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April 22, 2026

Short-term repeatability of monoexponential apparent diffusion coefficient in prostate cancer: dependence on b-value, tumor grade, lesion size, and lesion location

Key Points

The study aims to assess the repeatability of monoexponential apparent diffusion coefficient (ADCm) values in prostate cancer.
112 prostate cancer patients underwent two DWI scans with 12 b-values on the same day.
ADCm values were analyzed across various b-value combinations and lesion sizes.
Statistical methods included Bland-Altman plots, Spearman rank correlation, within-subject standard deviation, and coefficient of variation.
No observable trend differences in ADCm values were found across intensity ranges.
Correlation between ADCm repeatability and tumor aggressiveness was noted, with lower variability in higher Gleason grades.
The lowest repeatability was for lesions <5 mL, while lesions ≥5 mL showed better repeatability.

Abstract

BackgroundDiffusion-weighted magnetic resonance imaging (DWI) of prostate cancer (PCa) is commonly quantified using monoexponential apparent diffusion coefficient (ADCm) values. However, repeatability of ADCm as qualitative biomarker for PCa is not well established.PurposeTo evaluate repeatability of prostate ADCm.Material and MethodsA total of 112 patients with PCa who underwent two repeated prostate DWI scans (12 b-values, 0-2000 s/mm2) on the same day before prostatectomy. ADCm values were analyzed across different b-value combinations and PCa lesion sizes. Bland-Altman plots, Spearman rank correlation, within-subject standard deviation (wSD), and coefficient of variation (wCV) were calculated.ResultsBland-Altman plots demonstrated no observable trend differences across ADCm intensity ranges. The results indicate correlation of ADCm repeatability with PCa aggressiveness, expressed as Gleason Grade Group (GGG). Specifically, wCV decreased towards higher GGG compared with GGG=1, wCV was 2. Majority of evaluated lesions that had high wSD up to 0.2 × 10-3 mm2/s were found in lower GGGs. Different b-value combinations demonstrated varying effects on ADCm performance. The lowest repeatability was observed with the lesion size -3 mm2/s.ConclusionOur study demonstrated repeatability of ADCm mean values as quantitative imaging biomarkers for PCa detection and characterization.

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