Effect of b values and size of region of interest on apparent diffusion coefficient measurement and its reproducibility in liver diffusion-weighted MRI

• Published in: Chinese journal of academic radiology Vol. 4; no. 1; pp. 56 - 62
• Main Authors: Huang, Yucun, Xie, Liling, Cao, Zhi, Lu, Shaofan, Huang, Shengfu
• Format: Journal Article
• Language: English
• Published: Singapore Springer Singapore 01.03.2021
• Subjects: Imaging; Medicine; Medicine & Public Health; Original Article; Radiology; Liver diffusion-weighted imaging; Region of interest; Reproducibility; values; Apparent diffusion coefficient
• DOI: 10.1007/s42058-021-00053-7
• ISSN: 2520-8985

Objectives To investigate the effect of b value and size of region of interest (ROI) on apparent diffusion coefficient (ADC) measurement and its reproducibility in liver diffusion-weighted imaging (DWI). Methods Thirty-six volunteers underwent liver DWI twice with b values of 0, 100, 500, and 800 s/mm 2 . ADCs were measured with ROI of 50 mm 2 on ADC maps generated with different b values of (0, 100), (0, 500), (0, 800), (0, 100, 500), (0, 100, 800), (0, 500, 800), and (0, 100, 500, 800) s/mm 2 . ADCs from b values of (0, 800) s/mm 2 were measured with 4 ROI sizes (50, 100, 200 and 300 mm 2 ). ANOVA analysis was used to compare differences of ADCs among different ROI sizes and different combined b values. Bland–Altman method was used to assess reproducibility of ADC measurement. Results ADCs with larger ROI size were slightly higher than those with smaller one, while no statistical difference was found ( P  > 0.05). And reproducibility of ADC measurement with different ROI sizes was comparable (LOA 7.0–8.2% for right lobe, 14.15–17.4% for left lobe). ADCs statistically decreased with increased maximum b values ( P  < 0.05). ADC measurement achieved the best reproducible with maximum b value of 800 s/mm 2 regardless of the number of b values. Conclusions The b values influence ADC measurement and its reproducibility, while the ROI sizes do not affect them. Two b values of (0, 800) s/mm 2 and ROI of 50 mm 2 are recommended for liver ADC measurement.