The Use of Near-Infrared Indocyanine Green Fluorescence Imaging to Differentiate Benign Versus Malignant Adrenal Tumors.

Introduction: Despite advances in imaging modalities, a significant number of adrenal tumors are considered indeterminate and removed surgically. Currently, there is no intraoperative tool available to provide further information about the nature of indeterminate adrenal tumors. The aim of this study was to investigate whether near-infrared indocyanine green (ICG) imaging can be used in this regard.

Methods: This was an institutional review board-approved study. Within 9 years, 197 patients underwent robotic adrenalectomy with ICG imaging. Adrenal tumors were characterized prospectively as fluorescent or nonfluorescent intraoperatively. ICG was administered as a 2.5 mg dose, one to three times a procedure. No patient developed an allergic reaction. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated.

Results: Robotic transabdominal lateral adrenalectomy was performed in 155 patients and posterior retroperitoneal adrenalectomy in 42 patients. One hundred and eighty-four patients had benign adrenal tumors, 10 patients had malignant tumors, and three patients had tumors of uncertain malignant potential. Sensitivity, specificity, PPV, and NPV to predict a benign tumor were 87%, 38.5%, 95.2%, and 17.2%.

Conclusions: To our knowledge, this is the largest study on ICG imaging of adrenal tumors. High PPV to detect benign tumors suggests a utility of ICG to provide the surgeon with further information about the benign vs malignant nature of indeterminate adrenal tumors taken to surgery.