Numerical tissue characterization in MS via standardization of the MR image intensity scale

Image intensity standardization is a recently developed postprocessing meth od that is capable of correcting the signal intensity variations in MR imag es. We evaluated signal intensity of healthy and diseased tissues in 10 mul tiple sclerosis (MS) patients based on standardized dual fast spin-echo MR images using a numerical postprocessing technique. The main idea of this te chnique is to deform the volume image histogram of each study to match a st andard histogram and to utilize the resulting transformation to map the ima ge intensities into standard scale. Upon standardization, the coefficients of variation of signal intensities for each segmented tissue (gray matter, white matter, lesion plaques, and diffuse abnormal white matter) in all pat ients were significantly smaller (2.3-9.2 times) than in the original image s, and the same tissues from different patients looked alike, with similar intensity characteristics. Numerical tissue characterizability of different tissues in MS achieved by standardization offers a fixed tissue-specific m eaning for the numerical values and can significantly facilitate image segm entation and analysis. (C) 2000 Wiley-Liss, Inc.