Can clinicians safely reduce computed tomography (CT) imaging in settings where patients present with minor traumatic brain injuries (mTBIs) or concussions?

In settings where patients with acute mTBIs or concussions are assessed, efforts to reduce the use of CT scans warrant consideration. Using the Canadian CT Head Rule (CCHR) clinical decision rule (CDR), modest reductions in image ordering can be safely achieved.

A 38-year-old woman presented to an urgent care centre with a history of stumbling up 2 stairs and striking her forehead on a cement landing. She had amnesia for a second event whereby she was struck in the head by a door immediately after her fall. She denied nausea or vomiting. Although she exhibited periorbital bruising and a frontal hematoma (Figure 1A), she had otherwise normal neurologic examination findings (Figure 1B).

Examination findings: A) Periorbital bruising and a frontal hematoma and B) normal findings on a computed tomography scan.

mTBI in adults is defined as a head trauma–induced alteration in mental status that may or may not involve a loss of consciousness (LOC) in patients presenting with a Glasgow Coma Scale (GCS) score of 13 to 15. While concussions may result from mTBIs, they can also involve patients with minimal head injury (GCS score=15; no LOC, disorientation, or amnesia) or rotational or flexion-extension forces to the neck resulting in coup-contrecoup injury. While sports-related mTBIs or concussions have been highly publicized in elite athletes and celebrities, approximately 75% of concussions in Canada result from other mechanisms including falls, motor vehicle collisions, and physical assaults.1 Vulnerable road users (eg, cyclists, e-scooter users, pedestrians) are particularly at risk due to a lack of protection provided by standard vehicular frames.2

Noncontrast head CT scans are an important imaging modality in the care of adult patients with mTBI in emergency department (ED) settings. These images can initiate timely and life-saving interventions; however, most patients with mTBI or concussion have a low-risk mechanism and few meaningful findings on CT scans. In cases of minimal head injury, while no CDRs exist for CT scanning, CT scanning is rarely required. Moreover, less than 10% of adults experiencing an mTBI have serious brain injuries that require hospitalization, less than 2% require neurosurgical interventions, and most can be discharged from the ED or clinic based on clinical assessment alone. Unnecessary CT scans expose patients to additional ionizing radiation,3 delay discharge, and prompt investigations for previously undetected normal variants (ie, naturally occurring variations in cerebral anatomy that do not indicate disease but often lead to additional unnecessary investigations).4 They are also costly to obtain and report, especially if patients need to be transferred from a site without a CT scanner, such as in rural areas, urgent care, or doctors’ offices, and contribute to resource inefficiencies in the health care system.5

In Canada, both emergency medicine6 and radiology7 societies advise against advanced imaging for concussion through the Choosing Wisely campaign. Key messages from these recommendations include terms such as “avoid” or “don’t order” CT scans in patients presenting with mTBI unless “red flags” exist (eg, high-risk mechanisms, abnormal clinical examination findings, anticoagulant use, advanced age), or before a validated CDR is applied.

Overall, efforts to limit CT scans in patients presenting with mTBI or concussion appear warranted and Canadian evidence has provided considerable reassurances regarding safely accomplishing that goal.8

Efforts to optimize CT use in patients with mTBI have largely focused on the development of CDRs to predict intracranial injury. The “acceptable” proportion of CT scans varies based on the ED and factors such as severity of injury, patient volume, and admission rates. Ultimately, valid and reliable CDRs allow for safe discharge without further investigations. Most high-quality evidence suggests implementing CDRs should reduce CT scans by 25% in an ED setting; however, real-world evidence suggests a lower effect (Appendix, available from CFPlus*).

Restricting CT use for mTBI through the use of CDRs is shown to be sensitive, accurate, and safe (Appendix*). For example, the CCHR was developed rigorously using derivation, validation, and implementation phases in multiple EDs across Canada.8 The target population for the CCHR is adult patients (≥16 years of age) with mTBI who are not receiving anticoagulants, have not had a seizure, are not pregnant, and have a GCS score of 13 to 15. Using history and physical examination findings in patients presenting within 24 hours of injury, the CCHR encourages physicians to risk-stratify patients and obtain a CT scan in patients who exhibit high- and medium-risk criteria only.

Other CDRs and protocols have been developed; however, few comparative effectiveness studies have been reported. In head-to-head comparison of 2 common CDRs on patients with mTBI, the CCHR outperformed the New Orleans Criteria (NOC), another well-studied CDR for patients presenting with head injury.9 Overall, use of the CCHR appears to be more valid and efficient than use of the NOC.

