Fully automated deep learning model for the evaluation of cavum septum pellucidum development in normal fetuses using...

The cavum septum pellucidum (CSP) is an essential landmark in evaluating fetal brain development. The aim of this study was to assess the development of normal fetal CSP across different gestational ages (GAs) in a Chinese cohort using a deep learning (DL) model, and to provide reference for magnetic resonance imaging (MRI) prenatal diagnosis.

A retrospective analysis of 1,047 normal pregnant participants (mean GA 31.21±3.81 weeks) in the second and third trimester was conducted. Fetuses with central nervous system (CNS) anomalies were excluded. A fully automated DL model was developed to measure CSP volume, CSP length, CSP width, CSP height, ratio of CSP volume to whole brain volume, and ratio of CSP volume to cerebrum volume. Linear regression and second-order polynomial regression was used to assess the relationship between CSP measurements and GA.

CSP volume showed a second-order polynomial correlation with GA ( $y=-2660.033+198.241\ast x-3.087\ast x^2$ , P value <0.001); CSP length showed a linear correlation with GA ( $y=-7.589+0.533\ast x$ , P value <0.001); CSP width showed a second-order polynomial correlation with GA ( $y=-19.249+1.585\ast x-0.025\ast x^2$ , P value <0.001); CSP height showed a second-order polynomial correlation with GA ( $y=-9.052+1.108\ast x-0.017\ast x^2$ , P value <0.001); ratio of CSP volume to whole brain volume showed a linear correlation with GA ( $y=96.012-2.086\ast x$ , P value <0.001); and ratio of CSP volume to whole brain volume and ratio of CSP volume to cerebrum volume showed a downward trend ( $y=51.738-1.043\ast x$ , P value <0.001).

CSP volume, width, and height reach a maximum between 28 and 32 weeks of gestation. CSP length exhibits an upward trend after 22 weeks. The ratio of CSP volume to whole brain volume and ratio of CSP volume to cerebrum volume illustrate a downward trend after 22 weeks.