Prostate Volume and PSA-Density Estimation by Transabdominal Ultrasound: Prospective Evidence of Comparative Accuracy to MRI and Transrectal Ultrasound in Prostate Cancer Early Diagnostics

Background: Prostate-specific antigen (PSA) density is an easily available predictor for clinically significant PCa. While transrectal ultrasound (TRUS) is utilized for PSA density (PSAD) estimation, transabdominal ultrasound (TAUS) is a more accessible, noninvasive alternative that can be used to decide if follow-up diagnostics are necessary. This study aims to compare prostate volume (PV) and PSAD across TAUS, TRUS and MRI, comparing the clinical utility of TAUS and TRUS for PSAD-based risk stratification. Methods: Hundred and eighty men undergoing PCa diagnostics were included by collecting serum PSA, TRUS, MRI, and TAUS PV examinations. PV was calculated blindly by all operators and image quality was assessed. Agreement in PV measurements of all imaging modalities was analyzed in Bland-Altman diagrams. PCa risk derived from PSADTAUS and PSADTRUS was compared against MRI outcomes in Sankey diagrams and the percentage of misclassified PCa risk was reported. Results: After excluding 33 inadequate TAUS acquisitions, 147 patients were included. The average volume difference between TAUS and MRI was 2.5 mL (standard deviation (SD): 16.4), between TAUS and TRUS 11.5 mL (SD: 20.4), and between TRUS and MRI −9.0 mL (SD: 21.1). TAUS and TRUS underestimate PCa risk in 3%–4%, while the percentage of men with overestimated risk decreased when TAUS was used (7% vs. 13%). Conclusions: PVs obtained with TAUS are equivalent to MRI. Still, image quality varies with experience and interobserver variability needs further exploration, ensuring generalizable outcomes. Nevertheless, TAUS represents a valid alternative for PV and PSAD estimation, enabling a patient-friendly alternative for PCa risk assessment.