In vivo intravoxel incoherent motion measurements in the human placenta using echo-planar imaging at 0.5 T

This paper presents the first in vivo measurements of intravoxel incoherent motion in the human placenta, obtained using the pulsed gradient spin echo (PGSE) sequence. The aims of this study were two-fold. The first was to pr ovide an initial estimate of the values of the IVIM parameters in this orga n, which are currently unknown, The second aim was then to use these result s to optimize the sequence timings for future studies. The moving blood fra ction (f), diffusion coefficient (D), and pseudo-diffusion coefficient (D*) were measured. The average value of f was 26 +/- 6 % (mean +/- SD), D was 1.7 +/- 0.5 x 10(-3) mm(2)/sec, and D* was 57 +/- 41 x 10(-3) mm(2)/sec. Fo r the optimized values of b, the expected percentage uncertainty in the fit ted values of f, D, and D* for the placenta were sigma f/f = 14.9%, sigma D /D = 14.3%, sigma D*/D* = 44.9%, for an image signal-to-noise of 20:1, and a total imaging time of 800 sec. (C) 2000 Wiley-Liss, Inc.