MRI of Ventriculomegaly: Morphology and Outcome

1. Study Design: This is a descriptive study looking at the potential for MRI to aid in the diagnosis of fetal ventriculomegaly. It will also compare the specificity of MRI and ultrasound in diagnosing additional morphologic abnormalities.

450 pregnant women in the second and third trimester with ventriculomegaly will be asked to participate. Sonograms will be performed according the American Institute of Ultrasound in Medicine/American College of Radiology guidelines. In addition, views will be obtained of the fetal face, lips, outflow tracts, hands, and feet.

The gestational age of the fetus, interpretation of the sonogram, with sonographic abnormality and specific diagnosis will be prospectively recorded. Other data collected will be age and ethnicity of the patient, results of chromosomal analysis during the current pregnancy, and gestational age at the time of original diagnosis of abnormality during this pregnancy.

After screening for contraindications to MRI examination patients will undergo a 20 minute MRI examination. MRI examinations will be performed with a 1.5 T superconductive system (SIEMENS VISION, Erlangen, Germany or General Electric Twin, Milwaukee) using a 4-8 element body phased-array coil and/or body coil. The minimum rise time will be 600 microseconds (for a 25 milliTesla preset gradient amplitude). The whole body specific absorption rate will be kept under 1.5 watt/kilogram. Patients will be positioned supine with their feet entering the magnet bore first to minimize feelings of claustrophobia. A scout view will be obtained, and fetal images will be obtained with half Fourier single shot fast spin echo imaging imaging in the fetal sagittal, coronal, and axial planes (echo spacing of 4.2 msec, echo time=60 msec, echo train length=72, 1 acquisition, 3-5 mm section thickness, 26 x 35 cm field of view, 128 x 256 acquisition matrix). The refocusing flip angle will be minimized to decrease the amount of radiofrequency power deposition. Fetal anomalies seen with MRI will be recorded prospectively with knowledge of the sonographic findings.

Interpretation of the sonograms will be performed independently of the MR results. Interpretation of MRI examinations will be performed by reviewers with knowledge of the results of the ultrasound. The principal investigator will then combine the results from the two modalities. When the diagnosis differs between the modalities, the images will be reviewed by three radiologists and a consensus will be reached. The results of the sonogram and MRI will be communicated to the referring physician. Affect of any change in patient care will be assessed.