High-resolution CT with arch/neck/head CT angiography on a mobile stroke unit

Abstract

BackgroundMobile stroke units (MSUs) performance dependability and diagnostic yield of 16-slice, ultra-fast CT with auto-injection angiography (CTA) of the aortic arch/neck/circle of Willis has not been previously reported.MethodsWe performed a prospective observational study of the first-of-its kind MSU equipped with high resolution, 16-slice CT with multiphasic CTA. Field CT/CTA was performed on all suspected stroke patients regardless of symptom severity or resolution. Performance dependability, efficiency and diagnostic yield over 365 days was quantified.Results1031 MSU emergency activations occurred; of these, 629 (61%) were disregarded with unrelated diagnoses, and 402 patients transported: 245 (61%) ischemic or hemorrhagic stroke, 17 (4%) transient ischemic attack, 140 (35%) other neurologic emergencies. Total time from non-contrast CT/CTA start to images ready for viewing was 4.0 (IQR 3.5–4.5) min. Hemorrhagic stroke totaled 24 (10%): aneurysmal subarachnoid hemorrhage 3, hemorrhagic infarct 1, and 20 intraparenchymal hemorrhages (median intracerebral hemorrhage score was 2 (IQR 1–3), 4 (20%) spot sign positive). In 221 patients with ischemic stroke, 73 (33%) received alteplase with 31.5% treated within 60 min of onset. CTA revealed large vessel occlusion in 66 patients (30%) of which 9 (14%) were extracranial; 27 (41%) underwent thrombectomy with onset to puncture time averaging 141±90 min (median 112 (IQR 90–139) min) with full emergency department (ED) bypass. No imaging needed to be repeated for image quality; all patients were triaged correctly with no inter-hospital transfer required.ConclusionsMSU use of advanced imaging including multiphasic head/neck CTA is feasible, offers high LVO yield and enables full ED bypass.

Comparison of Mobile Stroke Unit With Usual Care for Acute Ischemic Stroke Management

“…This issue may be resolved in the future by using MSUs equipped with head/neck CT angiography that can substantially increase the yield of mechanical thrombectomy by bypassing the emergency department. 51…”

European Stroke Organisation (ESO) guidelines on mobile stroke units for prehospital stroke management

“…It should be considered that in B_PROUD 49 and BEST-MSU 50 , CT angiography was not performed routinely and if done, it was repeated for most MSU patients with prehospital CTA after hospital arrival, which aligns in-hospital management of both groups and masks potential benefits of an early initial CTA. 72 Data from the Australian MSU programme, indicated a difference in median time to MT when referring to data from a historical control group. This result was mainly achieved by bypassing the local non-MT centres.…”

Mobile Stroke Units: Evidence, Gaps, and Next Steps

“…During 365 days of MSU service in Memphis, where prehospital multiphase arch-to-head CT angiography is routinely performed, all MSU patients (n=27) treated with mechanical thrombectomy bypassed the ED and were admitted directly to the catheterization laboratory. 13 MSUs are associated with better functional outcomes in patients with stroke (Table 1). B_PROUD was a prospective, nonrandomized, controlled trial with blinded-end point assessment conducted in Berlin, Germany between 2017 and 2019.…”

“…During 365 days of MSU service in Memphis, where prehospital multiphase arch-to-head CT angiography is routinely performed, all MSU patients (n=27) treated with mechanical thrombectomy bypassed the ED and were admitted directly to the catheterization laboratory. 13…”

“…MSU CT scanners can perform CT angiograms; however, imaging is generally limited to the head and upper neck unless a full-body CT scanner with auto-injection capability is employed, and this configuration generally requires a larger ambulance. 13 Most MSUs operate in densely populated cities; however, MSUs can serve rural areas and can meet and treat patients with stroke who live remotely at intermediate locations by rendezvousing with standard ambulances. 14,15 MSUs cost about 1 million US dollars to purchase and up to 1 million US dollars per year to operate (costs depend on operating hours, use of telemedicine, personnel wages, and sophistication of ambulance and machinery).…”