title: In vivo measurement of T*2 and field inhomogeneity maps in the human heart at 1.5 T.
abstract: Cardiac echo-planar imaging suffers invariably from regions of severe distortion and T*2 decay in the myocardium. The purpose of this work was to perform local measurements of T*2 and field inhomogeneities in the myocardium and to identify the sources of focal signal loss and distortion. Field inhomogeneity maps and T*2 were measured in five normal volunteers in short-axis slices spanning from base to apex. It was found that T*2 ranged from 26 ms (SD = 7 ms, n = 5) to 41 ms (SD = 11 ms, n = 5) over most of the heart, and peak-to-peak field inhomogeneity differences were 71 Hz (SD = 14 Hz, n = 5). In all hearts, regions of severe signal loss were consistently adjacent to the posterior vein of the left ventricle; T*2 in these regions was 12 ms (SD = 2 ms, n = 5), and the difference in resonance frequency with the surrounding myocardium was 70-100 Hz. These effects may be caused by increased magnetic susceptibility from deoxygenated blood in these veins.
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
authors.forename: S B
authors.initials: SB
authors.lastname: Reeder
authors.forename: A Z
authors.initials: AZ
authors.lastname: Faranesh
authors.forename: J L
authors.initials: JL
authors.lastname: Boxerman
authors.forename: E R
authors.initials: ER
authors.lastname: McVeigh
mesh_terms: D016477:Artifacts; D003331:Coronary Vessels / Q000033:anatomy & histology; D017352:Echo-Planar Imaging / Q000295:instrumentation*; D006321:Heart / Q000033:anatomy & histology*; D006346:Heart Septum / Q000033:anatomy & histology; D006352:Heart Ventricles / Q000033:anatomy & histology; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation*; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation*; D012680:Sensitivity and Specificity