Magnetic resonance techniques for blood-flow measurement and vascular imaging

The authors review the history and physical principles behind vascular magnetic resonance imaging (MRI) techniques, developed to measure blood flow noninvasively and to display images of the vasculature. All these techniques have been used to create magnetic resonance angiograms, in which the vasculature is shown in a projection format similar to x-ray angiography. Signal loss limits the effectiveness of "white-blood" magnetic resonance angiography techniques, since slow flow and complex flow often cause a drop in signal and consequently a loss of accuracy in depicting vessel anatomy. "Black-blood" magnetic resonance angiography is described as a method that avoids these problems of signal loss. Selective black-blood magnetic resonance angiography is introduced as a technique for improving the visualization of the vasculature when other signal-void structures are present in the volume of interest.