Indocyanine green fluorescence imaging during partial adrenalectomy

Fluorescence and tracers in surgery: the coming future

The revolution that we are seeing in the world of surgery will determine the way we understand surgical approaches in coming years. Since the implementation of minimally invasive surgery, innovations have constantly been developed to allow the laparoscopic approach to go further and be applied to more and more procedures. In recent years, we have been in the middle of another revolutionary era, with robotic surgery, the application of artificial intelligence and image-guided surgery. The latter includes 3D reconstructions for surgical planning, virtual reality, holograms or tracer-guided surgery, where ICG-guided fluorescence has provided a different perspective on surgery. ICG has been used to identify anatomical structures, assess tissue perfusion, and identify tumors or tumor lymphatic drainage. But the most important thing is that this technology has come hand in hand with the potential to develop other types of tracers that will facilitate the identification of tumor cells and ureters, as well as different light beams to identify anatomical structures. These will lead to other types of systems to assess tissue perfusion without the use of tracers, such as hyperspectral imaging. Combined with the upcoming introduction of ICG quantification, these developments represent a real revolution in the surgical world. With the imminent implementation of these technological advances, a review of their clinical application in general surgery is timely, and this review serves that aim.

Imaging guided adrenalectomy with Indocyanine green fluorescence in a dog with a pheochromocytoma

IMPORTANCE

This case report presents the successful surgical removal of a pheochromocytoma in a dog using indocyanine green (ICG) fluorescence imaging.

CASE PRESENTATION

A 10-year-old, 6.87 kg, spayed female poodle was referred for an abdominal mass and eight episodes of vomiting. Computed tomography revealed masses in the spleen and left adrenal gland. Based on the plasma normetanephrine levels, the patient was diagnosed with pheochromocytoma. Subsequently, a total splenectomy and left adrenalectomy were performed. A dose of 5 mg/kg ICG was administered intravenously 24 h prior to surgery. Using ICG allowed visualization of tumor margins, aiding in complete resection and minimizing anesthesia-related risks.

CONCLUSIONS AND RELEVANCE

No evidence of recurrence or metastasis has been observed for 12 months. To our knowledge, this is the first report of the surgical removal of a pheochromocytoma using intraoperative ICG imaging in veterinary medicine. This case highlights the efficacy of ICG fluorescence imaging as a valuable tool for the surgical management of adrenal tumors in veterinary medicine.

Fluorescence-guided minimally-invasive resection of abdominal paragangliomas using indocyanine green

This retrospective study explores the utility of near-infrared (NIR) fluorescence imaging with indocyanine green (ICG) in enhancing the intraoperative identification and guidance for the resection of abdominal paragangliomas. They can be challenging to detect during minimally invasive surgery, due to their anatomical location, varying size and similar appearance in regard to their surrounding tissue. Patients with suspected abdominal paragangliomas planned for a minimally-invasive resection were included. As part of standard of care they received single intravenous dose of 5 mg ICG after abdominal exploration. NIR fluorescence imaging of the anatomical region of the suspected lesion was performed immediately following intravenous administration, to assess fluorescence signals, intraoperative identification, and histopathological correlation. Out of five resected suspicious lesions, four were imaged with NIR fluorescence, pathology confirming four as paragangliomas, the latter turned out to be an adrenal adenoma. NIR fluorescence identified all four lesions, surpassing the limitations of white-light visualization. Homogeneous fluorescence signals appeared 30-60 s post-ICG administration, which lasted up to 30 min. The study demonstrates the feasibility and potential clinical value of fluorescence-guided minimally-invasive resections of abdominal paragangliomas using a single intravenous ICG dose. These findings support the scientific basis for routine use of ICG-fluorescence-guided surgery in challenging anatomical cases, providing valuable assistance in lesion detection and resection.

Total adrenalectomy versus subtotal adrenalectomy for bilateral pheochromocytoma: meta-analysis

BACKGROUND

Bilateral pheochromocytomas are rare and often heritable. Total adrenalectomy leads to a definitive oncological cure, with subsequent definitive hypocortisolism. Subtotal adrenalectomy is a possible alternative. The aim of this study was to assess the effects of total adrenalectomy and subtotal adrenalectomy on bilateral pheochromocytoma in terms of post-surgical rate of recurrence, metastatic disease, and steroid dependence.

