CTA Modern CTA has been demonstrated to be comparable to the gold standard (catheter-based angiography) for the detection of hemodynamically significant stenoses (>50%) with sensitivity, specificity, and accuracy of 99%, 98%, and 98%, respectively [31]. Refinements in CT protocols have also compared favorably to MRA with no statistically significant difference between the two modalities in the evaluation of claudication or CLI [32]. Arterial opacification is significantly improved by using high-density compact contrast boluses, which is rapidly becoming the standard of care with equivalent iodine dose to previous standard bolus technique [33]. Potential drawbacks of CTA include the exposure to ionizing radiation and the use of iodinated contrast, which presents the potential for allergic reaction or contrast-induced nephropathy, particularly in those patients who already possess some degree of renal impairment. Metallic streak artifact is often problematic in patients with postsurgical changes or implanted hardware. Additionally, in extremely obese patients, the signal-to-noise ratio becomes somewhat prohibitive. Evaluation of densely calcified vessels can be difficult with CTA because of the similar density between plaque and contrast and the blooming artifact created by the former, leading to overestimation of the degree of stenosis in many cases, as well as the inability to determine patency in stented vessels. Because of the density of calcified plaque in relation to the relatively small lumen of the tibial vessels, CTA has traditionally suffered in the infrageniculate distribution [34]. Multiple studies have now validated dual-energy CTA as a practical and effective method for subtraction of calcified plaque and soft tissues, allowing for simultaneous creation of conventional CTA data sets and angiogram-like composite images of the vasculature alone.
Lower Extremity Arterial Revascularization Post Therapy Imaging. CTA Modern CTA has been demonstrated to be comparable to the gold standard (catheter-based angiography) for the detection of hemodynamically significant stenoses (>50%) with sensitivity, specificity, and accuracy of 99%, 98%, and 98%, respectively [31]. Refinements in CT protocols have also compared favorably to MRA with no statistically significant difference between the two modalities in the evaluation of claudication or CLI [32]. Arterial opacification is significantly improved by using high-density compact contrast boluses, which is rapidly becoming the standard of care with equivalent iodine dose to previous standard bolus technique [33]. Potential drawbacks of CTA include the exposure to ionizing radiation and the use of iodinated contrast, which presents the potential for allergic reaction or contrast-induced nephropathy, particularly in those patients who already possess some degree of renal impairment. Metallic streak artifact is often problematic in patients with postsurgical changes or implanted hardware. Additionally, in extremely obese patients, the signal-to-noise ratio becomes somewhat prohibitive. Evaluation of densely calcified vessels can be difficult with CTA because of the similar density between plaque and contrast and the blooming artifact created by the former, leading to overestimation of the degree of stenosis in many cases, as well as the inability to determine patency in stented vessels. Because of the density of calcified plaque in relation to the relatively small lumen of the tibial vessels, CTA has traditionally suffered in the infrageniculate distribution [34]. Multiple studies have now validated dual-energy CTA as a practical and effective method for subtraction of calcified plaque and soft tissues, allowing for simultaneous creation of conventional CTA data sets and angiogram-like composite images of the vasculature alone.