Search

Objectives: PSMA-PET has become the PET technique of choice to localise the site of biochemically recurrent prostate cancer (PCa). With hybrid PET/MRI, the advantages of MRI are added to molecular characteristic of PET. The aim of this study was to investigate the incremental value of PET/MR versus PET/CT in patients with biochemically recurrent PCa by head-to-head comparison., Methods: Thirty-four patients with biochemically recurrent PCa were prospectively included. They underwent [ 68 Ga]Ga-PSMA-11 PET/CT, followed by simultaneous PET/MR. All PET (PET CT , PET MR ), CT and MR images were evaluated for number of lesions and location. The number of lesions at specific sites was compared using Wilcoxon-sign-rank test. For PET, the maximum and mean standardised uptake values (SUVs) were calculated for each lesion compared using a two-sided paired t test., Results: PET CT and PET MR scans were positive in 19 and 20 patients, detecting 73 and 79 lesions respectively. All lesions detected on PET CT were also detected on PET MR . CT and MRI only were positive in 14 and 17 patients, detecting 38 and 50 lesions, respectively, which was significantly lower than PET CT and PET MR respectively. Combined interpretation showed more lesions on PET/MR than on PET/CT (88 vs 81). No significant difference in detection of presence of local recurrence nor distant metastases was found. SUV mean and SUV max values were significantly higher on PET MR than on PET CT in local recurrence and lymph node metastases., Conclusions: [ 68 Ga]Ga-PSMA-11 PET/MR was able to detect biochemically recurrent PCa at least as accurately as PET/CT for local recurrence, lymph node metastasis and distant metastasis., Key Points: • PSMA PET/MRI detects the location of biochemical recurrence at least as accurately as PET/CT. • Substitution of PET/CT by PET/MRI adds sensitivity in PSMA lesion detection also in the setting of distant recurrence due to both the MR and TOF PET components., (© 2021. European Society of Radiology.)

Background: Salvage radiotherapy (RT) (± androgen deprivation therapy (ADT)) is often used as a treatment in patients with biochemical recurrence (BCR) following radical prostatectomy (RP). Unfortunately, even after RT ± ADT, a significant number of patients will develop 'second' BCR. The aim of this study was to investigate the impact of postoperative treatments (adjuvant/salvage radiotherapy (RT) ± androgen deprivation therapy) on the recurrence pattern in patients with BCR following RP assessed by 11C-Choline PET/CT or 68 Ga-PSMA PET/CT., Methods: Patients who developed BCR following RP and who had at least one positive lesion on PET/CT were retrospectively assessed. Positive spots were mapped as local, lymph node (LN), skeletal or visceral recurrence. A distinction was made between locoregional (prostate bed and pelvic LN) and extrapelvic recurrence (skeletal, visceral and/or extrapelvic LN). Patients were categorized according to postoperative treatment received in three subgroups (RT, ADT and RT + ADT) and compared with the reference group (RP only). The impact of the radiation field was also investigated., Results: We identified 200 patients assessed by 68 Ga-PSMA-11 (80%) or 11 C-Choline PET/CT (20%). Patients who received postoperative RT + ADT had less LN recurrence distal to the common iliac bifurcation (26.7% vs 66.6%; p = 0.0004), but more recurrence to retroperitoneal LN than the reference group (38% vs. 14.4%, p = 0.02). Moreover, the RT + ADT subgroup had more extrapelvic recurrence compared to the reference group (66.2% vs 40.8%, p = 0.02). Patients who received RT to the prostate bed had more recurrence distal to the common iliac bifurcation compared to those who received RT to the prostate bed + pelvic LN (51.6% vs 26.1%, p = 0.0069)., Conclusion: Post-prostatectomy treatments (ADT and/or RT) and the postoperative radiation field (prostate bed vs. prostate bed + pelvis) have a significant impact on the recurrence pattern. This knowledge can help clinicians to counsel their patients on their chances of being eligible for (locoregional) metastasis-directed therapies.