Early Ischaemic Diffusion Lesion Reduction in Patients Treated with Intravenous Tissue Plasminogen Activator: Infrequent, but Significantly Associated with Recanalization

BACKGROUND AND PURPOSE: Recent studies have shown that thrombolysis could decrease or eliminate ischaemic diffusion-weighted imaging lesions. However, the features of such diffusion-weighted imaging lesion reduction are not well known. AIMS: To clarify, the frequency of and factors associated with lesion reduction were investigated. METHODS: Patients given intravenous tissue plasminogen activator therapy within three-hours of onset were prospectively enrolled. Magnetic resonance imaging including diffusion-weighted imaging and magnetic resonance angiography was performed four times: on admission, just after intravenous tissue plasminogen activator, 24 h from intravenous tissue plasminogen activator, and seven-days after intravenous tissue plasminogen activator. The diffusion-weighted imaging lesion volume was measured by manual trace using National Institutes of Health imaging software. All patients were divided into three groups according to the early diffusion-weighted imaging lesion volume change from admission to just after intravenous tissue plasminogen activator: the lesion reduction group (>20% decrease); the lesion growth group (>20% increase); and the lesion unchanged group. RESULTS: In total, 105 patients [56 males, median age 77 (interquartile range 70-83) years, and National Institutes of Health Stroke Scale score 16 (10-22)] were enrolled. Early diffusion-weighted imaging lesion reduction was observed in seven (7%) patients. The decreased lesion increased subsequently. On multivariate analysis, the glucose level on admission (odds ratio 0·95, 95% confidence interval 0·91 to 0·99, P = 0·045) and early recanalization (odds ratio 15·7, 95% confidence interval 1·61 to 153, P = 0·018) were independently related to early lesion reduction. CONCLUSION: Early diffusion-weighted imaging lesion reduction was observed in 7% of patients treated with intravenous tissue plasminogen activator. The decreased lesion increased subsequently. Initial glucose level and early recanalization were independently associated with early diffusion-weighted imaging lesion reduction.