What brain abnormalities can magnetic resonance imaging detect in foetal and early neonatal spina bifida: a systematic review

Abstract

Purpose Open spina bifida (OSB) encompasses a wide spectrum of intracranial abnormalities. With foetal surgery as a new treatment option, robust intracranial imaging is important for comprehensive preoperative evaluation and prognostication. We aimed to determine the incidence of infratentorial and supratentorial findings detected by magnetic resonance imaging (MRI) alone and MRI compared to ultrasound. Methods Two systematic reviews comparing MRI to ultrasound and MRI alone were conducted on MEDLINE, EMBASE, and Cochrane databases identifying studies of foetal OSB from 2000 to 2020. Intracranial imaging findings were analysed at ≤ 26 or > 26 weeks gestation and neonates (≤ 28 days). Data was independently extracted by two reviewers and meta-analysis was performed where possible. Results Thirty-six studies reported brain abnormalities detected by MRI alone in patients who previously had an ultrasound. Callosal dysgenesis was identified in 4/29 cases (2 foetuses ≤ 26 weeks, 1 foetus under any gestation, and 1 neonate ≤ 28 days) (15.1%, CI:5.7–34.3%). Heterotopia was identified in 7/40 foetuses ≤ 26 weeks (19.8%, CI:7.7–42.2%), 9/36 foetuses > 26 weeks (25.3%, CI:13.7–41.9%), and 64/250 neonates ≤ 28 days (26.9%, CI:15.3–42.8%). Additional abnormalities included aberrant cortical folding and other Chiari II malformation findings such as lower cervicomedullary kink level, tectal beaking, and hypoplastic tentorium. Eight studies compared MRI directly to ultrasound, but due to reporting inconsistencies, it was not possible to meta-analyse. Conclusion MRI is able to detect anomalies hitherto underestimated in foetal OSB which may be important for case selection. In view of increasing prenatal OSB surgery, further studies are required to assess developmental consequences of these findings.

The Role of Fetal Brain Magnetic Resonance Imaging in Current Fetal Medicine

“…When using MRI in fetuses meeting the criteria for fetal surgery on ultrasound findings, half of them were found to have corpus callosum abnormalities and/or ventricular wall abnormalities [ 16 ]. This number is in line with findings in a recent systematic review by our group [ 23 ]. Whether MRI is essential for this, hence adds information to US, has to our knowledge not been proven.…”

Longitudinal MRI in the context of in utero surgery for open spina bifida: A descriptive study

“…This is particularly useful in fetal OSB where the initial MRI assessment is usually performed prior to 25 + 6 weeks (the upper gestational age limit for prenatal surgery) which poses challenges due to small fetal size. 3,21,22 SRR is dependent on good quality original imaging obtained with sufficient image stacks in all three planes, as evident from our study given the number of unsuccessful reconstructions, which further supports following the standard ISUOG MRI acquisition criteria.…”

“…Whilst ultrasound remains the primary imaging modality for both first‐line screening and detailed assessment due to its low cost, real‐time capability and high spatial resolution, it is susceptible to variable image quality due to factors such as maternal habitus, fetal position, and reverberation artifacts from the calvarium 4–8 . Magnetic resonance imaging (MRI) is an important adjunct as it provides excellent soft tissue contrast and enhances visualization through multiplanar imaging with a large field‐of‐view 3 . Moreover, MRI is more likely to detect and characterize supratentorial anomalies (eg corpus callosum dysgenesis, heterotopia) 3,6,7,9,10 .…”

Clinical Assessment of Fetal Well‐Being and Fetal Safety Indicators

“…Magnetic resonance imaging (MRI) provides superior soft‐tissue definition compared with ultrasound, and overcomes several technical limitations of ultrasound, such as atypical fetal position, reduced amniotic fluid volume, or high maternal body mass index. Increasingly it is being used to complement ultrasound analyses, to improve the diagnosis of fetal anomalies following ultrasound detection, and/or for assessment prior to fetal surgery such as spina bifida closure 44,45 …”

“…Increasingly it is being used to complement ultrasound analyses, to improve the diagnosis of fetal anomalies following ultrasound detection, and/or for assessment prior to fetal surgery such as spina bifida closure. 44,45 Traditionally MRI has been used as a clinical adjunct to assess structural fetal anomalies in the central nervous system, but more recently it has been applied to other organ systems. 46,47 Fetal movements can cause artifacts in MRI, but various approaches can be used to reduce their negative effect on images, such as the adjustment of acquisition parameters.…”