Signal scaling improves the signal-to-noise ratio of measurements with segmented 2D-selective radiofrequency excitations
Article first published online: 25 FEB 2013
Copyright © 2013 Wiley Periodicals, Inc., a Wiley company
Magnetic Resonance in Medicine
Volume 70, Issue 6, pages 1491–1499, December 2013
How to Cite
Finsterbusch, J., Busch, M. G. and Larson, P. E. Z. (2013), Signal scaling improves the signal-to-noise ratio of measurements with segmented 2D-selective radiofrequency excitations. Magn Reson Med, 70: 1491–1499. doi: 10.1002/mrm.24610
- Issue published online: 18 NOV 2013
- Article first published online: 25 FEB 2013
- Manuscript Accepted: 1 DEC 2012
- Manuscript Revised: 29 NOV 2012
- Manuscript Received: 19 SEP 2012
- Deutsche Forschungsgemeinschaft. Grant Number: FI 1544/1
- Bundesministerium für Bildung und Forschung (Neuroimage Nord)
- 2D-selective RF excitations;
- signal scaling;
- noise reduction;
- single-voxel MR spectroscopy
Segmented 2D-selective radiofrequency excitations can be used to acquire irregularly shaped target regions, e.g., in single-voxel MR spectroscopy, without involving excessive radiofrequency pulse durations. However, segments covering only outer k-space regions nominally use reduced B1 amplitudes (i.e., smaller flip angles) and yield lower signal contributions, which decreases the efficiency of the measurement. The purpose of this study was to show that applying the full flip angle for all segments and scaling down the acquired signal appropriately (signal scaling) retains the desired signal amplitude but reduces the noise level accordingly and, thus, increases the signal-to-noise ratio.
The principles and improvements of signal scaling were demonstrated with MR imaging and spectroscopy experiments at 3 T for a single-line segmentation of a blipped-planar trajectory.
The observed signal-to-noise ration gain depended on the 2D-selective radiofrequency excitation's resolution, field-of-excitation, and its excitation profile and was between 40 and 500% for typical acquisition parameters.
Signal scaling can further improve the performance of measurements with segmented 2D-selective radiofrequency excitations, e.g., for MR spectroscopy of anatomically defined voxels. Magn Reson Med 70:1491–1499, 2013. © 2013 Wiley Periodicals, Inc.