METHODS

Systematic searches in the bibliographic databases PubMed, Embase, and Europe PMC were performed for 1945 to 1 June 2023. PRISMA guidelines were followed and the PICO strategy was applied to English-language studies comparing subtotal adrenalectomy with total adrenalectomy. A random-effects model was used to assess the different outcomes for studies with high heterogeneity. The Newcastle-Ottawa scale and the Risk Of Bias In Non-randomized Studies of Interventions ('ROBINS-I') tool were used to assess quality and risk of bias.

RESULTS

From a total of 12 909 studies, 1202 patients (from 10 retrospective studies) were eligible for the meta-analysis. In six studies, including 1176 patients, the recurrence rate after subtotal adrenalectomy and total adrenalectomy was 14.1 versus 2.6 per cent respectively (OR 4.91, 95 per cent c.i. 1.30 to 18.54; P = 0.020; I2 72 per cent). In nine studies, including 1124 patients, the rate of post-surgical steroid dependence was 93.3 versus 11.6 per cent after total adrenalectomy and subtotal adrenalectomy respectively (OR 0.003, 95 per cent c.i. 0.0003 to 0.03; P < 0.00001; I2 66 per cent). Based on two studies, including 719 patients, no differences were evident regarding the occurrence of post-surgery metastatic disease.

CONCLUSION

Subtotal adrenalectomy leads to less post-surgical primary adrenal insufficiency, but leads to a higher postoperative recurrence rate. Future prospective randomized studies, with clear eligibility criteria, are needed to confirm these results.

Characterization of indocyanine green fluorescence imaging patterns of pheochromocytomas

BACKGROUND

Indocyanine green (ICG) fluorescence is a new intraoperative imaging modality for adrenal tumors. Previous work suggested that pheochromocytomas did not show fluorescence, but experience is limited. The objective of this study is to analyze fluorescence imaging patterns of pheochromocytomas.

METHODS

This was an IRB-approved retrospective study. Patients who underwent adrenalectomy with ICG imaging were identified from a departmental database. Intraoperative fluorescence patterns were analyzed by reviewing surgical videos. Descriptive and comparative statistical analyses were performed to determine factors associated with different fluorescence patterns of pheochromocytomas.

RESULTS

Of the 46 pheochromocytomas included, 50% (n = 23) exhibited fluorescence. Parameters predicting fluorescence on univariate analysis were age, tumor size and hereditary. On multivariate analysis, tumor size was the only predictive parameter of ICG fluorescence, with loss of fluorescence at a threshold of > 3.2 cm (p = 0.004).

CONCLUSIONS

This is the largest cohort to date assessing fluorescence properties of pheochromocytomas. In contrast to previous studies, we demonstrated that smaller pheochromocytomas do exhibit fluorescence. This may support the application of intraoperative ICG imaging for smaller or bilateral pheochromocytomas, which may assist in identification and/or cortical-sparing during adrenalectomy.

Total versus partial adrenalectomy in bilateral pheochromocytoma - a systematic review and meta-analysis

BACKGROUND

In patients with bilateral pheochromocytoma, partial adrenalectomy offers the chance to preserve adrenal function and avoid the need for lifelong steroid supplementation. However, the risk of tumour recurrence raises questions about this procedure. The aim of our study was to compare partial and total adrenalectomy in bilateral pheochromocytoma through a systematic review with meta-analysis.

METHODS

A systematic search was carried out using databases (MEDLINE, EMBASE, Scopus, Web of Science, CENTRAL) and registers of clinical trials (ClinicalTrials.gov, European Trials Register, WHO International Trials Registry Platform). This meta-analysis included studies up to July 2022 without language restrictions. A random effects model meta-analysis was performed to assess the risk of tumor recurrence, steroid dependence and morbidity in these patients.

RESULTS

Twenty-five studies were included in the analysis involving 1444 patients. The relative risk (RR) of loss of adrenal hormone function during follow-up and the need for steroid therapy was 0.32 in patients after partial adrenalectomy: RR 0.32, 95% Confidence Interval (CI): 0.26-0.38, P < 0.00001, I2 = 21%. Patients undergoing partial adrenalectomy had a lower odds ratio (OR) for developing acute adrenal crisis: OR 0.3, 95% CI: 0.1-0.91, P=0.03, I2 = 0%. Partial adrenalectomy was associated with a higher risk of recurrence than total adrenalectomy: OR 3.72, 95% CI: 1.54-8.96, P=0.003, I2 = 28%.

