Fetal brain MR imaging.

In the past 10 years, improvements in MR imaging and faster imaging techniques have dramatically increased the use of in-utero fetal brain MR imaging. Challenging abnormalities now can be diagnosed prenatally through a careful analysis of morphology and signal changes. Using illustrations of normal brain development as a starting point, this article illustrates and discusses major brain malformations and specific morphologic changes, destructive lesions, and isolated ventriculomegalies, and the advantages and disadvantages of T1 and T2 sequences are provided.