456: MRI-based volumetric measurements of the brain in cytomegalovirus-infected fetuses with otherwise “normal” interpretation of brain MRI

Abstract

To compare magnetic resonance imaging (MRI)-based volumetric measurements of the brains of apparently normally developed fetuses versus those of fetuses suspected of being infected by cytomegalovirus (CMV). Brain MRI data of 25 apparently normal fetuses (control group) and 22 fetuses suspected of being infected by CMV (study group), all between 30-37 weeks of gestation, were collected retrospectively and analyzed. All MRI examinations were originally interpreted as being “normal” by a single senior pediatric neuroradiologist. Indications for MRI in the control group were based upon obstetrical history or suspected pathology by US. Suspected fetal CMV infection was based upon maternal seroconversion or a positive PCR for CMV in an amniotic fluid sample. Data for volumetric measurements were acquired using a 3D Fast Imaging Employing STeady-state Acquisition (FIESTA) sequence of the fetal brain and body (TR/TE=3/1.3sec, Matrix=256x256, 4mm slice thickness). Manual segmentation of the whole brain and the ventricular system were performed using AnalyzeDirect software by two independent qualified readers and validated by a senior pediatric radiologist. Interobserver variability was evaluated. Figure 1 displays the correlations between gestational age and total brain volume, excluding ventricles and CSF, of both groups. Figure 2 provides the volumes of ventricles of both groups. Interobserver agreement was excellent. The mean gestational age was equivalent for the study and control groups (33.04±1.2 and 32.24±1.64 weeks respectively P>0.05). The mean brain volume was 171,946±41,670 mm3 for the study group and 184,947±36,019 for the control group (P=0.24) and the mean ventricular volume was 8,410±2,139 mm3 and 6,876±2,096, respectively (P=0.028). The volume of ventricles of fetuses infected by CMV as measured in MRI is significantly greater than that of apparently normally developed fetuses at the same gestational age,with no significant differences in total brain volumes. Notably, conventional interpretation of the MRIs of all the fetuses was normal. Further studies with larger sample sizes are needed in order to provide normal MRI reference volumetric data of the fetal brain of both healthy and CMV-infected fetuses, and to establish whether this parameter has clinical significance.View Large Image Figure ViewerDownload Hi-res image Download (PPT)