Label-Free Enhancement of Adrenal Gland Visualization Using Near-Infrared Autofluorescence for Surgical Guidance.

Background: During adrenalectomy, surgeons have traditionally relied on their subjective visual skills to distinguish adrenal glands (AGs) from retroperitoneal fat and surrounding structures, while ultrasound and exogenous contrast agents have been employed for intraoperative AG visualization, all of which have their limitations. We present a novel label-free approach that uses near-infrared autofluorescence (NIRAF) detection, which demonstrates potential for enhanced intraoperative AG visualization and efficient tumor resection during adrenalectomies.

Methods: Patients undergoing adrenalectomy or nephrectomy were enrolled for this feasibility study. NIRAF emitted beyond 800 nm was detected in vivo from AGs and surrounding tissues during open adrenalectomies or nephrectomies. NIRAF was also measured ex vivo in excised AGs following robotic adrenalectomies. NIRAF images of tissues were captured using near-infrared (NIR) camera systems, whereas NIRAF intensities were recorded concurrently using fiber-optic probe-based NIR devices. Normalized NIRAF intensities (expressed as mean ± standard error) were analyzed and compared.

Results: Among the 55 enrolled patients, NIRAF intensity was elevated significantly for AGs versus retroperitoneal fat and other structures. NIR images of AGs also revealed a distinct demarcation of NIRAF between adrenal cortex and other periadrenal structures. NIRAF intensity in AGs was decreased markedly in malignant adrenal tumors, while benign adrenal cortical tumors and healthy adrenal cortex exhibited the strongest NIRAF levels.

Conclusions: Our preliminary findings indicate that NIRAF detection could be a promising label-free technology to enhance intraoperative AG visualization and holds immense potential for effective tumor demarcation during cortical-sparing adrenalectomies or adrenal-conserving surgeries.