Implementing protocols, CDRs, and other evidence-based medicine interventions among clinicians remains challenging. A recent evidence review found approximately half of the 10 studies devoted to implementation strategies to reduce inappropriate CT ordering for patients presenting to the ED with head injuries were from single centres, and the methods were often weak (eg, before-and-after, nonrandomized clinical trials) and publication bias could not be excluded.10 Moreover, despite multifaceted approaches, the impact of the interventions were often far more modest than predicted. For example, among the 10 studies, the median reduction in CT scan requests was only 3.4%.10

Evidence suggests the highest success rates in reducing CT scans for mTBI seen in ED settings involve initiatives that use a valid and reliable CDR adapted to the local context. In a United States (US) ED, a quality improvement cycle including education, using the CCHR CDR, and providing a handout resulted in a 12% reduction in CT scan ordering over an 8-week period.11 In another example at a US ED, researchers used education and a clinical decision support (CDS) that combined information from the CCHR, NOC, and the CT in Head Injury Patients (CHIP) decision rule, as well as a handout, which led to a 7.8% decrease in CT scan ordering over a 12-month period.12

For clinicians who work infrequently in an ED, yet who manage patients with a history of head injury, we recommend they become familiar with the CCHR, apply it in cases where the inclusion criteria are met, and feel confident with the outcome of the rule’s application. Those patients who meet criteria for minimal head injury or low-risk mTBI can be confidently discharged without obtaining a head CT scan. Patients who meet medium- and high-risk criteria should be transferred to an ED for CT scanning. For patients who sustained a more severe head injury (GCS score <13), CT imaging should be obtained without delay (Figure 2). Finally, in patients who sustain an mTBI, yet do not meet all the inclusion criteria, guidance is limited and many clinicians default to obtaining a CT scan.

Approach to CT scan ordering in adult patients with head injury

Emerging issues. There are several emerging controversies of which family physicians should be aware that may impact head CT scan ordering in the future. First, 2 important groups seen in the acute setting for head injury assessment are those receiving novel oral anticoagulants (NOACs) and patients older than 65 years. While research on these important patient considerations is under way, the bleeding risks associated with anticoagulant use13 mean CT imaging should be the default decision. Second, blood biomarkers indicating brain injury have been developed, validated, and approved by Health Canada.14 Ubiquitin C-terminal hydrolase-L1 (UCH-L1), which peaks immediately following injury (0 to 8 hours), and glial fibrillary acidic protein (GFAP), which peaks later after injury (0 to 20 hours), are being measured to further reduce CT scan ordering and prognosticate for patients who have an mTBI.14 For example, European guidelines include them as an additional test.15 A low-risk CDR assessment is still relied on to reassure patients and families; these guidelines recommend no imaging. In the event of a positive CDR assessment, CT scanning is only recommended when either of the biomarkers are present. While there is considerable interest in this new protocol, it lacks robust implementation evidence.

Patient communication. The individual decision regarding CT scanning should be based on the clinical presentation, best medical evidence, the experience of the clinician, and values and preferences of patients. For example, shared decisions with patients should centre around the low-risk criteria (eg, the relative paucity of evidence to support imaging in mTBI) and risks associated with imaging (eg, exposure to radiation, increases in ED length of stay, and the cost of resources).

Finally, clinicians treating patients who had an mTBI or concussion, regardless of whether CT imaging was ordered, are often asked to provide advice to patients (or their families, friends, coaches, etc) regarding recovery. Moreover, patients who are symptomatic may present to their primary care providers for similar guidance after presenting to the ED. While strict bedrest is no longer recommended, evidence suggests gradual return to work and activities and structured advice may initially be helpful to avoid postconcussive syndrome.16 The current guidelines are an iteratively changing document, and family physicians should be aware of emerging evidence for early nonvigorous exercise to reduce lost work time and help with resuming activity.17

Due to the patient’s amnesia for the second event and periorbital bruising, which can be a sign of basal skull fracture (a high-risk criterion in the CCHR8 and positive finding in the NOC18), a CT scan was obtained. The image findings did not reveal a basal skull fracture or intracerebral bleed. An extracranial hematoma was observed corresponding to her forehead hematoma. The patient was reassured, discharged with a head injury information sheet, and given instructions to follow up with her primary care physician as needed.

Choosing Wisely Canada is a campaign designed to help clinicians and patients engage in conversations about unnecessary tests, treatments, and procedures and to help physicians and patients make smart and effective choices to ensure high-quality care is provided. To date there have been 13 family medicine recommendations, but many of the recommendations from other specialties are relevant to family medicine. Articles produced by Choosing Wisely Canada are on topics related to family practice where tools and strategies have been used to implement one of the recommendations and to engage in shared decision-making with patients. If you are a primary care provider or trainee who has used Choosing Wisely recommendations or tools in your practice and you would like to share your experience, please contact us at infochoosingwiselycanada.org.

↵* The appendix (Common clinical decision rules to risk-stratify adult patients with minor traumatic brain injury [mTBI]) is available from https://www.cfp.ca. Go to the full text of the article online and click on the CFPlus tab.

Competing interests

Esther Yang and Dr Kevin Skoblenick have no conflicts of interest to declare. Dr Brian H. Rowe’s research is funded through a Scientific Director’s Grant (SOP 168483) by the Canadian Institutes of Health Research. He has also participated as an expert on a panel examining the role of biomarkers for mild traumatic brain injury and concussion sponsored by Abbott.

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La traduction en français de cet article se trouve à https://www.cfp.ca dans la table des matières du numéro de juillet/août 2025 à la page e188.