To evaluate the detection rate of local and whole-body recurrence by integrated [18F]F-PSMA-1007 PET/MR assessment of prostate cancer patients treated with prostatectomy with very low biochemical recurrence (<0.5 ng/ml). Therapeutic implications

Abstract

Objective

To analyse the efficacy of integrated assessment of [¹⁸F]F-PSMA-1007 PET/MRI on the early detection of local recurrence (LR) for prostate cancer patients with PSA levels <0.5 ng/ml after radical prostatectomy.

To assess the location of recurrence so that therapy may be tailored to patient.

Methods

Prospective study including 35 patients with prostate cancer (PCa), who were referred for a [¹⁸F]F-PSMA-1007 PET/MR after prostatectomy with a very initial PSA value increase (PSA < 0,5 ng/ml).

Simultaneous acquisition in a PET/MRI hybrid equipment (SIGNA-GE), 1 h after administration of 370% ± 10% MBq of [¹⁸F]F-PSMA-1007:

Prostate selective imaging (20 min): multiparametric PET + MRI (MRImp): DIXON, T1, T2, diffusion sequences post-gadolinium administration.

Whole body image (30 min): PET + MRI: DIXON, T1, T2, diffusion, STIR sequences.

A nuclear physician and a radiologist jointly reviewed the studies:

In order to assess LR, the “Prostate Imaging for Recurrence Reporting” system was used on MRI, as well as the Likert scale on the PET prostate imaging.

The remaining lesions were classified as N1 and M1a.

Results

PET/MRI was positive in 25 patients (71,4%) and negative in 10 patients (28,6%).

RL was detected in 15 patients (42.9%): in 2 (5.7%) MRI was superior; in 3 (8.6%) PET was superior; integrated PET/MRI showed improved results in 5 patients (14.3%) for the detection of LR.

Location of recurrences: LR in 11 patients (44.0%); N1 in 10 (40.0%); LR + N1 (8.0%) in 2; LR + N1 + M1a in 2 (8.0%).

In 20 patients (80%) the PET/MRI findings allowed radioguided radiotherapy implementation (11 on LR, and 9 on N1), whereas hormonal treatment was decided in 5 patients (20%) due to multimetastases/spread disease.

Conclusion

[¹⁸F]F-PSMA-1007 PET/MRI has a 71.4% recurrence detection rate after prostatectomy with PSA < 0.5 ng/ml. Its combined PET and MRI study increases the detection of LR by 14.3%, with a high N1 + M1a detection rate (56%), allowing radioguided radiotherapy in 80% of patients.