By James Markland
Concussions occur frequently, especially among athletes, accident victims, and the military. New technologies have emerged to detect their presence, especially in the case of mild traumatic brain injury (mTBI). One recently developed technology is called quantitative diffusion tensor imaging (qDTI), a new MRI technology that can detect brain damage not appearing on routine MRIs or CT scans.
DTI is a new and advanced MRI technique performed by a very powerful magnet that allows doctors to obtain microscopic evaluations of how water molecules move along the brain’s wire circuits. The process allows doctors to quantitatively measure how brain damage interferes with the normal water molecule movement.
The measure of the direction that water molecules flow through tissue is called fractional anisotropy (FA). Areas of low FA typically reflect axonal abnormalities. It should be noted that areas of high FA are also detected, but these are thought to perhaps be neurologically compensatory in nature. Indeed, recent studies show that patients with higher FA measures may experience better outcomes.
Diffusion MRI imaging is about 15 years old while qDTI was developed about 13 years ago. The first meaningful research with respect to concussion and qDTI was published in 2009. A comprehensive historical review of 100 scientific articles got the ball rolling in 2013.
Ed Soll, MD
One of the relatively few locations nationwide that offer this new technology is Doctors Imaging of Metairie, La. “The need to diagnose concussions quickly and accurately has become a major issue in the medical community, especially with the prevalence of head injuries among athletes,” said Edward Soll, MD, Doctors Imaging Concussion Program Director. Though the technology is new, Doctors Imaging has already successfully diagnosed patients whose conventional scans were negative. “With the new quantitative DTI scans at Doctors Imaging and other facilities, we can see evidence of brain injury that we weren’t able to see before and now can reliably diagnose brain injury and better treat patients and their symptoms.”
Concussions have traditionally been difficult to diagnose. The brain can appear normal on conventional CT and MRI scans, but patients can still experience long-lasting and debilitating symptoms including dizziness, headache, fatigue, nausea, depression, and problems with behavior, concentration, and memory. According to a study through the National Institutes of Health, the quantitative DTI scans can help solve those mysteries by showing a more detailed and complete image of brain functionality.
qDTI requires a powerful 3.0 Tesla MRI system, in contrast to the more common 1.5T machine. It also requires special DTI advanced neural imaging software and the installation of special computers to do the complicated data analysis. In the case of Doctors Imaging, this was accomplished in consultation with experts at Harvard’s McLean Hospital, cognitive psychologists from UCLA, and brain anatomists from Johns Hopkins.
Aside from its relatively recent introduction, one of the reasons there are very few centers performing quantitative DTI is that the process is not just a simple test but requires a team of experts to ensure the statistical validity of the results. “The evaluation involves development of a normal control group for purposes of comparison with people who have concussion-related problems,” said Soll. “So most facilities are not inclined to engage the process of adding quantitative DTI into their already busy workload.” Soll considers his personal involvement with the technology “a passion and a mission.”
There is virtually no downside to the administration of quantitative DTI. There is no radiation, no injections, and no harmful side effects. It’s performed on the same ultra high field MRI system that is used for regular MRI exams. However, specially developed software from Siemens Healthcare is required. In regard to the financial aspects, a portion of the qDTI examination may be reimbursable depending on the patient’s insurance, but the qDTI and post-processing analysis are ordinarily not reimbursable.
An increasing number of major universities worldwide are now using qDTI for concussion and mTBI evaluation. qDTI is also being used for research in other conditions like Parkinson’s disease, Alzheimer’s disease, post traumatic stress syndrome, and neurologic disorders where there is cognitive dysfunction. The NFL has an interest in this technology and has sponsored concussion research at several medical schools in the United States, most notably, the University of Pittsburgh.
According to Soll, it’s difficult to tell the long-term impact of qDTI. “I personally believe we are just scratching the surface regarding what this new technology will tell us about how the brain works in health and disease. But at any rate, if you are going to do qDTI, do it well,” Soll advised. “There are no shortcuts available with this technology.”
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