Review Article
Approach to imaging in mild traumatic brain injury
Jonathan Sivakumar
Discipline of Surgery, University of Sydney, Camperdown, NSW, Australia.
Article ID: 100051Z12JS2017
doi: 10.5348/Z12-2017-51-RA-16

Address correspondence to:
Dr. Jonathan Sivakumar,
Discipline of Sugery,
University of Sydney,
Camperdown, NSW 2006

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Sivakumar J. Approach to imaging in mild traumatic brain injury. J Case Rep Images Surg 2017;3:61–63.


Traumatic brain injury is a commonly encountered condition in the emergency department. Mild traumatic brain injury and its sequelae of diffuse axonal injury are difficult to diagnose with computed tomography scans as the preferred acute imaging modality. Our current decision on whether or not to scan a patient in the acute setting is best decided upon by the Canadian CT head rule. The role for MRI scans in diagnosing diffuse axonal injury is unclear, but current evidence suggests that they are preferred after the initial 48-hour period following head trauma.

Keywords: Diffuse axonal injury, Surgical imaging, Traumatic brain injury


While the definition has varied depending on circumstances, traumatic brain injury is defined as the result of the application of either external physical force or rapid acceleration/deceleration forces that disrupts brain function as manifested by immediately apparent impairments in cognitive or physical function [1]. This is further classified as mild, moderate, and severe, depending on the patient’s Glasgow Coma Scale (GCS) score [2] [3]. The majority of these cases present to hospital as minor traumatic brain injury, and previous studies suggest that 40% of these cases are secondary to motor-vehicle-related events [4].


In terms of neuroimaging following head injury, the decision on whether or not to scan tends to be guided by hospital-specific protocol, or is physician dependent. The general consensus, however, is that patients with new clinical symptoms or a change in GCS following head injury, should undergo a computed tomography (CT) scan of the brain. The specific clinical predictors for this are still very much debateable. The Canadian CT head rule study, as demonstrated in Table 1, has developed a highly sensitive clinical decision rule for the use of CT scan in patients with minor head injuries [5]. These patients are classified into whether or not imaging is required, based on the presence of five high-risk factors for neurosurgical intervention, and two medium-risk factors for clinically important lesions. The implementation of this guideline in other centers was associated with a modest reduction in CT use and an increased diagnostic yield of head CT scan for trauma to the head [6] [7].

Computed tomography scans are used in the assessment of head injury as they have widespread availability, rapid scanning times, and are compatible with medical devices. Furthermore, they are sensitive in demonstrating significant pathologies such as mass effect, abnormal ventricular size and configuration, bone injuries, as well as acute hemorrhage [8]. Despite its many advantages in the assessment of traumatic brain injury, CT scan is limited in that lesions with smaller dimensions than that of its resolution remain undetected [9]. Consequently, a common diagnosis of mild traumatic brain injury, or evidence of diffuse axonal injury (DAI), is likely to unnoticed on CT scans, and are better visualized with magnetic resonance imaging (MRI) [10] (Table 2). Magnetic resonance imaging scans, on the other hand, provide superior soft tissue details, compared with CT scans, when evaluating complicated minor traumatic brain injury, including improved ability to detect DAI [11] [12] [13]. In spite of this, the drawbacks of MRI include its limited availability in the acute trauma setting, long scanning times, high sensitivity to patient motion, poor compatibility with various medical devices, and relative insensitivity to subarachnoid hemorrhage. Diffuse axonal injury is a complication of traumatic brain injury induced by sudden acceleration-deceleration or rotational forces and the subsequent tissue injury is characterized by axonal stretching, disruption and eventual separation of nerve fibers in the white matter [14]. Current imaging modalities in clinical use tend to underestimate DAI, and while MRI scan does have better resolution than CT scan in detecting this pathology, there is still a high rate of false negative results for small lesions and milder forms of DAI [15]. Previous studies have quantitatively demonstrated that CT scans miss approximately 10–20% of abnormalities seen on MRI [13] [16]. Although MRI scans have greater sensitivity in detecting smaller lesions such as DAI, it is unclear whether the recognition of additional lesions on MRI would impact acute management of head trauma [9].

In light of the above information, and as CT scans are more convenient in the acute setting with an ability to evaluate for the four types of cranial hemorrhages, the current preference is to initially CT scan a patient following head injury, rather than use MRI scan. There is a role, however, for MRI scan in patient following the initial 48-hour observation period whose symptoms continue to persist [17].

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Table 1: Canadian computed tomography head injury or trauma rule

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Table 2: Diffuse axonal injury (Grading)


While current protocols guide us on when to image in the acute setting of head trauma, there is still difficulty in accurately diagnosing mild traumatic brain injury and its sequela, such as diffuse axonal injury. The approach of performing a CT scan of the head in the acute setting and then either a CT scan or MRI scan after 48–72 hours seems the most appropriate method of imaging.

