VP28.09: What brain abnormalities can magnetic resonance imaging detect in fetal and early neonatal spina bifida: a systematic review

Abstract

To determine in spina bifida fetuses, incidence of infratentorial and supratentorial findings detected by MRI compared to ultrasound in the context of fetal surgery. We conducted two systematic reviews of studies in fetuses with spina bifida, comparing MRI findings to ultrasound and MRI alone. Imaging findings were analysed at cut-off gestations of ≤26 weeks, ≥26 weeks and early neonatal period (≤28 days) to align with the commonly used upper limit gestational age (GA) for fetal surgery (26 weeks). MEDLINE, EMBASE and COCHRANE databases were studied from 1994–2020. Data was independently extracted by two reviewers and meta-analysis was performed where possible. 39 studies reported brain abnormalities detected by MRI in patients who previously had a detailed ultrasound (n = 1494 MRIs). Callosal dysgenesis was identified in 9/58 cases (8 fetuses and 1 neonate ≤28 days), (16.3%, CI:8.6–28.5%). Heterotopia was identified in 7/40 fetuses ≤26 weeks (19.8%, CI:7.7–42.2%), in 9/36 fetuses ≥26 weeks (25.3%, CI:13.7–41.9%) and 64/250 neonates ≤28 days (26.9%, CI:15.3–42.8%). Chiari II reversal detection in fetuses ≥26 weeks and neonates ≤28 days is (86.9%, CI:69.0–95.2%). For fetuses ≥26 weeks, detection of reduced ventriculomegaly postoperatively is 6.3% (CI:1.6–22.2%) and 76.8% (CI:63.1–86.4%) for increased ventriculomegaly. Additional abnormalities included changes in brain apparent diffusion co-efficient, angular ventricular appearance, reduction of supratentorial CSF, altered brain thickness and aberrant cortical folding. Eight studies compared MRI directly to ultrasound (n = 142 MRIs) but due to inconsistencies in reporting it was not possible to meta-analyse. In fetuses that have been identified with spina bifida on ultrasound, MRI detects abnormalities important for comprehensive intracranial assessment that may be relevant for selecting appropriate fetal surgery candidates.