EP01.07: Fetal intracranial space occupying lesions: MRI versus ultrasound

The purpose of this study was to evaluate the value of prenatal magnetic resonance imaging (MRI) in characterising fetal intracranial space occupying lesions in comparison to prenatal ultrasound. This retrospective study included 50 fetuses (mean age: 26 years, mean gestational weeks: 31+1 GW) with intracranial space occupying lesions, suspected by prenatal screening ultrasound. T2-weighted, T1-weighted, SSFP and diffusion-weighted sequences of the fetal brain were obtained on a 1.5 Tesla unit. Pathology (n=5), postmortem MRI (n=3) or postnatal US (n=42) was available as standard of reference. The Fetal MRI provided correct diagnosis in 49 cases (98%), while 35 (70%) by ultrasound and MRI failed in 1 case (2%), while ultrasound failed in 15 cases (30%). Fetal MR and ultrasound were concordant in 35 of 50 cases (70%), completely discordant in 4 (8%) and partially discordant in 11 (22%) cases. MRI could provide detailed information about the minor lesions, such as focal hemorrhage and periventricular nodules. Meanwhile it could provide whole view of the lesion in order to delineate the surrounding anatomical structure. But there are still some limitations of its soft tissue resolution in a case with teratoma, more effort is needed to improve the sequences.