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The aim of the present study is to investigate the synergic role of 68Ga-PSMA PET/MRI and 68Ga-DOTA-RM2 PET/MRI in prostate cancer (PCa) staging. We present pilot data on twenty-two patients with biopsy-proven PCa that underwent 68Ga-PSMA PET/MRI for staging purposes, with 19/22 also undergoing 68Gaa-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 68Ga-PSMA PET, 68Ga-DOTA-RM2 PET and on T2 MRI was computed. All imaging modalities detected the primary PCa in 18/19 patients, with 68Ga-DOTA-RM2 PET not detecting any lesion in 1/19 patients. In the remaining patients, 68Ga-PSMA and MRI were concordant. Seven patients presented seminal vesicles involvement on MRI, with two of these being also detected by 68Ga-PSMA, and 68Ga-DOTA-RM2 PET being negative. Regarding extraprostatic disease, 68Ga-PSMA PET, 68Ga-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 68Ga-PSMA PET, 68Ga-DOTA-RM2 PET and MRI in PCa characterization during the staging phase.

Purpose: The aim of the present study is to investigate the synergic role of 68Ga-PSMA PET/MRI and 68Ga-DOTA-RM2 PET/MRI in PCa staging. Methods: Fifteen patients with biopsy-proven PCa underwent both 68Ga-PSMA PET/MRI and 68Ga-DOTA-RM2 PET/MRI within one month. TNM classification based on image findings was performed and semi-quantitative PET and quantitative MRI parameters were collected for each scan. Finally, DICE score between regions of interest manually segmented on the primary tumor on 68Ga-PSMA PET, 68Ga-DOTA-RM2 PET and on T2 MRI was computed. Results: All imaging modalities detected the primary PCa in 15 patients, with slight differences regarding the multifocality of intra-prostatic findings. Two patients presented seminal vesicles involvement on MRI, one of these was also detected by 68Ga-PSMA, with no uptake on 68Ga-DOTA-RM2 images. Regarding extra prostatic disease, 68Ga-PSMA PET, 68Ga-DOTA-RM2 PET and MRI resulted positive in 6, 2 and 4 patients at lymph-nodal level, respectively, and at bone level in 2, 0 and 1 patients, respectively, with 68Ga-PSMA PET detecting more lesions compared to 68Ga-DOTA-RM2 PET. The different findings detected by 68Ga-PSMA PET and 68Ga-DOTA-RM2 PET might reflect the complementary role of these radiotracers, as they detected different foci of intraprostatic disease, seminal vesicle invasion, lymph nodal and bone involvement. Conclusion: These preliminary results suggest a synergic role of 68Ga-PSMA PET, 68Ga-DOTA-RM2 PET and mpMRI in PCa characterization during the staging phase. (EudraCT: 2018-001034-18)