Figure 2b. (a) Axial unenhanced in-phase T1-weighted MR image shows a heterogeneous mass that is both slightly hyperintense and hypointense relative to the adjacent psoas muscle. (b) Axial out-of-phase T1-weighted MR image shows no appreciable lipid component. (c) Coronal T2-weighted MR image demonstrates the mass with a stellate hyperintense center. Note that the mass adheres closely to the aorta but does not directly invade the lumen. Note also that the viable tumor rim lacks the typical T2-weighted hyperintensity of most paragangliomas. (d) On a contrast-enhanced arterial phase T1-weighted MR image, the mass demonstrates prompt peripheral enhancement with central nonenhancement.