DRD2 expression based on 18F-fallypride PET/MR predicts the dopamine agonist resistance of prolactinomas: A pilot study

Abstract

Abstract Purpose The dopamine agonists (DA) have been used widely to treat prolactinomas. However, it is difficult to predict whether the patient will be responsive to DA treatment. Methods We aimed to investigate whether the in vivo expression of DRD2 based on 18F-fallypride PET/MR could predict the therapeutic effect of DA on prolactinomas. Seven patients with prolactinomas who underwent surgery and further tumor immunohistochemistry completed 18F-fallypride PET/MR preoperatively. Imaging findings and immunohistochemical staining were compared with treatment outcomes. Results 18F-fallypride PET/MR was visually positive in 7 of 7 patients, and DRD2 target specificity could be confirmed by immunohistochemical staining. A significantly lower tracer standard uptake value (SUV) could be detected in the resistant patients (n = 3) than in the sensitive patients (n = 4; SUVmean, 4.67 ± 1.32 vs. 13.57 ± 2.42, p < 0.05). DRD2 expression determined by 18F-fallypride PET/MR corresponded with the DA treatment response. Conclusion 18F-fallypride PET/MR represents an effective diagnostic tool to predict DA response in patients with prolactinoma.