⁶⁸Ga-DOTATATE for Tumor Localization in Tumor-Induced Osteomalacia.

Abstract

Phosphaturic mesenchymal tumors (PMTs) are small, typically difficult to localize, and express somatostatin receptors. Recent work suggests imaging studies using ⁶⁸Gallium (⁶⁸Ga)-conjugated somatostatin peptide analogues, such as 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)TATE, which enables somatostatin receptor imaging with positron emission tomography (PET), may be useful at identifying these tumors. Our objective was to evaluate the use of ⁶⁸Ga-DOTATATE PET/computed tomography (CT) for tumor localization in tumor-induced osteomalacia (TIO). This was a single-center prospective study of patients with TIO. The study was conducted at the National Institutes of Health Clinical Center between February 2014 and February 2015. Eleven subjects (six females, five males) with TIO were included. Subjects underwent ⁶⁸Ga-DOTATATE PET/CT in addition to ¹¹¹In-pentetreotide single-photon emission CT (Octreoscan- SPECT/CT) and fluorodeoxyglucose-PET/CT (¹⁸F FDG-PET/CT) scan. Localization of PMTs on the previously described imaging modalities were determined. The tumor was successfully localized in 6/11 (54.5%) subjects (one was metastatic). The tumor was identified by ⁶⁸Ga-DOTATATE in all six cases. Both Octreoscan-SPECT/CT and ¹⁸F FDG-PET each identified the tumor in 4/6. In no cases was ⁶⁸Ga-DOTATATE the only imaging study to identify the tumor. In this first prospective study comparing ⁶⁸Ga-DOTATATE PET/CT to Octreoscan-SPECT/CT and ¹⁸F FDG-PET in TIO localization, ⁶⁸Ga-DOTATATE PET/CT demonstrated the greatest sensitivity and specificity, suggesting that it may be the best single study for localization of PMTs in TIO.