Magnetic resonance diffusion tensor imaging for characterizing diffuse andfocal white matter abnormalities in multiple sclerosis

High-resolution diffusion tensor imaging (DTI) was performed in 14 patients with clinically definite multiple sclerosis (MS) and the trace of the diff usion tensor ([D]) and the fractional anisotropy (FA) were determined in no rmal appearing white matter (NAWM) and in different types of focal MS lesio ns. A small but significant increase of the [D] in NAWM compared to control white matter ((840 +/- 85) x 10(-6) mm(2)/sec vs. (812 +/- 59) x 10(-6) mm 2/sec; P < 0.01) was found. In addition, there was a significant decrease i n the FA of normal-appearing regions containing well-defined white matter t racts, such as the genu of the internal capsule. In non-acute lesions, the [D] of T-1-hypointense areas was significantly higher than that of T-1-isoi ntense lesions ((1198 +/- 248) x 10(-6) mm(2)/sec vs. (1006 +/- 142) x 10(- 6) mm(2)/sec; P < 0.001), and there was a corresponding inverse relation of FA. Diffusion characteristics of active lesions with different enhancement patterns were also significantly different. DTI with a phase navigated int erleaved echo planar imaging technique may be used to detect abnormalities of isotropic and anisotropic diffusion in the NAWM and selected fiber tract s of patients with MS throughout the entire brain, and it demonstrates subs tantial differences between various types of focal lesions. (C) 2000 Wiley- Liss, Inc.