Serial FLAIR imaging after Gd-DTPA contrast: pitfalls in stroke trial magnetic resonance imaging.

BACKGROUND Most MRI protocols for stroke trials comprise 2 successive fluid-attenuated inversion-recovery (FLAIR) imaging acquisitions in which the first scan is done pre-Gd-DTPA contrast while the second is within the contrast clearance window. SUMMARY OF REPORT A 68-year-old male was diagnosed as having hyperacute right middle cerebral artery infarct and a subacute chronic small left occipital cortical infarct. The latter turned from hypointense to strikingly hyperintense on the second FLAIR image, resembling the picture of an acute-on-chronic infarction or hemorrhage. However, the second DWI and CT refuted either of these. CONCLUSIONS Image contrast using FLAIR in acute stroke trial imaging may also be affected by T1 effects of Gd-DTPA in chronic infarcts.