FRI689 First-line F18-choline PET/CT Versus Tc99m-sestaMIBI SPECT/CT In The Surgical Management Of Primary Hyperparathyroidism: The Multicentre APACH2 Phase III Trial

Disclosure: E. Quak: None. A. Lasne-cardon: None. M. Cavarec: None. B. Lireux: None. V. Bastit: None. N. Roudaut: None. P. Salaun: None. N. Keromnes: None. G. Potard: None. P. Vaduva: None. A. Esvant: None. F. Jegoux: None. O. Crouy-chanel: None. A. Devillers: None. C. Guery: None. C. Lasnon: None. R. Ciappuccini: None. M. Sali dauda: None. B. Legrand: None. A. Estienne: None. J. Grellard: None. S. Bardet: None. B. Clarisse: None. Introduction: Whether F18-choline PET/CT (FCH PET/CT) should replace Tc99m-sestaMIBI SPECT/CT (MIBI SPECT/CT) as a first-line imaging technique for preoperative localisation of parathyroid adenomas in primary hyperparathyroidism (pHPT) is unclear. Methods: We conducted a multicentre randomized open diagnostic intervention phase III trial in adults with primary hyperparathyroidism and indication for surgical treatment. Patients were assigned in a 1:1 ratio to receive first-line FCH PET/CT (FCH1) or MIBI SPECT/CT (MIBI1). In case of negative or inconclusive first-line imaging, patients received second-line FCH PET/CT (FCH2) after MIBI1 or MIBI SPECT/CT (MIBI2) after FCH1. The main aim of the trial was to compare the proportions of patients in whom the first-line imaging method resulted in successful mini-invasive parathyroidectomy (MIP) and cure, defined as the normalisation of serum calcium and parathyroid hormone levels at 1 month. We hypothesized a 30% superiority of FCH1 over MIBI1 for sample size determination (Quak et al, BMC Endocr Disord. 2021, PMID: 33413316). Results: From 11/2019 to 05/2022, 58 patients were assigned to receive FCH1 (n=30) or MIBI1 (n=28). Baseline patient characteristics were similar between groups. FCH1 was positive in 23/29 patients and led to successful MIP and cure in 22/23 patients. MIBI1 was positive in 18/28 and led to MIP in 16/17 operated patients, and video-assisted thoracoscopy (VATS) in 1/17 patient. Cure was obtained in 15/17 patients. The proportion of patients in whom the first-line imaging exam led to successful MIP and cure was 22 (76%) for FCH1 and 13 (50%) for MIBI1 (p=0.047). Diagnostic performances were superior for FCH1 than for MIBI1: sensitivity (92% vs 68%), specificity (100% vs 75%), positive predictive value (100% vs 94%), negative predictive value (67% vs 30%), and area under the ROC curve (96% vs 71%, p=0.022), respectively. Ten patients received FCH2 and 6 patients received MIBI2. FCH2 was positive in 8/10 patients, leading to 7/9 MIP and 2/9 bilateral cervical explorations