Proton magnetic resonance imaging (MRI), with or without contrast enhancement, has emerged in recent years as the preferred noninvasive neuroimaging modality for clinical evaluation and monitoring the therapeutic response of intracranial lesions.However, this increasingly powerful imaging modality is not without limitations: the technique often lacks the specificity to differentiate pathologic lesions (e.g., brain tumors) from normal post-operative or posttherapy changes, such as edema and radiation-induced necrosis, and it can miss pathologic changes that do not exhibit contrast-enhancement (e.g., low-grade brain neoplasms).