Deconstructing mastery in colorectal fluorescence angiography interpretation

Abstract

Introduction Indocyanine green fluorescence angiography (ICGFA) is commonly used in colorectal anastomotic practice with limited pre-training. Recent work has shown that there is considerable inconsistency in signal interpretation between surgeons with minimal or no experience versus those consciously invested in mastery of the technique. Here, we deconstruct the fluorescence signal patterns of expert-annotated surgical ICGFA videos to understand better their correlation and combine this with structured interviews to ascertain whether such interpretative capability is conscious or unconscious. Methods For fluorescence signal analysis, expert-annotated ICGFA videos (n = 24) were quantitatively interrogated using a boutique intensity tracker (IBM Research) to generate signal time plots. Such fluorescence intensity data were examined for inter-observer correlation (Intraclass Correlation Coefficients, ICC) at specific curve milestones: the maximum fluorescence signal (Fmax), the times to both achieve this maximum (Tmax), as well as half this maximum (T1/2max) and the ratio between these (T1/2/Tmax). Formal tele-interview with contributing experts (n = 6) was conducted with the narrative transcripts being thematically mapped, plotted, and qualitatively analyzed. Results Correlation by mathematical measures was excellent (ICC0.9–1.0) for Fmax, Tmax, and T1/2max (0.95, 0.938, and 0.925, respectively) and moderate (0.5–0.75) for T1/2/Tmax (0.729). While all experts narrated a deliberate viewing strategy, their specific dynamic signal appreciation differed in the manner of description. Conclusion Expert ICGFA users demonstrate high correlation in mathematical measures of their signal interpretation although do so tacitly. Computational quantification of expert behavior can help develop the necessary lexicon and training sets as well as computer vision methodology to better exploit ICGFA technology.

Clinical and computational development of a patient-calibrated ICGFA bowel transection recommender

“…For almost all cases, this method reflected actual expert surgical judgement (the clinical gold standard and one proven reliable and consistent [ 8 , 16 ] with regard to ICGFA interpretation). Although these recommendations are not clinically validated in this retrospective in silico research, the software also recommended a more distal safe transection in two patients.…”

“…Furthermore, the fluorescence signal is itself dependent on ICG’s pharmacokinetics which in turn vary with body habitus [ 13 ], physiology [ 14 ] and intra-operative factors, including anaesthesia [ 15 ]. Nevertheless, interpretation consistency did not improve when a protocol was applied to standardise these variables relating to the technique, as well patient and camera positioning [ 16 ]. Overall, these factors hinder interpretative consistency and limit technique dissemination and uptake, undermining the potential for ICGFA to become the gold standard clinical method for intraoperative perfusion assessment [ 8 , 17 , 18 ].…”

Advancing indocyanine green fluorescence flap perfusion assessment via near infrared signal quantification

“…Selective ICGFA used only in grey cases would seem more efficient, but acquiring such visual ICGFA interpretative competence requires experiential learning, incrementally accrued by routine use. 26 ICGFA quantification may support visual interpretation and over time could permit the development of thresholds or artificial intelligence (AI) to predict flap compromise at the instance of the index operation. Such tools could obviate ICGFA learning curves and reduce the need for unplanned flap salvage procedures.…”

Evaluating clinical near-infrared surgical camera systems with a view to optimizing operator and computational signal analysis

“…This would necessitate shorter distances (and less bowel visualized), diminishing the IOD. If the demarcation zone is missed, redosing and reassessing is an option; however, interpretation 32 and quantification may be complicated by background fluorescence from incompletely cleared ICG (despite its short half-life of 3-5 minutes 32 ). Other work by our group (under submission) has demonstrated that a protocol in which camera distance is arbitrarily standardized (without calculating the IOD) resulted in poorer interpretation consistency than ad libitum use.…”

“…The effect of CPR results in a relatively attenuated peak fluorescence at the peripheries. Although its impact on judgment has not been investigated, experts in the field have been demonstrated to unconsciously interpret these perfusions curve features 32 as part of their decision-making process. Psychological research on visual fixation shows that observers perceive the center not necessarily at the geometric middle of the screen but in the lower third 33 and tend to neglect brighter cues in favor of nearby less luminescent ones 33 .…”