Diffusion Weighted MRI Patterns Caused by Acute Border Zone Infarction

Purpose: We investigated the causes and mechanisms driving acute border zone infarctions using diffusion-weighted imaging (DWI). Materials and Methods: We analyzed DWI in 104 patients (male: 72 years, female: 32 years, age range: 44 to 84 years) with acute border zone infarction. The DWI patterns were classified as follows: pattern A- An acute border zone infarction combined with multiple small disseminated cortical infarctions, pattern B- An acute border zone infarction only. Results: The most common cause of acute border zone infarctions was extracranial internal carotid artery (ICA) stenosis (45 cases, 43%). Other causes included middle cerebral artery stenosis (22 cases, 21%), intracranial ICA stenosis (14 cases, 13%), unknown, (12 cases 12%), iatrogenic (6 cases, 6%) and cardiogenic (5 cases, 5%), respectively. The most common pattern for DWI was pattern A (83 cases, 80%). We performed a transcranial Doppler in 7 of 75 cases (11%), and found at least 1 embolic pulse. Conclusion: The most common pattern of DWI for acute border zone infarctions was pattern A. We propose that the mechanisms driving acute border zone infarctions are emboli coupled with hypoperfusion.