CONCLUSION

Partial adrenalectomy for bilateral pheochromocytoma is a treatment that offers a chance of preserving adrenal hormonal function, but is associated with a higher risk of local tumor recurrence. There was no difference for the risk of metastasis and in overall mortality among the group with bilateral pheochromocytomas undergoing total or partial adrenalectomy. This study is in line with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) and AMSTAR (A Measurement Tool to Assess Systematic Reviews) Guidelines (10, 11).

SYSTEMATIC REVIEW REGISTRATION

https://osf.io/zx3se.

Minimally invasive techniques in benign and malignant adrenal tumors

Minimally invasive adrenalectomy has become the main treatment modality for most adrenal lesions. Both laparoscopic transabdominal and retroperitoneoscopic approaches are safe and feasible options, each with respective advantages, including better surgical outcomes, fewer complications, and faster recovery over open adrenalectomy. While open surgery remains a valid modality in treatment of adrenocortical cancer in the presence of some findings such as invasion, robotic platforms, and minimally invasive surgery have gained popularity as technology continues to evolve. Organ preservation during adrenalectomy is feasible in some conditions to prevent adrenal insufficiency. Ablative technologies are increasingly utilized in benign and malignant tumors, including the adrenal gland, with various outcomes. A multidisciplinary team, an experienced surgeon, and a high-volume center are recommended for any surgical approaches and management of adrenal lesions. This review article evaluated recent findings and current evidence on minimally invasive adrenalectomy.

Operative approach and case volume are associated with negative resection margins for adrenocortical carcinoma

BACKGROUND

Surgical resection with negative margins is the treatment of choice for adrenocortical carcinoma (ACC). This study was undertaken to determine factors associated with negative resection margins.

METHODS

National Cancer Database was queried from 2010 to 2016 to identify patients with AJCC/ENSAT Stage I-III ACC who underwent adrenalectomy. Patient, tumor, facility, and operative characteristics were compared by margin status (positive-PM or negative-NM) and operative approach (open-OA, laparoscopic-LA, or robotic-RA). Multivariable logistic regression was used to identify factors associated with PM.

RESULTS

Eight hundred and eighty-one patients were identified, of which 18.4% had PM and 81.6% had NM. Patients with advanced pathologic T stage and pathologic N1 stage were more likely to have PM (vs. NM) (T3, 49.7% vs. 24.8%, p < 0.01; T4, 26.2% vs. 10.0%, p < 0.01; N1, 6.7% vs. 3.5%, p < 0.01). Patients undergoing OA (vs. LA and RA) were more likely to have advanced clinical T stage (T4, 16.6% vs. 5.7% vs. 7.8%, p < 0.01) and larger tumors (> 6 cm, 84.6% vs. 64.1% vs. 62.3%, p < 0.01). High-volume centers (≥ 5 cases) were more likely to utilize OA. Patients undergoing LA (vs. RA) were more likely to require conversion to open (20.3% vs. 7.8%, p = 0.011). On multivariable analysis, factors associated with higher odds of PM included T3 disease (OR 7.02, 95% CI 2.66-18.55), T4 disease (OR 10.22, 95% CI 3.66-28.53), and LA (OR 1.99, 95% CI 1.28-3.09). High-volume centers were associated with lower odds of PM (OR 0.67, 95% CI 0.45-0.98). There was no significant difference in margin status between OA and RA (OR 1.44, 95% CI 0.71-2.90).

CONCLUSION

Centers with higher ACC case volumes have lower odds of PM and utilize OA more often. LA is associated with higher odds of PM, whereas RA is not. These factors should be considered when planning the operative approach for ACC.

The Role of Intraoperative Indocyanine Green (ICG) and Preoperative 3-Dimensional (3D) Reconstruction in Laparoscopic Adrenalectomy: A Propensity Score-matched Analysis

BACKGROUND

Laparoscopic adrenalectomy (LA) is considered the "gold standard" treatment of adrenal lesions that are often coincidentally diagnosed during the radiologic workup of other diseases. This study aims to evaluate the intraoperative role of indocyanine green (ICG) fluorescence associated with preoperative 3-dimensional reconstruction (3DR) in laparoscopic adrenalectomy in terms of perioperative outcomes. To our knowledge, this is the first prospective case-controlled report comparing these techniques.

MATERIALS AND METHODS

All consecutive patients aged≥18 and undergoing laparoscopic transperitoneal adrenalectomy for all adrenal masses from January 1, 2019 to January 31, 2022 were prospectively enrolled. Patients undertaking standard LA and those undergoing preoperative 3D reconstruction and intraoperative ICG fluorescence were matched through a one-on-one propensity score matching analysis (PSM) for age, gender, BMI, CCI score, ASA score, lesion histology, tumor side, and lesion diameter. Differences in operative time, blood loss, intraoperative and postoperative complications, conversion rate, and length of stay were analyzed.

