Lesion Stiffness Measured by Magnetic Resonance Elastography: A Novel Biomarker for Differentiating Benign, Premalignant and Malignant Prostate Lesions

<b>Background/Objectives</b>: This study aimed to assess whether magnetic resonance elastography (MRE)-derived stiffness measurements of the central gland, entire gland, and lesions of the prostate differ among benign, premalignant, and malignant lesions and to evaluate their diagnostic performance in distinguishing these groups. <b>Methods</b>: This prospective study enrolled 113 men (mean age, 62.7 ± 7.2 years). Patients were categorized into benign (<i>n</i> = 75), premalignant (<i>n</i> = 15; atypical small acinar proliferation and high-grade prostatic intraepithelial neoplasia), and malignant (<i>n</i> = 23; adenocarcinoma) lesion groups based on histopathological findings. MRE-derived stiffness was measured at the lesion, central gland, and entire gland levels. Other evaluated parameters included diffusion restriction, contrast retention, prostate-specific antigen (PSA) levels, prostate volume, and Prostate Imaging Reporting and Data System (PI-RADS) score. <b>Results</b>: Mean central gland stiffness did not differ between benign and premalignant lesions, but was markedly higher in the malignant group (Benign: 3.3 ± 0.2 vs. Premalignant: 3.4 ± 0.2 vs. Malignant: 3.6 ± 0.3 kPa; <i>p</i> < 0.001). A similar pattern was observed for entire gland stiffness (Benign: 3.3 ± 0.4 vs. Premalignant: 3.3 ± 0.4 vs. Malignant: 4.1 ± 0.6 kPa; <i>p</i> < 0.001). Median lesion stiffness increased stepwise from benign to premalignant to malignant lesions (Benign: 3.6 vs. Premalignant: 5.8 vs. Malignant: 7.7 kPa; <i>p</i> < 0.001). Central and entire gland stiffness distinguished malignant lesions but failed to differentiate premalignant lesions from benign lesions. Lesion stiffness demonstrated superior diagnostic accuracy in distinguishing premalignant from benign (AUC 0.82; accuracy 83.3%) and malignant lesions from premalignant lesions (AUC 0.86; accuracy 82.5%) compared to central and entire gland stiffness. <b>Conclusions</b>: MRE-derived lesion stiffness is a promising diagnostic biomarker, effectively distinguishing benign, premalignant, and malignant prostate lesions. Prostate gland stiffness measured by MRE, especially lesion-specific measurements, may be considered as an additional candidate procedure that can be accommodated in multiparametric magnetic resonance imaging.