Figure 11b. Benign tumor: desmoid tumor in a 27-year-old woman. Oblique sagittal T1-weighted image (a), coronal T2-weighted image (b), and gadolinium-enhanced T1-weighted image (c) of the right brachial plexus demonstrate an irregular enhancing mass (arrowheads) infiltrating the brachial plexus (solid arrows). This mass has the characteristic decreased T2 signal intensity seen in desmoid tumors. In a, open arrow = subclavian vein.