Diagnostic performance of microUltrasound at MRI-guided confirmatory biopsy in patients under active surveillance for low-risk prostate cancer.

BACKGROUND

Active surveillance (AS) represents a standard of care of low-risk prostate cancer (PCa). However, the identification and monitoring of AS candidates remains challenging. Microultrasound (microUS) is a novel high-resolution imaging modality for transrectal ultrasonography (TRUS). We explored the impact of microUS TRUS and targeted biopsies in mpMRI-guided confirmatory biopsies.

METHODS

Between October 2017 and September 2021, we prospectively enrolled 100 patients scheduled for MRI-guided confirmatory biopsy at 1 year from diagnosis of ISUP 1 PCa. TRUS was performed using the ExactVu microUS system; PRI-MUS protocol was applied to identify suspicious lesions (i.e., PRIMUS score ≥ 3). All patients received targeted biopsies of any identified microUS and mpMRI lesions and complementary systematic biopsies. The proportion of patients upgraded to clinically significant PCa (defined as ISUP ≥ 2 cancer; csPCa) at confirmatory biopsies was determined, and the diagnostic performance of microUS and mpMRI were compared.

RESULTS

Ninety-two patients had a suspicious MRI lesion classified PI-RADS 3, 4, and 5 in respectively 28, 16, and 18 patients. MicroUS identified 82 patients with suspicious lesions, classified as PRI-MUS 3, 4, and 5 in respectively 20, 50, and 12 patients, while 18 individuals had no lesions. Thirty-four patients were upgraded to ISUP ≥ 2 cancer and excluded from AS. MicroUS and mpMRI showed a sensitivity of 94.1% and 100%, and an NPV of 88.9% and 100%, respectively, in detecting ISUP ≥ 2 patients. A microUS-mandated protocol would have avoided confirmatory biopsies in 18 patients with no PRI-MUS ≥ 3 lesions at the cost of missing four upgraded patients.

CONCLUSIONS

MicroUS and mpMRI represent valuable imaging modalities showing high sensitivity and NPV in detecting csPCa, thus allowing their use for event-triggered confirmatory biopsies in AS patients. MicroUS offers an alternative imaging modality to mpMRI for the identification and real-time targeting of suspicious lesions in AS patients.