Steps in evaluating brain tumors

Identify images (CT, MR): Evaluate all MR sequences.
MRI is superior to CT.

Locate the lesion: Intra-axial vs. extra-axial.
Location suggests tumors likely to occur in that site based on the structure that is present at that site.

MR signal: Evaluate T1 and T2 wtd. signals to characterize cyst, calcification, blood, fat, etc.

Enhancement: Look at pre-contrast T1 and post-contrast T1 images as a pair. Most tumors enhance with contrast because blood brain barrier is broken. It is the character of enhancement that is helpful.

Age of the patient: First decade vs. adult.

Clinical history:

Differential diagnosis: Common lesions

Diagnosis:

Anatomical sites of tumor

Intra-axial: Metastasis, Astrocytoma

Ventricles: Ependymoma

Skull base/extra-axial tumors:

Anterior cranial fossa:

• Meningioma

Middle cranial fossa:

• Sellar: Pituitary Macroadenoma
• Parasellar: Meningioma/Schwannoma

Posterior cranial fossa:

• Cerebellopontine angle: Schwannoma / Meningioma
• Foramen magnum: Meningioma

Age group

Children and young adults:

• Medulloblastoma
• Ependymoma
• Craniopharyngioma
• Gliomas grade 1 astrocytoma
  • Pilocytic Astrocytoma
  • Ganglioglioma

Adults:

• Metastasis most common
• Astrocytomas
  • grade II Astrocytoma
  • grade III Astrocytoma
  • grade IV Glioblastoma
• Meningioma
• Schwannoma
• Pituitary Macroadenomas