title: Adverse effects of metallic artifacts on voxel-wise analysis and tract-based spatial statistics in diffusion tensor imaging.
abstract: Background Diffusion tensor imaging (DTI) is a magnetic resonance imaging (MRI) technique that reflects the Brownian motion of water molecules constrained within brain tissue. Fractional anisotropy (FA) is one of the most commonly measured DTI parameters, and can be applied to quantitative analysis of white matter as tract-based spatial statistics (TBSS) and voxel-wise analysis. Purpose To show an association between metallic implants and the results of statistical analysis (voxel-wise group comparison and TBSS) for fractional anisotropy (FA) mapping, in DTI of healthy adults. Material and Methods Sixteen healthy volunteers were scanned with 3-Tesla MRI. A magnetic keeper type of dental implant was used as the metallic implant. DTI was acquired three times in each participant: (i) without a magnetic keeper (FAnon1); (ii) with a magnetic keeper (FAimp); and (iii) without a magnetic keeper (FAnon2) as reproducibility of FAnon1. Group comparisons with paired t-test were performed as FAnon1 vs. FAnon2, and as FAnon1 vs. FAimp. Results Regions of significantly reduced and increased local FA values were revealed by voxel-wise group comparison analysis (a P value of less than 0.05, corrected with family-wise error), but not by TBSS. Conclusion Metallic implants existing outside the field of view produce artifacts that affect the statistical analysis (voxel-wise group comparisons) for FA mapping. When statistical analysis for FA mapping is conducted by researchers, it is important to pay attention to any dental implants present in the mouths of the participants.
authors.affiliation: 1 School of Allied Health Sciences, Kitasato University, Kanagawa, Japan.
authors.forename: Masami
authors.initials: M
authors.lastname: Goto
authors.affiliation: 2 Department of Radiology, Nihon University School of Medicine, Tokyo, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Abe
authors.affiliation: 3 Department of Physiology, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Junichi
authors.initials: J
authors.lastname: Hata
authors.affiliation: 4 Department of Radiology, Juntendo University, Tokyo, Japan.
authors.forename: Issei
authors.initials: I
authors.lastname: Fukunaga
authors.affiliation: 5 Department of Radiology, Tokyo Metropolitan Geriatric Hospital, Tokyo, Japan.
authors.forename: Keigo
authors.initials: K
authors.lastname: Shimoji
authors.affiliation: 6 Department of Radiology, University of Tokyo Hospital, Tokyo, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Kunimatsu
authors.affiliation: 1 School of Allied Health Sciences, Kitasato University, Kanagawa, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Gomi
mesh_terms: D000328:Adult; D016880:Anisotropy; D016477:Artifacts; D001921:Brain / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D015921:Dental Implants; D056324:Diffusion Tensor Imaging / Q000379:methods*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008670:Metals; D012016:Reference Values; D015203:Reproducibility of Results; D055815:Young Adult
chemical_list: D015921:Dental Implants; D008670:Metals
keywords: Diffusion tensor imaging (DTI); magnetic resonance imaging (MRI); metallic artifact; tract-based spatial statistics (TBSS); voxel-wise analysis