MRI of fetal GI tract abnormalities.

We describe the magnetic resonance (MR) patterns of a variety of fetal gastrointestinal (GI) abnormalities. Thirty-two fetuses between 23 and 38 weeks' gestation with abnormal appearance of the GI tract by ultrasound underwent MR imaging with T1- and T2-weighted sequences. The MR aspect of intestinal atresia (duodenal atresia, one case; small bowel atresia, nine cases) included dilatation of the bowel loops, accurate assessment of the normal bowel distal to the atresia (except in the patient with multiple atresia and apple-peel syndrome), and micro-rectum with decreased T1 signal (except in the patient with duodenal atresia). Megacystis-microcolon-intestinal hypoperistalsis syndrome (one case) was indicated by an abnormal signal of the entire bowel and an abnormal pattern for the urinary tract. Meconium pseudocysts (two cases) were easily differentiated from enteric cysts (two cases). High anorectal malformations with (two cases) or without (one case) urinary fistula and cloacal malformation (one case) are described and MR findings are discussed. The capability of MR imaging to demonstrate the normal bowel with intraperitoneal anomalies (e.g., congenital diaphragmatic hernia, and sacrococcygeal teratoma) is emphasized. MR imaging is informative in the diagnosis of GI tract abnormalities, especially the severe malformations, with much more accuracy than sonography.