18F-fluoro-ethyl-tyrosine PET co-registered with MRI in patients with persisting acromegaly

Abstract

Abstract Purpose To report our experience with 18F-fluoro-ethyl-tyrosine (FET) positron emission tomography-computed tomography (PET-CT) co-registered with MRI (FET-PET/MRICR) in the care trajectory for complex acromegaly patients. Methods In 10 patients with insufficiently controlled acromegaly referred to our team to evaluate surgical options, FET-PET/MRICR was used to support decision-making if MRI alone and multidisciplinary team evaluation did not provide sufficient clarity to proceed to surgery. Results FET-PET/MRICR showed suspicious (para)sellar tracer uptake in all patients. In 5 patients FET-PET/MRICR was fully concordant with conventional MRI, and in 1 patient partially concordant. FET-PET/MRICR identified new suspicious foci in 4 other patients. Surgical re-exploration was performed in 9 patients (aimed at total resection (6), debulking (2), diagnosis (1)), and 1 patient underwent radiation therapy. In 7 of 9 (78%) operated patients FET-PET/MRICR findings were confirmed intraoperatively, and in 6 patients (67%) also histologically. IGF-1 decreased significantly in 8 patients (89%). All patients showed clinical improvement. Complete biochemical remission was achieved in 3 patients (50% of procedures in which total resection was anticipated feasible). Biochemistry improved in 5 and was unchanged in 1 patient. No permanent complications occurred. Outcome categorized by integrated outcome quadrants (IOQs) defined by preoperative intended effect versus permanent complications at 6 months was IOQ-1 (goal achieved without complications) in 6 (67%) and IOQ-3 (goal not achieved, no complications) in 3 patients. Conclusion In complex acromegaly cases FET-PET/MRICR can provide additional information to aid decision-making by the multidisciplinary pituitary team, especially when (further) surgery is being considered.