Introduction: Recent endovascular trials excluded patients with large ischemic cores on diffusion-weighted imaging (DWI) or perfusion CT using automated volumetric analysis.
Hypothesis: We investigated whether the largest diameter of the DWI lesion measured on a single slice could accurately predict large ischemic cores, as defined by automated volumetric analysis; such findings could result in a simple tool for predicting clinical outcome.
Methods: Magnetic resonance imaging data from the multicenter AXIS 2-trial were used. Patients were included within 9h of symptom onset and received intravenous thrombolysis if eligible. The maximum diameter of the diffusion lesion was measured on the slice with the largest lesion extension. Maximum diameters on a single slice were compared with the volumes of > 50 ml, >70ml and >100ml determined by standard volumetric analysis. We also assessed whether and for which threshold, largest lesion diameter was a predictor of poor clinical outcome defined as modified ranking scale (mRS) 5 or 6.
Results: A total of 304 patients were included of which 50 (16%) presented with a carotid occlusion. 96 (32%) patients had a DWI-volume of more than 50 ml, 63 (21%) more than 70ml and 46 (15%) more than 100ml. A diameter of respectively 5.5, 6.5 and 7 cm on a single slice with the largest lesion extension was the best predictor of a DWI lesion volume of more than 50 (sensitivity (sens) 97%, specificity (spec) 80%), 70 (sens 95%, spec 83%) and 100ml (sens 100%, spec 85%). The maximum diameter was a reasonable predictor of poor clinical outcome with an AUC of 0.76 (95%CI: 0.68-0.83). The optimal cut off point was found to be 5.5 cm (sens 71%, spec 67%).
Conclusion: Measuring the maximum lesion diameter on a single slice on DWI identifies patients with large ischemic cores with a high sensitivity and specificity. This finding can be useful in clinical practice and for future clinical trials where rapid and uniform decision making to exclude patients with a malignant profile from endovascular therapy is essential.