In the USA, over 44,500 people are diagnosed with primary brain tumors each year, approximately 20,500 of which are malignant (1). Primary brain tumors were the cause of death of approximately 12,920 people in 2009, according to an estimate by the American Cancer Society (2). Over 140,000 people in the USA are diagnosed each year with brain metastases, most commonly from lung, breast, and colon cancer primaries (3, 4). Nuclear imaging plays an important role in the diagnosis and management of both primary and metastatic brain tumors. This chapter will review the brain tumor pathology and clinical management and will discuss the role of nuclear imaging with a particular emphasis on the most common clinical indication for nuclear brain tumor imaging: evaluate for tumor recurrence versus post-radiation necrosis.

Staging

Gliomas

Gliomas are derived from glia which comprise 90% of the cells within the brain and play an important role in cellular homeostasis. Gliomas are subdivided into astrocytic, oligodendroglial, and mixed oligoastrocytic types (Table 5.1).

The WHO classification separates gliomas into Grades I–IV on the basis of histological features. Since they are often heterogeneous, gliomas are classified based on the most malignant sample of tissue analyzed. Low grade gliomas (Grades I–II) are characterized by high cellularity, pleomorphism, and a low cellular proliferation rate or mitotic index. High grade gliomas (Grade III–IV) have high cellularity and pleomorphism and a high mitotic index.