Echo-planar diffusion-weighted MRI in the diagnosis of acute ischemic stroke: characterisation of tissue abnormalities and limitations in the interpretation of imaging findings

Introduction: An accurate diagnosis is frequently difficult in early stroke . Diffusion-weighted (DW) magnetic resonance imaging (MR[) allows visualiza tion of ischemic parenchyma and quantitative assessment of tissue changes b efore unequivocal abnormalities appear on T-2-weighted MRI. Methods: We analyzed 105 MRI examinations of patients with acute stroke (<2 4 h) with regard to patterns of abnormalities in T-2-weighted and DW MRI. F urthermore we assessed the influence of artifacts related to DW echo-planar single-shot MRI on image interpretation. Results: Depending on the time of patient assessment there were three partl y overlapping T-2/DW patterns:(l) in the very early phase (less than or equ al to 1.5 h after symptom onset) there was noT(2) abnormality and no defini te abnormality of diffusion; (2) no T-2 abnormality and restricted diffusio n (1.5-4 h);(3) T-2 hyperintensity and restricted diffusion (23 h). Typical artifacts (susceptibility distortions, N/2 artifact, chemical shift artifa ct and eddy currents artifact) had to be considered when interpreting image s. Conclusions: Provided typical artifacts are taken into consideration, echo- planar DW MRI allows a more precise diagnostic assessment in acute stroke.