Emergency department-based computed tomography scanners: rationale and clinical importance

Abstract

Introduction The optimal location of computed tomography (CT) scanners for emergency department (ED) patients within hospital infrastructure remains debated in emergency medicine. Evidence for ED-based CT scanners originally came from trauma patients [1–3]. However, critically ill nontrauma patients constitute the majority of ED visits requiring advanced imaging and include time-sensitive conditions such as stroke, acute aortic dissection (AAD), and cardiac arrest. This article examines available evidence for ED-based CT in critically ill nontrauma patients, acknowledging both benefits and operational considerations. Time to imaging: quantifying the advantage ED-located CT scanners consistently reduce time from imaging order to scan acquisition. Cabilan et al. [4] conducted a before-and-after study of 3031 CT scans, comparing outcomes when the CT scanner was adjacent versus temporarily relocated remotely. Remote location was associated with 27–36 min delays in time-to-CT, a 14% greater porter demand, and 8 min additional transport time [4]. Similar time savings were reported by other authors [5]. These delays compound throughout the patient journey: delayed diagnosis, delayed specialist consultation, delayed treatment, and delayed disposition. For time-sensitive conditions, these delays potentially translate into worse clinical outcomes. The clinical perspective: nontrauma time-sensitive conditions Stroke: time-sensitive benefit Acute ischemic stroke provides compelling evidence for ED-based CT. Bonadio et al. [6] examined 148 stroke arrivals before and after relocating the CT scanner from an upper floor into the ED. The proportion of patients achieving door-to-CT times less than 20 min increased from 47 to 74%, and ultrarapid scans (<10 min) more than doubled. The Cabilan study demonstrated that in presumed stroke patients, time-to-brain perfusion was delayed by up to 10 min when the CT scanner was remote [4]. Given the time-dependent efficacy of thrombolytic therapy and mechanical thrombectomy [7], these improvements are clinically meaningful and likely translate into improved functional outcomes. European multicenter data confirm that time intervals exceeding 4 h from symptom onset to cerebral imaging adversely affect revascularization outcomes [8] and that optimizing in-hospital time from arrival to imaging improves reperfusion therapy delivery [9,10]. Acute aortic dissection: impact on outcomes A retrospective cohort study examined 145 patients with AAD over 17 years and compared outcomes before and after relocating the CT scanner from 130 m away to just 17 m from the ED resuscitation area, combined with 24-h ED specialist coverage [11]. Missed AAD diagnoses decreased from 37 to 20%, and in-hospital mortality decreased from 52 to 26%. While concurrent implementation of specialist coverage limits exclusive attribution of these benefits to CT location, the findings strongly suggest that immediate imaging access combined with specialist oversight substantially improves outcomes of AAD patients presenting to the ED. Proximity enabled rapid evaluation of patients too unstable for transport. Cardiac arrest and beyond: hybrid emergency rooms First introduced in Japan, hybrid emergency rooms are resuscitation rooms equipped with a CT scanner and angiography system allowing for simultaneous resuscitation, rapid CT imaging, endovascular treatment, and emergency surgery of trauma and nontrauma patients [12]. In patients with cardiac arrest, hybrid emergency rooms as compared with resuscitation rooms without a CT-scanner/angiography, were associated with faster initiation of extracorporeal cardiopulmonary resuscitation, earlier percutaneous coronary intervention, and lower in-hospital mortality [13]. Critically ill patients: transport safety and workflow For critically ill nontrauma patients, ED-based CT benefits further extend beyond life-saving diagnostic yields and time savings to safety considerations. Transport of unstable patients to radiology departments carries inherent risks, including monitoring interruptions, ventilator disconnections, and hemodynamic instability [14]. The Cabilan study’s finding of an 8 min shortening of transport time quantifies this burden [4]. ED-based CT eliminates these transport risks while maintaining full resuscitation capabilities. The availability argument and multidisciplinary team access While dedicated CT availability could theoretically be achieved through priority access to radiology scanners, practical realities limit this. Critically ill ED patients require dedicated imaging access accommodating ongoing resuscitation, multidisciplinary team presence, and unpredictable clinical deterioration. These patients cannot occupy shared radiology scanners without disrupting scheduled workflows. An ED-based CT scanner enables the entire multidisciplinary team – emergency physicians, surgeons, anesthesiologists, intensivists, nurses, and radiologists – to remain immediately available. When the CT scanner is in the ED, transition from diagnosis to treatment is seamless: surgical teams can evaluate patients immediately, and treatment decisions can be made collaboratively. Remote CT scanners require patient transport, team fragmentation, and inevitably communication delays. Furthermore, the ED-based CT scanner allows iterative clinical assessment. If initial imaging raises new questions or clinical status changes, repeat imaging can be obtained immediately without another transport cycle. This flexibility is valuable in evolving situations such as deteriorating stroke or postcardiac arrest patients. Operational considerations and limitations Setting up a dedicated ED-based CT scanner requires addressing various logistical and departmental issues with radiology. Twenty-four-hour radiology technologist coverage and timely radiologist interpretation are essential. Managing scanners outside the traditional radiology department while maintaining core services requires careful workforce planning. The radiologist’s responsibility for justifying radiation use must be preserved through clear protocols. Concerns about overdiagnosis merit attention. Ready CT availability may lower scanning thresholds, potentially increasing inappropriate examinations, thereby increasing the frequency of incidental findings. Improved diagnostic rates for conditions like AAD likely reflect more liberal scanning criteria, increasing negative studies. While finding true positives justifies some negative scans, risks of overdiagnosis, radiation exposure, and resource utilization must be monitored through clinical decision support and evidence-based protocols. Cost implications include funding, facility modifications, and ongoing staffing, but must be weighed against improved outcomes, reduced complications, and decreased length of stay. Such cost-effectiveness analyses are still needed. Conclusion Originally implemented for trauma based on strong mortality reduction data, ED-based CT scanners consistently reduce time to imaging and improve outcomes also for nontrauma critically ill patients. While ‘availability matters more than location’ is conceptually appealing, true availability – immediate, uninterrupted imaging access with full multidisciplinary team presence and iterative assessment capability – inherently requires physical proximity. Critically ill ED patients cannot occupy shared radiology CT scanners without disrupting workflows, nor can multidisciplinary teams maintain continuous presence in remote locations. The solution is dedicated ED-based CT scanners, planned and operated in collaboration with radiology departments to ensure appropriate oversight, adequate staffing, quality assurance, and radiation safety. Operational challenges, including 24-h coverage, workflow integration, and safeguards against overutilization, must be addressed through joint protocols. High-volume EDs with substantial populations of stroke, AAD, cardiac arrest, and other critically ill patients should prioritize ED-based CT scanners as an essential component of optimized emergency care. Acknowledgements Conflicts of interest There are no conflicts of interest.

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