RESULTS

After propensity score matching analysis, we obtained a cohort of 36 patients divided into 2 groups of 18 patients each. The operative time and intraoperative blood loss were shorter in patients of the 3DR group ( P =0,004 and P =0,004, respectively). There was no difference in terms of length of stay, conversion rate, and intraoperative and postoperative complications between the 2 groups.

CONCLUSIONS

The use of intraoperative ICG in LA and preoperative planning with 3DR images is a safe and useful addition to surgery. Furthermore, we observed a reduction in terms of operating time and intraoperative blood loss.

Indocyanine green (ICG) fluorescence guide for the use and indications in general surgery: recommendations based on the descriptive review of the literature and the analysis of experience

Indocyanine Green is a fluorescent substance visible in near-infrared light. It is useful for the identification of anatomical structures (biliary tract, ureters, parathyroid, thoracic duct), the tissues vascularization (anastomosis in colorectal, esophageal, gastric, bariatric surgery, for plasties and flaps in abdominal wall surgery, liver resection, in strangulated hernias and in intestinal ischemia), for tumor identification (liver, pancreas, adrenal glands, implants of peritoneal carcinomatosis, retroperitoneal tumors and lymphomas) and sentinel node identification and lymphatic mapping in malignant tumors (stomach, breast, colon, rectum, esophagus and skin cancer). The evidence is very encouraging, although standardization of its use and randomized studies with higher number of patients are required to obtain definitive conclusions on its use in general surgery. The aim of this literature review is to provide a guide for the use of ICG fluorescence in general surgery procedures.

Tailored Approach in Adrenal Surgery: Retroperitoneoscopic Partial Adrenalectomy

The interest on partial adrenalectomy has steadily increased over the past twenty years. Adrenal pathologies are mostly benign, making an organ-preserving procedure attractive for many patients. The introduction of minimally invasive techniques played probably an important role in this process because they transformed a complex surgical procedure, related to the difficult access to the retroperitoneal space, into a simple operation improving the accessibility to this organ. In this review we summarize the role of partial retroperitoneoscopic adrenalectomy over the years and the current indications and technique.

Robotic approach for partial adrenalectomy

Although safe and feasible, partial adrenalectomy is not a widespread procedure. Endorsement of robotic technologies and fluorescence techniques in adrenal surgery might help develop partial adrenalectomy and could avoid unnecessary total adrenalectomies. When performed in selected cases, partial adrenalectomy is associated with good postoperative outcomes comparable with those reported after total adrenalectomy. It has been hypothesized that one of the advantages of the robotic approach in adrenal-sparing surgery is to reduce manipulation of the gland allowing preservation of the vascularization of the residual adrenal, overcoming some limits when performing a laparoscopic conventional approach. A major drawback of the robotic surgery is its cost, but the overcost due to the use of the robotic system could be balanced by the execution of a high number of partial adrenalectomies leading to fewer life-long replacement steroid treatment. Partial adrenalectomy could become the recommended management for small benign and hormonal active adrenal tumors. Indocyanine green fluorescence (IGF) also seems to be a useful technique to help surgeons identify the adrenal gland and to locate small tumors from the normal adrenal tissue in difficult patients. It is likely that the use of a robotic approach associated with IGF may extend indications of partial adrenalectomy in the years to come.

Robot-assisted adrenalectomy: state of the art

Currently, laparoscopic adrenalectomy is worldwide considered the gold standard technique. Both transperitoneal and retroperitoneal approaches have proved their efficacy with excellent outcomes. Since the introduction of da Vinci System (Intuitive Surgical, Sunnyvale, CA), robotic surgery has made many steps forward gaining progressively more diffusion in the field of general and endocrine surgery. The robotic technique offers advantages to overcome some laparoscopic shortcomings (rigid instruments, loss of 3D vision, unstable camera). Indeed, the robotic system is provided of stereoscopic 3D-magnified vision, additional degree of freedom, tremor-filtering technology and a stable camera. Recently, several case series have demonstrated the feasibility and the safety of robot-assisted adrenalectomy in high-volume centers with outcomes comparable to laparoscopic adrenalectomy. Notwithstanding, the technical advantages of the robotic system have not yet demonstrated significant improvements in terms of outcomes to undermine laparoscopic adrenalectomy. Moreover, robotic adrenalectomy harbor inherits drawbacks, such as longer operative time and elevated costs, that limit its use. In particular, the high cost associated with the use of the robotic system is primarily related to the purchase and the maintenance of the unit, the high instruments cost and the longer operative time. Notably, these aspects make robotic adrenalectomy up to 2.3 times more costly than laparoscopic adrenalectomy. This literature review summarizes the current available studies and provides an overview about the robotic scenario including applicability, technical details and surgical outcomes.

