Quantification of fluorescence angiography for visceral perfusion assessment: measuring agreement between two software algorithms.

BACKGROUND: Indocyanine green fluorescence angiography (ICG-FA) may reduce perfusion-related complications of gastrointestinal anastomosis. Software implementations for quantifying ICG-FA are emerging to overcome a subjective interpretation of the technology. Comparison between quantification algorithms is needed to judge its external validity. This study aimed to measure the agreement for visceral perfusion assessment between two independently developed quantification software implementations. METHODS: This retrospective cohort analysis included standardized ICG-FA video recordings of patients who underwent esophagectomy with gastric conduit reconstruction between August 2020 until February 2022. Recordings were analyzed by two quantification software implementations: AMS and CPH. The quantitative parameter used to measure visceral perfusion was the normalized maximum slope derived from fluorescence time curves. The agreement between AMS and CPH was evaluated in a Bland-Altman analysis. The relation between the intraoperative measurement of perfusion and the incidence of anastomotic leakage was determined for both software implementations. RESULTS: Seventy pre-anastomosis ICG-FA recordings were included in the study. The Bland-Altman analysis indicated a mean relative difference of + 58.2% in the measurement of the normalized maximum slope when comparing the AMS software to CPH. The agreement between AMS and CPH deteriorated as the magnitude of the measured values increased, revealing a proportional (linear) bias (R2 = 0.512, p < 0.001). Neither the AMS nor the CPH measurements of the normalized maximum slope held a significant relationship with the occurrence of anastomotic leakage (median of 0.081 versus 0.074, p = 0.32 and 0.041 vs 0.042, p = 0.51, respectively). CONCLUSION: This is the first study to demonstrate technical differences in software implementations that can lead to discrepancies in ICG-FA quantification in human clinical cases. The possible variation among software-based quantification methods should be considered when interpreting studies that report quantitative ICG-FA parameters and derived thresholds, as there may be a limited external validity.

Fluorescence perfusion assessment of vascular ligation during ileal pouch-anal anastomosis.

BACKGROUND: Intraoperative fluorescence angiography (FA) is of potential added value during ileal pouch-anal anastomosis (IPAA), especially after vascular ligation as part of lengthening measures. In this study, time to fluorescent enhancement during FA was evaluated in patients with or without vascular ligation during IPAA. METHODS: This is a retrospective cohort study of all consecutive patients that underwent FA-guided IPAA between August 2018 and December 2019 in our tertiary referral centre. Vascular ligation was defined as disruption of the ileocolic arcade or ligation of interconnecting terminal ileal branches. FA was performed before and after ileoanal anastomotic reconstruction. During FA, time to fluorescent enhancement was recorded at different sites of the pouch. RESULTS: Thirty-eight patients [55.3% male, median age 45 years (IQR 24-51 years)] were included, of whom the majority (89.5%) underwent a modified-2-stage restorative proctocolectomy. Vascular ligation was performed in 15 patients (39.5%), and concerned central ligation of the ileocolic arcade in 3 cases, interconnecting branches in 10, and a combination in 2. For the entire cohort, time between indocyanine green (ICG) injection and first fluorescent signal in the pouch was 20 s (IQR 15-31 s) before and 25 s (IQR 20-36 s) after anal anastomotic reconstruction. Time from ICG injection to the first fluorescent signal at the inlet, anvil and blind loop of the pouch were non-significantly prolonged in patients that received vascular ligation. CONCLUSIONS: Results from this study indicate that time to fluorescence enhancement during FA might be prolonged due to arterial rerouting through the arcade or venous outflow obstruction in case of vascular ligation.

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

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

Completion surgery following transanal endoscopic microsurgery: assessment of quality and short- and long-term outcome.

AIM: Patients with unfavourable pathology after transanal endoscopic microsurgery (TEM) should be offered completion surgery (CS) if appropriate. The aim of this retrospective cohort study was to assess the short-term outcome and long-term oncological results of CS and identify factors compromising the quality of resection specimens. METHOD: Data were retrieved and analysed on patients who underwent CS from a comprehensive national TEM database (1992-2008) and the institutional prospective database from the Oxford University Hospitals (2008-2011). RESULTS: There were 36 patients eligible for analysis. Postoperative complications occurred in 19 and were minor (grade I-II) in 13 and major (grade III-V) in six patients. The quality of the resected specimen was graded as good in 23 (64%), moderate in six (16.6%) and poor in seven (19.4%). Full-thickness excision by TEM (P = 0.03), an interval to CS greater than 7 weeks (P = 0.05) and distally located lesions (P = 0.04) were associated with increased risk for an inferior surgical specimen. Overall survival after CS was 91% at 1 year and 83% at 5 years. Patients with a 'good' TME specimen had significantly improved disease-free survival compared with patients with an 'inferior' specimen (100 vs 51%, P = 0.001). CONCLUSION: Patients having full-thickness TEM excision, distally placed lesions and a long interval (> 7 weeks) to CS were likely to have an inferior TME specimen. The results confirm that CS after TEM does not negatively influence local recurrence and survival, but the reduced disease-free survival in patients with an inferior specimen is of concern.

Transanal glove port is a safe and cost-effective alternative for transanal endoscopic microsurgery.

BACKGROUND: Transanal endoscopic microsurgery (TEM) is a minimally invasive technique for excision of rectal tumours that avoids conventional pelvic resectional surgery along with its risks and side-effects. Although appealing, the associated cost and complex learning curve limit TEM utilization by colorectal surgeons. Single-port laparoscopic principles are being recognized as transferable to transanal work and hybrid techniques are in evolution. Here the clinical application of a new technique for transanal access is reported. METHODS: Consecutive non-selected patients eligible for TEM over a 3-month period (and selected patients thereafter) were offered a procedure performed via a 'glove TEM port'. This access device was constructed on-table using a circular anal dilator (CAD), wound retractor and standard surgical glove, along with standard, straight laparoscopic trocar sleeves and instruments. RESULTS: Fourteen patients underwent full-thickness resection of benign (8) or malignant (6) rectal pathology. CAD insertion failed in one patient and conventional TEM assistance was needed in another, leaving 12 procedures completed successfully by glove TEM alone as planned (completion rate 86 per cent overall, 92 per cent after initiation). The median (range) duration of operation and resected specimen area were 93 (30-120) min and 12 (3-152) cm(2) respectively. There was no intraoperative and minimal postoperative morbidity, with a median follow-up of 5.7 (2.7-9.4) months. CONCLUSION: The glove TEM port is a safe, inexpensive and readily available access tool that may obviate the use of specialized equipment for transanal resection of rectal lesions.