Abstract 3467: Disappearance Of The Acute Diffusion Weighted Imaging Lesion After Treatment With tPA
Background: MRI with diffusion weighted imaging (DWI) is significantly more sensitive than head CT in the determination of acute ischemic stroke. In patients presenting with acute ischemic cerebrovascular syndrome (AICS), we sought to determine the probability of finding a normal DWI post treatment with tPA, despite a clinical syndrome and pretreatment MRI consistent with acute ischemia. While previous studies report a rate of stroke mimic (SM) of 3 to 10%, a more recent report estimates up to 21% of patients treated based on head CT were either stroke mimic or neuroimaging negative cerebral ischemia.
Methods: We queried the LESION database for patients who presented with clinical syndrome consistent with AICS, underwent acute MRI screening and then underwent follow-up MRI at either 2hrs or 24hrs post treatment with iv-tPA. Experienced Stroke neurologist interpreted the follow up scans and identified those with absence of the initial DWI lesion. We excluded patients whose TOAST was small vessel disease or those with brainstem infarcts, given the higher incidence of false negative MRI in these types of stroke.
Results: There were 195 patients who met inclusion criteria. Of these there were a total of 4 patients in whom early follow up imaging failed to reveal the previously seen DWI lesion for which they were treated. This represents 2.0% of patients. The causative lesion did reappear on subsequent imaging in 2 out of the 4 patients. In an additional 6 patients, the initial MRI was negative prior to treatment with none of these patients developing a DWI lesion post iv-tPA. Four of the six patients were determined to be stroke mimics after their work-up was completed.
Conclusions: We found that 2.0% of patients with positive DWI prior to iv-tPA had follow-up imaging that failed to show the initial DWI lesion. In addition, 2.7% of patients treated had negative pre and post tPA imaging. We conclude that the true incidence of neuroimaging negative stroke post iv-tPA is unlikely to be greater than 5% in those patients screened with MRI. While the pathophysiological basis is not yet know, the transient disappearance of the DWI lesion may give rise to a higher rate of patients being interpreted as stroke mimics in those initially screened with head CT.
- © 2012 by American Heart Association, Inc.