Abstract
CONTEXT: Phosphaturic mesenchymal tumors (PMTs) are small, typically difficult to localize, and express somatostatin receptors. Recent work suggests imaging studies using (68)Gallium ((68)Ga)-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. OBJECTIVE: Our objective was to evaluate the use of (68)Ga-DOTATATE PET/computed tomography (CT) for tumor localization in tumor-induced osteomalacia (TIO). DESIGN: This was a single-center prospective study of patients with TIO. SETTING: The study was conducted at the National Institutes of Health Clinical Center between February 2014 and February 2015. SUBJECTS: Eleven subjects (six females, five males) with TIO were included. INTERVENTION: Subjects underwent (68)Ga-DOTATATE PET/CT in addition to (111)In-pentetreotide single-photon emission CT (Octreoscan- SPECT/CT) and fluorodeoxyglucose-PET/CT ((18)F FDG-PET/CT) scan. MAIN OUTCOME MEASURES: Localization of PMTs on the previously described imaging modalities were determined. RESULTS: The tumor was successfully localized in 6/11 (54.5%) subjects (one was metastatic). The tumor was identified by (68)Ga-DOTATATE in all six cases. Both Octreoscan-SPECT/CT and (18)F FDG-PET each identified the tumor in 4/6. In no cases was (68)Ga-DOTATATE the only imaging study to identify the tumor. CONCLUSIONS: In this first prospective study comparing (68)Ga-DOTATATE PET/CT to Octreoscan-SPECT/CT and (18)F FDG-PET in TIO localization, (68)Ga-DOTATATE PET/CT demonstrated the greatest sensitivity and specificity, suggesting that it may be the best single study for localization of PMTs in TIO.