TTo this day, neuroimaging remains the reference standard for evaluating suspected head trauma, primarily to identify or exclude structural injuries such as intracranial haemorrhage or skull fracture. In cases of mild traumatic brain injury (mTBI), imaging is typically used to rule out more serious pathology, rather than to confirm concussion, as conventional CT and MRI frequently appear normal.

A key limitation of imaging is its limited accessibility and practicality outside hospital settings, particularly in non-urban, remote, or field environments, where timely access to advanced imaging may be unavailable. Even within urban healthcare systems, imaging is resource-intensive and cannot be deployed at the point of injury.

In practice, neuroimaging is costly, logistically demanding, and poorly suited to large-volume or frontline assessment, underscoring the need for complementary approaches that can provide objective insight into brain injury biology closer to the point of care.

To this day, neuroimaging remains the reference standard for evaluating suspected head trauma, primarily to identify or exclude structural injuries such as intracranial haemorrhage or skull fracture. In cases of mild traumatic brain injury (mTBI), imaging is typically used to rule out more serious pathology, rather than to confirm concussion, as conventional CT and MRI frequently appear normal.

A key limitation of imaging is its limited accessibility and practicality outside hospital settings, particularly in non-urban, remote, or field environments, where timely access to advanced imaging may be unavailable. Even within urban healthcare systems, imaging is resource-intensive and cannot be deployed at the point of injury.

In practice, neuroimaging is costly, logistically demanding, and poorly suited to large-volume or frontline assessment, underscoring the need for complementary approaches that can provide objective insight into brain injury biology closer to the point of care.

Computed tomography (CT) is the first-line imaging modality for evaluating acute head injury, primarily to identify or exclude clinically significant intracranial pathology such as haemorrhage, skull fracture, or mass effect. Indications for CT are based on validated clinical decision rules and include depressed level of consciousness (GCS <15), focal neurological deficits, signs of raised intracranial pressure, post-traumatic seizures, or high-risk mechanisms of injury¹–³.

Importantly, CT is not used to diagnose concussion or mTBI; in most cases of mTBI, CT findings are normal. A brief loss of consciousness (LOC) alone does not mandate imaging, as it is not independently associated with worse long-term neurological outcome. Imaging decisions should therefore be guided by established criteria rather than symptom presence alone¹–³.

CT remains the imaging study of choice in the acute setting due to its speed, availability, sensitivity for acute haemorrhage, and suitability for unstable patients. Compared with MRI, CT enables rapid triage and monitoring but exposes patients to ionising radiation¹.

Magnetic resonance imaging (MRI) is not routinely indicated in the acute assessment of uncomplicated mTBI. Its role is primarily reserved for patients with persistent symptoms (>7–14 days), unexpected clinical deterioration, or discrepancy between symptoms and CT findings⁴,⁵.

MRI provides greater sensitivity for subtle injuries, including diffuse axonal injury, microhaemorrhage, and non-acute pathology, particularly when advanced sequences are used. Delayed or evolving lesions may be more readily detected on MRI than CT⁴. However, MRI is less accessible, more time-consuming, and generally impractical in unstable or field settings.

Positron emission tomography (PET) is a functional imaging modality that assesses metabolic and biochemical activity within the brain. PET is well established in the evaluation of neurodegenerative disease, epilepsy, and oncology, but its role in traumatic brain injury—particularly mTBI—remains investigational⁶–⁸.

In TBI research, PET has been used to study altered glucose metabolism, neuroinflammation, and protein aggregation following injury. While these approaches have provided valuable mechanistic insights, PET (often combined with CT)is not used in routine clinical assessment of mTBI, due to limited availability, cost, radiation exposure, and uncertain impact on clinical decision-making⁶–⁸. Similarly, functional MRI (fMRI) remains primarily a research tool in this context.

Because children are more sensitive to ionising radiation, paediatric head injury imaging follows stricter criteria.

1. Stiell IG, Wells GA, Vandemheen K, et al. The Canadian CT Head Rule for patients with minor head injury. Lancet. 2001;357(9266):1391–1396.
2. Haydel MJ, Preston CA, Mills TJ, et al. Indications for computed tomography in patients with minor head injury. N Engl J Med. 2000;343(2):100–105.
3. National Institute for Health and Care Excellence (NICE). Head injury: assessment and early management (NG232). London: NICE; 2023.
4. Yuh EL, Mukherjee P, Lingsma HF, et al. Magnetic resonance imaging improves outcome prediction in mild traumatic brain injury. Ann Neurol. 2013;73(2):224–235.
5. Shenton ME, Hamoda HM, Schneiderman JS, et al. A review of magnetic resonance imaging and diffusion tensor imaging findings in mild traumatic brain injury. Brain Imaging Behav. 2012;6(2):137–192.
6. Amen DG, Raji CA, Willeumier K, et al. Functional neuroimaging in traumatic brain injury. Am J Psychiatry. 2015;172(7):617–628.
7. Nakashima T, Uematsu H, Tsuji Y, et al. Glucose metabolism in traumatic brain injury measured by FDG-PET. J Nucl Med. 2007;48(9):1385–1391.
8. Wang GJ, Volkow ND, Franceschi D, et al. Regional brain metabolism during recovery from concussion. Ann Neurol. 2012;71(1):54–65.