Mobile CT: Technical Aspects of Prehospital Stroke Imaging before Intravenous Thrombolysis

Purpose: To reduce the time from symptom onset to treatment with tissue plasminogen activator (tPA) in ischemic stroke, an ambulance was equipped with a CT scanner. We analyzed process and image quality of CT scanning during the pilot study regarding image quality and safety issues. Materials and Methods: The pilot study of a stroke emergency mobile unit (STEMO) ran over a period of 12 weeks on 5 weekdays from 7a. m. to 6:30 p. m. A teleradiological service for the justifying indication and reporting was established. The radiographer was responsible for the performance of the CT scan on the ambulance. 64 cranial CT scans and 1 intracranial CT angiography were performed. We compared times from ambulance alarm to treatment decision (time of last brain scan) with a cohort of 50 consecutive tPA treatments before implementation of STEMO. Results: 62 (95%) of the 65 scans performed had sufficient quality for reading. Technical quality was not optimal in 45 cases (69%) mainly caused by suboptimal positioning of patient or eye lense protection. Motion artefacts were observed in 8 exams (12%). No safety issues occurred for team or patients. 23 patients were treated with thrombolysis. Time from alarm to last CT scan was 18 minutes shorter than in the tPA cohort before STEMO implementation. Conclusion: A teleradiological support for primary stroke imaging by CT on-site is feasible, quality-wise of diagnostic value and has not raised safety issues.