title: Traumatic axonal injury: Relationships between lesions in the early phase and diffusion tensor imaging parameters in the chronic phase of traumatic brain injury.
abstract: This prospective study of traumatic brain injury (TBI) patients investigates fractional anisotropy (FA) from chronic diffusion tensor imaging (DTI) in areas corresponding to persistent and transient traumatic axonal injury (TAI) lesions detected in clinical MRI from the early phase. Thirty-eight patients (mean 24.7 [range 13-63] years of age) with moderate-to-severe TBI and 42 age- and sex-matched healthy controls were included. Patients underwent 1.5-T clinical MRI in the early phase (median 7 days), including fluid-attenuated inversion recovery (FLAIR) and T2* gradient echo (T2*GRE) sequences. TAI lesions from the early phase were characterized as nonhemorrhagic or microhemorrhagic. In the chronic phase (median 3 years), patients and controls were imaged at 3 T with FLAIR, T2*GRE, T1, and DTI sequences. TAI lesions were classified as transient or persistent. The FLAIR/T2*GRE images from the early phase were linearly registered to the FA images from the chronic phase and lesions manually segmented on the FA-registered FLAIR/T2*GRE images. For regions of interest (ROIs) from both nonhemorrhagic and microhemorrhagic lesion, we found a significant linear trend of lower mean FA from ROIs in healthy controls to ROIs in patients without either nonhemorrhagic or microhemorrhagic lesions and further to transient and finally persistent lesion ROIs (P < 0.001). Histogram analyses showed lower FA in persistent compared with transient nonhemorrhagic lesion ROIs (P < 0.001), but this was not found in microhemorrhagic lesion ROIs (P = 0.08-0.55). The demonstrated linear trend of lower FA values from healthy controls to persistent lesion ROIs was found in both nonhemorrhagic and microhemorrhagic lesions and indicates a gradual increasing disruption of the microstructure. Lower FA values in persistent compared with transient lesions were found only in nonhemorrhagic lesions. Thus, clinical MRI techniques are able to depict important aspects of white matter pathology across the stages of TBI. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Department of Neuroscience, Norwegian University of Science and Technology, Trondheim, Norway.|Department of Medical Imaging, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway.
authors.forename: Kent Gøran
authors.initials: KG
authors.lastname: Moen
authors.affiliation: Department of Neuroscience, Norwegian University of Science and Technology, Trondheim, Norway.|Department of Neurosurgery, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway.
authors.forename: Anne
authors.initials: A
authors.lastname: Vik
authors.affiliation: Department of Physical Medicine and Rehabilitation, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway.|Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Alexander
authors.initials: A
authors.lastname: Olsen
authors.affiliation: Department of Neuroscience, Norwegian University of Science and Technology, Trondheim, Norway.|Department of Physical Medicine and Rehabilitation, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway.
authors.forename: Toril
authors.initials: T
authors.lastname: Skandsen
authors.affiliation: Department of Neuroscience, Norwegian University of Science and Technology, Trondheim, Norway.|Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Asta Kristine
authors.initials: AK
authors.lastname: Håberg
authors.affiliation: Department of Public Health and General Practice and Department of Laboratory Medicine, Children's and Women's Health, Norwegian University of Science and Technology, Trondheim, Norway.|Department of Physiotherapy, Trondheim Municipality, Trondheim, Norway.
authors.forename: Kari Anne I
authors.initials: KA
authors.lastname: Evensen
authors.affiliation: Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Live
authors.initials: L
authors.lastname: Eikenes
mesh_terms: D000293:Adolescent; D000328:Adult; D016880:Anisotropy; D001369:Axons / Q000473:pathology*; D000070642:Brain Injuries, Traumatic / Q000000981:diagnostic imaging* / Q000473:pathology*; D002648:Child; D002908:Chronic Disease; D056324:Diffusion Tensor Imaging; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D011446:Prospective Studies; D055815:Young Adult
keywords: brain injuries; diffusion magnetic resonance imaging; fractional anisotropy; longitudinal studies; magnetic resonance imaging