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

Abstract

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. 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. 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. 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.