Utility of 18F-AlF-NOTA-Octreotide PET/CT in the Localization of Tumor-Induced Osteomalacia

Context: Tumor-induced osteomalacia (TIO) is a paraneoplastic disorder, usually caused by benign mesenchymal tumors that produce high levels of fibroblast growth factor 23. The only curative therapy is resection of the causative tumors. Objective: This research was conducted to evaluate the efficacy of F-18-AlF-NOTA-octreotide (F-18-OC) positron emission tomography/computed tomography (PET/CT) in detecting TIO and its impact on patient management. Methods: Retrospective analysis was conducted of 17 patients with hypophosphatemic osteomalacia suspected to be TIO. A F-18-OC PET/CT study was performed in all 17 patients to localize the tumor and Ga-68-DOTATATE PET/CT was performed in 4 out of 17 patients; both 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: The F-18-OC PET/CT scans were positive in 14 patients. Furthermore, 4 of 14 patients were scanned with both F-18-OC and Ga-68-DOTATATE PET/CT. Both studies were able to localize the tumor in all 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. Serum phosphate levels normalized, confirming the diagnosis of TIO. F-18-OC PET/CT sensitivity, specificity, and accuracy were 87.5%, 100%, and 88.2% respectively. F-18-OC PET/CT findings affected patient management in 88.2% of cases. Conclusion: F-18-OC PET/CT scan is useful in the detection of tumors causing TIO. Further studies with larger patient populations are needed to validate the result.

Automated summary

This study retrospectively analyzed 17 cases and found that F-18-OC PET/CT scans had a positive impact on the diagnosis of TIO in 14 patients. After surgical removal of the lesions, patients' symptoms improved rapidly, and serum phosphate levels normalized.