Ultrafast MRI of the fetus.

During the last decade there has been increasing interest in MRI for the evaluation of ultrasound-detected fetal abnormalities. Motion artefacts previously precluded detailed imaging, but this is now possible using single-shot rapid acquisition sequences. These ultrafast techniques with subsecond images capture 'snap-shot' views of the fetus. By virtue of the infinitely long relaxation time (TR) these images are heavily T2-weighted so that fluid around and within the fetus delineates the anatomy. Currently, fetal MRI has shown to be most beneficial in the investigation of cerebral abnormalities suspected from sonography, and in the detection of subtle associated anomalies. It clearly has a role in the evaluation of complex somatic abnormalities, and is helpful in the evaluation of fetuses prior to surgery. We present a pictorial review of our experience with single-shot fast spin-echo (SSFSE) imaging, demonstrating normal anatomy of the fetal brain and body. In addition we present cerebral and somatic abnormalities to illustrate cases where we have found fetal MRI to be a useful adjunct to sonography.