Fetal magnetic resonance imaging and three-dimensional ultrasound in clinical practice: general aspects.

Ultrasonography is used routinely during pregnancy to screen and diagnose fetal anomalies. Two-dimensional ultrasound is usually adequate in women at low risk for malformations. When technical factors limit optimal evaluation or a malformation is suspected, further imaging with three-dimensional ultrasound and magnetic resonance imaging is becoming increasingly common. Three-dimensional ultrasound allows the manipulation of data acquired from two-dimensional ultrasound to recreate an infinite number of views, thereby enhancing the ability to evaluate the fetal anatomy. When three-dimensional ultrasound is either unavailable or inadequate, fetal magnetic resonance imaging permits detailed evaluation of the suspected anomaly and assesses the presence of associated anomalies. In this chapter, we review the techniques, advantages, limitations, and clinical applications of these two fetal imaging modalities.