A visual quantification of tissue distinction in robotic transabdominal lateral adrenalectomy: comparison of indocyanine green and conventional views.

ABSTRACT

BACKGROUND: Recent studies have reported the feasibility of indocyanine green fluorescence imaging of adrenal tumors to guide dissection. Although the adrenal has been reported to concentrate the dye more than surrounding tissues, the amount of tissue distinction and how this compares with conventional vision has not been quantified before. The aim of this study is to quantify this distinction using color analysis. METHODS: This was an institutional review board-approved retrospective study. By excluding adrenal cortical carcinoma, metastasis and pheochromocytoma, video recordings of 50 patients who underwent robotic transabdominal lateral adrenalectomy with indocyanine green (ICG) imaging for adrenocortical tumors between August 2015 and May 2018 were reviewed. Using a color analysis software, the pixel intensity of adrenal tumors versus adjacent retroperitoneal tissues was calculated for conventional red, green and blue, as well as indocyanine green (ICG) scales. Statistical analysis was performed using ANOVA. RESULTS: A total of 50 patients underwent unilateral robotic transabdominal lateral adrenalectomy. All procedures were completed robotically without a conversion to laparoscopy or open. Morbidity was 4%. Measured pixel intensity of adrenal tumors was higher than adjacent retroperitoneal tissues for all conventional color and ICG modes (p < 0.0001), with the gradient being more pronounced for ICG green versus conventional red, green and blue modes. CONCLUSIONS: To our knowledge this is the first study attempting to encode tissue planes in robotic adrenalectomy. The results show that the visual contrast distinction observed between adrenal and adjacent retroperitoneal tissues can be quantified using pixel intensity. ICG enabled the distinction of tissue planes with a wider gradient compared to conventional RGB view, quantifying its subjective benefits reported in prior studies.