Diffusion-weighted imaging of the fetal brain in vivo.

A method of performing diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) of the fetal brain in utero is proposed. The major difficulty of performing diffusion imaging in utero is the presence of motion. By modifying conventional single-shot spin-echo echo-planar DWI with a short repetition time sequence, a sequence that performs DWI and DTI within a breath-hold of the mother (13 sec and 18 sec, respectively) was devised. T(1) weighting caused by the use of short repetition times is compensated by interspersing diffusion imaging with additional b=0 image acquisitions. In utero fetal brain DWI and DTI were performed using this sequence. Quantitative analysis revealed minimal differences in the obtained apparent diffusion coefficient (ADC; directionally averaged ADC) values when using this sequence. The method can be readily implemented in a clinical setting and is especially useful when scanning mothers who cannot tolerate lengthier breath-holds.