Fetal brain development at 25-39 weeks gestational age: A preliminary study using intravoxel incoherent motion diffusion-weighted imaging

Abstract

Background: The fetal brain developmental changes of water diffusivity and perfusion has not been extensively explored.

Purpose/hypothesis: To evaluate the fetal brain developmental changes of water diffusivity and perfusion using intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI).

Study type: Prospective.

Population: Seventy-nine normal singleton fetuses were scanned without sedation of healthy pregnant women.

Field strength/sequence: 5 T MRI/T₁ /₂ -weighted image and IVIM-DWI.

Assessment: Pure diffusion coefficient (D), pseudodiffusion coefficient (D*), and perfusion fraction (f) values were calculated in the frontal (FWM), temporal (TWM), parietal (PWM), and occipital white matter (OWM) as well as cerebellar hemisphere (CH), basal ganglia region (BGR), thalamus (TH), and pons using an IVIM model.

Statistical tests: One-way analysis of variable (ANOVA) followed by Bonferroni post-hoc multiple comparison was employed to reveal the difference of IVIM parameters among the investigated brain regions. The linear and the nonlinear polynomial regression analyses were utilized to reveal the correlation between gestational age (GA) and IVIM parameters.

Results: There were significant differences in both D (F(7,623) = 96.64, P = 0.000) and f values (F(7,623) = 2.361, P = 0.0219), but not D* values among the varied brain regions. D values from TWM (r² = 0.1402, P = 0.0002), PWM (r² = 0.2245, P = 0.0002), OWM (r² = 0.2519, P = 0.0002), CH (r² = 0.2245, P = 0.0002), BGR (r² = 0.3393, P = 0.0001), TH (r² = 0.1259, P = 0.0001), and D* value from pons (r² = 0.2206, P = 0.0002) were significantly correlated with GA using linear regression analysis. Quadratic regression analysis led to results similar to those using the linear regression model.

Data conclusion: IVIM-DWI parameters may indicate fetal brain developmental alterations but the conclusion is far from reached due to the not as high-powered correlation between IVIM parameters and GA.

Level of evidence: 2 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2019;50:899-909.

Keywords: brain development; fetus; gestational age; intravoxel incoherent motion; white matter.