Comparison between MRI screening and CT-plus-MRI screening for thrombolysis within 3 h of ischemic stroke

Although MRI may provide much information on brain pathology to aid in patient selection for thrombolysis, the concern remains that MRI screening may increase time-to-treatment. We hypothesized that CT-plus-MRI screening might be a valuable time-efficient alternative for selection of patients requiring thrombolysis.

We reviewed acute stroke patients who received intravenous tissue plasminogen activator (tPA) (with or without intra-arterial urokinase) initiated within 3 h of stroke between March 2004 and March 2007. MRI was the routine screening imaging employed until November 2005. Thereafter, CT-plus-MRI screening was performed; tPA of 0.6 mg/kg was infused intravenously after exclusion of hemorrhage by CT screening, and subsequently a further decision on thrombolysis (i.e., intravenous tPA of 0.3 mg/kg, or intra-arterial urokinase) was made after MRI screening. We compared times-to-treatment and clinical outcomes between MRI screening and CT-plus-MRI-screening groups, and identified factors associated with good clinical outcome (modified Rankin Scale < or =2 at 3 months).

Eighty-nine patients were included in the analysis; 43 were MRI-screened, and 46 were CT-plus-MRI-screened. Although the MRI-screening group had a longer door-to-needle time (p<0.001), these patients showed better 3-month outcomes compared to CT-plus-MRI-screening group (p=0.01). Multivariate analysis showed that MRI screening (odds ratio 3.97, 95% confidence interval 1.30-12.17, p=0.02) was independently associated with a good outcome at 3 months. In CT-plus-MRI-screening group, although time-to-initial imaging and time-to-tPA were shorter, time-to-MRI and time-to-additional thrombolysis were delayed.

These results suggest that early patient selection using MRI may be more effective than reduction of times-to-treatment in improvement of thrombolytic outcomes.