The Addition of MRI to CT Based Stroke and TIA Evaluation Does Not Impact One year Outcomes

The 2010 American Academy of Neurology guideline for the diagnosis of acute ischemic stroke recommends MRI with diffusion weighted imaging (DWI) over noncontrast head CT. No studies have evaluated the influence of imaging choice on patient outcome. We sought to evaluate the variables that influenced one-year outcomes of stroke and TIA patients, including the type of imaging utilized.

Patients were identified from a prospectively collected stroke and TIA database at a single primary stroke center during a one-year period. Data were abstracted from patient electronic medical records. The primary outcome measure was death, myocardial infarction, or recurrent stroke within the following year. Secondary outcome measures included predictors of getting an MRI study.

727 consecutive patients with a discharge diagnosis of stroke or TIA were identified (616 and 111 respectively); 536 had CT and MRI, 161 had CT alone, 29 had MRI alone, and one had no neuroimaging. On multiple logistic regression analysis, there were no differences in primary or secondary outcome measures among different imaging strategies. Predictors of the primary outcome measure included age and NIHSS, while performance of a CT angiogram (CTA) predicted a decreased odds of death, stroke, or MI. The strongest predictor of having an MRI was admission to a stroke unit.

These results suggest that long-term (one-year) patient outcomes may not be influenced by imaging strategy. Performance of a CTA was protective in this cohort. A randomized trial of different imaging modalities should be considered.