MR goes beyond imaging concussion to fleshing out its features, case by case

When it comes to imaging the brains of concussed patients, CT is the workhorse plowing the field and MRI the thoroughbred mastering the equine obstacle course.

That’s a nutshell paraphrase of a technology review and update by members of the radiology department at the New York University School of Medicine in Manhattan. The piece is running in the June edition of Radiology.

Xin Wu, MD, and colleagues note that research related to MR imaging of mild traumatic brain injury (mTBI) has exploded largely on the strength of new analytical methods to parse the image data.

They point out that CT is a fine first-line modality for all traumatic brain injury, but it can’t do much to provide long-term prognostic information.

Various burgeoning iterations of MRI can fill that bill by revealing fine changes in brain structure, function and metabolism.

Reviewing some key ways MRI is advancing medicine’s understanding of how to best treat concussion patients, Wu and her team list a number of particularly exciting advances. Among these:

• Structural MR imaging, diffusion-tensor imaging, susceptibility-weighted imaging and brain-iron imaging demonstrate macrostructural and microstructural changes after mTBI. “Recent work with diffusion imaging using higher order tensor models attempts to improve injury detection and understanding of axonal pathophysiology by resolving crossing fibers in tractography and more accurately modeling intravoxel diffusion,” the authors write.
• Functional brain activation has been shown to be altered by both task-mediated blood oxygen level-dependent functional MR imaging and resting state functional MR imaging. “This includes alterations in the default mode network, suggesting disruptions of intrinsic neural connectivity." 
• Metabolic changes to the brain “are present as documented using MR spectroscopy, with the primary finding of decreased N-acetylaspartate, a marker of neuronal injury.”

Continued progress in identifying imaging biomarkers of mTBI and personalizing these measures “can contribute to improved diagnosis, prognosis, and management of this common pathologic condition,” the authors write.

“We are at the threshold of piecing together a more detailed and complete understanding of the mechanisms of injury and recovery after mTBI,” they conclude. “Further work is warranted to allow for specific diagnosis, early detection and stratification, ultimately pointing the way toward targeted treatments.”