Diffusion- and perfusion-weighted MRI patterns in borderzone infarcts

Background and Purpose-The pathophysiology of borderzone infarcts: is not w ell understood. We investigated whether combined diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) could identify pathophysiologic ally meaningful categories of borderzone infarcts. Methods-Seventeen patients with borderzone infarcts were identified from th e Beth Israel Deaconess Medical Center Stroke Database. All patients had DW I and PWI, the majority of them within the first 24 hours of symptom onset. Results-Three patterns of perfusion abnormalities were associated with the diffusion lesions: 1, normal perfusion (5 patients); 2, localized perfusion deficits matching the area of restricted diffusion (5 patients); and 3, ex tensive perfusion deficits involving 1 or more vascular territories (7 pati ents). All but 1 patient with pattern I had transient peri-infarct hypotens ion as the presumed stroke mechanism. Two patients with pattern 2 had cardi ac or aortic embolic sources; none had large-artery disease or arterial hyp otension. Reperfusion was detected in all patients with this pattern who su bmitted to a follow-up study. All patients with pattern 3 had severe stenos is or occlusion of a large artery: the internal carotid, anterior cerebral, or middle cerebral. Conclusion-We postulate that the perfusion abnormality varies according to the mechanism of the borderzone infarction. Transient perfusion deficits oc curring with hypotension in the absence of significant large-artery disease may not be revealed by PWI. Embolism may cause some cases of small borderz one perfusion deficits, Critical large-artery disease may cause large terri torial perfusion deficits and predispose to borderzone infarction.