Unenhanced MR angiography: techniques and clinical applications in @entity1 with XXXX .

@entity1 @entity8 @entity455 @entity82 @entity740 @entity5642 @entity3040 @entity2287
Alongside the two conventional unenhanced magnetic resonance (MR) angiographic techniques, namely time-of-flight and phase-contrast MR angiography, several novel techniques have since been developed, including electrocardiograph (ECG)-gated fast spin echo (FSE), steady-state free precession (SSFP), and arterial spin labeling. These techniques are increasingly being used to avoid severe complications caused by contrast materials, such as iodinated contrast material-induced @entity8 and @entity2287 -induced @entity3040 systemic @entity82 . However, image acquisition and interpretation with these techniques are more complicated than with contrast-enhanced MR angiography because of numerous types of artifacts. Appropriate use of these techniques can allow diagnosis of @entity455 in @entity1 with @entity740 without using contrast materials. For example, time-of-flight angiography is the main technique for evaluating intracranial arteries. Phase-contrast imaging is increasingly being used for physiologic evaluation rather than morphologic evaluation. Meanwhile, ECG-gated FSE MR angiography can show peripheral arteries in more detail. SSFP MR angiography with or without arterial spin labeling can provide high-resolution images of blood vessels including renal arteries, the aorta, and coronary arteries. Black-blood imaging is also used to evaluate vessel walls and @entity5642 including plaque, dissection, and thrombi. The authors review the principles of the currently available unenhanced MR angiographic techniques, along with their advantages and limitations, and describe their clinical applications. This article should help readers select the most appropriate unenhanced MR angiographic technique to assess @entity455 in @entity1 with @entity740 . Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.312105075/-/DC1.
