Prostate magnetic resonance imaging and the value of experience: An intrareader variability study

Area of Science:

• Radiology
• Urology
• Oncology

Background:

• Multiparametric magnetic resonance imaging of the prostate (mpMRIp) is crucial for prostate cancer detection.
• Standardized reporting systems like PI-RADS v2 aim to improve consistency in mpMRIp interpretation.
• Understanding intraobserver variability is essential for validating diagnostic accuracy over time.

Purpose of the Study:

• To assess the intraobserver agreement of an experienced genitourinary radiologist in reporting prostate mpMRI scans.
• To evaluate changes in diagnostic performance metrics after a period of increased experience.

Main Methods:

• An experienced radiologist re-reported 100 mpMRIp scans using PI-RADS v2 after gaining significant additional experience (>1000 scans).
• Intraobserver agreement was quantified using Cohen's kappa.
• Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated and compared.

Main Results:

• Moderate intraobserver agreement (Cohen's kappa = 0.55) was observed for lesion identification.
• Re-reading showed a significant increase in specificity (43% to 89%) and PPV (62% to 87%).
• Sensitivity decreased from 94% to 72% (p=0.01), and NPV decreased from 89% to 77%.

Conclusions:

• Intraobserver agreement in mpMRIp reporting using PI-RADS v2 is moderate, even for experienced radiologists.
• Improved specificity and PPV with experience offset reduced sensitivity, reinforcing mpMRIp's role in prebiopsy assessment.
• mpMRIp is validated as a valuable tool for prebiopsy prostate cancer screening.