Quantitative comparison of MR diffusion‐weighted imaging for liver focal lesions between 3.0T and 1.5T: Regions of interest of the minimum‐spot ADC, the largest possible solid part, and the maximum diameter in lesions

PURPOSE: To quantitatively compare the apparent diffusion coefficient (ADC) values of 3.0T and 1.5T magnetic resonance (MR) diffusion-weighted imaging (DWI) protocols using regions of interest (ROIs) for the minimum ADC, largest solid part, and maximum diameter of lesions, for the detection of liver focal lesions. MATERIALS AND METHODS: In total, 26 patients with 28 liver focal lesions prospectively underwent both 1.5T and 3.0T DWI of the liver. The protocols included respiratory-triggered (RT), breath-holding (BH), and free-breathing (FB) acquisitions. The ADC values were measured at both field strengths using three methods: ROIs with the minimum ADC, the largest solid part, and the maximum diameter of lesions. Bland-Altman tests and paired t-tests were used to compare ADC values in the liver focal lesions obtained at 1.5T and 3.0T. RESULTS: The 3.0T and 1.5T protocols differed significantly with regard to the ADC values of the RT, BH, and FB acquisitions, for ROIs of both the largest solid part (P = 0.005, P = 0.014, and P = 0.022, respectively) and maximum diameter of lesions (P < 0.001, P = 0.001, and P = 0.001, respectively). CONCLUSION: When using DWI for quantitative analysis of liver focal lesions, field strength could exert a negative effect depending on the ROI. The ADC values from ROIs of both the largest solid part and maximum diameter of lesions may differ between 1.5T and 3.0T protocols.J. Magn. Reson. Imaging 2016;44:1320-1329.