Contrast-enhanced 3-D MR venography (MRV) techniques have been described at both 1.5T and 3T to assess for vTOS [19]. Breath-hold venous phase contrast-enhanced 3-D MRV and equilibrium phase imaging is obtained using a 3-D gradient-echo pulse sequence with fat suppression. These can be obtained in both neutral and stressed positions with the exact protocol customized to institutional needs. A coronal oblique 3-D slab is often obtained covering bilateral subclavian and axillary vessels. Unenhanced mask imaging is followed by multiphase contrast- enhanced dynamic acquisition in the same orientation. Noncontrast time-of-flight MRV may be considered, particularly in patients with contraindications to gadolinium-based contrast; however, these techniques suffer from flow artifacts that could lead to false diagnosis of stenosis or thrombosis [19]. Noncontrast MRV also requires long acquisition times when combined with postural maneuvers that may be difficult to achieve for patients with severe clinical symptoms. CTA chest and CTV chest specifically denote studies tailored to evaluate the chest and thoracic outlet. These include evaluation of central vessels as well as subclavian and axillary arteries and veins, respectively. This is distinct from CTA upper extremity and CTV upper-extremity protocols, which are designed to evaluate the entire limb peripherally to the level of the wrist. Discussion of Procedures by Variant Variant 1: Neurogenic thoracic outlet syndrome. Initial imaging and follow-up imaging after surgery or intervention. Arteriography Upper Extremity Selective upper-extremity arteriography is unable to directly image neurologic structures. This procedure is therefore not considered a first-line test for nTOS pre- or postoperatively. Catheter Venography Upper Extremity Dedicated endovascular catheter venography is unable to directly image neurologic structures. This procedure is therefore not considered a first-line test for nTOS pre- or postoperatively.
Thoracic Outlet Syndrome. Contrast-enhanced 3-D MR venography (MRV) techniques have been described at both 1.5T and 3T to assess for vTOS [19]. Breath-hold venous phase contrast-enhanced 3-D MRV and equilibrium phase imaging is obtained using a 3-D gradient-echo pulse sequence with fat suppression. These can be obtained in both neutral and stressed positions with the exact protocol customized to institutional needs. A coronal oblique 3-D slab is often obtained covering bilateral subclavian and axillary vessels. Unenhanced mask imaging is followed by multiphase contrast- enhanced dynamic acquisition in the same orientation. Noncontrast time-of-flight MRV may be considered, particularly in patients with contraindications to gadolinium-based contrast; however, these techniques suffer from flow artifacts that could lead to false diagnosis of stenosis or thrombosis [19]. Noncontrast MRV also requires long acquisition times when combined with postural maneuvers that may be difficult to achieve for patients with severe clinical symptoms. CTA chest and CTV chest specifically denote studies tailored to evaluate the chest and thoracic outlet. These include evaluation of central vessels as well as subclavian and axillary arteries and veins, respectively. This is distinct from CTA upper extremity and CTV upper-extremity protocols, which are designed to evaluate the entire limb peripherally to the level of the wrist. Discussion of Procedures by Variant Variant 1: Neurogenic thoracic outlet syndrome. Initial imaging and follow-up imaging after surgery or intervention. Arteriography Upper Extremity Selective upper-extremity arteriography is unable to directly image neurologic structures. This procedure is therefore not considered a first-line test for nTOS pre- or postoperatively. Catheter Venography Upper Extremity Dedicated endovascular catheter venography is unable to directly image neurologic structures. This procedure is therefore not considered a first-line test for nTOS pre- or postoperatively.