Acute Cerebral Ischemia-Infarction

KEY FACTS

Terminology

• Interrupted blood flow to brain resulting in cerebral ischemia/infarction with variable neurologic deficit

Imaging

• Major artery (territorial) infarct

  • Generally wedge-shaped; both GM and WM involved

• Embolic infarcts

  • Often focal/small, at GM-WM interface

• NECT

  • Hyperdense vessel = clot (dense middle cerebral artery sign)

  • Loss of GM-WM distinction in first 3 hours (50-70%)

    • –

      Insular-ribbon sign: GM-WM interface lost

    • –

      Disappearing basal ganglia sign

  • Calcified embolus

    • –

      Do not miss this (high risk of recurrent stroke)

• CTA: Excellent for major vessel occlusions

• pCT: CBF/CBV “mismatch” estimates penumbra

• MR

  • Parenchymal ± intraarterial FLAIR hyperintensity

  • ↑ intensity on DWI with corresponding ↓ on apparent diffusion coefficient

  • ↓ cerebral blood flow (CBF), cerebral blood volume on perfusion MR

Top Differential Diagnoses

• Normal vessel (MCA normally slightly hyperdense to brain)

• Nonvascular causes of hypodense brain (neoplasm, cerebritis, etc.)

Pathology

• Severely ischemic core; CBF < (6-8 cm³)/(100 g/min)

• Peripheral penumbra; CBF between (10-20 cm³)/(100 g/min)

Clinical Issues

• 2nd most common cause of death worldwide

• Most common cause of morbidity in USA

• Rx: IV thrombolysis (< 3 hours of onset), clot retrieval

TERMINOLOGY

IMAGING