Rodgers Christopher T, Clarke William T, Snyder Carl, Vaughan J Thomas, Neubauer Stefan, Robson Matthew D
Oxford Centre for Clinical Magnetic Resonance Research (OCMR), University of Oxford, Level 0, John Radcliffe Hospital, Oxford, United Kingdom.
Magn Reson Med. 2014 Aug;72(2):304-15. doi: 10.1002/mrm.24922. Epub 2013 Sep 4.
Phosphorus magnetic resonance spectroscopy ((31)P-MRS) affords unique insight into cardiac energetics but has a low intrinsic signal-to-noise ratio (SNR) in humans. Theory predicts an increased (31)P-MRS SNR at 7T, offering exciting possibilities to better investigate cardiac metabolism. We therefore compare the performance of human cardiac (31)P-MRS at 7T to 3T, and measure T1s for (31)P metabolites at 7T.
Matched (31)P-MRS data were acquired at 3T and 7T, on nine normal volunteers. A novel Look-Locker CSI acquisition and fitting approach was used to measure T1s on six normal volunteers.
T1s in the heart at 7T were: phosphocreatine (PCr) 3.05 ± 0.41s, γ-ATP 1.82 ± 0.09s, α-ATP 1.39 ± 0.09s, β-ATP 1.02 ± 0.17s and 2,3-DPG (2,3-diphosphoglycerate) 3.05 ± 0.41s (N = 6). In the field comparison (N = 9), PCr SNR increased 2.8× at 7T relative to 3T, the Cramer-Ráo uncertainty (CRLB) in PCr concentration decreased 2.4×, the mean CRLB in PCr/ATP decreased 2.7× and the PCr/ATP SD decreased 2×.
Cardiac (31)P-MRS at 7T has higher SNR and the spectra can be quantified more precisely than at 3T. Cardiac (31)P T1s are shorter at 7T than at 3T. We predict that 7T will become the field strength of choice for cardiac (31)P-MRS.
磷磁共振波谱（(31)P-MRS）能提供关于心脏能量代谢的独特见解，但在人体中的固有信噪比（SNR）较低。理论预测在7T时(31)P-MRS的SNR会增加，这为更好地研究心脏代谢提供了令人兴奋的可能性。因此，我们比较了7T和3T时人体心脏(31)P-MRS的性能，并测量了7T时(31)P代谢物的T1值。
对9名正常志愿者在3T和7T时采集匹配的(31)P-MRS数据。采用一种新颖的Look-Locker CSI采集和拟合方法对6名正常志愿者测量T1值。
7T时心脏中的T1值为：磷酸肌酸（PCr）3.05±0.41秒，γ-ATP 1.82±0.09秒，α-ATP 1.39±0.09秒，β-ATP 1.02±0.17秒，2,3-二磷酸甘油酸（2,3-DPG）3.05±0.41秒（N = 6）。在磁场比较中（N = 9），相对于3T，7T时PCr的SNR增加了2.8倍，PCr浓度的克拉美-罗界（CRLB）降低了2.4倍，PCr/ATP的平均CRLB降低了2.7倍，PCr/ATP的标准差降低了2倍。
7T时心脏(31)P-MRS的SNR更高，并且与3T时相比，光谱可以更精确地定量。7T时心脏(31)P的T1值比3T时短。我们预测7T将成为心脏(31)P-MRS的首选场强。
