Using Sagittal Length to Differentiate Between PRI-MUS 4 and PRI-MUS 5 Lesions

Purpose: Micro-ultrasound (micro-US) has been shown to have equivalent prostate cancer detection to MRI. However, unlike Prostate Imaging Reporting and Data System (PI-RADS), the PRI-MUS system does not use tumor size to distinguish between 4 and 5 lesions. Reliance solely on acoustic features may lead to variability in interpretation among operators and suboptimal cancer detection rates. In this study, we aimed to evaluate whether sagittal length improves the cancer detection rates for PRI-MUS 4 and 5 lesions. Materials and Methods: We evaluated 275 PRI-MUS 5 and 5 lesions from men who underwent micro-ultrasound–guided biopsy at the University of California, Los Angeles (UCLA) medical center. Micro-US sagittal length was used as a differentiating factor between PRI-MUS 4 and 5 lesions by determining the Positive predictive value (PPV) at multiple thresholds. Chi-square analysis was used to compare the PPV of PRI-MUS version1 (V1) and PRI-MUS version2 (V2) for Grade Group ≥ 2 prostate cancer. Results: PPV of micro-US for PRI-MUS V1 4 and 5 lesions was 50.9% and 85.5%, respectively. Using a threshold of 2 cm, the PPV of micro-US for the PRI-MUS V2 4 and 5 scoring system was 60.3% and 88.4%. This corresponds to a slight increase of 2.9% in PPV for lesions with a score of 5 and a 9.4% increase for lesions assigned a PRI-MUS score of 4 ( P = .06). Conclusion: This study proposes sagittal length as an objective criterion for lesion classification, with a threshold of 2.0 cm for PRI-MUS 5 upgrading. This approach improves the PPV of PRI-MUS 4 lesions by approximately 10% while preserving the PPV of PRI-MUS 5 lesions.