Multiple endocrine neoplasia type 1 or 4: detection of hyperfunctioning parathyroid glands with 18F-fluorocholine PET/CT. Illustrative cases and pitfalls.

BACKGROUND 18F-fluorocholine (FCH) PET/CT is now well established to detect HFPTG in sporadic primary hyperparathyroidism (pHPT), but only a limited evidence is available about the utility of FCH PET/CT to detect the hyperfunctioning parathyroid glands (HFPTG) in patients with multiple endocrine neoplasia (MEN) type 1 or 4. The pHPT in this context frequently consists in a multiglandular disease with small hyperplastic glands rather than adenomas, which is challenging for imaging modalities. METHODS The data of patients with MEN1 or MEN4 after parathyroidectomy referred to FCH PET/CT for presurgical localisation of HFPTG were retrospectively reviewed, in search for diagnostic performance and for potential pitfalls. RESULTS In the present cohort, 16 patients referred to FCH PET/CT as part of their initial pHPT work-up were subsequently operated, 44 abnormal parathyroid glands (PT) were resected of which 32 (73%) had been detected on FCH PET/CT and 2 considered as equivocal foci. In 9 patients referred to FCH PET/CT for recurrent pHPT who were subsequently operated, 14 abnormal PT were resected, all had been detected on FCH PET/CT. FCH PET/CT permitted an unilateral approach for PTx in 4 of them; In one patient with MEN4 and pHPT, the HFPTG could not be visualised on FCH PET/CT, but was localised by ultrasonography. Several causes of false positive, false negative results, incidental finding and pitfalls are listed and discussed. CONCLUSIONS FCH PET/CT has a positive benefit/risk ratio in the detection of HFPTG in case of MEN1 (the data in MEN4 being currently very limited) with the most effective detection rate of current imaging modalities for HFPTG, few pitfalls, and an adequate impact on patient management compared to sestaMIBI SPECT and ultrasonography.