Abstract 51: Degree of Clot Enhancement on Admission CT Predicts Revascularization Efficacy in Acute Ischemic Stroke
Background: Thrombi in the setting of acute ischemic stroke have been classified in pathology studies as “red clots” (erythrocyte rich) versus “white clots” (platelet/fibrin rich). Current strategies in lysing these clots include pharmacological agents and mechanical devices. Despite these treatment options, thrombolysis fails in a significant portion of patients and may lead to hemorrhagic complications. Having insight into the clot composition may provide clinicians with a way to triage patients to the appropriate treatment. The purpose of the study was to investigate whether the lysability of thrombi in acute ischemic stroke can be predicted by measuring the Hounsfield (HU) on the admission non-contrast CT (NCT), post-contrast enhanced CT (CECT) and CTA.
Methods: We studied 53 patients with acute anterior and posterior circulation large vessel ischemic strokes treated at our institution with IV tPA, IA tPA, and/or mechanical thrombectomy devices (Merci). The HU of the clot was measured on NCT, CECT and CTA. The HU of the homologous contralateral cerebral artery was also measured for standardization purposes. The obtained HU was corrected for hematocrit by using an accepted correction formula HUclot/HUcontralateral. The volume of the clot was calculated using the formula for a cylinder with an elliptical base (π x R x r xH). Recanalization was assessed by TICI grade (0-3).
Results: There is a strong correlation between the HU of the thrombus on preintervention NCT and postintervention TICI grade among all patients regardless of pharmacological or mechanical treatment (Table 1). Patients with TICI≥2 demonstrated higher HU on NCT compared to patients with TICI<2 among all treatment modalities. On CECT and CTA, patients with higher TICI scores tended to have a lower HU, however, this did not reach statistical significance. There was no correlation between clot volume and lysability.
Conclusion: Thrombi with lower HU on NCT appear to be more resistant to pharmacological and mechanical thrombectomy and likely represent “white clots.” While thrombi with higher HU are less resistant to acute stroke therapies and likely represent “red clots.” Measuring the HU of the thrombus on the admission NCT provides the stroke team with a rapid method to analyze the clot composition, a potentially useful discriminator in selecting the most appropriate reperfusion strategy for an individual patient.
- © 2012 by American Heart Association, Inc.