Screening of fetal CNS anomalies by MR imaging

MR with ultrafast imaging techniques is, nowadays, a standard clinical service in most medical centers for prenatal counseling when sonographic examination is not conclusive or a complicated pregnancy is encountered. Compared with other imaging modalities, MR has multi-faceted superiorities in that it uses non-ionization radiation, it has freedom in selecting an imaging plane, it produces standardized and easily reproducible imaging views, it provides excellent tissue contrast and overview of the fetus, there is no scanning dead space, and no limit to penetration depth. Central nervous system anomalies are the most common indications for fetal MR imaging.

Among the various ultrafast imaging techniques, T2-weighted imaging, e.g., spin echo-based half-Fourier acquisition single-shot turbo spin-echo and gradient echo-based steady-state free precession, and T1-weighted imaging, e.g., fast low angle shot and fast spoiled gradient recalled sequences, are commonly used.

In the future, morphometry in three dimensions, real-time imaging, and the functional and metabolic evaluation of the fetal brain will be the important ongoing challenges.