Magnetic resonance imaging and the detection of fetal brain anomalies, injury, and physiologic adaptations.

PURPOSE OF REVIEW: Magnetic resonance imaging is playing an increasingly prominent role in depicting brain maturation, especially gyral formation that follows a temporospatial pattern, and in detecting developmental abnormalities of the cortex and other brain sectors. Knowledge of the technical advantages and limitations of in-utero magnetic resonance imaging techniques, relative to those of the postnatal period, is essential to optimize magnetic resonance sequences for early diagnosis. This includes an understanding of the changes in both brain anatomy and magnetic resonance signals that occur with an increase in gestational age.

RECENT FINDINGS: Magnetic resonance imaging has evolved has an important adjunct in the diagnosis of brain malformations, particularly in the late-second or third trimester. Noxious conditions elicit more of a chronic rather than acute response in the fetal brain, which differs from that observed postnatally. Clinical applications of proton magnetic resonance spectroscopy may help elucidate fetal brain maturation and its abnormalities from a metabolic point of view.

SUMMARY: Indications for fetal brain magnetic resonance imaging have increased because of improvements in magnetic resonance techniques and the ability to detect subtle changes within the cerebral parenchyma, especially in fetuses at increased risk of brain damage.