Burst excitation for quantitative diffusion imaging with multiple b-values

A quantitative imaging sequence has been developed to exploit the intrinsic sensitivity of Burst NMR data to molecular diffusion. In the scan time of a single spin echo experiment, it is possible to acquire many images of the same slice, with a different T-2 and diffusion weighting. Under favorable conditions, it is possible to obtain both the diffusion coefficient and T-2 from the same experiment; or, by correcting for T-2 relaxation using a con trol image, more precise diffusion coefficients may be measured. The quanti tative values in rat brain are in agreement with those from conventional ex periments. The major gains of this method are the potentially reduced scan time, the higher number of acquired images corresponding to different diffu sion weightings, the reduced sensitivity to inter-scan motion artifact and to local variations in magnetic susceptibility, and an automatic co-registr ation between T-2 and diffusion images. Problems with the sequence include a lower signal-to-noise ratio than is achievable with diffusion-weighted sp in-echo imaging, the limitation of measuring only in-plane components of di ffusion and, at present, single-slice acquisition. (C) 2000 Wiley-Liss, Inc .