Emerging magnetic resonance imaging techniques in open spina bifida in utero

Abstract

Magnetic resonance imaging (MRI) has become an essential diagnostic modality for congenital disorders of the central nervous system. Recent advancements have transformed foetal MRI into a clinically feasible tool, and in an effort to find predictors of clinical outcomes in spinal dysraphism, foetal MRI began to unveil its potential. The purpose of our review is to introduce MRI techniques to experts with diverse backgrounds, who are involved in the management of spina bifida. We introduce advanced foetal MRI postprocessing potentially improving the diagnostic work-up. Importantly, we discuss how postprocessing can lead to a more efficient utilisation of foetal or neonatal MRI data to depict relevant anatomical characteristics. We provide a critical perspective on how structural, diffusion and metabolic MRI are utilised in an endeavour to shed light on the correlates of impaired development. We found that the literature is consistent about the value of MRI in providing morphological cues about hydrocephalus development, hindbrain herniation or outcomes related to shunting and motor functioning. MRI techniques, such as foetal diffusion MRI or diffusion tractography, are still far from clinical use; however, postnatal studies using these methods revealed findings that may reflect early neural correlates of upstream neuronal damage in spinal dysraphism.

Keywords: Diffusion tensor imaging; Foetus; Infant (newborn); Magnetic resonance imaging; Spinal dysraphism.

Fig. 1

Super-resolution (SR) reconstruction of foetal MRI. For each case (normal development, pre-operative, and post-operative images of spina bifida foetus undergoing foetal surgery and myeloschisis), we demonstrate the super-resolution T2-weighted MRI (left images) and two surface reconstructions that were based on the segmentation of the reconstructed image (right images)

Fig. 2

Diffusion tensor imaging in spinal dysraphism. a Diffusion tractography of a foetus with spinal dysraphism, 26th week of gestation. The fibre tracts (colour representing spatial orientation) have been overlaid on a coronal plane, T2-weighted MR image. b Sagittal T2-weighted MRI of a newborn with spina bifida, corrected prenatally, showing signs of tethered cord. c Sagittal fractional anisotropy image of the same myelon cross-section, demonstrating increased anisotropy in the region of the tethering. d Diffusion tensor principal vector orientations in the same region. e Diffusion tractography of the myelon