title: Magnetic resonance diffusion-weighted imaging: reproducibility of regional apparent diffusion coefficients for the normal fetal brain.
abstract: OBJECTIVE
  To evaluate the reproducibility of regional apparent diffusion coefficient (ADC) measurements of the normal fetal brain in the second and third trimesters of pregnancy.
  
  
  METHODS
  Fifty normal singleton fetuses from healthy pregnant women between 19 and 37 weeks' gestation were studied without sedation. Single-shot diffusion-weighted images of the fetal brain were obtained using a 1.5-Tesla magnetic resonance scanner and a six-channel body array coil. ADC maps were created using 0 and 1000 b-values along three orthogonal directions. Two examiners independently measured ADC values in the cerebellar hemispheres (CH), pons, thalamus, basal ganglia (BG), centrum semiovale (CSO), and frontal (FWM), parietal (PWM), temporal (TWM) and occipital (OWM) white matter. Correlation between ADC values and menstrual age was assessed by linear regression analysis. The bias and agreement of ADC measurements were determined using Bland-Altman plots.
  
  
  RESULTS
  ADC values either remained constant (BG, FWM, PWM, TWM, OWM, CSO) or decreased (CH, pons, thalamus) with advancing menstrual age. Mean intraobserver bias for ADC measurements was not significantly different from zero. Small interobserver differences in mean ADC measurements (i.e. a small mean bias) were detected for CH (1.26 ± 0.20 vs 1.20 ± 0.18 μm(2) /ms, P = 0.006), PWM (1.37 ± 0.29 vs 1.33 ± 0.26 μm(2) /ms, P = 0.02) and CSO (1.36 ± 0.29 vs 1.33 ± 0.28 μm(2) /ms, P < 0.0001). Measurement agreement was acceptable.
  
  
  CONCLUSIONS
  ADC measurements in normal unsedated fetuses in the second and third trimesters are reproducible except for small differences for PWM, CH and CSO between examiners.
authors: Department of Diagnostic Radiology, Oakland University William Beaumont School of Medicine, Rochester, MI 48073, USA. AndrewC.Boyer@beaumont.edu
authors: A C
authors: AC
authors: Boyer
authors: L F
authors: LF
authors: Gonçalves
authors: W
authors: W
authors: Lee
authors: A
authors: A
authors: Shetty
authors: A
authors: A
authors: Holman
authors: L
authors: L
authors: Yeo
authors: R
authors: R
authors: Romero
mesh_terms: D001921:Brain / Q000033:anatomy & histology / Q000196:embryology*; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D005333:Fetus / Q000033:anatomy & histology*; D006801:Humans; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011263:Pregnancy Trimester, Third; D011296:Prenatal Diagnosis; D015203:Reproducibility of Results