Given the need to assess the subclavian vein as well as venous collaterals in vTOS, noncontrast MRI is insufficient alone; the addition of IV contrast, particularly when an MRV protocol is performed, provides optimal assessment. The combination of soft-tissue and vascular assessment provided by MRI with IV contrast makes it an excellent modality when compared with US and CT; however, the longer acquisition times may prove difficult for highly symptomatic patients. MRI with IV contrast may also be performed in the postintervention setting to evaluate interval changes in the thoracic outlet and assess adequate decompression. MRA Chest MRA is not optimized for evaluation of the venous structures. If there are overlapping symptoms, review of the other variants in this document may help with protocol optimization. Interestingly, in one study [19], all patients with arterial compression were found to have venous compression during arm abduction. In patients with venous compression on one side, 71% had significant bilateral venous compression. Of these patients with bilateral imaging findings, only 21% had bilateral clinical symptoms or findings suggestive of TOS. Therefore, MRA has the potential to overdiagnose vTOS, and clinical symptoms must be taken into account. MRA may also be performed in the postintervention setting to evaluate interval changes in the thoracic outlet, assess adequate decompression, and confirm arterial patency. MRV Chest MRV is commonly performed in conjunction with MRI chest [34-36]. The primary MRV finding is narrowing of the subclavian vein; however, other findings, such as complete occlusion, collateral vessel formation, and visualization of thrombus, aid in the diagnosis of vTOS. Interestingly, in one study [19], all patients with arterial compression were found to have venous compression during arm abduction. In patients with venous compression on one side, 71% had significant bilateral venous compression.
Thoracic Outlet Syndrome. Given the need to assess the subclavian vein as well as venous collaterals in vTOS, noncontrast MRI is insufficient alone; the addition of IV contrast, particularly when an MRV protocol is performed, provides optimal assessment. The combination of soft-tissue and vascular assessment provided by MRI with IV contrast makes it an excellent modality when compared with US and CT; however, the longer acquisition times may prove difficult for highly symptomatic patients. MRI with IV contrast may also be performed in the postintervention setting to evaluate interval changes in the thoracic outlet and assess adequate decompression. MRA Chest MRA is not optimized for evaluation of the venous structures. If there are overlapping symptoms, review of the other variants in this document may help with protocol optimization. Interestingly, in one study [19], all patients with arterial compression were found to have venous compression during arm abduction. In patients with venous compression on one side, 71% had significant bilateral venous compression. Of these patients with bilateral imaging findings, only 21% had bilateral clinical symptoms or findings suggestive of TOS. Therefore, MRA has the potential to overdiagnose vTOS, and clinical symptoms must be taken into account. MRA may also be performed in the postintervention setting to evaluate interval changes in the thoracic outlet, assess adequate decompression, and confirm arterial patency. MRV Chest MRV is commonly performed in conjunction with MRI chest [34-36]. The primary MRV finding is narrowing of the subclavian vein; however, other findings, such as complete occlusion, collateral vessel formation, and visualization of thrombus, aid in the diagnosis of vTOS. Interestingly, in one study [19], all patients with arterial compression were found to have venous compression during arm abduction. In patients with venous compression on one side, 71% had significant bilateral venous compression.