Figure 4b. Metastatic breast cancer in a 58-year-old woman. Axial T1-weighted image (a) and sagittal T1-weighted nonenhanced (b) and gadolinium-enhanced (c) images show an infiltrating mass (arrowheads) encasing the left subclavian vessels and brachial plexus. The subclavian vein (straight arrow) is nearly obliterated with what proved at biopsy to be metastatic breast cancer. Curved arrow = subclavian vein.