Name : Morteza
Family : Sanei Taheri
Affiliation :Radiology Department,Shohada Tajrish Hospital,SBMU
Academic Degree : Associate Professor of Radiology
Resident : Afarin Sadeghian
Gender : Male
Age : 65
65-year-old man with a sudden onset of encephalopathy
Axial diffusion-weighted MR images and ADC map show bilateral areas of cortical restriction diffusion in association with abnormal regions of hyper-intense signal in the same locations, suggestive of acute infarcts in distribution of external (cortical) border zone infarcts at the junctions of the anterior cerebral artery and middle cerebral artery territories (blue arrows) and the middle cerebral artery and posterior cerebral artery territories (red arrows).Isolated cortical border zone infarcts may be embolic in nature and are less frequently associated with hemodynamic compromise zone infarct.According to the chest CT scan findings as multiple varying-size pulmonary nodules in both lung fields, metastatic disease and tumoral process could be considered as a causative factor for hyper coagulative state and small-size emboli. Color overlays on axial T2-weighted magnetic resonance (MR) images of normal cerebrum (Fig.9) show probable locations of external (blue) and internal (red) border zone infarcts.
1.Cortical watershed infarcts,2.Carcinomatous encephalitis
Cortical watershed infarcts
Discussion (Related Text)
Border zone or watershed infarcts are ischemic lesions that occur in characteristic locations at the junction between two main arterial territories. These lesions constitute approximately 10% of all brain infarcts and are well described in the literature. Their pathophysiology has not yet been fully elucidated, but a commonly accepted hypothesis holds that decreased perfusion in the distal regions of the vascular territories leaves them vulnerable to infarction. Two types of border zone infarcts are recognized: external (cortical) and internal (subcortical). To select the most appropriate methods for managing these infarcts, it is important to understand the underlying causal mechanisms. Internal border zone infarcts are caused mainly by hemodynamic compromise, whereas external border zone infarcts are believed to result from embolism but not always with associated hypoperfusion. Various imaging modalities have been used to determine the presence and extent of hemodynamic compromise or misery perfusion in association with border zone infarcts, and some findings (eg, multiple small internal infarcts) have proved to be independent predictors of subsequent ischemic stroke. A combination of several advanced techniques (eg, diffusion and perfusion magnetic resonance imaging and computed tomography, positron emission tomography, transcranial Doppler ultrasonography) can be useful for identifying the pathophysiologic process, making an early clinical diagnosis, guiding management, and predicting the outcome.The external border zone is closer to the cortical surface, where penetrating arteries originate, and thus it has a better chance of developing a collateral supply through leptomeningeal or dural anastomoses. Unilateral posterior external border zone infarcts have been related to cerebral emboli either of cardiac origin or from the common carotid artery, whereas bilateral infarcts are more likely to be caused by underlying hemodynamic impairment (vascular stenosis).
1.RadioGraphics 2011; 31:1201–1214,2.AJNR 24:427–435, March 2003