From the Departments of *Nuclear Medicine and PET, and †Endocrinology, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
Clin Nucl Med. 2015 Jan;40(1):e6-e10. doi: 10.1097/RLU.0000000000000460.
Tumor-induced osteomalacia (TIO) is a rare paraneoplastic syndrome, usually caused by small benign mesenchymal tumors. The localization of these tumors is challenging, however, essential for the management. We compared the utility of F-FDG PET/CT and Ga DOTATATE PET/CT to detect the site of primary tumor in patients with suspicion of TIO.
Retrospective analysis of 6 patients with hypophosphatemic osteomalacia and suspicion of TIO was performed. Ga DOTATATE PET/CT study was performed in all 6 patients to localize the tumor. F-FDG PET/CT was performed in 4 of 6 patients. F-FDG and Ga DOTATATE PET/CT studies were performed within 1 week of each other. Both studies were interpreted blindly without the knowledge of other imaging findings.
All patients had symptoms of osteomalacia and hypophosphatemia. All except 1 patient had increased level of fibroblast growth factor 23. The lag time (symptoms to PET diagnosis) ranged from 1.5 to 22 years. In 4 patients, where both studies were performed, F-FDG and Ga DOTATATE PET/CT were able to localize the tumor in 2 and 3 patients. Ga DOTATATE PET/CT detected tumor in 5 (83.3%) of 6 patients.
Ga DOTATATE PET/CT performed better than F-FDG PET/CT and is useful in the detection of tumors causing oncogenic osteomalacia. Therefore, in clinically suspected cases of hypophosphatemic osteomalacia, Ga DOTATATE PET/CT may be performed as first-line imaging investigation to avoid delay in the treatment of this devastating but curable disease. However, further studies with large patient population are warranted to validate our data.
肿瘤相关性骨软化症（TIO）是一种罕见的副瘤综合征，通常由小的良性间叶肿瘤引起。然而，这些肿瘤的定位具有挑战性，对于治疗至关重要。我们比较了 F-FDG PET/CT 和 Ga DOTATATE PET/CT 在怀疑 TIO 的患者中检测原发肿瘤部位的效用。
对 6 例低磷性骨软化症和怀疑 TIO 的患者进行了回顾性分析。所有 6 例患者均进行 Ga DOTATATE PET/CT 研究以定位肿瘤。6 例中有 4 例患者进行了 F-FDG PET/CT 检查。F-FDG 和 Ga DOTATATE PET/CT 检查在彼此 1 周内进行。两项研究均在不知道其他影像学发现的情况下进行盲法解读。
所有患者均有骨软化症和低磷血症的症状。除 1 例患者外，所有患者的成纤维细胞生长因子 23 水平均升高。症状至 PET 诊断的潜伏期为 1.5 至 22 年。在 4 例同时进行两项研究的患者中，F-FDG 和 Ga DOTATATE PET/CT 能够在 2 例和 3 例患者中定位肿瘤。Ga DOTATATE PET/CT 在 6 例患者中的 5 例（83.3%）中检测到肿瘤。
Ga DOTATATE PET/CT 优于 F-FDG PET/CT，在检测引起致癌性骨软化症的肿瘤方面具有优势。因此，在临床上怀疑低磷性骨软化症的病例中，Ga DOTATATE PET/CT 可作为一线影像学检查，以避免治疗这种毁灭性但可治愈疾病的延误。然而，需要进行更大规模的患者人群研究来验证我们的数据。
