To be able to recognize the different types of border zone infarcts. To understand the underlying causal mechanisms of border zone infarcts. To describe the imaging features of border zone infarcts. To know how to select the best imaging tools.

Border zone infarcts, also known as watershed infarcts, are ischemic lesions that occur at the junction between two main cerebral vascular territories. Fig. 1 They are precipitated by hemodynamic impairment; however, microembolic etiology cannot be excluded. They account approximately 10% of all cerebral infarctions and are seen mostly in the elderly because of the higher incidence of hypotensive episodes, microemboli and arterial stenosis.

1. Classification Of Border Zone Infarcts Border zone infarcts can be divided into two main types: external (cortical) and internal (subcortical); however, mixed types also have been described. 1.1. External border zone infarcts (cortical) Fig. 2 These infarcts are located between major arterial territories and can be subdivided into: Anterior : between ACA and MCA. Fig. 4 Posterior: between MCA and PCA. Fig. 5 Paramedian white matter: between ACA and MCA. Fig. 5, Fig. 6 1.2. Internal border zone infarcts (subcortical) Fig. 3, Fig. 8...

Radiologists should be aware of these types of ischemic lesions because they are present in up to 10% of all brain infarcts. External border zone infarcts are usually wedge-shaped, are believed to be caused by embolism, sometimes associated with hypoperfusion, and tend to have a benign clinical course. Internal border zone infarcts typically have a rosary or string of beads appearance in the centrum semiovale, being the main cause hemodynamic compromise. They have higher risk for future stroke and increased morbidity. The best imaging tools...

Gabriela Elva Urquieta Gamón, MD Department of Radiology Caja Petrolera de Salud - Santa Cruz Hospital Santa Cruz de la Sierra – Bolivia Universidad Mayor de San Andrés – La Paz – Bolivia [email protected] German Anibal Arango Bonnet, MD Department of Radiology McGill University Health Center - Montreal General Hospital Montreal - Canada [email protected] Elar Jiménez Ruiz, MD Department of Radiology Caja Petrolera de Salud - Santa Cruz Hospital Santa Cruz de la Sierra – Bolivia Maria Ángela Machado Heredia, MD Department of Radiology Caja...

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