Contrast-enhanced MRA versus nonenhanced MRA: Pros and cons

Magnetic resonance angiography (MRA) continues to evolve rapidly, having grown from a variety of flow-dependent techniques through contrast-enhanced techniques, each with its own specific advantages and requirements. Recent technical developments such as the introduction of 3T scanners, the increasing sophistication of radiofrequency (RF) architecture, and the dissemination of parallel acquisition techniques have greatly increased the power and practicality of contrast-enhanced MRA, such that it is now highly competitive with computed tomographic angiography (CTA) in most vascular territories. Nonetheless, non-contrast-enhanced MRA is still widely used, particularly in neurovascular imaging. As a result, it is crucial that interpreting physicians are familiar with the basic principles, relative advantages, and limitations of each of these methods, including associated potential diagnostic pitfalls. The authors present the progression of nonenhanced and enhanced MRA to date, illustrating key characteristics as well as discussing the current applications of each in diagnostic imaging.