Alexander Rauscher: Applying Physics in Medical Imaging
“I’m an MRI scientist with physics training, which is very helpful to advance MRI,” explains Alexander Rauscher. Growing up in Salzburg, Rauscher’s interest in medicine was triggered by his civilian service work as a nurse in a Salzburg hospital. Combine that with his academic training in engineering physics, a large dash of neuroscience, and a solid grasp of signal processing, and you end up with a 2015 recipient of the Canada Research Chair (CRC) Tier II award in Developmental Neuroimaging! You also get an ARIT poster that highlights several facets of Rauscher’s recent work with magnetic resonance imaging (MRI).
The first study, published in the American Journal of Neuroradiology in 2016, used two types of MRI scans – FLAIR and T2 – to improve detection of brain lesions in multiple sclerosis (MS) patients. Basically, the MRI signal from cerebral spinal fluid (CSF) is suppressed in FLAIR, and the signal from white matter is low in T2, but MS lesions are bright both scans. The new approach, called FLAIR2, multiplies the two scans, resulting in CSF-suppressed images with excellent contrast between MS lesions, white matter, and gray matter – with three times the spatial resolution of conventional approaches. Rauscher and his team had previously presented a scan that is very sensitive to tissue damage due to MS. “Our work on MRI of multiple sclerosis will probably be used in drug trials to measure brain tissue repair,” Rauscher says. “Such a scan is urgently needed to test new [MS] drugs, and our approaches seem quite promising.”
Another study, in PLOS ONE 2016, examined changes in myelin (the fatty “insulation” of nerve fibers) in brains of college hockey players after impact-related mild traumatic brain injuries. Forty-five college hockey players were scanned pre-season; Controls were age-matched students not involved in contact sports. 11 of the players suffered concussions and were scanned 72 hours, 2 weeks, and 2 months after injury. Reduction in myelin water fraction was still evident 2 weeks post-injury, but recovered by 2 months. This recovery is encouraging, but the findings will play a role in medical management of concussed athletes. “Players will have to pause longer than 1 or 2 weeks,” says Rauscher. “Our data suggest that 3 weeks should be the minimum.” There is still a need to investigate the effects of repeated brain trauma, as well as links between myelin disruption/recovery and neurocognitive performance.
A related report (in Frontiers in Neurology 2016) used MRI to determine brain volume changes and to detect micro-hemorrhages in the same cohorts of ice hockey players and controls. Results indicate that concussions did not cause acute brain volume increases, and no micro-hemorrhages were seen, even with advanced MRI scans. However, athletes both with and without concussions showed significant reductions in brain volume (ca. 3 cm2) during the hockey season, compared to controls! Future work should determine whether volume reductions continue to accumulate over several seasons of contact sports, and whether brain volumes revert to baseline values after athletic participation ends.
The fourth paper, in revision at Magnetic Resonance in Medicine, focuses on quantitative susceptibility mapping (QSM). Magnetic susceptibility contrast variations reflect differences in materials such as their microstructure, composition, and disease-induced damage. Technical advances in QSM promise to have clinical applications, especially in vascular disease, neurodegeneration, and inflammation. “I like that some of our work has direct and immediate impact and helps people around the world who undergo diagnostic imaging,” says Rauscher. MS and brain trauma patients, both present and future, undoubtedly agree!
The preceding article is part of a series featuring the scientific work of 20 young Austrian researchers, all who are active members of the OSTA's Research and Innovation Network Austria. The initial presentation of their work took place at the ASCINA poster session under the auspices of the "Austrian Research and Innovation Talk" in Toronto on October 21, 2016. Three of these scientists were subsequently awarded the ASCINA award the same evening, honoring their outstanding scientific work.