期刊论文

Zhou, Xin

英文

Journal of Magnetic Resonance

1090-7807

2016

263

92-100

10.1016/j.jmr.2015.12.022

Since we can only achieve an implicit solution according to Eqs. (8), (10), or Eqs. (11), (12), the optimal parameters of the CVFA scheme can be obtained via a numerical method. Fig. 3 shows the relationship between TR/T1 and the fraction of VFA excitation pulses in the CVFA scheme for different numbers of CFA excitation pulses. Fig. 3 shows that as TR/T1 is reduced, the fraction of VFA excitation pulses becomes more independent of that ratio. The fraction remains at about 30% when TR is much

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The longitudinal magnetization of hyperpolarized media, such as hyperpolarized129Xe,3He, etc., is nonrenewable. When the MRI data acquisition begins at the k-domain center, a constant flip angle (CFA) results in an image of high signal-to-noise ratio (SNR) but sacrifices the accuracy of spatial information. On the other hand, a variable flip angle (VFA) strategy results in high accuracy but suffers from a low SNR. In this paper, we propose a novel scheme to optimize both the SNR and accuracy, called constant-variable flip angles (CVFA). The proposed scheme suggests that hyperpolarized magnetic...