Quantitative flow measurements on phantoms and on blood vessels with MR

A broad spectrum of MR methods has been published in the last few years for the visualization and the quantification of flow in human blood vessels. We describe the results of an extended study to measure the flow quantitatively using the MR phase modulation method. A gradient echo sequence which allows short repetition times was synchronized with the ECG. The instantaneous velocity profiles and the integrated flow rate can be determined throughout the cardiac cycle in up to 45 consecutive time intervals. The instantaneous velocity distributions can be displayed as 2D profiles over the lumen of the blood vessel. The technique has been successfully evaluated with a set of phantom experiments. Following this, quantifications of the blood flow rates in vivo were performed on the abdominal aortas of healthy volunteers. The MR flow results were compared to those obtained with conventional Doppler ultrasound examinations. The results of both methods are in good quantitative agreement.