Quantification of blood velocity and flow rates in the uterine vessels using echo planar imaging at 0.5 Tesla

Purpose: To measure uterine artery and vein blood velocity and flow rate profiles using MRI during normal pregnancy.

Materials and methods: A two-shot velocity magnitude-encoded echo planar imaging (EPI) sequence is used at a magnetic field 0.5T. Data analysis procedures, necessary to overcome problems associated with low signal to noise ratio (SNR), and a spatial resolution comparable to the vessel size were used.

Results: The measured blood flow values averaged over nine volunteers for the mean velocity are 5.33 and 3.97 cm/s and for the unilateral flow rate are 203 and 274 mL/min (for the arteries and veins respectively). Values for the flow rate are consistent with ultrasound Doppler studies. Arterial velocity measurements are more pulsatile than venous ones and validation calculations performed on average velocity values would suggest that the nature of blood flow in the uterine vessels is laminar.

Conclusion: This study presents the first report of noninvasive quantitative measurements of uterine artery and vein blood velocity and flow rate profiles using MRI during normal pregnancy. Consistent and reproducible measurements have been obtained by subject specific sequence optimization and data analysis procedures.