title: Magnetization transfer SWIFT MRI consistently detects histologically verified myelin loss in the thalamocortical pathway after a traumatic brain injury in rat.
abstract: Traumatic brain injury (TBI) is associated with various neurocognitive deficits, and rapid assessment of the damage is potentially important for the prevention and treatment of these deficits. Imaging assessment of mild or moderate damage outside the primary lesion area after TBI, however, remains challenging. Magnetization transfer (MT) has clearly been underutilized in imaging the damage caused by TBI. Here, we applied the MT ratio (MTR) using sweep imaging with Fourier transformation (SWIFT) to study microstructural tissue damage in the thalamocortical pathway outside the primary lesion in a lateral fluid percussion injury rat model of TBI, 5 months after injury. MTR was decreased in layers VIb-IV of the barrel cortex and related subcortical areas, mainly indicating demyelination, which was verified by histology. The largest MTR change in the cortex was in layer VIb (-8.2%, pFDR= 0.01), and the largest MTR change in the subcortical areas was in the caudal-most portion of the internal capsule (-11.0%, pFDR< 0.005). These areas exhibited the greatest demyelination and substantial cellularity attributed to gliosis. Correlation analysis of group-averaged results from the subcortical areas revealed an excellent correlation of MTR with myelin (r2= 0.94, p < 0.001), but no correlation with increased cellularity as detected by Nissl staining. Thus, MTR using SWIFT can be a valuable tool for the assessment of subtle changes after TBI in both cortical and subcortical areas.
authors.affiliation: A. I. Virtanen Institute for Molecular Sciences, Department of Neurobiology, University of Eastern Finland, Kuopio, Finland.
authors.forename: Lauri Juhani
authors.initials: LJ
authors.lastname: Lehto
authors.affiliation: A. I. Virtanen Institute for Molecular Sciences, Department of Neurobiology, University of Eastern Finland, Kuopio, Finland.
authors.forename: Alejandra
authors.initials: A
authors.lastname: Sierra
authors.affiliation: A. I. Virtanen Institute for Molecular Sciences, Department of Neurobiology, University of Eastern Finland, Kuopio, Finland.
authors.forename: Olli
authors.initials: O
authors.lastname: Gröhn
mesh_terms: D000465:Algorithms; D000818:Animals; D000070642:Brain Injuries, Traumatic / Q000000981:diagnostic imaging* / Q000473:pathology*; D002540:Cerebral Cortex / Q000000981:diagnostic imaging* / Q000473:pathology; D003711:Demyelinating Diseases / Q000000981:diagnostic imaging* / Q000473:pathology*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D007089:Image Enhancement / Q000379:methods; D008297:Male; D009186:Myelin Sheath / Q000473:pathology; D009434:Neural Pathways / Q000000981:diagnostic imaging / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D013788:Thalamus / Q000000981:diagnostic imaging* / Q000473:pathology
keywords: magnetization transfer; myelin; sweep imaging with Fourier transformation; traumatic brain injury