Prenatal prediction of survival in isolated diaphragmatic hernia using observed to expected total fetal lung volume determined by magnetic resonance imaging based on either gestational age or fetal body volume.

OBJECTIVES: To compare the predictive value of the prenatal observed to expected (o/e) lung volume as measured by fetal magnetic resonance imaging (MRI), based on an algorithm using either the gestational age or fetal body volume (FBV), for neonatal survival of fetuses with isolated congenital diaphragmatic hernia (CDH). METHODS: We included 53 fetuses with a prenatal diagnosis of isolated CDH, 26 without and 27 with prenatal tracheal occlusion, who were assessed by fetal MRI, liveborn after 32 weeks, and in whom follow-up until discharge from the neonatal care unit was available. Measurements of lung volumes were expressed as a percentage of the appropriate mean (o/e total fetal lung volume (TFLV) x 100) either for gestational age or for FBV. Measurements of FBV were expressed as a percentage of the appropriate mean (o/e FBV x 100) for gestation. Fetuses with prenatal intervention were all assessed > or = 24 h after balloon removal. Regression analysis was used to examine the effect on postnatal survival of either o/e TFLV based on gestational age or based on FBV, gestation at delivery, side of CDH, intrathoracic position of the liver and prenatal intervention. Receiver-operating characteristics (ROC) curves were constructed for the prediction of survival by o/e TFLV based on gestational age and o/e TFLV based on FBV, for all fetuses, as well as for those with o/e FBV between 90 and 110% and those with values beyond that range. A power calculation for the number of fetuses needed to show a difference between the ROC curves was performed. RESULTS: Regression analysis demonstrated that o/e TFLV based on gestational age and on FBV were the only independent predictors of postnatal survival. The area under the ROC curve for prediction of postnatal survival from the o/e TFLV based on gestational age was 0.811, and for that based on FBV it was 0.868 (P < 0.001 for both). For fetuses with o/e FBV between 90 and 110%, and those with values < 90% and > 110%, the area for measurements based on gestational age was 0.895 and 0.733, respectively; when based on FBV it was 0.906 and 0.833 (P < 0.01 for all). A minimum of 273 patients would be needed to provide a probability of 90% of detecting a difference between the areas under both ROC curves. CONCLUSIONS: In fetuses with isolated CDH, lung volume as measured by fetal MRI was significantly correlated with survival. Prediction tended to be better by o/e TFLV based on FBV rather than gestational age. The difference in the prediction of survival between o/e TFLV based on FBV or gestational age was dependent on fetal biometry.

Magnetic resonance imaging of the fetal lung: a pictorial essay.

Ultrasound, which is now a widely available and generally accepted, low-cost technique with real-time properties, is the screening investigation of choice in fetal medicine. However, enthusiasm for fetal prenatal magnetic resonance imaging (MRI) is rising, because of the absence of known biological risks, the increasing ease of performing of fetal MRI and the superb contrast resolution provided. Over the last 10 years, the technology has advanced dramatically. Fast imaging sequences have allowed better MRI visualization of the unborn patient than ever before. As a consequence, experience with fetal MRI is gradually expanding. We are beginning to appreciate the clinical conditions where fetal MRI can complement the ultrasound findings. Apart from the central nervous system, MRI of the fetal lung has received the most attention. Fetal MRI can be used to assess thoracic structural anomalies, lung development as well as maturation. The introduction of fetal therapy for severe lung hypoplasia, associated with congenital diaphragmatic hernia (CDH), has recently boosted the application. This review aims to highlight MRI techniques used to image the lungs of the unborn child and to point out their strengths and limitations in specific conditions.

A diffusion-weighted template for gestational age-related apparent diffusion coefficient values in the developing fetal brain.

OBJECTIVE: To determine the pattern of apparent diffusion coefficient (ADC) values in the normal fetal brain obtained with diffusion-weighted images (DWI) on magnetic resonance imaging (MRI) as a template for normal brain development throughout gestation. METHODS: This was a prospective study of 46 fetuses without suspicion of brain pathology undergoing a total of 66 ultrasound examinations between 17 and 37 weeks of gestation. At T2-weighted MRI, four left and four right brain regions were delineated on transverse slices of the native DWI using a b-value of 0 s/mm2 (b0 images). We examined native b-value images and calculated ADC(avg), ADC(low) and ADC(high) in the basal ganglia, cerebellar hemisphere, frontal parenchyma and occipital parenchyma. Linear regression analysis was used to assess the relationship between gestational age and b0 values as well as the calculated ADC values. RESULTS: Delineations were successful in all fetuses for all regions except for the cerebellar hemispheres in four fetuses. There was a negative correlation between gestational age and b0 values in all examined anatomical regions (P<0.002). For ADC(avg), there were no significant changes in the basal ganglia with increasing gestational age, a positive correlation in the frontal (P<0.0001) and occipital (P=0.03) parenchyma and a negative correlation in the cerebellar hemispheres (P=0.01). For ADC(low), there was a negative correlation between gestational age and the cerebellum (P=0.0002) and basal ganglia (P=0.047), but no correlation for the frontal or occipital parenchyma. For ADC(high), there was a positive correlation with gestational age for the frontal parenchyma (P=0.004), occipital parenchyma (P=0.02) and basal ganglia (P=0.03) but there was no correlation for the cerebellum. CONCLUSIONS: DWI b0 values decreased in the left and right basal ganglia, cerebellar hemisphere, frontal parenchyma and occipital parenchyma between 17 and 37 weeks of gestation and ADC(avg) values increased in two out of four cerebral regions. It remains to be determined to what extent these observations differ in fetuses with suspicion of brain anomalies and whether such measurements will be useful and more predictive of outcome compared with standard MRI sequences.