In vivo quantification of blood velocity in mouse carotid and pulmonary arteries by ECG-triggered 3D time-resolved magnetic resonance angiography.

Blood flow velocity is a functional parameter of fundamental importance in diagnosis and follow-up of various vascular diseases. Vascular pathologies can be efficiently studied in animal models, especially in small rodents. ECG-gated magnetic resonance imaging (MRI) assessment of blood velocity in small animals is a challenge because of limited spatial resolution and high-frequency physiological parameters. Here it is shown that a bright-blood cine-3D-MRI method can be used to measure blood velocity at specific times of the cardiac cycle in mouse pulmonary and carotid arteries. The method used a series of time-of-flight (TOF) acquisitions in a volume of interest at different times after signal cancellation in the same volume. This scheme was repeated at different periods of the cardiac cycle by varying the delay between the ECG R-wave peak and signal cancellation. Velocity values in mouse pulmonary artery varied from 35 cm/s in systole to 0-10 cm/s in diastole. A similar pattern was displayed in carotid arteries (18 and 2.5 cm/s, in systole and diastole, respectively). Results are discussed in terms of efficiency, limitation, and comparison with other methods. 2009 John Wiley & Sons, Ltd.