“Chess-Board Pattern” Spatial Modulation of Magnetization

Heart motion is a complex combination of translation, rotation, and concentric contraction. Evaluation of these complex motions has been difficult using conventional slice-selective methods. Noninvasive tagging of the heart has been obtained by the use of slice-selective radiofrequency pulses. Through spatial modulation of the magnetization the entire image can be labeled in different patterns. Two new pulse sequences are presented, giving a chess-board like spatial modulation. These pulse sequences have several advantages compared with the previously published methods, as the modulation time is half that required to obtain a 2-dimensional grid, the area in the image with high signal intensity was significantly larger, and the radiofrequency power deposition was substantially decreased. By labeling the heart at diastole the chess-board pattern tagging of the heart wall could be followed through systole. Using this method the complex motions of the heart can be mapped.