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Purpose: To evaluate the effects of exposure to routine magnetic resonance (MR) imaging at 1.5 T during pregnancy on fetal growth and neonatal hearing function in relation to the dose and timing of in utero exposure in a group of newborns at low risk for congenital hearing impairment or deafness. Materials and Methods: This retrospective case-control study was approved by the local ethics committee, and written informed consent was waived. Between January 2008 and December 2012, a group of 751 neonates exposed to MR imaging in utero and a group of control subjects comprising 10 042 nonexposed neonates, both groups with no risk factors for hearing impairment at birth, were included. Neonatal hearing screening was performed by means of otoacoustic emission testing and auditory brain stem response according to national guidelines, and the prevalence of hearing impairment in the two groups was compared by using a noninferiority test with Wilson score confidence intervals. The effect of MR exposure on birth weight percentile was examined between the singleton neonates in the exposed group and a randomly chosen subset of 1805 singleton newborns of the nonexposed group by performing an analysis of variance. Results: The rate of hearing impairment or deafness was found to be 0% (0 of 751) in the neonates in the exposed group and was not inferior to that in the nonexposed group (34 of 10 042 [0.34%], P < .05). There was no between-group difference in birth weight percentiles (50.6% for exposed vs 48.4% for nonexposed; P =.22). Conclusion: This study showed no adverse effects of exposure to 1.5-T MR imaging in utero on neonatal hearing function or birth weight percentiles., SCOPUS: ar.j, info:eu-repo/semantics/published

Purpose: To prospectively define fetal density in the second half of pregnancy by using magnetic resonance (MR) imaging and to compare estimates of fetal weight based on ultrasonography (US) and MR imaging with actual birth weight. Materials and Methods: Written informed consent was obtained for this ethics committee - approved study. In this cross-sectional study between March 2011 and May 2012, fetal density was calculated as actual birth weight at delivery divided by fetal body volume at MR imaging in 188 fetuses between 20 weeks and 2 days and 42 weeks and 1 day of gestational age. Regression analysis was used to investigate the effect of variables, including sex, on fetal density. The US estimate of fetal weight was performed according to Hadlock et al, and the MR estimate of fetal weight was calculated based on the equation developed by Baker et al. US and MR estimates of fetal weight were compared with actual birth weights by using regression analysis. Results: Median fetal density was equal to 1.04 (range, 0.95-1.18). Fetal density was significantly associated with gestational age at delivery but not with fetal sex. In 26.6% of fetuses, the US estimate of fetal weight had a relative error of more than 10%, while a similar relative error for the MR estimate of fetal weight occurred in only 1.1% of fetuses. The limits of agreement were narrower with the MR estimate of fetal weight compared with the US estimate of fetal weight. Conclusion: In the second half of pregnancy, fetal density varies with gestational age. Fetal weight estimates by using fetal MR imaging are better than those by using prenatal US. © RSNA, 2013., SCOPUS: ar.j, info:eu-repo/semantics/published

Objective: To help elucidate the mechanism of action of the Arabin cervical pessary in pregnancies at high risk for preterm delivery. Methods: Cervical length and uterocervical angle were evaluated in relation to gestational age in 198 pregnancies not at high risk for preterm birth that underwent clinical fetal magnetic resonance imaging (MRI). Additionally, in 73 singleton pregnancies at high risk for preterm birth, an Arabin cervical pessary was placed at 14-33 weeks' gestation. We performed MRI of the cervix immediately before and after placement and at monthly follow-up until removal of the pessary. In a subgroup of 54 pregnancies with a short cervix and pessary placement at 17-31 weeks' gestation, the uterocervical angle and cervical length at follow-up were compared with the preplacement values. Results: In pregnancies not at high risk for preterm birth, the uterocervical angle did not vary, but cervical length showed a significant decrease with gestational age (r = -0.15, P < 0.05). Among the high-risk patients, the cervical pessary was successfully placed at first attempt in 60 (82.2%) and by the second attempt in 66 (90.4%), remaining well positioned until removal. In five patients we failed to place the pessary after two attempts, in one patient the pessary dislodged during follow-up and in one case the pessary was partly placed in the external cervical canal and triggered labor the next day. Among the subgroup of 54 patients, the median uterocervical angle immediately after pessary placement was significantly more acute than that prior to placement in the 46 (85.2%) who delivered after 34 weeks (132° vs 146°, P < 0.01), but was unchanged in the eight patients who delivered before 34 weeks (143° vs 152°, P > 0.05). Conclusion: In patients at high risk for preterm delivery, correct placement of the Arabin cervical pessary should be checked immediately; this can be performed quickly and easily using MRI. This study provides some evidence that, in singleton p, SCOPUS: ar.j, FLWIN, info:eu-repo/semantics/published