Hypertensive heart disease: MR tissue phase mapping reveals altered left ventricular rotation and regional myocardial long-axis velocities.

OBJECTIVES: The aim of this study was the evaluation of left ventricular (LV) segmental 3D velocities in patients with hypertensive heart disease using magnetic resonance (MR) tissue phase mapping (TPM). METHODS: LV radial, long-axis and rotational myocardial velocities were assessed by TPM in patients with LV hypertrophy and preserved EF (n = 18, age = 53 ± 12 years) and volunteers (n = 20, age = 51 ± 4 years). Systolic and diastolic peak and time-to-peak velocities were mapped onto a 16-segment LV model. 3D myocardial motion was displayed on an extended visualisation model. Correlation coefficients were calculated to investigate differences in regional dynamics. RESULTS: Patients revealed diastolic dysfunction as expressed by decreased peak long-axis velocities in all (except apical) segments (basal, P ≤ 0.01; two midventricular segments, P = 0.02, P = 0.03). During systole, hypertrophy was associated with heterogeneous behaviour for long-axis velocities including an increase in anteroseptal apical and midventricular regions (P = 0.001), a reduction in mid-inferior segments (P = 0.03) and enhanced septal velocities (P < 0.05). Segmental correlation analysis revealed altered dynamics of LV base rotation and increased dyssynchrony of lateral long-axis motion. CONCLUSIONS: Patients with hypertensive heart disease demonstrated alterations in systolic long-axis motion, basal rotation and dyssynchrony. Longitudinal studies are needed to investigate the value of regional wall motion abnormalities regarding disease progression and outcome.

Off-resonance-dependent slice profile effects in balanced steady-state free precession imaging.

The purpose of this study was the simulation and measurement of balanced steady-state free precession (bSSFP) slice profiles for a detailed analysis of the influence of off-resonance effects on slice profile shape and bSSFP signal intensity. Due to the frequency response function of the bSSFP sequence, measurements that are not on-resonance result in broadened effective slice profiles with different off-resonance-dependent shapes and signal intensities. In this study, bSSFP slice profile effects and their dependence on off-resonance were investigated based on bSSFP signal simulations of phantom data as well as blood and tissue. For a better assessment of the similarity of measured and simulated slice profiles the field map was integrated in the slice profile simulations. The results demonstrate that simulations can accurately predict bSSFP slice profiles. Both measurements and simulations indicate that there is a substantial increase in signal intensity close to the banding artifacts, i.e., at spatial locations with off-resonance frequencies corresponding to a dephasing/TR = +/- pi resulting in signal void (bands). For routine bSSFP imaging, off-resonance-dependent slice broadening may thus result in a substantial difference between nominal and true slice thickness and lead to spatially varying slice thickness and signal intensities across the imaging slice.