DOI: 10.1007/s00259-018-3971-xPages: 1710-1720

Diagnostic performance and impact on patient management of 68Ga-DOTA-TOC PET/CT for detecting osteomalacia-associated tumours

1. Hôpital Tenon, AP-HP, Médecine nucléaire

2. Centre Antoine Lacassagne, Médecine nucléaire

3. Sorbonne Université, Faculté de Médecine P&M Curie

4. Hôpital Tenon, AP-HP, Radiopharmacie

5. Hôpital Lariboisière, AP-HP, Rhumatologie

6. Université Paris Diderot

7. Hôpital Cochin, AP-HP, Rhumatologie

8. Université Paris Descartes

Correspondence to:
Jean-Noël Talbot
Tel: +33-15-6016556
Email: jean-noel.talbot@aphp.fr

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Abstract

Purpose

Oncogenic osteomalacia is an endocrine disorder induced by small benign tumours (TIO) producing excessive fibroblast growth factor-23 (FGF23). The only way of curing oncogenic osteomalacia is surgical resection of the culprit TIO, which is extremely difficult to detect using conventional imaging modalities due to its small size and variable location in the body. Since TIO frequently overexpress somatostatin receptors, a clinical utility of SPECT or PET with radiolabelled somatostatin analogues has been reported. Among them, 68Ga-DOTA-TOC has recently been granted a marketing authorization, facilitating its routine application. We report here the results of the first series evaluating the diagnostic performance of 68Ga-DOTA-TOC PET/CT in detecting TIO and its impact on patient management.

Methods

68Ga-DOTA-TOC PET/CT and clinical and imaging data from 15 patients with clinical and biochemical signs of oncogenic osteomalacia were retrospectively reviewed. The 68Ga-DOTA-TOC PET/CT findings were compared with the results of post-surgical pathology and clinical and biochemical follow-up.

Results

68Ga-DOTA-TOC PET/CT resulted in the detection of one focus suspicious for TIO in nine of 15 patients (60%), and a tumour was surgically removed in eight. Post-operative pathology confirmed a TIO in those eight patients whose symptoms diminished promptly and biochemical anomalies resolved. 68Ga-DOTA-TOC PET/CT sensitivity, specificity and accuracy were 73%, 67% and 71%, respectively. 68Ga-DOTA-TOC PET/CT findings affected patient management in 67% of cases. In particular, 68Ga-DOTA-TOC PET/CT was able to detect the TIO with a negative or a false-positive result of a previous 111In-pentetreotide SPECT/CT in 5/8 patients (63%) or a previous FDG PET/CT in 7/11 patients (64%). No close relationship was found between the positivity of 68Ga-DOTA-TOC PET/CT and the serum level of a biochemical marker. However, a true-positive result of 68Ga-DOTA-TOC PET/CT was obtained in only one patient with a non-elevated serum level of FGF23.

Conclusion

68Ga-DOTA-TOC PET/CT is an accurate imaging modality in the detection of TIO; in particular, it is worthwhile after failure of somatostatin receptor SPECT(/CT) or FDG PET/CT.

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  • Accepted: Feb 4, 2018
  • Online: Mar 12, 2018

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