CT Angiography for Arm Artery Evaluation

Advantages of CTA

The American College of Radiology recommends CTA as the most appropriate imaging modality for evaluating arterial blockages or stenosis in the arm, providing excellent visualization of vessel anatomy while being less invasive than conventional angiography 1, 2
CTA offers volumetric (3D) imaging, enabling extensive image post-processing, including multiplanar reformatted and maximum-intensity projection images to create a detailed arterial road map 3, 4
CTA provides simultaneous analysis of both vascular structures and surrounding anatomy, allowing for comprehensive assessment of potential causes of arterial compromise 1, 2
The sensitivity and specificity of CTA for detection of stenoses >50% diameter are 90% to 100% when compared with conventional angiography 4

The American College of Radiology suggests using a multislice CT scanner with collimation of 0.6 mm and reconstruction slice thickness between 0.5-1.0 mm for upper extremity CTA 5
Patient-adapted injection of non-ionic iodinated contrast agent (≥350 mg/mL) using a power injector (≥4 mL/s) is recommended for CTA 5
Arterial compression should be assessed using arterial cross-sections produced by sagittal reformation of data, as axial slices alone can lead to misrepresentation of stenosis degree 1, 2
Reliance on axial slices alone can lead to underestimation of stenosis in 43% of cases, while sagittal reformations reduce this to only 10% 1, 2

Conventional angiography is invasive and carries risks of catheterization, and is now primarily reserved for cases where endovascular intervention is planned rather than for diagnostic purposes alone 1, 3
CTA has largely replaced conventional angiography as the reference standard for arterial imaging in many institutions 4, 6
MRA with contrast provides excellent soft tissue contrast and vascular assessment, but has longer acquisition times and may be contraindicated in patients with certain implanted devices 2, 4
Duplex ultrasound is useful for initial screening and in patients with contrast allergy or renal dysfunction, but is operator-dependent and may have limitations in visualizing deeper vessels 6, 7

For suspected thoracic outlet syndrome affecting arm arteries, CTA in both neutral and elevated arm positions is recommended to assess for dynamic arterial compression 1, 2
CTA is valuable for post-intervention assessment to evaluate for vessel patency and complications such as restenosis, occlusion, or aneurysm formation 1, 2

Heavily calcified atheromatous disease can limit the ability to interpret CT images 4
Volume-rendered images are preferred over surface displays with 3D shading, as the latter can overestimate stenosis in 16% of cases (versus 7% with volume rendering) 1, 2
Timing of contrast administration is critical to avoid venous contamination or inadequate arterial opacification 3
Dual-energy CTA can reduce blooming and beam-hardening artifact created by heavily calcified disease and metallic stents when available 4