- Poster presentation
- Open Access
Myocardial skeletal muscle signal spoiling using a crusher coil: a human cardiac phosphorus (31P) MR spectroscopic imaging study at 7 Tesla
© Schaller et al; licensee BioMed Central Ltd. 2015
- Published: 3 February 2015
- Phase Encode Gradient
- Similar Signal Reduction
- Bottom Slice
- Skeletal Muscle Signal
- Slice Signal
31P-MRS provides direct insights into myocardial energy supply (ATP, ADP, phosphocreatine (PCr) and inorganic phosphate). An initial study demonstrated that 7T cardiac 31P-MRS has 2.8x greater SNR than at 3T. However, the translation of more sophisticated 31P-MRS protocols to 7T is particularly challenged by increased RF heating of tissue at 7T. Chen and Ackerman introduced the surface spoiling coil in 1990: a concept that was recently further developed (Boer MRM 2014) for lipid suppression in human brain 1H-CSI. In this work, we introduce the first crusher coil for cardiac 31P-MRS at 7T. This allows us to saturate more efficiently skeletal muscle signal removing the RF heating associated with RF saturation bands.
Data were acquired with a Siemens 7T scanner. Localization used a 10cm 1H Tx/Rx RF coil (Rapid Biomedical) to acquire CINE FLASH images. 31P-MR spectra were acquired with a custom 10cm 31P Tx/Rx loop. The magnetic field generated by the crusher coil was simulated and optimized using Matlab (Mathworks). A capacitor initially charged by a power supply unit (PSU) was used to drive the current pulse in the crusher coil during a short spoiling duration (100μs). Spoiling was timed to coincide with the existing phase encoding gradients. A 2D-CSI experiment was performed on a two-compartment phantom with the 31P RF coil and the crusher coil placed above it. The BISTRO saturation band (Luo, MRM 2001) covered the entire top slice. The spoiling efficiency was then confirmed in vivo using 3D-CSI.
A crusher coil is an efficient alternative to BISTRO saturation bands for suppressing skeletal muscle during cardiac 31P-MRS at 7T. The flexibility offered by using the crusher coil will allow us to employ sequence modules that would otherwise be SAR-prohibitive e.g. adiabatic excitation for absolute quantitation, 1H-31P NOE enhancement or saturation-transfer pulses for future clinical studies at 7T, without having to compromise the skeletal muscle suppression.
This study was supported by a Sir Henry Dale Fellowship from the Wellcome trust and the Royal Society [098436/Z/12/Z].
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.