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Abstract Purpose To assess the utility of 18 Ffluoroethyl-L-tyrosine PET co-registered with magnetic resonance imaging ( 18 FFET-PET/MRI CR ) in patients with difficult-to-localize prolactinoma to inform clinical decision-making and (surgical) treatment planning. Methods Retrospective cohort study of 17 consecutive patients with prolactinoma undergoing 18 FFET-PET/MRI CR between October 2020 and September 2022 for either (1) additional information in case of difficult-to-visualize remnants after prior transsphenoidal surgery (TSS), or pharmacological treatment, or (2) radiological diagnosis in absence of a (clear) adenoma on diagnostic/post-treatment conventional MRI. Results 18 FFET-PET/MRI CR identified a lesion in 14/17 patients, yet failed to identify active lesions in 2 patients with negative conventional MRI despite prolactin > 7.5 times upper limit of normal. 18 FFET-PET/MRI CR results were inconclusive in 1 patient due to diffuse tracer uptake 10 weeks post-surgery. 18 FFET-PET/MRI CR was completely concordant with a suspected lesion on conventional MRI in 10/17 patients, and partially concordant in 3/17 patients. New foci were identified in 4/17 patients. The 18 FFET-PET/MRI CR conclusions influenced clinical shared decision-making in 15/17 patients, of whom 7 patients underwent TSS and 8 refrained from TSS. One patient underwent TSS despite negative 18 FFET-PET/MRI CR , and one patient underwent additional imaging. Intraoperative findings corresponded with 18 FFET-PET/MRI CR in 5/8 patients, and immunohistochemistry was positive in 5/8 patients. The treatment goal was achieved in 7/8 patients, and remission was achieved in 5/7 patients in whom total resection was considered feasible. Conclusion 18 FFET-PET/MRI CR can be of added value in the preoperative decision-making process for selected patients with difficult-to-localize prolactinoma (remnants), or patients lacking a substrate on conventional MRI.
Trigt et al. (Tue,) studied this question.