O-020 Novel cone beam CT technology improves image quality for stroke assessment: a prospective series

Background & Purpose Time is essential for treatment of acute ischemic stroke (AIS) for patients with large-vessel occlusion (LVO). It is now well established that decreasing the time between stroke-onset to groin-puncture significantly improves functional outcomes for these patients.1 One potential method of shortening this time is to by-pass the CT department and bring patients directly to the angiosuite for baseline imaging. However, in order for this to gain mainstream acceptance, the diagnostic quality of cone beam CT (CB-CT) performed in the angiosuite needs to be able to exclude haemorrhages, define the stroke core and ideally demonstrate brain perfusion and collaterals for select patients. We plan to present the recent results of 4 ongoing studies aimed to assess the imaging quality of the latest generation CB-CT scans and technology: 1. Non-contrast circular CB-CT scans; 2. Non-contrast dual-axis CB-CT scans; 3. Contrast-enhanced CB-CT Perfusion scans; and 4. Motion compensation post-processing algorithm technology. Methods Patients with AIS who received endovascular mechanical thrombectomy were prospectively included in this monocentric study (n=105). Study 1: Image quality of non-contrast circular CB-CT scans were analyzed using 2 quantitative and 6 qualitative measures and were compared to CT. Study 2: 6 types of image artifacts were compared between circular and dual-axis CB-CT scans. Study 3: Clot detection, ischemic core and collateral blood supply was assessed on CB-CT Perfusion imaging and compared to baseline CT and DSA imaging. Study 4: Motion artifacts were assessed on all scans before and after post-processed using a motion artifact correction algorithm. Results Study 1: Newer non-contrast CB-CT circular scans had higher mean contrast-to-noise ratio and lower mean image noise compared to older generation protocols. The largest image quality improvements included grey/white matter differentiation (59% improvement), and reduction of image noise and artefacts (63% & 50% improvement, respectively). Study 2: Dual-axis CB-CT scans had significantly improved beam hardening and cone-beam artifacts compared to circular scans. Study 3: CB-CT stroke perfusion imaging software accurately demonstrates vessel patency, ischemic core, and collateral blood supply. Study 4: 51% of all AIS CB-CT scans had motion artifacts, of which 91% improved after post-processing with our motion correction algorithm. Overall 76% of the scans were sufficient for clinical decision making prior to correction, which improved to 93% after post processing with our algorithm. Conclusions The latest generation of CB-CT scans & technology allow for exclusion of haemorrhages, stroke core definition and demonstration of brain perfusion and collaterals. These improvements suggest that CB-CT is acceptable for emergency stroke imaging assessment before mechanical thrombectomy, which may reduce door-to-groin puncture times and improve patient outcomes. Reference Bourcier R, Goyal M, Liebeskind DS, et al. Association of time from stroke onset to groin puncture with quality of reperfusion after mechanical thrombectomy: a meta-analysis of individual patient data from 7 randomized clinical trials. JAMA Neurol 2019. doi:10.1001/jamaneurol.2018.4510 Disclosures N. Cancelliere: None. P. Nicholson: None. F. Nijnatten: 5; C; Philips. E. Hummel: 5; C; Philips. P. Withagen: 5; C; Philips. P. van de Haar: 5; C; Philips. R. Agid: None. B. Hallacoglu: 5; C; Philips. M. van Vlimmeren: 5; C; Philips. V. Mendes Pereira: 1; C; Philips.