Amniotic fluid volume: Rapid MR-based assessment at 28-32 weeks gestation

Area of Science:

• Obstetrics and Gynecology
• Medical Imaging
• Fetal Medicine

Background:

• Accurate assessment of amniotic fluid volume (AFV) is crucial for monitoring fetal well-being.
• Established ultrasound techniques like single deepest vertical pocket (SDVP) and amniotic fluid index (AFI) have limitations in precision.
• Magnetic Resonance Imaging (MRI) offers advanced visualization capabilities for fetal assessments.

Purpose of the Study:

• To evaluate the accuracy of rapid MRI projection hydrography (PH) for estimating AFV.
• To compare PH-derived AFV measurements with conventional ultrasound methods (SDVP and AFI).
• To establish manual multi-section planimetry (MSP) as a proxy reference standard for AFV measurement.

Main Methods:

• Recruited 35 pregnant women (28-32 weeks gestation) with healthy singleton pregnancies.
• Performed same-day ultrasound (SDVP, AFI) and MRI (PH, MSP) assessments of AFV.
• Utilized linear regression and Bland-Altman analysis to compare measurement techniques.

Main Results:

• MRI PH demonstrated a strong correlation with the reference standard MSP (R²=0.802, p<0.001).
• Ultrasound SDVP showed a moderate relationship with AFV (R²=0.470, p<0.001).
• Ultrasound AFI exhibited a weaker correlation with AFV (R²=0.208, p=0.007).

Conclusions:

• Rapid MRI PH is a more accurate predictor of AFV than current ultrasound techniques.
• The PH method shows potential for integration into routine MR fetal assessments.
• Further validation across diverse gestational ages is recommended, particularly for suspected polyhydramnios or oligohydramnios.