Effect of gradient linearity and static magnetic field homogeneity on diffusion weighted image: A phantom study

In this study, we assessed image quality and geometric accuracy as a function of the gradient physical linearity used for diffusion-weighted imaging (DWI) on both conventional-bore and wide-bore scanners. The signal to noise ratio (SNR) was calculated using b = 1000 DWI images for all acquisitions. To evaluate geometric accuracy, the diameter of a phantom on an image slice was measured in four directions. In comparison with the enhanced gradient mode, the default and maximum gradient modes showed higher SNRs with both bore sizes. There were significant differences in SNR among the various gradient modes of the two bore sizes. The geometric accuracy evaluations showed no statistically significant differences in the measured lengths among the various gradient modes and both bore sizes. The wide bore using default and maximum gradient mode showed higher SNR than the conventional bore, and comparable geometric accuracy.