Ultra high field MRI at 8 Tesla of subacute hemorrhagic stroke

Purpose: Optimal treatment strategies and neurologic outcome after stroke d epend on an accurate characterization of the lesion. There is a need for hi gh resolution noninvasive imaging for assessment of the infarct size, perfu sion, and vascular territory. MRI at the ultra high field (UHF) of 8 T offe rs unprecedented resolution, but its utility fur stroke evaluation has not been determined yet. Method: A 55-year-old man with hypertension experienced sudden onset of spe ech arrest and right-sided hemiparesis that resolved in < 24 h with minimal neurologic deficit. MRI at 1.5 T showed initially a left posterior frontal lesion with subacute infarct (hyperintense on T2-weighted spin echo images ) and right-sided frontal and periventricular lesions consistent with chron ic infarct. There were many smaller white matter lesions. Delayed studies s howed high signal changes involving the gray matter only on T1-weighted ima ges. Results: Gradient echo and rapid acquisition with relaxation enhancement (R ARE) multislice images revealed a serpentine area of low signal in the left posterior frontal robe gray matter suggestive of a hemorrhagic infarct, ri ght-sided frontal lesion also showing iron deposits, multiple periventricul ar and cortical areas with abnormal high signal regions that were consisten t with old infarcts, and numerous small vessels readily visible, more promi nent on the right. Conclusion: MRI at 8 T displays lesions with a high resolution and striking anatomic derails. Susceptibility to iron and sensitivity to detect blood p roducts are increased at 8 T. The imaging characteristics at high field are different from those at low field, but both represent findings of iron pro ducts.