Answer
MRI provides superior delineation of the normal anatomy of the brachial plexus because of its multiplanar capabilities. The absence of streak artifact from bone and accurate identification of vessels are some of the advantages of MRI. It also has superior soft-tissue contrast, and it is more accurate than other methods in documenting or excluding brachial plexus involvement by the tumor. [19]
Compared with other techniques, MRI is more accurate in the evaluation of extension to the vertebral body, spinal canal, brachial plexus, and subclavian artery. This advantage is important, because vertebral body, spinal canal, and upper brachial plexus invasion are contraindications to surgical resection.
In a study of 31 patients with Pancoast tumors, MRI had a sensitivity of 88%, a specificity of 100%, and an overall accuracy of 94%. [10]
(See the images below.)
Pancoast tumor. Sagittal fast spin-echo T2-weighted MRI shows collapsed vertebrae and cord compression at C7, T1, and T2 caused by a soft tissue mass.
Pancoast tumor. Sagittal gradient-echo T2-weighted MRI demonstrates a soft tissue mass involving C7, T1, and T2, with collapse of the vertebrae and moderate cord compression.
Pancoast tumor. Axial T1-weighted image shows cord compression caused by a large, enhancing mass. The right subclavian artery is not involved.
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Pancoast tumor. A 53-year-old man with a 50 pack-year history of smoking began experiencing upper back pain for several weeks. PA chest radiograph shows asymmetry of the apices (superior sulcus). The right apex is more opaque than the left. When the image is enlarged, the partially destroyed second and third right posterior ribs near the costovertebral junction can be seen.
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Pancoast tumor. Axial nonenhanced CT image of the upper dorsal spine demonstrates a soft tissue mass destroying the vertebra on the right and the right posterior elements, including the pedicle and part of the posterior spinous process.
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Pancoast tumor. Sagittal fast spin-echo T2-weighted MRI shows collapsed vertebrae and cord compression at C7, T1, and T2 caused by a soft tissue mass.
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Pancoast tumor. Sagittal gradient-echo T2-weighted MRI demonstrates a soft tissue mass involving C7, T1, and T2, with collapse of the vertebrae and moderate cord compression.
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Pancoast tumor. Axial T1-weighted image shows cord compression caused by a large, enhancing mass. The right subclavian artery is not involved.
