Purpose To perform a preliminary clinical feasibility study of the real-time fluoroscopic tracking technique for bolus chase MR angiography (MRA) of peripheral vasculature to image three stations extending from the aortoiliac bifurcation to the pedal arteries. Materials and Methods 21 subjects comprised of eight healthy volunteers (3 male; mean age: 48 yr; age range: 30–81 yr) and 13 patients with suspected peripheral arterial disease (5 male; mean age: 67 yr; age range: 47–81 yr) were enrolled in an IRB-approved and HIPAA-compliant prospective study and provided informed consent. All subjects were imaged with the fluoroscopic tracking MRA protocol. Ten patients were additionally imaged with a clinical CT angiography (CTA) runoff exam. Two readers scored the MRA studies for vessel signal and sharpness and presence of confounding artifact and venous contamination at 35 arterial segments. Mean aggregate scores were assessed. The paired MRA and CTA studies were additionally scored for visualization of disease, reading confidence, and overall diagnostic quality and compared using a Wilcoxon signed rank test. Results Real-time fluoroscopic tracking performed well technically in all studies. Vessel segments were scored good to excellent in all evaluation categories with the following exceptions: for vessel signal and sharpness, the abdominal aorta, iliac arteries, distal plantar arteries, and plantar arch were scored fair to good; and for presence of confounding artifact, the abdominal aorta and iliac arteries were scored fair. The MRA and CTA studies did not differ significantly in any scoring category (Reader 1: p=0.50, 0.39, and 0.39; Reader 2: p=0.41, 0.61, 0.33). CTA tended to be favored overall as it was scored “substantially better” in 20% (4/20) and 25% (5/20) of the pooled evaluations for the visualization of disease and overall image quality categories, respectively, versus 5% (1/20) for MRA in both categories. Conclusion Three-station bolus chase MRA using real-time fluoroscopic tracking provided high-spatial-resolution arteriograms of the peripheral vasculature, enabled precise triggering of table motion, and compared well to CTA.

Two hypotheses were tested: (a) that view-to-view variations in bulk phase and modulus of magnetization in vascular volume elements can indicate the presence of disordered blood flow, and (b) that a substantial loss of signal intensity on magnetic resonance (MR) angiograms of poststenotic regions is due to view-to-view changes in magnetization. To test these hypotheses, a technique was developed in which view-to-view variations in transverse magnetization were used to create angiographic projection images, which showed only disordered flow (disordered flow maps) in vitro and in vivo. In phantom studies, this technique recovered signal intensity downstream from stenoses. A combination of disordered flow maps with morphologic images improved visualization of stenotic regions and provided information on characteristics of local flow. These results show that view-to-view variations in transverse magnetization occur in regions of disordered flow and are an important cause of loss of signal intensity. This technique can provide information about dynamic blood flow and improve depiction of anatomic structures on MR angiograms.