ORLANDO — MRI for evaluating fetal and intracranial lesions shows promise, but challenges remain, Asad U. Sheikh, M.D., said at the annual meeting of the American Institute of Ultrasound in Medicine.
“MRI has become more useful for evaluating fetal and intracranial lesions. We're starting to see application as the technology advances for abdominal lesions as well. But still, we have considerable difficulty with interpretation,” explained Dr. Sheikh, director of the division of maternal-fetal medicine at the University of South Alabama.
Dr. Sheikh reported on two specific cases of schizencephaly, a brain lesion characterized by abnormal choronal migration.
The first case was of a 20-year-old woman at 19 weeks' gestation who presented with maternal serum alpha fetoprotein (AFP) elevated by 4.4 multiples of the median (MOM). Initial ultrasound evaluation indicated a left-sided intracranial cyst, Dr. Sheikh said. Investigators found that tests for karyotype and infection proved negative.
When they performed another sonogram, they found a large cystic structure replacing the left frontal temporal region. After the 35th week of gestation, they performed MRI, which showed bilateral schizencephaly. The patient delivered vaginally at term.
The second case was a 27-year-old woman at 21 weeks' gestation with an elevated AFP of 3.6 MOM; she was in her fourth pregnancy. Ultrasound revealed bilateral ventriculomegaly.
Amniocentesis was declined, and infection studies were negative. The physicians performed fetal MRI at 24 weeks' gestation and found left-sided schizencephaly and agenesis of the corpus callosum. The image quality was poor, due to fetal movement, however. The patient delivered vaginally at term.
Dr. Sheikh and his team performed MRIs to confirm their earlier diagnoses.
In the first case, they confirmed the findings of bilateral schizencephaly.
For the second patient, they performed cranial computed tomography, which illustrated bilateral schizencephaly with left more involved than right. Additionally, they observed agenesis of the corpus callosum.
Dr. Sheikh notes that these cases are unique in terms of the elevation in maternal serum AFP, which led to further evaluation. However, he points out that ventricular anomalies detected by ultrasound studies were more “precisely defined by prenatal MRI.”
He believes MRI should be considered to further delineate intracranial anomalies to better prepare families and care providers for postnatal expectations; however, there are limitations, he noted.
“One of the current limitations is that MRI is much more costly than ultrasound is, and there is limited availability. In addition, we don't know what the false-positive and false-negative diagnoses will be with fetal application of MRI. Nevertheless, it seems to be a promising new tool,” he concluded.