Finally, CT and MR remain the primary imaging modalities for characterization of adrenal lesions. Recently developed techniques may offer additional information. The value of PET and PET/CT has already been proven and other new functional imaging techniques such as diffusion weighted imaging and MR spectroscopy may play an important role in lesion characterization in the near future. These exciting techniques may soon to be routinely available and could potentially further obviate the need for adrenal biopsies that are performed in indeterminate cases.