[123I]Iodometomidate imaging in adrenocortical carcinoma

Abstract

Context: Imaging with [123I]iodometomidate ([ 123I]IMTO) has been shown to diagnose adrenocortical lesions with high sensitivity and specificity. Objective: Our objective was to evaluate the clinical utility of [123I]IMTO imaging in adrenocortical carcinoma (ACC). Design: We conducted a prospective monocentric diagnostic study and a prospective case series at a single tertiary referral center. Patients and Interventions: Fifty-eight patients with histologically confirmed ACC, all European Network for the Study of Adrenal Tumors stage IV (with distant metastases), received 185 MBq [123I]IMTO. Sequential planar whole-body scans until 24 hours post injection and single photon emission computed tomography/computed tomography (SPECT/CT) hybrid imaging 4 to 6 hours post injection were performed. Main Outcome Measures: Outcome measures included uptake of [123I]IMTO in ACC lesions, sensitivity and specificity of [123I]IMTO imaging compared with conventional imaging, and number of patients eligible for [131I]IMTO therapy. Results: Of 430 lesions detected by conventional imaging, 30% showed strong, 8% moderate, and 62% no tracer accumulation. [123I]IMTO detected both primary and metastatic lesions of ACC. However, a substantial percentage of lesions failed to show [123I]IMTO uptake. The overall sensitivity and specificity values were 38% and 100%, respectively. Thirty-four patients (59%) had at least 1 [123I]IMTO-positive lesion. Cortisol and aldosterone secretion by ACC was positively correlated to [123I]IMTO uptake (P = .01); cytotoxic chemotherapy and mitotane treatment presumably did not influence tracer uptake. Twenty-one patients (36.2%) had radiotracer uptake in all lesions ≥2 cmand therefore were potential candidates for targeted systemic radiotherapy with [131I]IMTO. Conclusion: About one-third of patients with ACC show specific retention of [123I]IMTO in metastatic lesions. This study provides support for the conduct of a prospective trial to determine whether the first molecular informed therapy using [131I]IMTO will be of value to patients with metastatic ACC. Copyright © 2013 by The Endocrine Society.