In vivo comparison of CSPAMM and DENSE for cardiac motion analysis

Introduction Tagging has shown great promise for analyzing cardiac motion patterns [1]. Two different methods have been proposed to utilize the phase associated with harmonic modulation of magnetization to enable tissue tracking. Using Displacement ENcoding with Stimulated Echoes (DENSE) [2] tagged magnetization is demodulated by decoding gradients permitting motion tracking from the signal phase. In contrast, HARmonic Phase (HARP) [3] analysis of Complementary SPAtial Modulation of Magnetization (CSPAMM) [4] data decomposes tagged data into its harmonic components during post-processing. In order to improve the signal-to-noise ratio, harmonic components can be combined with appropriate phase referring to peak-combination HARP as introduced in [5]. The relation between DENSE and HARP is illustrated in Figure 1 including the possibility of signal combination. Following the insight of the Fourier shift theorem, it has been argued that the information content of DENSE and HARP should be identical [6]. However, a formal comparison of DENSE and HARP has not been undertaken to date. In this study, DENSE and HARP data were obtained consecutively in the same subjects and circumferential shortening, rotation and time-to-peak motion were evaluated with and without employing signal peak combination.