title: Longitudinal Brain Magnetic Resonance Imaging CO2 Stress Testing in Individual Adolescent Sports-Related Concussion Patients: A Pilot Study.
abstract: BACKGROUND
  Advanced neuroimaging studies in concussion have been limited to detecting group differences between concussion patients and healthy controls. In this small pilot study, we used brain magnetic resonance imaging (MRI) CO2 stress testing to longitudinally assess cerebrovascular responsiveness (CVR) in individual sports-related concussion (SRC) patients.
  
  
  METHODS
  Six SRC patients (three males and three females; mean age = 15.7, range = 15-17 years) underwent longitudinal brain MRI CO2 stress testing using blood oxygen level-dependent (BOLD) MRI and model-based prospective end-tidal CO2 targeting under isoxic conditions. First-level and second-level comparisons were undertaken using statistical parametric mapping (SPM) to score the scans and compare them to an atlas of 24 healthy control subjects.
  
  
  RESULTS
  All tests were well tolerated and without any serious adverse events. Anatomical MRI was normal in all study participants. The CO2 stimulus was consistent between the SRC patients and control subjects and within SRC patients across the longitudinal study. Individual SRC patients demonstrated both quantitative and qualitative patient-specific alterations in CVR (p < 0.005) that correlated strongly with clinical findings, and that persisted beyond clinical recovery.
  
  
  CONCLUSIONS
  Standardized brain MRI CO2 stress testing is capable of providing a longitudinal assessment of CVR in individual SRC patients. Consequently, larger prospective studies are needed to examine the utility of brain MRI CO2 stress testing as a clinical tool to help guide the evaluation, classification, and longitudinal management of SRC patients.
authors.affiliation: Department of Anesthesia and Perioperative Medicine, University of Manitoba, Winnipeg, MB, Canada; University of Manitoba, Winnipeg, MB, Canada; Health Sciences Centre, Winnipeg, MB, Canada; Canada North Concussion Network, Winnipeg, MB, Canada.
authors.forename: W Alan C
authors.initials: WA
authors.lastname: Mutch
authors.affiliation: University of Manitoba, Winnipeg, MB, Canada; Canada North Concussion Network, Winnipeg, MB, Canada; Department of Surgery, University of Manitoba, Winnipeg, MB, Canada; Department of Pediatrics and Child Health, University of Manitoba, Winnipeg, MB, Canada; Section of Neurosurgery, University of Manitoba, Winnipeg, MB, Canada; Pan Am Concussion Program, Winnipeg, MB, Canada; Children's Hospital Research Institute of Manitoba, University of Manitoba, Winnipeg, MB, Canada; Pan Am Clinic Foundation, Winnipeg, MB, Canada.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Ellis
authors.affiliation: University of Manitoba, Winnipeg, MB, Canada; Health Sciences Centre, Winnipeg, MB, Canada; Canada North Concussion Network, Winnipeg, MB, Canada; Department of Radiology, University of Manitoba, Winnipeg, MB, Canada.
authors.forename: Lawrence N
authors.initials: LN
authors.lastname: Ryner
authors.affiliation: Pan Am Concussion Program, Winnipeg, MB, Canada; Pan Am Clinic Foundation, Winnipeg, MB, Canada.
authors.forename: Marc P
authors.initials: MP
authors.lastname: Morissette
authors.affiliation: University of Manitoba, Winnipeg, MB, Canada; College of Medicine, University of Manitoba, Winnipeg, MB, Canada.
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Pries
authors.affiliation: University of Manitoba, Winnipeg, MB, Canada; Department of Community Health Sciences, University of Manitoba, Winnipeg, MB, Canada.
authors.forename: Brenden
authors.initials: B
authors.lastname: Dufault
authors.affiliation: University of Manitoba, Winnipeg, MB, Canada; Health Sciences Centre, Winnipeg, MB, Canada; Canada North Concussion Network, Winnipeg, MB, Canada; Pan Am Concussion Program, Winnipeg, MB, Canada; Department of Radiology, University of Manitoba, Winnipeg, MB, Canada.
authors.forename: Marco
authors.initials: M
authors.lastname: Essig
authors.affiliation: Department of Medical Imaging, University of Toronto, Toronto, ON, Canada; University Health Network Cerebrovascular Reactivity Research Group, Toronto, ON, Canada.
authors.forename: David J
authors.initials: DJ
authors.lastname: Mikulis
authors.affiliation: University Health Network Cerebrovascular Reactivity Research Group, Toronto, ON, Canada; Department of Physiology, University of Toronto, Toronto, ON, Canada; University of Toronto, Toronto, ON, Canada.
authors.forename: James
authors.initials: J
authors.lastname: Duffin
authors.affiliation: University Health Network Cerebrovascular Reactivity Research Group, Toronto, ON, Canada; Department of Physiology, University of Toronto, Toronto, ON, Canada; University of Toronto, Toronto, ON, Canada; Department of Anesthesia, University of Toronto, Toronto, ON, Canada.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Fisher
keywords: adolescent; blood oxygen level-dependent imaging; cerebrovascular reactivity; longitudinal; magnetic resonance imaging; post-concussion syndrome; sports-related concussion