MR may be better than ultrasound at predicting preterm birth
March 16, 2016
by
Lauren Dubinsky, Senior Reporter
Even though ultrasound is the standard for predicting preterm birth, MR of the cervix provides more accurate results, according to a new study conducted in the radiology department at Sapienza University in Rome. The results were published online in the journal Radiology.
Preterm birth is a significant perinatal health problem throughout the world, not only in terms of associated mortality, but also with regard to short- and long-term mobility and financial implications for health care systems, according to the World Health Organization.
When women are in their second trimester of pregnancy and ultrasound shows that their cervix measures 15 millimeters or less, they are considered to be at a higher risk of preterm birth. But ultrasound doesn't provide information on changes in cervical tissue in the antepartum phase just prior to childbirth.
The researchers used an MR technique called diffusion-weighted imaging (DWI) to examine 30 pregnant women who had been referred for suspected fetal or placental abnormalities. DWI has been used often for abdominal and pelvic disease, but has not been tested for the evaluation of the cervix in pregnant patients.
The technique works by showing differences in the mobility of water molecules in tissue. The results can be used to generate apparent diffusion coefficient (ADC) maps that give the measure of local cell density.
Each of the women evaluated for the study had a short cervix as shown on ultrasound and a positive fetal fibronectin test between 23 and 28 weeks of gestation. Fetal fibronectin is what helps to hold the fetal sac to the uterine lining and if it is present before week 35 of gestation that may mean a higher risk of preterm birth.
Eight out of 30 of the women delivered within a week of the MR exam and the remaining women delivered an average of 55 days later. The researchers found that high ADC values found with MR are correlated with imminent delivery of asymptomatic patients with a short cervix.
They concluded that MR is a "powerful imaging biomarker in evaluating patients with impending delivery." But they are planning on conducting larger, multi-center trials to confirm the role of sub glandular ADC analysis in predicting preterm birth.