Intraoperative imaging for remnant viability assessment in bilateral posterior retroperitoneoscopic partial adrenalectomy in an experimental model

BACKGROUND

A surgical approach preserving functional adrenal tissue allows biochemical cure while avoiding the need for lifelong steroid replacement. The aim of this experimental study was to evaluate the impact of intraoperative imaging during bilateral partial adrenalectomy on remnant perfusion and function.

METHODS

Five pigs underwent bilateral posterior retroperitoneoscopic central adrenal gland division (9 divided glands, 1 undivided). Intraoperative perfusion assessment included computer-assisted quantitative fluorescence imaging, contrast-enhanced CT, confocal laser endomicroscopy (CLE) and local lactate sampling. Specimen analysis after completion adrenalectomy (10 adrenal glands) comprised mitochondrial activity and electron microscopy.

RESULTS

Fluorescence signal intensity evolution over time was significantly lower in the cranial segment of each adrenal gland (mean(s.d.) 0·052(0·057) versus 0·133(0·057) change in intensity per s for cranial versus caudal parts respectively; P = 0·020). Concordantly, intraoperative CT in the portal phase demonstrated significantly lower contrast uptake in cranial segments (P = 0·031). In CLE, fluorescein contrast was observed in all caudal segments, but in only four of nine cranial segments (P = 0·035). Imaging findings favouring caudal perfusion were congruent, with significantly lower local capillary lactate levels caudally (mean(s.d.) 5·66(5·79) versus 11·58(6·53) mmol/l for caudal versus cranial parts respectively; P = 0·008). Electron microscopy showed more necrotic cells cranially (P = 0·031). There was no disparity in mitochondrial activity (respiratory rates, reactive oxygen species and hydrogen peroxide production) between the different segments.

CONCLUSION

In a model of bilateral partial adrenalectomy, three intraoperative imaging modalities consistently discriminated between regular and reduced adrenal remnant perfusion. By avoiding circumferential dissection, mitochondrial function was preserved in each segment of the adrenal glands. Surgical relevance Preservation of adrenal tissue to maintain postoperative function is essential in bilateral and hereditary adrenal pathologies. There is interindividual variation in residual adrenocortical stress capacity, and the minimal functional remnant size is unknown. New intraoperative imaging technologies allow improved remnant size and perfusion assessment. Fluorescence imaging and contrast-enhanced intraoperative CT showed congruent results in evaluation of perfusion. Intraoperative imaging can help to visualize the remnant vascular supply in partial adrenalectomy. Intraoperative assessment of perfusion may foster maximal functional tissue preservation in bilateral adrenal pathologies and procedures.

Indocyanine green fluorescence imaging for robotic adrenalectomy

Despite the novel and innovative developments in minimal invasive platforms and the expanding indications regarding adrenal surgery, surgeons are still confronted with some obstacles. The use of intraoperative indocyanine green aims to overcome these problems, but there is still limited data and ongoing debates in terms of robot-assisted adrenal surgery. The aim of this article is to discuss the benefit of indocyanine green fluorescence imaging for robot-assisted adrenalectomy and provide up-to date data.

Water-Soluble NIR Absorbing and Emitting Indolizine Cyanine and Indolizine Squaraine Dyes for Biological Imaging

Organic dyes that absorb and emit in the near-infrared (NIR) region are potentially noninvasive, high-resolution, and rapid biological imaging materials. Indolizine donor-based cyanine and squaraine dyes with water-solubilizing sulfonate groups were targeted in this study due to strong absorptions and emissions in the NIR region. As previously observed for nonwater-soluble derivatives, the indolizine group with water-solubilizing groups retains a substantial shift toward longer wavelengths for both absorption and emission with squaraines and cyanines relative to classically researched indoline donor analogues. Very high quantum yields (as much as 58%) have been observed with absorption and emission >700 nm in fetal bovine serum. Photostability studies, cell culture cytotoxicity, and cell uptake specificity profiles were all studied for these dyes, demonstrating exceptional biological imaging suitability.