Preliminary Results of an Ongoing Prospective Clinical Trial on the Use of Ga-PSMA and Ga-DOTA-RM2 PET/MRI in Staging of High-Risk Prostate Cancer Patients.

The aim of the present study is to investigate the synergic role of Ga-PSMA PET/MRI and Ga-DOTA-RM2 PET/MRI in prostate cancer (PCa) staging. We present pilot data on twenty-two patients with biopsy-proven PCa that underwent Ga-PSMA PET/MRI for staging purposes, with 19/22 also undergoing Gaa-DOTA-RM2 PET/MRI. TNM classification based on image findings was performed and quantitative imaging parameters were collected for each scan. Furthermore, twelve patients underwent radical prostatectomy with the availability of histological data that were used as the gold standard to validate intraprostatic findings. A DICE score between regions of interest manually segmented on the primary tumour on Ga-PSMA PET, Ga-DOTA-RM2 PET and on T2 MRI was computed. All imaging modalities detected the primary PCa in 18/19 patients, with Ga-DOTA-RM2 PET not detecting any lesion in 1/19 patients. In the remaining patients, Ga-PSMA and MRI were concordant. Seven patients presented seminal vesicles involvement on MRI, with two of these being also detected by Ga-PSMA, and Ga-DOTA-RM2 PET being negative. Regarding extraprostatic disease, Ga-PSMA PET, Ga-DOTA-RM2 PET and MRI resulted positive in seven, four and five patients at lymph-nodal level, respectively, and at a bone level in three, zero and one patients, respectively. These preliminary results suggest the potential complementary role of Ga-PSMA PET, Ga-DOTA-RM2 PET and MRI in PCa characterization during the staging phase.