In multiple meta-analyses and prospective studies, contrast-enhanced MRA for the detection of hemodynamically significant arterial stenosis has yielded a sensitivity and specificity up to 97% and 96%, respectively, when compared to DSA [31-34]. Compared to CTA, MRA does not suffer from artifact related to calcium within small vessels. In addition, time- resolved sequences allow for dynamic visualization and separation of arterial and venous flow, allowing for increased diagnostic accuracy. In a study comparing to DSA, contrast-enhanced, time-resolved MRA at 3T with calf compression to prevent venous contamination demonstrated superior visualization of below-the-knee arterial vasculature than DSA [35]. Contrast-enhanced MRA may be an optimal imaging modality for patients at high risk for calcification of the distal arterial vessels, particularly patients with suspected significant arterial calcific plaque burden [16,36]. The imaging-related disadvantages of MRA include low signal-to-noise ratio, limited spatial resolution, longer acquisition times, and a greater potential for artifact-related image degradation, namely, from motion and susceptibility from metal stents and orthopedic hardware; techniques have been developed to address some of these issues [37-40]. Safety risks inherent to MRI should also be considered, such as magnetic field bioeffects. MRA of the abdomen and pelvis can be obtained in addition to bilateral lower extremity runoff when aortoiliac disease is a concern or if the aorta and iliac arteries have not already been imaged and to assess for vascular suitability before endovascular intervention. MRA Abdomen and Pelvis with Bilateral Lower Extremity Runoff Without IV Contrast Noncontrast MRA techniques have been in use for decades in the form of 2-D and 3-D time-of-flight. However, noncontrast MRA is rarely used in the setting of PAD or ALI because of long acquisition times relative to contrast- enhanced MRA and CTA.
Sudden Onset of Cold Painful Leg. In multiple meta-analyses and prospective studies, contrast-enhanced MRA for the detection of hemodynamically significant arterial stenosis has yielded a sensitivity and specificity up to 97% and 96%, respectively, when compared to DSA [31-34]. Compared to CTA, MRA does not suffer from artifact related to calcium within small vessels. In addition, time- resolved sequences allow for dynamic visualization and separation of arterial and venous flow, allowing for increased diagnostic accuracy. In a study comparing to DSA, contrast-enhanced, time-resolved MRA at 3T with calf compression to prevent venous contamination demonstrated superior visualization of below-the-knee arterial vasculature than DSA [35]. Contrast-enhanced MRA may be an optimal imaging modality for patients at high risk for calcification of the distal arterial vessels, particularly patients with suspected significant arterial calcific plaque burden [16,36]. The imaging-related disadvantages of MRA include low signal-to-noise ratio, limited spatial resolution, longer acquisition times, and a greater potential for artifact-related image degradation, namely, from motion and susceptibility from metal stents and orthopedic hardware; techniques have been developed to address some of these issues [37-40]. Safety risks inherent to MRI should also be considered, such as magnetic field bioeffects. MRA of the abdomen and pelvis can be obtained in addition to bilateral lower extremity runoff when aortoiliac disease is a concern or if the aorta and iliac arteries have not already been imaged and to assess for vascular suitability before endovascular intervention. MRA Abdomen and Pelvis with Bilateral Lower Extremity Runoff Without IV Contrast Noncontrast MRA techniques have been in use for decades in the form of 2-D and 3-D time-of-flight. However, noncontrast MRA is rarely used in the setting of PAD or ALI because of long acquisition times relative to contrast- enhanced MRA and CTA.