Role of MRI in fetal abdominal cystic masses detected on prenatal sonography

Our aim was to determine the role of fetal MRI in sonographically detected abdominal cystic masses. Fifty-six fetuses in 56 women with fetal malformation underwent sonography and MRI. Out of the 56 fetuses, 6 had intra-abdominal cystic masses and formed our study group. MRI findings were compared with ultrasonographic findings regarding detection, anatomical localization and tissue characterization. MR findings were considered to have affected management if subsequent treatment was influenced by the MR findings and diagnosis. Final individual diagnoses were: meconium pseudocyst (n = 2), mesenteric cyst, hydrometrocolpos, chylous ascitis, and gross hydronephrosis with pelvic-ureteric junction obstruction (n = 1 each). MRI was superior to sonography and had supplemental value because of better anatomical localization in five cases. MRI better characterized the nature of cystic masses in two fetuses (Chylous ascitis, and hydrometrocolpos). In two patients with meconium pseudocyst, tissue characterization was inferior with MRI. Overall, addition of MRI changed the diagnosis and management in four cases. Our preliminary results suggest that because of its excellent anatomical localization and contrast resolution, MRI has a supplemental value to antenatal sonography in delineation and characterization of abdominal cystic masses.