Discrepancies in volume: impact of Artemis segmented magnetic resonance imaging, ultrasound, and ExactVu measurements on prostate specific antigen density and National Comprehensive Cancer Network risk stratification

Abstract

Introduction: The combination of magnetic resonance imaging (MRI) and ultrasound (US) allows for better lesion targeting and diagnostic probability compared to random prostate biopsies. The Artemis Fusion Biopsy system and ExactVu micro-US technology capitalize on this advantage and provide higher-resolution imaging of the prostate during biopsy. Their accuracy in measuring prostate volume and resulting implications on prostate specific antigen (PSA) density and risk stratification, however, has not been evaluated. We hypothesized that PSA densities as measured by these modalities will demonstrate clinically insignificant differences compared to standard measurement.

Material and methods: We retrospectively reviewed all prostate fusion biopsy cases performed at our health system with Artemis or ExactVu systems from April 2021 to July 2023 and compared the PSA density calculated from the volume obtained with these systems to standard measurement with ellipsoid calculation from MRI. Change in National Comprehensive Cancer Network (NCCN) prostate cancer risk stratification was analyzed for each system.

Results: Artemis MRI segmentation (0.179 ng/ml, p = 0.04) and US (0.181 ng/ml, p = 0.067) underestimated and ExactVu micro-US (0.247 ng/ml, p <0.001) overestimated PSA density. Risk stratification changed in 1.2% of Artemis MRI segmentation cases, 1.6% of Artemis US cases, and 1.2% of ExactVu micro-US cases.

Conclusions: Despite differences in PSA density, choice of fusion biopsy system has minimal clinical impact on risk stratification and any of these studied systems may be used without fear of misrepresenting a patient's disease state.

Keywords: PSA density; prostate MRI; prostate biopsy; prostate cancer; prostate cancer risk stratification; prostate ultrasound.