title: Normal renal development investigated with fetal MRI.
abstract: OBJECTIVE
  To evaluate age-dependent changes in fetal kidney measurements with MRI.
  
  
  METHODS
  Fetal MRI examinations were used to study the kidney length (218 fetuses), signal intensities of renal tissue, renal pelvis, and liver tissue on T2-weighted images (223 fetuses), and the whole-kidney apparent diffusion coefficient (107 fetuses). A 1.5 T superconducting unit with a phased array coil was used in patients from 16 to 39 weeks' gestation. The imaging protocol included T2-weighted single-shot fast spin-echo, T2-weighted balanced angiography and diffusion-weighted sequences. Slice thickness ranged from 3 to 5mm.
  
  
  RESULTS
  Fetal kidney length as a function of gestational age was expressed by the linear regression: kidney length (mm)=0.190 x gestational age (d) -8.034 (R(2) = 0.883, p < 0.001). Paired t-test analysis showed a highly statistically significant difference between the ratio of renal tissue signal intensity to renal pelvis signal intensity and the ratio of liver signal intensity to renal pelvis signal intensity on T2-weighted images (t = -50.963, d.f. = 162, p < 0.001), with renal tissue hyperintense to liver tissue. The apparent diffusion coefficient in relation to gestational age was described by the equation: ADC (microm(2)/s) = 0.0302 x square (gestational age (d)) -14.202 x gestational age (d) +2,728.6 (R(2) = 0.225, p < 0.001).
  
  
  CONCLUSIONS
  The length, signal intensity on T2-weighted images, and apparent diffusion coefficient of the fetal kidney change significantly with gestational age. The presented data may help in the prenatal diagnosis of renal anomalies.
authors.affiliation: Department of Radiology, Medical University of Vienna, Währinger Gürtel 18-20, A-1090 Vienna, Austria.
authors.forename: Linde
authors.initials: L
authors.lastname: Witzani
authors.forename: Peter Christian
authors.initials: PC
authors.lastname: Brugger
authors.forename: Marcus
authors.initials: M
authors.lastname: Hörmann
authors.forename: Gregor
authors.initials: G
authors.lastname: Kasprian
authors.forename: Csilla
authors.initials: C
authors.lastname: Csapone-Balassy
authors.forename: Daniela
authors.initials: D
authors.lastname: Prayer
mesh_terms: D005260:Female; D005865:Gestational Age; D006801:Humans; D007668:Kidney / Q000196:embryology*; D016014:Linear Models; D008279:Magnetic Resonance Imaging / Q000379:methods*; D012016:Reference Values