前立腺MRIの品質評価：PI-QUALと画像品質に影響を与える要因

Since the introduction of Prostate Imaging Reporting and Data System (PI-RADS), prostate MRI has become an essential tool for detecting clinically significant prostate cancer, determining tumor stage, and guiding targeted biopsy. However, variability in image quality across institutions continues to affect diagnostic accuracy. To address this issue, the Prostate Imaging Quality (PI-QUAL) scoring system was developed as a standardized framework for evaluating the quality of prostate MRI. PI-QUAL v1 established the first quality control system for multiparametric MRI (mpMRI) but had limitations, including the inability to assess biparametric MRI (bpMRI) and a strong reliance on biopsy correlation. The updated PI-QUAL v2 simplified technical requirements, incorporated bpMRI assessment, and introduced a reproducible 3-point scale with adjustment rules that balance quality assurance with the diagnostic advantages of mpMRI. Factors influencing image quality include magnetic field strength and susceptibility- and motion-related artifacts. Complementary approaches, such as the Prostate Signal Intensity Homogeneity Score and artificial intelligence-based evaluation tools, have also been proposed. Overall, PI-QUAL v2 enhances reproducibility and broadens clinical applicability, providing a practical framework for ensuring high-quality prostate MRI. Future progress is expected through standardized data collection, structured training, and multidisciplinary collaboration.