Utility of Indocyanine Green in Intraoperative Imaging of Adrenal Tumors

Abstract

Backgrounds:

Indocyanine green (ICG) is a fluorescent biocompatible dye that emits light in the near-infrared spectrum upon excitation, enabling real-time visualization of vascular anatomy and tissue perfusion during surgery. Its favorable safety profile and rapid pharmacokinetics have led to widespread adoption across surgical specialties. More recently, ICG fluorescence imaging has been utilized for tumor localization in adrenalectomy, improving intraoperative decision-making, particularly in complex anatomical regions.

Methods:

A comprehensive literature search was conducted using PubMed, EMBASE, and Google Scholar databases. Tailored search strategies were applied for each topic addressed in this review. Articles were considered eligible for inclusion if they met the following criteria: (1) original research studies, randomized controlled trials, or systematic reviews with or without meta-analysis; (2) studies involving human subjects; and (3) publications in the English language. All selected studies underwent independent review by 2 authors, and any discrepancies were resolved through discussion with a third reviewer.

Results:

ICG fluorescence imaging is a valuable adjunct for adrenal gland identification, as the adrenal cortex demonstrates strong fluorescence due to its rich vascularization, allowing clear differentiation from surrounding retroperitoneal tissue. Adrenocortical tumors typically exhibit a hyperfluorescent pattern, whereas medullary tumors and malignant lesions more commonly demonstrate hypofluorescence, likely reflecting differences in their underlying biochemical and anatomical characteristics. Furthermore, ICG is particularly useful in partial adrenalectomy for bilateral tumors, facilitating precise tumor localization and resection while preserving functional adrenal cortical tissue.

Conclusions:

ICG fluorescence imaging is a valuable adjunct in adrenal surgery, enabling real-time visualization of adrenal anatomy, vascular structures, and tissue perfusion. Its application improves gland identification, facilitates accurate tumor localization, and supports cortical-sparing approaches by preserving functional adrenal tissue.