Multiple studies have demonstrated the utility of CTV with IV contrast in evaluation of the upper-limb 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 in 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], thus advancing the case for evaluation of these studies using these multiplanar tools in addition to standard reformations. CTV may be performed in the postintervention setting to evaluate interval changes in the thoracic outlet, assess adequate decompression, and follow-up on vessel patency or complications. Recurrent or persistent venous thrombosis may require reintervention. MRI Chest MRI for vTOS is performed to delineate anatomy and evaluate the pertinent anatomic spaces in both neutral and arms-abducted positions. Noncontrast MRI findings include effacement of fat adjacent to the subclavian vein. T1- weighted imaging performed in sagittal and axial planes can also demonstrate causative lesions, including cervical ribs, congenital fibromuscular anomalies, and muscular hypertrophy. Venous compression has been routinely demonstrated in all 3 compartments of the thoracic outlet in both asymptomatic and symptomatic populations when the arms were abducted [17]. Therefore, a finding of compression on abduction must be interpreted carefully. In symptomatic patients, venous thrombosis and collateral circulation Thoracic Outlet Syndrome are detected in both neutral and stressed arm positions, suggesting these findings are more reliably diagnostic of vTOS. They represent an objective, but likely chronic, finding of clinically significant venous compression.
Thoracic Outlet Syndrome. Multiple studies have demonstrated the utility of CTV with IV contrast in evaluation of the upper-limb 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 in 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], thus advancing the case for evaluation of these studies using these multiplanar tools in addition to standard reformations. CTV may be performed in the postintervention setting to evaluate interval changes in the thoracic outlet, assess adequate decompression, and follow-up on vessel patency or complications. Recurrent or persistent venous thrombosis may require reintervention. MRI Chest MRI for vTOS is performed to delineate anatomy and evaluate the pertinent anatomic spaces in both neutral and arms-abducted positions. Noncontrast MRI findings include effacement of fat adjacent to the subclavian vein. T1- weighted imaging performed in sagittal and axial planes can also demonstrate causative lesions, including cervical ribs, congenital fibromuscular anomalies, and muscular hypertrophy. Venous compression has been routinely demonstrated in all 3 compartments of the thoracic outlet in both asymptomatic and symptomatic populations when the arms were abducted [17]. Therefore, a finding of compression on abduction must be interpreted carefully. In symptomatic patients, venous thrombosis and collateral circulation Thoracic Outlet Syndrome are detected in both neutral and stressed arm positions, suggesting these findings are more reliably diagnostic of vTOS. They represent an objective, but likely chronic, finding of clinically significant venous compression.