In vivo assessment of putative functional placental tissue volume in placental intrauterine growth restriction (IUGR) in human fetuses using diffusion tensor magnetic resonance imaging.

OBJECTIVES: Intrauterine growth restriction (IUGR) is a diagnostic challenge, since ultrasound fetal biometry (UFB) provides only a 50% detection rate for IUGR. This may be attributable to the fact that UFB does not allow a direct evaluation of functional placental tissue. We hypothesized that direct assessment, using magnetic resonance diffusion tensor imaging (DT-MRI), can provide better detection of IUGR by reliably distinguishing between normal and non-functional placental tissue.
METHODS: Patients with normal placenta function (n = 21) and suspected IUGR (n = 14) according to UFB were examined. DT-MRI-based properties of areas of the placenta that were judged to represent normal functional tissue, in normal pregnancies, were used to perform volumetry of the putative functional placental tissue (PFPT) in a control- and an IUGR-group. Fractional anisotropy (FRC), as well as maximum and mean diffusivity were also calculated.
RESULTS: PFPT volumetry showed a significant reduction of functional placental tissue in the IUGR group of up to 33%. Analysis of global PFPT, maximum diffusivity, mean diffusivity, and FRC also showed a significant difference.
CONCLUSIONS: PFPT volume is dramatically reduced in IUGR. Several DT-MRI parameters suggest an additional placental micro-architecture disturbance in IUGR. PFPT volumetry appears to be a promising tool for improving the detection of IUGR.