  1. Savitsky B, Givon A, Rozenfeld M, Radomislensky I, Peleg K. Traumatic brain injury: It is all about definition. Brain Inj 2016;30(10):1194–200.   [CrossRef]   [Pubmed]    Back to citation no. 1
  2. Parikh S, Koch M, Narayan RK. Traumatic brain injury. Int Anesthesiol Clin 2007;45(3):119–35.   [CrossRef]   [Pubmed]    Back to citation no. 2
  3. Jennett B. Epidemiology of head injury. J Neurol Neurosurg Psychiatry 1996 Apr;60(4):362–9.   [Pubmed]    Back to citation no. 3
  4. Kraus JF, Nourjah P. The epidemiology of mild, uncomplicated brain injury. J Trauma 1988 Dec;28(12):1637–43.   [Pubmed]    Back to citation no. 4
  5. Stiell IG, Wells GA, Vandemheen K, et al. The Canadian CT head rule for patients with minor head injury. Lancet 2001 May 5;357(9266):1391–6.   [Pubmed]    Back to citation no. 5
  6. Sharp AL, Huang BZ, Tang T, et al. Implementation of the Canadian CT head rule and its association with use of computed tomography among patients with head injury. Ann Emerg Med July 2017 21.   [CrossRef]   [Pubmed]    Back to citation no. 6
  7. Valle Alonso J, Fonseca Del Pozo FJ, Vaquero Álvarez M, Lopera Lopera E, Garcia Segura M, García Arévalo R. Comparison of the Canadian CT head rule and the new orleans criteria in patients with minor head injury in a Spanish hospital. [Article in Spanish]. Med Clin (Barc) 2016 Dec 16;147(12):523–30.   [CrossRef]   [Pubmed]    Back to citation no. 7
  8. Davis PC; Expert panel on neurologic imaging. Head trauma. Am J Neuroradiol 2007 Sep;28(8):1619–21.   [Pubmed]    Back to citation no. 8
  9. Lee B, Newberg A. Neuroimaging in traumatic brain imaging. NeuroRx 2005 Apr;2(2):372–83.   [CrossRef]   [Pubmed]    Back to citation no. 9
  10. Coles JP. Imaging after brain injury. Br J Anaesth 2007 Jul;99(1):49–60.   [CrossRef]   [Pubmed]    Back to citation no. 10
  11. Gentry LR. Imaging of closed head injury. Radiology 1994 Apr;191(1):1–17.   [CrossRef]   [Pubmed]    Back to citation no. 11
  12. Gentry LR, Godersky JC, Thompson B. MR imaging of head trauma: Review of the distribution and radiopathologic features of traumatic lesions. Am J Roentgenol 1988 Mar;150(3):663–72.   [CrossRef]   [Pubmed]    Back to citation no. 12
  13. Mittl RL, Grossman RI, Hiehle JF, et al. Prevalence of MR evidence of diffuse axonal injury in patients with mild head injury and normal head CT findings. Am J Neuroradiol 1994 Sep;15(8):1583–9.   [Pubmed]    Back to citation no. 13
  14. Chung SW, Park YS, Nam TK, Kwon JT, Min BK, Hwang SN. Locations and clinical significance of non-hemorrhagic brain lesions in diffuse axonal injuries. J Korean Neurosurg Soc 2012 Oct;52(4):377–83.   [CrossRef]   [Pubmed]    Back to citation no. 14
  15. Ma J, Zhang K, Wang Z, Chen G. Progress of research on diffuse axonal injury after traumatic brain injury. Neural Plast 2016;2016:9746313.   [CrossRef]   [Pubmed]    Back to citation no. 15
  16. Doezema D, King JN, Tandberg D, Espinosa MC, Orrison WW. Magnetic resonance imaging in minor head injury. Ann Emerg Med 1991 Dec;20(12):1281–5.   [CrossRef]   [Pubmed]    Back to citation no. 16
  17. Halstead ME, Walter KD, The Council on sports medicine and fitness. Sport-related concussion in children and adolescents. Pediatrics 2010 Sep;126(3):597–615.   [CrossRef]   [Pubmed]    Back to citation no. 17

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Author Contributions
Jonathan Sivakumar – Substantial contributions to conception and design, Acquisition of data, Analysis and interpretation of data, Drafting the article, Revising it critically for important intellectual content, Final approval of the version to be published
Guarantor of Submission
The corresponding author is the guarantor of submission.
Source of Support
Conflict of Interest
Author declare no conflict of interest.
© 2017 Jonathan Sivakumar. This article is distributed of Creative Commons Attribution License which permits unrestricted use, distribution and reproduction in any medium provided the original author(s) and original publisher are properly credited. Please see the copyright policy on the journal website for more information.