This section will focus on imaging characteristics of CNS tumors that are commonly seen in a neuro-oncology center. Since these conditions can be difficult to distinguish from others that mimic tumor, such as infarct, demyelination, and vascular lesions, we will give examples to help understand the subtlety of their important differences. Many tumors have a classic appearance because of their association with specific anatomic locations and signal characteristics. We will also discuss leptomeningeal disease that sometimes has a subtle appearance and can be difficult to diagnose. Once a patient is treated for a CNS primary tumor, changes on follow-up imaging can be difficult to categorize as treatment related versus progression of disease. Advanced imaging is sometimes of value in these instances.