Methods and reproducibility of cardiac/respiratory double-triggered H-1-MRspectroscopy of the human heart

Localized H-1-MR spectroscopy is sensitive to motion and has mostly been ap plied to the brain. For the human heart, cardiac and respiratory motion lea d to displacements on the order of the localized voxel and lead to substant ial Variations of voxel content, lineshape, water suppression, and signal p hase and amplitude. Combined respiratory and cardiac double triggering can avoid these complications to a large extent, Three methods of double trigge ring are evaluated, with reproducibility established in nine subjects for a method based on respiratory modulation of the ECG amplitude and a Visual f eedback mechanism. Quantitated with respect to water, within-subject reprod ucibilities for this setup were 9% for trimethylammonium compounds, 10% for creatine/phosphocreatine, and 13% for lipids, ANOVA showed significant dif ferences between subjects which may relate to natural variability between s ubjects or exact location within the heart. Unresolved issues for this tech nique are its susceptibility to precise placement of ECG electrodes and the reasons for failure in 20% of examination. With this technique it is possi ble to investigate open questions in cardiac pathophysiology, such as the c reatine content in chronic heart disease. Variants of this triggering metho d may also improve cardiovascular MRI methods relying on data acquired in s everal heartbeats. Magn Reson Med 42:903-910, 1999, (C) 1999 Wiley-Liss, In c.