Magnetic resonance imaging (MRI) may be more accurate than computed tomography (CT) in detecting bleeding in acute stroke and more accurate in revealing chronic bleeding such as hemorrhagic transformation of an ischemic stroke, according to a study in the October 20th issue of the Journal of the American Medical Association.

Noncontrast CT has been the standard brain imaging technique used for initial evaluation of patients with acute stroke symptoms, largely due to its capacity to rule out the presence of hemorrhage, according to background information in the article. MRI has been suggested as an alternative to CT in an emergency department setting because of its ability to outline the presence, size, location, and extent of hyperacute ischemia.

Chelsea S. Kidwell, MD, and her American colleagues examined MRI and CT scans in 200 patients showing signs of stroke in order to compare accuracy in detecting acute hemorrhage. The average age of patients was 75 years, with 55 percent women. MRI and CT scans were performed within six hours of symptom onset.

Researchers stopped the study early after an unplanned interim analysis revealed that MRI was detecting acute bleeding not detected by CT. In diagnosing any type of bleeding, MRI identified 71 positive patients, while CT identified 29 positive patients. Acute bleeding was diagnosed in 25 participants on both MRI and CT, with 4 additional patients identified in MRI scans not found in corresponding CT. Chronic bleeding, most often microbleeds, was visualized on 49 patient MRIs, although not on their CT scans.

The authors wrote: “… MRI may be able to detect regions of hemorrhagic transformation of an acute ischemic stroke not evident on CT. Our study confirms the superiority of MRI for detection of chronic hemorrhage, particularly microbleeds. The role of these findings in the decision-making process for treatment of patients who are candidates for thrombolytic [clot-dissolving] therapy is currently unknown.”

They concluded by saying: “… MRI may be acceptable as the sole imaging technique for acute stroke at centers with expertise in interpreting these findings.”