[Diffusion-weighted MR imaging of the normal fetal brain: marker of fetal brain maturation].
OBJECTIVE
To determine the reliability and variations of apparent diffusion coefficient (ADC) values in normal fetuses. Materials and methods. Retrospective study (2007-2008) on 22 normal fetal MR examinations, performed between 30 and 34 of gestation, using a routine protocol (T1W and T2W images in 3 planes, b=1,000 diffusion-weighted imaging) without sedation. ADC values were measured by placing 3 adjacent regions of interest (ROI) including a centrally located ROI over the right frontal and occipital white matter (6 ROI).


METHODS
reproducibility of adjacent ADC values (intraclass correlation coefficient: ICC) and comparison between frontal and occipital ADC values (Wilcoxon).


RESULTS
The mean ADC value was 1.78 mm(2)/s for the frontal white matter (+ or - 0.10) and 1.66 mm(2)/s for the occipital white matter (+ or - 0.12) with excellent reproducibility (ICC=0.91 in the frontal lobe) and good reproducibility for adjacent measurements (ICC=0.7). A linear inverse correlation existed between ADC values and gestational age in the occipital lobes, and a significant fronto-occipital gradient existed after 32 weeks of gestational age.


CONCLUSIONS
ADC value measurements are reliable and inversely correlated with gestational age due to fetal brain maturation. The existence of a fronto-occipital gradient after 32 weeks of gestational age could be a marker of normal maturation used in clinical practice.
Cartry
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C
Service d'Imagerie Pédiatrique, Hôpital St-Vincent-de-Paul, AP-HP, 82, avenue Denfert Rochereau, 75674 Paris cedex 14.
Viallon
V
V
Hornoy
P
P
Adamsbaum
C
C
D001921:Brain / Q000196:embryology* / Q000254:growth & development*; D038524:Diffusion Magnetic Resonance Imaging; D005333:Fetus / Q000196:embryology*; D006801:Humans; D012189:Retrospective Studies