Single injection protocol for coronary and lower extremity CT angiographies in patients suspected for peripheral arterial disease

Abstract

To evaluate the feasibility of a single injection protocol for coronary CT angiography (CTA) and lower extremity CTA in patients suspected for peripheral arterial disease (PAD).This prospective observational study included a total of 103 patients who showed an ankle brachial index ≤0.9 and underwent the single injection protocol for coronary and lower extremity CTA. All CTAs used iodinated contrast (weight × 0.06 mL/s × 20 seconds). A prospective Electrocardiogram (ECG)-gated coronary CTA was performed, followed by helical lower extremity CTA beginning 9 seconds after coronary CTA. Using catheter angiography as reference standard, diagnostic ability of CTA was evaluated.The mean total volume of iodinated contrast used was 70 ± 14 mL. Contrast opacification in the superficial femoral artery was adequate (408 ± 97 Hounsfield Units [HU]) and PAD was detected in 72.8% (75/103). The estimated radiation doses for lower extremity and coronary CTA were 3.6 ± 1.2 and 5.5 ± 4.5 mSv. A significant coronary stenosis was detected in 47 patients (45.6%). Coronary CT image quality was recorded as excellent in 86.4%, acceptable in 11.7%, and unacceptable for 1.9%. Contrast opacification within the superficial femoral artery was adequate in all cases while 27.2% needed an additional scan below the calf to capture the contrast bolus arrival in the smaller lower extremity vessels. Segment based sensitivity, specificity, positive, and negative predictive values were 57.9%, 97.9%, 73.8%, and 95.9% for the coronary CTA, and 63.4%, 91.5%, 76.3%, and 85.3% for peripheral CTA.A single injection protocol for coronary CTA and lower extremity CTA is feasible with a relatively small volume of iodinated contrast.

Figure 1

Example set of each score for image quality on images orthogonal to the centerline of the vessel as follows: excellent (free of motion artifact), acceptable (small motion artifact), and unacceptable (severe motion artifact).

Figure 2

A 60-year-old woman with claudication showing ankle brachial index of 0.93/0.7. A single contrast injection CT angiography (CTA) protocol to assess both the coronaries and the lower extremity runoff was performed. (A) Coronary CTA showed an occlusion of mid segment in the right coronary artery (RCA) (arrow), 75% stenosis in the diagonal branch (double arrow), and 90% stenosis in the left circumflex artery (LCx) (open arrow). (B) Lower extremity CTA showed 75% stenosis in the left common iliac artery. (C, D) Both coronary catheter angiography (C) and peripheral angiography (D) confirmed lesions and the percutaneous intervention was performed.