title: Myocardial T₂ mapping with respiratory navigator and automatic nonrigid motion correction.
abstract: Quantitative T₂ mapping was recently shown to be superior to T₂-weighted imaging in detecting T₂ changes across myocardium. Pixel-wise T₂ mapping is sensitive to misregistration between the images used to generate the parameter map. In this study, utility of two motion-compensation strategies-(i) navigator gating with prospective slice correction and (ii) nonrigid registration-was investigated for myocardial T₂ mapping in short axis and horizontal long axis views. Navigator gating provides respiratory motion compensation, whereas registration corrects for residual cardiac and respiratory motion between images; thus, the two strategies provided complementary functions. When these were combined, respiratory-motion-induced T₂ variability, as measured by both standard deviation and interquartile range, was comparable to that in breath-hold T₂ maps. In normal subjects, this combined motion-compensation strategy increased the percentage of myocardium with T₂ measured to be within normal range from 60.1% to 92.2% in short axis and 62.3% to 92.7% in horizontal long axis. The new motion-compensated T₂ mapping technique, which combines navigator gating, prospective slice correction, and nonrigid registration to provide through-plane and in-plane motion correction, enables a method for fully automatic and robust free-breathing T₂ mapping.
authors.affiliation: Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA.
authors.forename: Shivraman
authors.initials: S
authors.lastname: Giri
authors.forename: Saurabh
authors.initials: S
authors.lastname: Shah
authors.forename: Hui
authors.initials: H
authors.lastname: Xue
authors.forename: Yiu-Cho
authors.initials: YC
authors.lastname: Chung
authors.forename: Michael L
authors.initials: ML
authors.lastname: Pennell
authors.forename: Jens
authors.initials: J
authors.lastname: Guehring
authors.forename: Sven
authors.initials: S
authors.lastname: Zuehlsdorff
authors.forename: Subha V
authors.initials: SV
authors.lastname: Raman
authors.forename: Orlando P
authors.initials: OP
authors.lastname: Simonetti
mesh_terms: D000465:Algorithms; D016477:Artifacts; D006321:Heart / Q000033:anatomy & histology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D009038:Motion; D010363:Pattern Recognition, Automated / Q000379:methods*; D015203:Reproducibility of Results; D055425:Respiratory-Gated Imaging Techniques / Q000379:methods*; D012680:Sensitivity and Specificity