title: Amniotic fluid volume: Rapid MR-based assessment at 28-32 weeks gestation.
abstract: OBJECTIVE
  This work evaluates rapid magnetic resonance projection hydrography (PH) based amniotic fluid volume (AFV) estimates against established routine ultrasound single deepest vertical pocket (SDVP) and amniotic fluid index (AFI) measurements, in utero at 28-32 weeks gestation. Manual multi-section planimetry (MSP) based measurement of AFV is used as a proxy reference standard.
  
  
  METHODS
  Thirty-five women with a healthy singleton pregnancy (20-41 years) attending routine antenatal ultrasound were recruited. SDVP and AFI were measured using ultrasound, with same day MRI assessing AFV with PH and MSP. The relationships between the respective techniques were assessed using linear regression analysis and Bland-Altman method comparison statistics.
  
  
  RESULTS
  When comparing estimated AFV, a highly significant relationship was observed between PH and the reference standard MSP (R(2) = 0.802, p < 0.001). For the US measurements, SDVP measurement related most closely to amniotic fluid volume, (R(2) = 0.470, p < 0.001), with AFI demonstrating a weaker relationship (R(2) = 0.208, p = 0.007).
  
  
  CONCLUSIONS
  This study shows that rapid MRI based PH measurement is a better predictor of AFV, relating more closely to our proxy standard than established US techniques. Although larger validation studies across a range of gestational ages are required this approach could form part of MR fetal assessment, particularly where poly- or oligohydramnios is suspected.
  
  
  CONCLUSIONS
  • MR projection hydrography can be used to estimate amniotic fluid volume. • MR projection hydrography relies on the T2w signal from amniotic fluid. • Amniotic fluid volume (AFV) is more accurately assessed than with ultrasound.
authors.affiliation: Department of Radiology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK. nicholas.hilliard@addenbrookes.nhs.uk.
authors.forename: N J
authors.initials: NJ
authors.lastname: Hilliard
authors.affiliation: Department of Radiology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
authors.forename: R
authors.initials: R
authors.lastname: Hawkes
authors.affiliation: Department of Radiology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
authors.forename: A J
authors.initials: AJ
authors.lastname: Patterson
authors.affiliation: Department of Radiology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
authors.forename: M J
authors.initials: MJ
authors.lastname: Graves
authors.affiliation: Department of Radiology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
authors.forename: A N
authors.initials: AN
authors.lastname: Priest
authors.affiliation: Department of Radiology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
authors.forename: S
authors.initials: S
authors.lastname: Hunter
authors.affiliation: Department of Obstetrics and Fetal Medicine, Imperial College Healthcare NHS Trust, London, UK.
authors.forename: C
authors.initials: C
authors.lastname: Lees
authors.affiliation: Department of Radiology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
authors.forename: P A
authors.initials: PA
authors.lastname: Set
authors.affiliation: Department of Radiology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
authors.forename: D J
authors.initials: DJ
authors.lastname: Lomas
mesh_terms: D000328:Adult; D000653:Amniotic Fluid / Q000000981:diagnostic imaging*; D005260:Female; D005865:Gestational Age; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015588:Observer Variation; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods*; D016216:Ultrasonography, Prenatal; D055815:Young Adult
keywords: Amniotic Fluid; Comparative Study; Magnetic Resonance Imaging; Pregnancy; Ultrasound