The use of power images to perform quantitative analysis on low SNR MR images

Abstract

Zero-mean noise introduced into quadrature detected MRI signals is generally rectified by the reconstruction algorithm to give a nonzero background intensity in the displayed image. In low signal-to-noise ratio (SNR) images, this background will inflate region of interest (ROI) signal measurements, leading to improper T2 and diffusion fits. A method is described here which separates signal from noise by computing power images from traditional magnitude data. Parameters measured from such power images show closer agreement with true values that do those derived from magnitude images. Because the correction algorithm is the same for all pixel intensities, it can be used with regions of interest with heterogeneous values.