Fusion-Assisted PI-RADS v2.1 Assessment on Prostate mpMRI: A Multi-reader Observer Performance Study

Although PI-RADS v2.1 offers a standardized assessment framework, substantial inter-reader variability persists in the evaluation of score-related imaging features. In particular, differentiating benign hyperplastic nodules from malignant lesions within the transition zone poses a major clinical challenge. The aim of the study was to determine the impact of using an mpMRI fusion imaging technique to improve the diagnostic performance of PI-RADS v2.1 for prostate cancer (PCa).

This multicenter retrospective study included 327 patients. The study utilized a sparse representation-based algorithm to generate fusion images, combining pseudo-color ADC maps reflecting tumor cellular density with the anatomical details of T2WI. An expert fellowship-trained urogenital radiologist interpreted all 327 scans based on PI-RADS v2.1. Two radiologists evaluated the cases under both conventional reading and fusion-assisted reading modes to compare reading times and diagnostic performance.

Fusion imaging facilitates enhanced visualization of tumor lesions. Apart from facilitating better tumor visualization, the fusion approach greatly streamlined the reading process and cut down interpretation time. The technique substantially reduced reading times (in Center 1, the average time decreased from 114.94 s to 94.84 s). Regarding diagnostic performance, the accuracy of the senior radiologist in Center 1 increased from 81.59% to 93.86%, and the agreement (Kappa value) improved from 0.632 to 0.877. Furthermore, the fusion technique effectively narrowed the experience gap between readers. As a cognitive aid, T2WI-ADC fusion imaging significantly improves the detection of transition zone lesions and diagnostic performance.

The application of mpMRI fusion imaging as a supplementary diagnostic modality is conducive to narrowing inter-reader discrepancies and improving agreement across readers at different experience levels.