MR volumetry of brain and CSF in fetuses referred for ventriculomegaly.

OBJECTIVE: The purpose of this study was to validate the method of performing fetal brain volumetry. In particular, our objectives were to assess which imaging plane is most reproducible for the performance of brain volumetry measurements and to ascertain inter- and intraobserver variability in determining brain volume in fetuses referred for ventriculomegaly (VM). SUBJECTS AND METHODS: In this prospective study, 50 consecutive fetuses at 17-37 weeks of gestational age referred for MRI for VM underwent fast spin-echo T2-weighted imaging. Supratentorial brain parenchyma, lateral ventricles, and extraaxial and cerebellar volumetric measurements were manually obtained in three planes by three radiologists. Inter- and intraobserver variability were assessed. The relationship between volumes and gestational age, and lateral ventricular diameter were assessed. RESULTS: Volumes increased with gestational age. The presence of VM correlated with increased lateral ventricle diameter. The effect of imaging plane was negligible. Inter- and intraobserver variability were low. CONCLUSION: Supratentorial parenchyma and lateral ventricular volumes can be reliably measured on fetal MRI, and imaging plane was not an important factor in measurement. Further studies are needed to correlate these indexes with long-term postnatal outcomes.

Evaluation of real-time single-shot fast spin-echo MRI for visualization of the fetal midline corpus callosum and secondary palate.

OBJECTIVE: The objective of our study was to assess the visibility of the fetal corpus callosum and soft palate on standard single-shot fast spin-echo (SSFSE) imaging versus real-time (RT) SSFSE imaging. SUBJECTS AND METHODS: Part 1 of the study was a prospective analysis using a questionnaire rating the ease of use and utility of RT imaging. Part 2 of the study was a retrospective analysis of 69 fetal MRI studies with RT sagittal midline imaging of the head, face, or both. Standard and RT SSFSE image sets were de-identified, randomized, and shown to three pediatric neuroradiologists who rated on a 5-point scale whether the images were midline and how well they could see and characterize as normal the corpus callosum and secondary palate. The imaging results were correlated with postnatal diagnosis. Statistical methods included the Wilcoxon's signed rank test, McNemar chi-square test, and analysis of variance. RESULTS: Prospectively, the RT SSFSE technique was ranked as excellent in all the categories assessed. Retrospective analysis showed that the midline view obtained with RT SSFSE imaging was helpful in diagnosing the normal and abnormal secondary palate, allowing improved diagnosis of 19 (30.6%) of 62 cases of normal palate and four (57.1%) of seven cases of abnormal palate, when compared with the standard SSFSE technique. RT SSFSE imaging improved the ability to diagnose a normal corpus callosum on the midline view in 13 (27.6%) of 47 fetuses of 20 or more weeks gestational age. CONCLUSION: The RT SSFSE technique can aid in obtaining images in planes that are critical to the evaluation of a moving fetus, particularly when a midline sagittal view of the corpus callosum or palate is required. The use of this technique may lead to improved diagnosis of CNS or orofacial abnormalities in fetuses.

Evaluation of the agreement between 3-dimensional ultrasonography and magnetic resonance imaging for fetal lung volume measurement.

OBJECTIVE: The purpose of this study was to assess the agreement between 3-dimensional ultrasonography (3DUS) and magnetic resonance imaging (MRI) for lung volumetry in fetuses with and without abnormalities associated with lung hypoplasia. METHODS: Fifty-nine singleton pregnancies were evaluated. Cases were separated into groups 1 and 2, according to the presence or absence of malformations associated with lung hypoplasia, respectively. Fetal lung volume was calculated by the Virtual Organ Computer-Aided Analysis (VOCAL) program of the 3DUS and the MRI. In both groups, measurements performed with all VOCAL angles were compared among themselves and with those obtained by MRI. Bland-Altman tests and analysis of variance were used for this purpose. RESULTS: In groups 1 and 2, the mean lung volume obtained with each rotation angle of the VOCAL technique was significantly smaller than the mean volume calculated by MRI (P < .001), and the mean volume obtained with the 30 degrees rotation step was significantly smaller than those obtained with the other rotation steps of the VOCAL technique. Bland-Altman tests confirmed this underestimation and showed a broad 95% confidence interval when the VOCAL angles were compared with those of MRI and when the 30 degrees rotation step was compared with the other VOCAL steps. CONCLUSIONS: There was a substantial discrepancy between 3DUS and MRI and between the 30 degrees rotation step of the VOCAL technique and the other rotation angles, for lung volume measurement in fetuses with and without abnormalities associated with lung hypoplasia.

Real-time magnetic resonance imaging aids prenatal diagnosis of isolated cleft palate.

OBJECTIVE: Cleft of the secondary palate without cleft lip is difficult to visualize sonographically. This study was performed to assess the utility of sonography, standard magnetic resonance (MR) imaging, and real-time MR imaging in the diagnosis of isolated cleft palate. METHODS: We prospectively assessed 5 fetuses at risk for isolated cleft palate on the basis of family history, micrognathia, or both, using sonography and standard and real-time single-shot fast spin echo MR sequences. Written informed consent was obtained under our Institutional Review Board-approved Health Insurance Portability and Accountability Act-compliant protocol. Images were assessed for confidence in a diagnosis of cleft or normal palate. Prenatal and postnatal diagnoses were compared. RESULTS: In 3 fetuses, micrognathia was visualized by sonography and MR imaging with standard and real-time sequences. One fetus at 19 weeks had a wide cleft of the entire secondary palate, and another fetus at 33 weeks had a cleft of the soft palate; these defects were seen only with real-time MR imaging. One 35-week gestational age fetus had a cleft soft palate that was visualized on standard and real-time MR imaging. Two fetuses with no abnormalities had the normal midline secondary palate seen only on real-time MR imaging. In all fetuses, real-time images were helpful in assessing the secondary palate because the entire midline naso-oropharynx could be visualized. CONCLUSIONS: Real-time MR imaging allows for rapid assessment of the midline structures, providing accurate diagnosis of isolated cleft palate.