Signal-to-noise ratio index

The authors propose a measure of MR imaging system performance termed the signal-to-noise ratio index (SNRI). The SNRI is a signal-to-noise ratio measurement determined from two images that have been corrected for phantom nonuniformity and normalized to voxel volume. It is an image-based measurement, and it provides a performance index that was demonstrated to be independent of voxel size, position within the phantom, and nutation angle inconsistencies above 900. The SNRI allows automated imager performance analysis while separating signal-to-noise ratios from uniformity issues. The SNRI may be quite useful for quality control as well as being a system performance parameter