Like MRA, CTA is a cross-sectional technique, which shows nonvascular findings as well as vascular lesions associated with aneurysms and cystic adventitial disease that are not detected with the projectional technique of catheter arteriography. CTA alone can be used to plan treatment, including assessment of the length, severity, and number of stenoses [15,16]. Compared with catheter angiography, the sensitivity and specificity of CTA for detection of stenoses >50% diameter are 90% to 100% [10,17-20]. Accuracy in patients with bypass grafts is excellent compared with duplex US [21]. CTA is also more clinically useful than duplex US [21]. However, heavily calcified atheromatous disease can limit the ability to interpret CT images. This drawback is usually more pronounced in tibial arteries. Identification of patients who may be unsuitable candidates for CTA of the tibial arteries (eg, >80 years of age, diabetic, on dialysis) will reduce the number of nondiagnostic studies [22]. Dual-energy CTA can reduce blooming and beam-hardening artifact created by heavily calcified atheromatous disease and metallic stents [23]. CTA without IV contrast can be performed before CTA with IV contrast to fine-tune the scan range and identify calcified plaque and calcium within thrombus [24]. Compared with MRA, CT has the advantages of more rapid acquisition, better safety in patients with pacemakers or defibrillators, and generally less severe artifacts from metal. Finally, claustrophobia is far less of a problem. CTA of one or both lower extremities can be performed without imaging the abdomen and pelvis when aortoiliac disease is not a concern or the state of the aorta and iliac arteries is already known. MRA Abdomen and Pelvis with Bilateral Lower Extremity Runoff With IV Contrast Contrast-enhanced MRA (CE-MRA) techniques continue to evolve and improve.
Lower Extremity Arterial Claudication Imaging Assessment for Revascularization. Like MRA, CTA is a cross-sectional technique, which shows nonvascular findings as well as vascular lesions associated with aneurysms and cystic adventitial disease that are not detected with the projectional technique of catheter arteriography. CTA alone can be used to plan treatment, including assessment of the length, severity, and number of stenoses [15,16]. Compared with catheter angiography, the sensitivity and specificity of CTA for detection of stenoses >50% diameter are 90% to 100% [10,17-20]. Accuracy in patients with bypass grafts is excellent compared with duplex US [21]. CTA is also more clinically useful than duplex US [21]. However, heavily calcified atheromatous disease can limit the ability to interpret CT images. This drawback is usually more pronounced in tibial arteries. Identification of patients who may be unsuitable candidates for CTA of the tibial arteries (eg, >80 years of age, diabetic, on dialysis) will reduce the number of nondiagnostic studies [22]. Dual-energy CTA can reduce blooming and beam-hardening artifact created by heavily calcified atheromatous disease and metallic stents [23]. CTA without IV contrast can be performed before CTA with IV contrast to fine-tune the scan range and identify calcified plaque and calcium within thrombus [24]. Compared with MRA, CT has the advantages of more rapid acquisition, better safety in patients with pacemakers or defibrillators, and generally less severe artifacts from metal. Finally, claustrophobia is far less of a problem. CTA of one or both lower extremities can be performed without imaging the abdomen and pelvis when aortoiliac disease is not a concern or the state of the aorta and iliac arteries is already known. MRA Abdomen and Pelvis with Bilateral Lower Extremity Runoff With IV Contrast Contrast-enhanced MRA (CE-MRA) techniques continue to evolve and improve.