Reproducibility of apparent diffusion coefficient measurement in normal prostate peripheral zone at 1.5T MRI - 28/06/22
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Highlights |
• | Despite high inter individual variability, there is no significant mean bias (10 × 10−6 mm²/s, P = 0.58) between the ADC values measured in the prostate peripheral zone on two different MRI scanners. |
• | In the prostate peripheral zone, the lowest detectable ADC difference varies from 85 × 10−6 to 311 × 10−6 mm²/s across MRI scanners, b-value combinations and periods of the day. |
• | In the prostate peripheral zone, the lowest b-value has a major influence on ADC calculation, at least up to 300 s/mm². |
Abstract |
Purpose |
The purpose of this study was to quantify the influence of factors of variability on apparent diffusion coefficient (ADC) estimation in the normal prostate peripheral zone (PZ).
Materials and methods |
Fifty healthy volunteers underwent in 2017 (n = 17) or 2020 (n = 33) two-point (0, 800 s/mm²) prostate diffusion-weighted imaging in the morning on 1.5 T scanners A and B from different manufacturers. Additional five-point (50, 150, 300, 500, 800 s/mm²) acquisitions were performed on scanner B in the morning and evening. ADC was measured in PZ at midgland using ADC maps reconstructed with various b-value combinations. ADC distributions from 2017 and 2020 were compared using Wilcoxon rank sum test. ADC obtained in the same volunteers were compared using Bland Altman methodology. The 95% confidence interval upper limit of the repeatability/reproducibility coefficient defined the lowest detectable ADC difference.
Results |
Forty-nine participants with a mean age of 24.6 ± 3.8 [SD] years (range: 21–37 years) were finally included. ADC distributions from 2017 and 2020 were not significantly different and were combined. Despite high individual variability, there was no significant bias (10 × 10−6 mm²/s, P = 0.58) between ADC measurements made on both scanners. On scanner B, differences in lowest b-values chosen within the 0–500 s/mm² range for two-point ADC computation induced significant biases (56-109 × 10−6 mm²/s, P < 0.0001). ADC was significantly lower in the morning (bias: 33 × 10−6 mm²/s, P = 0.006). The number of b-values had little influence on ADC values. The lowest detectable ADC difference varied from 85 × 10−6 to 311 × 10−6 mm²/s across scanners, b-value combinations and periods of the day.
Conclusions |
The MRI scanner, the lowest b-value used and the period of the day induce substantial variability in ADC computation.
Le texte complet de cet article est disponible en PDF.Keywords : Prostate, Diffusion magnetic resonance imaging, Healthy volunteers, Reproducibility of results
Abbreviations : ADC, CI, CoV, DWI, IQR, MRI, PI-RADS, PZ, RC, ROI, SD, TE, TZ
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