Blood flow measurements in the aorta and major arteries with MR velocity mapping.

The purpose of this study was to measure antegrade and retrograde flow in the aorta and the major arterial pathways in the body noninvasively with cine magnetic resonance (MR) velocity mapping, to determine the hemodynamic significance of retrograde flow in arteries. Two hundred forty cine velocity maps for blood flow measurements were obtained at 29 sites in the aorta and the major arteries in 31 healthy human subjects of varying age at rest. Synchronous or isolated antegrade and retrograde flow was found in the entire aorta and in arteries supplying muscles. No retrograde flow was found in arteries supplying internal organs, such as the internal carotid or splanchnic arteries. The retrograde flow in the aorta and the extremity arteries contributes substantially to supplying diastolic perfusion of internal organs such as the heart, brain, and kidneys. Antegrade flow tends to be helical in the thoracic aorta.