Analysis of 270 fetuses with non‐visualisation of the cavum septi pellucidi and vergae on in‐utero MR imaging

OBJECTIVE: The primary aim of this paper is to present a retrospective analysis of fetuses in which the cavum septi pellucidi and vergae (CSPV) was not present, or was not in its expected position on in utero MR (iuMR) imaging. We will use this information to describe the possible causes of that finding and provide a diagnostic approach using iuMR imaging. METHODS: This is a retrospective study from a single institution using data from an 18 year period (2000-2017) and it includes fetuses in which the CSPV was not visualised on iuMR. Those studies were reviewed and classified as CSPV 'not present', 'disrupted' or 'mal-positioned' and we describe the neuropathologies present in each of the groups. RESULTS: 270 fetuses met the entrance criteria and the CSPV was described as 'mal-positioned' in 56% of fetuses, 'disrupted' in 26% and 'not present' in 18%. Mal-positioned CSPV were present only in cases of agenesis of the corpus callosum and three specific patterns of mal-positioning are described. Disrupted CSPV was present in fetuses with hydrocephalus or pathologies causing extensive brain parenchymal injury. 'Not present' CSPV was found in cases with holoprosencephaly or when absence of the CSPV appeared to be an isolated finding. CONCLUSION: We have described a large cohort of fetuses with non-visualisation of a normal CSPV on iuMR imaging and present a categorical classification system based on the CSPV being 'not present', 'disrupted' and 'mal-positioned'. This approach should help in the diagnosis of the underlying cause of a CSPV abnormality. This article is protected by copyright. All rights reserved.