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2Brain

Anatomy

Eective description and analysis of cere-bral pathology requires knowledge of vis-ible cerebral structures (lobes, basal nuclei, ventricles), vascular territories, and arte-rial and venous anatomy. Cerebral anatomy is shown in Fig. 2.1. Cerebral vascular ter-ritories and anatomy are seen in Fig. 2.2.

◆ Clinical Presentations and Dierential Diagnosis

Clinical Presentations and Appropriate Initial Studies

Trauma

Noncontrast head CT is indicated. Head or neck CT angiography should be considered if injury mechanism or initial findings indi-cate a likely cervical vascular injury.

• Skull fracture

• Epidural hematoma

• Subdural hematoma

• Venous epidural hematoma

• Traumatic subarachnoid hemorrhage

• Contusion

• Diuse axonal injury

• Skull fracture

• Temporal bone fracture

• Facial bone fracture

Headache

Noncontrast head CT is indicated. Postcon-trast head CT or MRI may be considered in immunocompromised patients, in those with underlying malignancy and concern for metastatic disease, and in patients oth-erwise at risk for brain abscess.

• Subarachnoid hemorrhage

• Venous sinus thrombosis

• Meningitis

• Hydrocephalus

• Cerebral hemorrhage

• Mass (tumor or abscess)

• Sinusitis

• Otitis/mastoiditis

◆Imaging and AnatomyImaging

Head CT (Noncontrast)

Indications: Head injury, altered mental status, seizure, suspected hemorrhage or infarct.

Technique: 5-mm axial images in soft tissue and bone algorithm

Head CT (Noncontrast Helical)

Indications: Head injury with concurrent imaging of the face and cervical spine.

Technique: Helical 0.6-mm dataset with 5-mm axial, 2-mm sagittal, and 2-mm coronal reformations of head, face, and cervical spine. Images obtained from skull vertex to thoracic inlet.

CT Arteriogram

Indications: Subarachnoid hemorrhage.

Suspected aneurysm or vascular malformation. Acute cerebral infarct. Penetrating injury.

Technique: Helical 0.6-mm dataset with 2.5-mm axial, 2-mm sagittal, and 2-mm coronal reformations. Images can be obtained from the vertex either to the skull base or to the thoracic inlet depending on the indication.

Contrast: 60–100 mL at 3–4 mL/sec in arterial phase.

CT Venogram

Indications: Suspected venous sinus thrombosis (atypical headache). Trauma to skull base with potential venous sinus disruption.

Technique: Helical 0.6-mm dataset with

2.5-mm axial, 2-mm sagittal, and 2-mm coronal reformations. Images obtained from vertex to skull base.

Contrast: 60–100 mL at 3–4 mL/sec in venous phase (30–45 sec delay).