EP22.06: Morphology of maternal structures in fetal MRI: a retrospective, clinical‐anatomical data analysis

Abstract

Fetal MRI has become an important tool in prenatal diagnostics and is also capable of evaluating extrafetal and maternal structures. They are of significant relevance when it comes to obstetrical outcome. This study aims to investigate values for maternal cervical length and width (in case of depiction of a cervical mucus plug (CMP)) and width of the urinary tract in fetal MRI examinations. Correlation analysis between those values and gestational age (GA) was performed. Furthermore, filling degree of maternal urinary bladder and visually captured abnormalities of maternal structures were evaluated. 453 Fetal MRI examinations (1.5 Tesla and 3 Tesla) of singleton pregnancies performed in 2014 at Vienna General Hospital were evaluated. Subjects with unknown GA, cervical insufficiency or maternal kidney disease were excluded, resulting in a total of 348 included cases. Cervical length and width were measured on sagittal T2 sequences, width of renal pelvis and ureters were measured on axial T2 sequences and filling degree of the urinary bladder was scored using T2 sequences. Mean cervical length was 41.5 millimetres (mm) ± 8.8, 36.7 mm ± 9.4 and 34.2 mm ± 8.7 for GA 18-21, 22-35 and 36-42 respectively. Statistical analysis showed significant (p < 10-2) correlation between GA and cervical length, latter decreasing along gestation. Although correlation between width of urinary tract structures and GA was not significant, trends of positive correlation between them were observed. Regarding the values of uterine cervix in MRI are in line with ultrasound-based studies while assessment of the urinary tract is often complicated by restricted field of view. Other parameters influencing cervical morphology (e.g. maternal age, height, ethnicity) have not been taken into account and should be subject of ongoing studies. Hence, the efficacy of fetal MRI when it comes to depicting maternal structures requires further investigation.