Utility of 18F-AlF-NOTA-octreotide PET/CT in the localization of Tumor-Induced Osteomalacia.

Purpose Tumor-induced osteomalacia (TIO) is a paraneoplastic disorder, usually caused by benign mesenchymal tumors that produce high levels of the hormone fibroblast-growth-factor 23 (FGF23). The only curative therapy of the disease is resection of the causative tumors. This research was conducted to evaluate the efficacy of 18F-AlF-NOTA-octreotide ( 18F-OC) PET/CT in detecting TIO and its impact on patient management. Methods Retrospective analysis of 17 patients with hypophosphatemic osteomalacia suspected of TIO was performed. 18F-OC PET/CT study was performed in all 17 patients to localize the tumor. 68Ga-DOTATATE PET/CT was performed in 4 out of 17 patients. 18F-OC and 68Ga-DOTATATE PET/CT studies were performed within 1 week of each other. Both studies were interpreted blindly without the knowledge of other imaging findings. The image findings were compared with the results of histopathological examinations and clinical follow-ups. Results 18F-OC PET/CT scans were positive in 14 patients. Moreover, 4 out of 14 patients were performed with both 18F-OC and 68Ga-DOTATATE PET/CT. Both studies were able to localize the tumor in all the 4 patients. In total, 14 patients had surgery to remove the lesions. Postsurgical pathological examination confirmed causative tumors in these patients whose symptoms diminished promptly. The serum phosphate levels became normal confirming the diagnosis of TIO. 18F-OC PET/CT sensitivity, specificity and accuracy were 87.5%, 100% and 88.2% respectively. 18F-OC PET/CT findings affected patient management in 88.2% of cases. Conclusion 18F-OC PET/CT scan is useful in the detection of tumors causing TIO. Further studies with larger patient population are needed to validate the result.