Impact of standardising indocyanine green fluorescence angiography technique for visual and quantitative interpretation on interuser variability in colorectal surgery

Aim/Background Intra-operative colonic perfusion assessment via indocyanine green fluorescence angiography (ICGFA) aims to address malperfusion-related anastomotic complications; however, its interpretation suffers interuser variability (IUV), especially early in ICGFA experience. This work assesses the impact of a protocol developed for both operator-based judgement and computational development on interpretation consistency, focusing on senior surgeons yet to start using ICGFA. Methods Experienced and junior gastrointestinal surgeons were invited to complete an ICGFA-experience questionnaire. They subsequently interpreted nine operative ICGFA videos regarding perfusion sufficiency of a surgically prepared distal colon during laparoscopic anterior resection by indicating their preferred site of proximal transection using an online annotation platform (mindstamp.com). Six ICGFA videos had been prepared with a clinical standardisation protocol controlling camera and patient positioning of which three each had monochrome near infrared (NIR) and overlay display. Three others were non-standardised controls with synchronous NIR and overlay picture-in-picture display. Differences in transection level between different cohorts were assessed for intraclass correlation coefficient (ICC) via ImageJ and IBM SPSS. Results 58 clinicians (12 ICGFA experts, 46 ICGFA inexperienced of whom 23 were either finished or within one year of finishing training and 23 were junior trainees) participated as per power calculations. 63% felt that ICGFA should be routinely deployed with 57% believing interpretative competence requires 11–50 cases. Transection level concordance was generally good (ICC = 0.869) across all videos and levels of expertise (0.833–0.915). However, poor agreement was evident with the standardised protocol videos for overlay presentation (0.208–0.345). Similarly, poor agreement was seen for the monochrome display (0.392–0.517), except for those who were trained but ICG inexperienced (0.877) although even here agreement was less than with unstandardised videos (0.943). Conclusion Colorectal ICGFA acquisition and display standardisation impacts IUV with this specific protocol tending to diminish surgeon interpretation consistency. ICGFA video recording for computational development may require dedicated protocols. Graphical abstract