Impact of baseline tissue status (diffusion-weighted imaging lesion) versus perfusion status (severity of hypoperfusion) on hemorrhagic transformation.

BACKGROUND AND PURPOSE The frequency of hemorrhagic transformation (HT) on gradient echo imaging and its impact on stroke outcomes continues to be debated. We investigated the factors associated with HTs and the influence of the HTs observed on gradient echo imaging on the early course after a stroke. METHODS We analyzed the data from a prospectively maintained registry of patients who were eligible for recanalization therapy. Serial diffusion-weighted imaging and perfusion-weighted imaging were performed, and HTs were assessed on follow-up gradient echo imaging. Tmax perfusion lesion maps were generated and hypoperfused regions were divided into severe (Tmax >or=8 seconds) delay and mild (Tmax >or=2 seconds but Tmax <8 seconds) delay. The factors associated with HTs, including the mode of recanalization therapy, pretreatment diffusion-weighted imaging and perfusion-weighted imaging lesion volumes, and reperfusion indices, were evaluated. The early clinical outcome was assessed during the first 7 days of admission. RESULTS A total of 184 patients were included in this study. HTs were noted in 73 (39.7%) patients. Multiple logistic regression analysis identified aggressive treatment (OR, 5.12; 95% CI, 1.73 to 15.18) and a large area of severe perfusion delay (OR for highest quartile of Tmax >8 seconds, 12.91; 95% CI, 3.69 to 45.17) as independent predictors of HTs. Neither risk factor profiles nor diffusion-weighted imaging lesion volumes were associated with HTs. There was a poor correlation between the radiological (HT types) and clinical (asymptomatic or symptomatic) categories of HTs. Even a parenchymal hematoma was not always associated with symptomatic worsening or affected the early clinical outcomes. CONCLUSIONS The results of this study indicate that the perfusion status (severe perfusion delay) rather than the tissue status (diffusion-weighted imaging lesions) and aggressive treatment were independently associated with HTs. HT on gradient echo imaging was common but usually associated with severe hypoperfusion and not always associated with clinical deterioration.