T2*-Weighted MRI versus Oxygen Extraction Fraction PET in Acute Stroke.

Background: Mapping high oxygen extraction fraction (OEF) in acute stroke is of considerable interest to depict the at-risk tissue. Being sensitive to deoxyhemoglobin, T2*-weighted MRI has been suggested as a potential marker of high OEF. Methods: We compared T2*-weighted images from pre-contrast arrival perfusion scans against quantitative positron emission tomography in 5 patients studied 7–21 h after onset of carotid territory stroke. OEF and T2* signal were obtained in the voxels with significantly high OEF. Results: All patients showed increased OEF. No significant relationship between OEF and T2*-weighted signal was found either within or between subjects. Conclusion: We found no indication that T2*-weighted MRI in the way implemented in this investigation was sensitive to high OEF in acute stroke. Copyright © 2009 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]