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14Emergency Imaging

Extraparenchymal Mass

• Meningioma

• Calvarial or dural metastasis

• Epidermoid

•Schwannoma (cranial nerves 5, 8, and 9)

• Arachnoid cyst

• Aneurysm

Sellar and Suprasellar Mass (Mnemonic: SATCHMO)

• Sellar tumor (pituitary adenoma), sarcoidosis

• Aneurysm

• Teratoma (and germ cell tumors)

• Craniopharyngioma

• Hypothalamic glioma

• Meningioma (planum sphenoidale) and metastasis

• Optic glioma

Ring Enhancing Mass (Mnemonic: MAGIC DR)

• Metastasis

• Abscess

• Glioma

• Infarct (evolving)

• Contusion (evolving)

• Demyelinating disease

• Radiation necrosis

Hemorrhagic Metastases (Mnemonic: CT/MR)

• Choriocarcinoma

• Thyroid carcinoma

• Melanoma

• Renal cell carcinoma

Remember that lung and breast carcinoma, even though less frequently hemorrhagic, are much more common and are more likely to be the cause of a hemorrhagic metastasis.

Acute Focal Neurologic Decit

Noncontrast head CT is indicated to exclude hemorrhage in suspected stroke. Noncon-trast head CT should be obtained to detect or exclude cerebral hemorrhage. MRI with a diusion-weighted sequence can confirm the clinical suspicion of infarct in patients whose initial CT appears to be normal. CT or MR angiography and perfusion studies can be obtained to better characterize the extent of ischemia and identify vascular stenoses or occlusion.

• Ischemic infarct

• Lacunar infarct

• Embolic infarct

• Border-zone (watershed) infarct

• Hypertensive hemorrhage

• Amyloid angiopathy with hemorrhage• Ruptured arteriovenous malformation

Altered Mental Status

Noncontrast head CT is indicated. Post-contrast head CT or MRI may be consid-ered in immunocompromised patients, in thosewith underlying malignancy and concern for metastatic disease, in patients otherwise at risk for brain abscess, and to evaluate further subtle abnormalities on noncontrast CT.

• Cerebritis (herpes encephalitis)

• Infarct

• Hemorrhage

• Parenchymal volume loss

• Chronic subdural hematoma

Dierential Diagnoses

Intraparenchymal Mass

• Glioma

• Metastasis

• Lymphoma

• Abscess

• Arteriovenous malformation