What is the ideal timeline to do MRIs, fMRIs, DTIs, and fiber tracking in order to determine if someone has suffered a head injury? And how long after a potential head injury can traces still be found within the brain?
In 2013, the diagnosis of traumatic brain injury, and in particular mild traumatic brain injury, is still based on the initial symptoms at the time of the injury that is, a witnessed or self-report change in conscious (loss of consciousness, amnesia, or confusion).
Imaging plays little role in terms of diagnosis. However, in the acute setting of head injury, a CT scan is the imaging modality of choice if intracranial bleeding is suspected. Standard MRI can occasionally detect small hemorrhages not seen on a CT scan, typically within the first few weeks of injury. Sometimes these MRI findings can aid the clinician in making a diagnosis of TBI retrospectively when the presenting symptoms were unclear. But these microhemorrhages occur too infrequently (approximately, a third of the time after concussion) to justify the routine use of MRI.
fMRI and DTI are still considered research tools and not routinely used to either diagnose traumatic brain injury or to monitor recovery. In a research setting, fMRI abnormalities correlate closely with cognitive deficits and tend to resolve when they resolve. DTI abnormalities, on the other hand, can persist for a year or more after injury.
- S Niyogi. Head Trauma Rehabil Vol. 25, No. 4, pp. 241–255.
- Z. Kou. J Head Trauma Rehabil Vol. 25, No. 4, pp. 267–282.
Dr. Bazarian is an emergency physician with a strong research interest in traumatic brain injury. He is associate professor of Emergency Medicine, Neurology, and Neurosurgery at the Center for Neural Development and Disease, University of Rochester Medical Center.