Presentation Authors: Laurence Klotz*, Dixon Woon, Toronto, Canada
Introduction: High resolution micro-ultrasound (micro-US) is a novel technology which offers the potential to image PCa and perform targeted biopsies with significantly improved cancer visualization compared to conventional ultrasound, potentially obviating the need for MRI. Micro-US incorporates a scoring system (PRIMUS, Grades 1-5) that is similar to the PIRADS-2 system used for MRI. This facilitates assignment of a risk category based on the characteristics of the region of interest. We evaluate the NPV and PPV for each PRIMUS risk category.
Methods: 50 patients underwent prostate biopsy using micro-US (ExactVu micro-US, Exact Imaging, Markham, Canada). 32 were undiagnosed men at risk for PCa, and 18 had been previously treated with focal therapy with HIFU or TULSA and were undergoing post treatment biopsies. In the undiagnosed patients, targeted and 12 core systematic biopsies were performed. 28 had had a prior MRI. Physicians were blinded to the MRI results at the time of biopsy.
Results: The NPV for PRIMUS scores = 2 with a positive micro-US and negative MRI. All patients with a PIRADS score 4-5 had a PRIMUS 4-5 lesion on micro-US at the same location. The PPV for each PRIMUS score for all PCa grades was 1: 0%, 2: 33%, 3: 29%, 4: 63%, 5: 67%, and for GG >= 2, 1: 0%, 2: 0%, 3: 4%, 4:38%, 5: 67%.
Conclusions: High resolution micro-ultrasound with targeted biopsy appears to offer comparable sensitivity, specificity, PPV and NPV to MP-MRI, in the setting of both primary diagnosis and post-treatment recurrence. Micro-ultrasound-based biopsies combine imaging and targeting in a single session and involves substantially less cost and complexity than MRI combined with fusion targeting.
Source of Funding: None. The Exact Vue system was provided by Exact Imaging, Markham Ontario