However, CT with IV contrast has the advantage of providing assessment of vascular patency, which is a potential complication in postintervention setting for patients with aTOS. CTA Chest CTA is performed to evaluate arterial compression in neutral and elevated arm positions. An indentation of the anterior wall of the subclavian artery as it passes around the anterior scalene muscle may be observed [13] as well as displacement of the subclavian vessels. Arterial compression is assessed by using arterial cross-sections produced by sagittal reformation of data. Sagittal reformation can show the location and severity of the arterial compression, and volume-rendered images allow simultaneous analysis of bones and subclavian artery. Arterial stenosis is expressed as the percentage of reduction of the cross-sectional area or the diameter of the artery [1]. Multiple studies have demonstrated the utility of CT in evaluation of the upper-limb arteries and veins; however, reliance on axial slices alone can lead to misrepresentation of the degree of any stenosis, with one study showing underestimation of stenosis found in 43% of transverse CT scans but only 10% of sagittal reformations. Overestimation of stenosis was also more frequent on surface displays with 3-D shading (16%) than on volume rendered images (7%) [12], advancing the case for evaluation of these studies on vascular workstations. For arterial compression, there is evidence of good correlation of CT findings with operative findings and results of decompression [41]. CTA may be performed in the postintervention setting to evaluate interval changes in the thoracic outlet, assess adequate decompression, and follow-up vessel patency or complications. Recurrent or persistent venous thrombosis may require reintervention. CTV Chest CTV is performed for evaluation of venous compression. This specific modality is therefore of limited use in aTOS.
Thoracic Outlet Syndrome. However, CT with IV contrast has the advantage of providing assessment of vascular patency, which is a potential complication in postintervention setting for patients with aTOS. CTA Chest CTA is performed to evaluate arterial compression in neutral and elevated arm positions. An indentation of the anterior wall of the subclavian artery as it passes around the anterior scalene muscle may be observed [13] as well as displacement of the subclavian vessels. Arterial compression is assessed by using arterial cross-sections produced by sagittal reformation of data. Sagittal reformation can show the location and severity of the arterial compression, and volume-rendered images allow simultaneous analysis of bones and subclavian artery. Arterial stenosis is expressed as the percentage of reduction of the cross-sectional area or the diameter of the artery [1]. Multiple studies have demonstrated the utility of CT in evaluation of the upper-limb arteries and veins; however, reliance on axial slices alone can lead to misrepresentation of the degree of any stenosis, with one study showing underestimation of stenosis found in 43% of transverse CT scans but only 10% of sagittal reformations. Overestimation of stenosis was also more frequent on surface displays with 3-D shading (16%) than on volume rendered images (7%) [12], advancing the case for evaluation of these studies on vascular workstations. For arterial compression, there is evidence of good correlation of CT findings with operative findings and results of decompression [41]. CTA may be performed in the postintervention setting to evaluate interval changes in the thoracic outlet, assess adequate decompression, and follow-up vessel patency or complications. Recurrent or persistent venous thrombosis may require reintervention. CTV Chest CTV is performed for evaluation of venous compression. This specific modality is therefore of limited use in aTOS.