P-001 Delayed enhancement ct angiography for acute thromboembolic ischemia: core infarct volume prediction and outcomes following complete mechanical thrombectomy

Background During acute thromboembolic cerebral ischemia, identification of the occlusion and assessment of core infarct volume to determine endovascular treatment eligibility are a priority. We sought to demonstrate that using the CT angiography source images (CTA-SI) with a delayed enhancement protocol could be utilized in the acute setting to both identify the occlusion and estimate the core infarct volume and that patients who underwent endovascular mechanical thrombectomy with complete recanalization had favorable outcomes utilizing this imaging method to determine treatment eligibility. Methods A retrospective analysis was performed on patients presenting between 2014 and 2016 with an acute middle cerebral artery or carotid terminus thromboembolus on CTA who underwent endovascular mechanical thrombectomy with a final thrombolysis in cerebral perfusion (TICI) score of either 0 or 3 and had post-procedural diffusion weighted imaging (DWI) performed within 48 hours of the sentinel CTA. The volume of hyperintensity on the diffusion weight images was considered the final core infarct volume and was compared to infarct volumes manually measured on the pretreatment CTA-SI by a neurointerventional radiologist. To evaluate clinical outcomes, the initial and discharge National Institutes of Health Stroke Scales (NIHSS), 90 day modified Rankin Scale (mRS), and incidence of hemorrhagic conversions were analyzed. Results Twenty patients had a final TICI score of 3 and eight had a score of 0. CTA-SI core infarct volumes for the TICI 3 group averaged 25.2 ml, ranging from 0.0 ml – 123.7 ml, and DWI core infarct volumes averaged 34.4 ml, ranging from 1.0 ml – 146.0 ml. CTA-SI infarct volumes for the TICI 0 group averaged 47.1 ml, ranging from 0.0 ml-132.1ml, and DWI core infarct volumes averaged 137.7 ml, ranging from 7.6 ml-302.1ml. CTA-SI and DWI lesion volumes for the TICI 3 group did not significantly correlate with an average difference of 9.2 ml. The average volume difference for the TICI 0 group was 90.6 ml. The CTA-SI overestimated infarct volumes in six of the TICI 3 patients, all less than 1 ml, and none of the TICI 0 patients. The CTA-SI predominately underestimated lesion volumes; however, the CTA-SI to recanalization time averaged 144 min and the CTA to DWI time averaged 25.1 hours. Clinically, the TICI 3 group experienced an average NIHSS improvement of 11.4, had no incidences of hemorrhagic conversion, and 75% had a 90 day mRS of 0–2 while the TICI 0 group had an NIHSS improvement of 2.3, 25% hemorrhagic conversion incidence, 38% inpatient mortality, and none with a mRS of 0–2. Conclusions CTA-SI with a delayed enhancement protocol can be used as the sole imaging technique to triage patients to endovascular therapy. While lesion volumes were not significantly similar in the recanalized group, there was no significant overestimation by the CTA-SI and thus would not be expected to exclude patients from endovascular treatment. The CTA-SI actually tended to underestimate core infarct volumes which is likely related to continued core infarct expansion during recanalization delay, as volume expansion was much greater in the nonrecanalized group, and further cytotoxic edema accumulation prior to the DWI. Despite the volume underestimation, clinical outcomes were favorable for the TICI 3 group. Disclosures J. West: None. J. Hise: None. K. Layton: None.