Department of Biomedical Engineering and Case Center for Imaging Research, Case Western Reserve University, Cleveland, Ohio.
Department of Electrical and Computer Engineering and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois.
NMR Biomed. 2021 Feb;34(2):e4435. doi: 10.1002/nbm.4435. Epub 2020 Oct 27.
The goal of this study was to evaluate the accuracy, reproducibility, and efficiency of a P magnetic resonance spectroscopic fingerprinting ( P-MRSF) method for fast quantification of the forward rate constant of creatine kinase (CK) in mouse hindlimb. The P-MRSF method acquired spectroscopic fingerprints using interleaved acquisition of phosphocreatine (PCr) and γATP with ramped flip angles and a saturation scheme sensitive to chemical exchange between PCr and γATP. Parameter estimation was performed by matching the acquired fingerprints to a dictionary of simulated fingerprints generated from the Bloch-McConnell model. The accuracy of P-MRSF measurements was compared with the magnetization transfer (MT-MRS) method in mouse hindlimb at 9.4 T (n = 8). The reproducibility of P-MRSF was also assessed by repeated measurements. Estimation of the CK rate constant using P-MRSF (0.39 ± 0.03 s ) showed a strong agreement with that using MT-MRS measurements (0.40 ± 0.05 s ). Variations less than 10% were achieved with 2 min acquisition of P-MRSF data. Application of the P-MRSF method to mice subjected to an electrical stimulation protocol detected an increase in CK rate constant in response to stimulation-induced muscle contraction. These results demonstrated the potential of the P-MRSF framework for rapid, accurate, and reproducible quantification of the chemical exchange rate of CK in vivo.
本研究旨在评估 P 磁共振波谱指纹分析（P-MRSF）方法用于快速定量小鼠后肢肌酸激酶（CK）正向速率常数的准确性、可重复性和效率。P-MRSF 方法使用交错采集磷酸肌酸（PCr）和γATP，采用 ramped 翻转角和对 PCr 和γATP 之间化学交换敏感的饱和方案来获取波谱指纹。通过将获得的指纹与来自 Bloch-McConnell 模型的模拟指纹字典进行匹配来进行参数估计。在 9.4T（n=8）下，将 P-MRSF 测量的准确性与磁化转移（MT-MRS）方法进行了比较。通过重复测量还评估了 P-MRSF 的可重复性。使用 P-MRSF（0.39±0.03 s）估计 CK 速率常数与使用 MT-MRS 测量值（0.40±0.05 s）具有很强的一致性。使用 2 分钟采集 P-MRSF 数据，可实现小于 10%的变化。将 P-MRSF 方法应用于接受电刺激方案的小鼠，检测到 CK 速率常数在响应刺激诱导的肌肉收缩时增加。这些结果表明，P-MRSF 方法在体内快速、准确和可重复地定量 CK 化学交换率具有潜力。
