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.

Reduced Fetal Cerebral Oxygen Consumption Is Associated With Smaller Brain Size in Fetuses With Congenital Heart Disease

“…The imaging technique we used for T2 mapping in this study was adapted from a new sequence designed for myocardial T2 mapping which employs a T2 preparation pulse followed by a rapid SSFP readout with TE 1.15ms and TR 3.97ms 7,14,15 . An interval of 4 seconds between the individual T2 preparation images was employed to ensure adequate magnetization recovery, and five T2 preparation images with T2 prep times spread evenly across the expected T2 of the vessel were obtained for each T2 map.…”

Normal values of native T1 and T2 relaxation times on 3T cardiac MR in a healthy pediatric population aged 9–18 years

“…20,21 For that purpose, three short axis slices (one basal, one mid-ventricular, and one apical) were obtained. 20,21 For that purpose, three short axis slices (one basal, one mid-ventricular, and one apical) were obtained.…”

Free-Breathing 3 T Magnetic Resonance T2-Mapping of the Heart

“…For each T 2 map, the imaging sequence was repeated with 3 incremental TE T2prep (0, 30, and 60 ms). After acquisition of the 3 source images, affine coregistration (15) was applied to increase the accuracy of the T 2 -mapping before the final pixel-by-pixel computation of the T 2 maps was performed using a custom-written Matlab analysis tool in which the optimized Eq. (1) was incorporated.…”