A thorough history should be obtained, and an appropriate physical examination with a specific emphasis on the neurologic exam should be performed.

A patient’s performance status should be evaluated using a validated scale such as the Karnofsky performance scale (KPS), ECOG performance status, neurologic function status (NFS), or mini mental status exam (MMSE).

All patients should have an MRI of the brain performed for diagnostic and treatment planning purposes. MRI sequences should include precontrast T1-weighted, precontrast T2-weighted, and fluid-attenuated inversion recovery (FLAIR) images. Multiplanar (axial, sagittal, and coronal) post-contrast gadolinium-enhanced T1-weighted images should also be obtained. For enhancing tumors, high-resolution modes such as magnetization-prepared rapid gradient echo (MP-RAGE) are utilized for accurate delineation of the disease of interest. A constructive interference in steady state (CISS) or 3D fast imaging with steady state acquisition (3D FIESTA) may be useful for identifying the cranial nerves. Fat suppression MRI scans are also useful in determining target volumes for some tumors such as optic nerve sheath meningiomas.

On diagnostic CT scans, meningiomas appear as well-circumscribed, extra-axial masses that displace adjacent parenchymal tissue. They are isodense or hyperdense when compared to the normal brain tissue and demonstrate strong homogeneous contrast enhancement. Calcifications may be visualized in 20–30 % of meningiomas, and approximately half of cranial base meningiomas are associated with adjacent bone changes such as hyperostosis and osteolysis (Pieper et al. 1999).

Typically, meningiomas are isointense or hypointense to gray matter on T1-weighted MR images and isointense, hypointense, or hyperintense on T2-weighted images. On the FLAIR sequence, meningiomas are typically hyperintense to gray matter (Tsuchiya et al. 1996).

Approximately 90 % of meningiomas demonstrate strong homogenous enhancement with gadolinium; 10 % demonstrate mild enhancement (Pamir et al. 2010) (Fig. 4a, b).

Approximately two-thirds of meningiomas exhibit a characteristic dural thickening, classically known as a “dural tail,” which extends 0.5–3.0 cm from the meningioma mass. Imaging criteria for defining the dural tail include (Rokni-Yazdi and Sotoudeh 2006; Goldsher et al. 1990):

Approximately 60 % of meningiomas are accompanied by peritumoral edema, seen most frequently with meningiomas of the olfactory groove, parasagittal region, and convexity (Pamir et al. 2010).

On diagnostic CT scans, pituitary microadenomas appear hypodense and exhibit less contrast enhancement than a normal pituitary gland (Swearingen and Biller 2008).

Typically, pituitary microadenomas are hypointense to the normal pituitary gland on T1-weighted MR images, but can be isointense in 25 % of cases (Bonneville et al. 2005). The isointensity of pituitary adenomas on T2-weighted images can be quite variable; for example, approximately 80 % of prolactinomas and 67 % of GH-secreting microadenomas are isointense or hypointense (Swearingen and Biller 2008; Bonneville et al. 2005).

Macroadenomas exhibit variable MRI features, but are typically hypointense on T1-weighted MR images and hyperintense to the normal pituitary gland on T2-weighted MR images (Swearingen and Biller 2008).

Pituitary adenomas that are partially cystic may be hypointense on T1-weighted MR images. If there is a significant protein or lipid concentration in the pituitary cysts or if there is intralesional hemorrhage, there may be areas of hyperintensity observed on T1-weighted MR images.

Pituitary adenomas demonstrate heterogeneous, partial, or incomplete enhancement with gadolinium (in contrast to the strong homogeneous enhancement visualized with sellar or parasellar meningiomas) (Taylor et al. 1992) (Fig. 5a, b).

In pituitary adenomas with suprasellar extension, it is important to measure the extent of disease through the diaphragm sellae, including the closest distance between the tumor and the optic chiasm and optic nerves (Fig. 6a, b).

A complete hormonal evaluation should be performed including measurement of the serum prolactin concentration, serum insulin-like growth factor (IGF)-1, serum growth hormone levels after a glucose load, 24-h urine cortisol, ACTH, LH, FSH, free T4, T3, and serum TSH.

Visual field and visual acuity testing should be performed to determine any pattern of vision loss.

On diagnostic CT scans, vestibular schwannomas appear as well-demarcated isodense masses that demonstrate enhancement with IV contrast. The absence of calcifications helps to differentiate these tumors from meningiomas radiographically.

Typically, vestibular schwannomas are isointense or hypointense to the pons on T1-weighted MR images and heterogeneously hyperintense on T2-weighted images (Fig. 7).

Vestibular schwannomas demonstrate strong homogeneous enhancement with gadolinium.

For diagnostic evaluation of vestibular schwannomas, a thin-slice T1-weighted gadolinium-enhanced MRI of the cerebellopontine angle is helpful.

A constructive interference in steady state (CISS) or 3D fast imaging with steady state acquisition (3D FIESTA) sequence can produce high-resolution images of the tumor and vestibulocochlear nerve by outlining the structures surrounded by CSF.

Ancillary testing performed at diagnosis includes pure tone and speech audiometry, brainstem-evoked response audiometry, and vestibular testing.

On CT scans, AVMs appear as tortuous vessels that are isodense or hyperdense. Calcifications may be present in the vessels or the surrounding brain. AVMs demonstrate strong enhancement with IV contrast. Hemorrhages may be visualized around the nidus and the adjacent brain.

On CTA, the feeding arteries and draining veins demonstrate enhancement.

Typically, AVMs appear as hypointense flow voids on both T1-weighted and T2-weighted MR images.

The nidus of the AVM demonstrates strong gadolinium enhancement, and the draining veins are also visualized on contrast-enhanced MR images (Fig. 8a, b).