Introduction

Positron emission tomography (PET) using prostate specific membrane antigen (PSMA) detects prostate cancer lesions with a higher sensitivity and specificity when compared to standard imaging. Hybrid PET Magnetic Resonance Imaging (MRI) has now been introduced to provide potentially improved characterization of lesions with added PET avidity. We evaluate the utilization of this novel imaging modality at the Princess Alexandra Hospital (PAH) and assess our initial outcomes.

Methods

A retrospective review of all PSMA PET MRI scans undertaken at the PAH since the introduction of the technology was performed. Imaging data was collected alongside baseline clinical data, PSA, previous histology, previous treatments, indication of scans, requesting clinicians and clinical outcomes.

Results

A total of 187 PSMA PET MRI scans were performed at the PAH from April 2015 to October 2016. The median age of imaged patients was 68, with a median PSA of 6ng/ml and Gleason score of 7 at the time of scan. 153 scans were positive for PSMA avid disease (81.8%). Scans were requested in the setting of biochemical recurrence (n=94), preoperative staging (n=77), evaluation of treatment response (n=11) and diagnostic purposes (n=5). Urologists requested PSMA PET MRI most frequently with 111 scans, of which 58.6% requested for preoperative staging. Radiation oncologists requested 69 scans with 75.4% of these in the biochemical recurrence setting. Only 7 scans were requested by medical oncologists. Amongst patients with biochemical recurrence the lowest PSA of a positive scan was 0.02 ng/ml. In this group 43 patients had prior surgery with 19 positive scans (44%). 51 patients were treated with ADT and or EBRT and 46 had positive scans (90.2%). 29 patients had tissue samples to validate PSMA PET MRI. 26 patients (89.7%) had adenocarcinoma on histology correlating with avid lesions on PSMA PET.

Conclusions

PSMA PET MRI has had rapid uptake in use since introduction at the PAH. Urologists and radiation oncologists appear to utilize this imaging modality most; Urologists for a preoperative “one stop shopâ€� staging study and radiation oncologists in biochemical recurrence. From this data is also appears that a positive PSMA PET/MRI is highly suggestive of prostate cancer, with a specificity of 89.7%. Hybrid PET/MRI may be used to stage men locally and systemically with one scan, with lower radiation and at PSA ≤1 ng/ml. This modality has the potential to significantly improve prostate cancer staging and allow early identification of recurrent disease.

Funding

None