title: Association of placental T2 relaxation times and uterine artery Doppler ultrasound measures of placental blood flow.
abstract: OBJECTIVE
  To investigate whether, in the second trimester of pregnancy, placental T2 relaxation time (determined using magnetic resonance imaging (MRI)) is related to impedance to flow in the uterine arteries.
  
  
  METHODS
  In 40 singleton pregnancies at 24-29 weeks' gestation, uterine artery pulsatility index (PI) was measured by Doppler ultrasound and T2 relaxation time was measured by echo planar MRI at 1.5 T. The significance of the associations between T2 relaxation time, uterine artery PI and birth weight were examined.
  
  
  RESULTS
  In 25 pregnancies that delivered small for gestational age (SGA) neonates with birth weight below the 10th percentile, compared to those with appropriate for gestational age (AGA) birth weight, the T2 relaxation time was significantly decreased (88 ms vs. 149 ms, p < 0.0001) and uterine artery PI was increased (1.96 vs. 1.00, p < 0.0001). There were significant associations between placental T2 relaxation time and log10 uterine artery PI (r = -0.749, p < 0.0001), and between T2 relaxation and birth weight percentile (r = 0.693, p < 0.0001).
  
  
  CONCLUSIONS
  The T2 relaxation time during the second trimester is shorter in pregnancies that subsequently deliver SGA neonates and the measurement is strongly correlated with impedance to flow in the uterine arteries.
authors.affiliation: Harris Birthright Research Centre, King's College Hospital, London, UK. irisderwig@hotmail.com
authors.forename: I
authors.initials: I
authors.lastname: Derwig
authors.forename: G J
authors.initials: GJ
authors.lastname: Barker
authors.forename: L
authors.initials: L
authors.lastname: Poon
authors.forename: F
authors.initials: F
authors.lastname: Zelaya
authors.forename: P
authors.initials: P
authors.lastname: Gowland
authors.forename: D J
authors.initials: DJ
authors.lastname: Lythgoe
authors.forename: K
authors.initials: K
authors.lastname: Nicolaides
mesh_terms: D000328:Adult; D001724:Birth Weight; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age / Q000502:physiology; D008279:Magnetic Resonance Imaging; D010920:Placenta / Q000098:blood supply* / Q000473:pathology / Q000503:physiopathology*; D011225:Pre-Eclampsia / Q000503:physiopathology; D011247:Pregnancy; D011673:Pulsatile Flow; D016216:Ultrasonography, Prenatal; D055988:Uterine Artery / Q000000981:diagnostic imaging*