1.9 ± 0.6 (2a-2b; p < 0.0001) vs. 1.2 ± 0.3 (3a-3b; p < 0.0001). At 4 h, lactates were 4.36 ± 1.32 (ROI 1) vs. 1.83 ± 0.81 (2a-2b; p < 0.0001) vs. 1.35 ± 0.67 (3a-3b; p < 0.0001). At 6 h, lactates were 4.16 ± 2.55 vs. 1.8 ± 1.2 vs. 1.45 ± 0.83 at ROI 1 vs. 2a--2b (p = 0.013) vs. 3a-3b (p = 0.0035). Mean V 0 and V max (pmolO2/second/mg of tissue) were significantly impaired after 4 and 6 h at ROI 1 (V 0 (4h) = 34.83 ± 10.39; V max (4h) = 76.6 ± 29.09; V 0 (6h) = 44.1 ± 12.37 and V max (6h) = 116.1 ± 40.1) when compared to 2a--2b (V 0 (4h) = 67.1 ± 17.47 p = 0.00039; V max (4h) = 146.8 ± 55.47 p = 0.0054; V 0 (6h) = 63.9 ± 28.99 p = 0.03; V max (6h) = 167.2 ± 56.96 p = 0.01). V 0 and V max were significantly higher at 3a-3b.

CONCLUSIONS

FLER may identify the future anastomotic site even after repetitive assessments and long-standing bowel ischemia.

Improving outcomes and cost-effectiveness of colorectal surgery

In order to truly make an impact on improving the cost effectiveness, and most importantly, the outcomes of patients undergoing colorectal surgery, all aspects of care need to be scrutinized, re-evaluated, and refined. To accomplish this, everything from the way we train surgeons to the adoption of a minimally invasive approach for colorectal disease, along with the use of adjunct intraoperative measures to decrease morbidity and mortality, may all need to be incorporated within an ERAS program. Only then will this approach lead the provider to a patient-centric care plan which can successfully reduce metrics such as morbidity, mortality, and length of stay (even with the obligatory readmission rate) and provide it all at a lower cost of care.