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 nephropathy and gadolinium-induced nephrogenic systemic fibrosis. 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 vascular diseases in patients with chronic kidney disease 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 intravascular abnormalities 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 vascular diseases in patients with chronic kidney disease. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.312105075/-/DC1.

MCT has shown performance comparable to that of conventional FAC in terms of pancreatic and biliary depiction and safety.

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The PCM can rapidly assess renal function using a small amount of blood almost equally to that of determined in the laboratory, which may help reduce the risk of contrast material-induced complications.

Circulation Journal Official Journal of the Japanese Circulation Society http://www. j-circ.or.jp ultidetector computed tomographic (CT) coronary angiography is used widely to detect coronary artery disease (CAD) because it is accurate and noninvasive. The novel application of the angiographic view has currently improved the clinical feasibility, especially for explaining disease distribution and severity to the patient and for discussing the treatment strategy in conference. 1-3 Single-center studies have reported 30-95% sensitivity and 86-98% specificity for detecting obstructive CAD using 16-detector CT, compared with conventional coronary angiography (CCA) as the reference modality, and 93-97% sensitivity and 95-99% specificity using 64-detector CT. 4,5 In multicenter studies also, 16-detector CT had 89% sensitivity and 65% specificity for detecting CAD in a segment-based analysis, and in a patient-based analysis, 16-detector CT had 98% sensitivity and 54% specificity and 64-detector CT had 85% sensitivity and 90% specificity. 5,6 Thus, 64-detector CT is superior to 16-detector CT in identifying the presence and severity of obstructive CAD, but it increases the patient's radiation exposure when the retrospective electrocardiogram (ECG)-gated helical technique is used, because the helical pitch is smaller and the tube power is higher. Effective doses reported with 64-detector CT (9.5-21.4 mSv) are higher than those reported in 16-detector CT (3.1-9.4 mSv) studies, as well as those required for CCA. 7 CT examination with an effective dose of 10 mSv may increase cancer deaths by approximately 1 in 2,000 cases.