Preliminary analysis of dynamic [68Ga]PSMA^HBED-CC PET/MRI in primary prostate cancer

Objectives We aimed to analyse the dynamic uptake of [⁶⁸Ga]PSMA^HBED-CC of primary prostate cancer (PC) and to identify Gleason score specific patterns.

Methods 14 patients with biopsy proven PC were examined prior to prostatectomy. After injection of 2 MBq/kg [⁶⁸Ga]PSMA^HBED-CC list mode scanning for 45 minutes with a Siemens mMR was started. Simultaneously T2w, DWI, DCE and 3D SPACE sequences using an endorectal coil were acquired. The PC was identified using all MRI sequences and focal [⁶⁸Ga]PSMA^HBED-CC uptake and validated on histological whole mount sections including Gleason grading and score (GS). VOI time-activity-curves (TAC) were generated with 2 minute frames.

Results Two patients had GS 6, 7 GS 3+4, 3 GS 4+3, and 2 GS 8. All PC were diagnosed on [68Ga]PSMA^HBED-CC PET. All PC with GS 6 and 6 of 7 GS 3+4 showed an initial steep increase of [68Ga]PSMA with a peak within 5 minutes followed by a successive decline until minute 45 p.i.. One PC with GS 3+4 showed an increasing TAC until minute 6 and then reaching a plateau. All PC with GS 4+3 as well as GS 8 had an increasing TAC over time.

Conclusions We identified two different TAC: an early peak followed from a decreasing uptake in low GS, and an increasing TAC in higher GS. This is very preliminary but promising data and is verified in a larger patient population at the moment.

Research Support None.