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Can a Brain Scan Detect Brain Injury?

Mild traumatic brain injuries (mTBIs) can be challenging to diagnose and treat, as they often do not manifest in major symptoms such as unconsciousness that is mainly seen in moderate to severe TBI cases. But there are various types of brain scans — also called neuroimaging — that can sometimes visualize brain damage. Computed tomography (CT) is typically performed during diagnosis of TBIs to visualize the brain.

But does brain damage show on a CT scan? Often this type of imaging is not very helpful in cases of mild TBI since they usually do not result in major structural alterations that can be detected using this technique. In fact, many individuals who suffer a mTBI do not undergo CT imaging.

Traumatic Brain Injury MRI and Functional mRI

Another commonly used brain scan is magnetic resonance imaging (MRI). An MRI scan produces a static image of the brain that can be used to determine structural or volumetric changes. An MRI is more effective in detecting a mild traumatic brain injury than a CT scans. Moreover, MRI scans can yield valuable information through the many image analysis techniques and measurements that can be performed.

A specialized type of MRI, called functional magnetic resonance imaging (fMRI) has shown even more promise. The fMRI improves upon the original MRI by showing activity in the brain as measured by blood flow. The original MRI shows a static image of the brain. But the fMRI adds an extra layer of information on what areas of the brain are functioning.

fMRIs can also be carried out while TBI participants perform certain tasks in order to measure whether the activity and response in the brain to the task is comparable to those seen in healthy controls. For example, although individuals with mTBIs performed equally well compared to controls on a verbal task, the fMRI activity patterns were actually significantly different and this change was still present even one year post-injury and in individuals who were no longer experiencing symptoms.

Diffusion Tensor Imaging MRI

Additional imaging techniques have been investigated in recent years to determine if they would more accurately detect a mild TBI. This research is essential to brain injury survivors as it could result in earlier diagnosis, treatment, and cognitive rehabilitation plans. In their review article, Smith et al. emphasize the value of these alternatives: “The heterogeneity of TBI has made the development of a classification system difficult. Advanced imaging modalities may provide the key for an improved classification system, allowing for the clustering of TBI patients with similar pathologies, better assessments of new therapies in clinical trials, and improved prognostication” (Smith et al., 2019).

Scientists have used these techniques to visualize and identify anatomical changes that occur in the brain after TBI, in the short-term and long-term. The neuroimaging techniques include positron emission tomography (PET), and magneto- or electro-encephalography (MEG/EEG). The imaging technique that has shown the most promise is another specialized type of MRI called diffusion tensor imaging (DTI).


DTI is a recent and advanced type of MRI that measures water diffusion in the brain. The purpose of measuring water diffusions is to investigate the structural integrity of the brain’s structures and axons (the brain’s cells). When trauma to the brain occurs, there is primary damage due to the brain’s impact on inside of the skull. But, sometimes more important is the secondary injuries that occur following the physical impact.

The secondary injuries following TBI include injury to the axons. DTI is important for detecting these axonal changes. In mTBI patients at 24 hours and 1 month post-injury, DTI is capable of detecting a decrease in integrity of axonal tracts. Some patients showed improvements in this measure indicating that recovery from axonal injury is possible.

Moreover, DTI scans can be essential because they are able to detect injuries in mTBI patients who had normal mRI or CT scans. This makes DTI a valuable method for detecting and measuring the extent of injury at the level of the brain, even in the absence of overt symptoms. DTI measures can even help predict outcomes during the recovery period and can therefore help guide treatment.

References
Belanger, H. G., Vanderploeg, R. D., Curtiss, G., & Warden, D. L. (2007). Recent neuroimaging techniques in mild traumatic brain injury. The Journal of neuropsychiatry and clinical neurosciences, 19(1), 5–20. https://doi.org/10.1176/jnp.2007.19.1.5

Bigler, E. D., Abildskov, T. J., Goodrich-Hunsaker, N. J., Black, G., Christensen, Z. P., Huff, T., Wood, D. M., Hesselink, J. R., Wilde, E. A., & Max, J. E. (2016). Structural Neuroimaging Findings in Mild Traumatic Brain Injury. Sports medicine and arthroscopy review, 24(3), e42–e52. https://doi.org/10.1097/JSA.0000000000000119

Belanger, H. G., Vanderploeg, R. D., Curtiss, G., & Warden, D. L. (2007). Recent neuroimaging techniques in mild traumatic brain injury. The Journal of neuropsychiatry and clinical neurosciences, 19(1), 5–20. https://doi.org/10.1176/jnp.2007.19.1.5

Smith, L. G. F., Milliron, E., Ho, M., Hu, H. H., Rusin, J., Leonard, J., & Sribnick, E. A. (2019). Advanced neuroimaging in traumatic brain injury: an overview, Neurosurgical Focus FOC, 47(6), E17. Retrieved Sep 24, 2021, from https://thejns.org/focus/view/journals/neurosurg-focus/47/6/article-pE17.xml

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