Quantification of creatine kinase reaction rate in mouse hindlimb using phosphorus‐31 magnetic resonance spectroscopic fingerprinting

Abstract

The goal of this study was to evaluate the accuracy, reproducibility, and efficiency of a 31 P magnetic resonance spectroscopic fingerprinting (31 P-MRSF) method for fast quantification of the forward rate constant of creatine kinase (CK) in mouse hindlimb. The 31 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 31 P-MRSF measurements was compared with the magnetization transfer (MT-MRS) method in mouse hindlimb at 9.4 T (n = 8). The reproducibility of 31 P-MRSF was also assessed by repeated measurements. Estimation of the CK rate constant using 31 P-MRSF (0.39 ± 0.03 s −1) showed a strong agreement with that using MT-MRS measurements (0.40 ± 0.05 s −1). Variations less than 10% were achieved with 2 min acquisition of 31 P-MRSF data. Application of the 31 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 31 P-MRSF framework for rapid, accurate, and reproducible quantification of the chemical exchange rate of CK in vivo.

Robust dual‐angle T1 measurement in magnetization transfer spectroscopy by time‐optimal control

“…Therefore CK reaction rates obtained with BIR‐4 exhibited statistically significant differences between the two acquisitions with a 2 ppm frequency shift. In our in vivo investigation, only OC excitation yielded CK reaction rates (Figure 9E) that align well with the existing literature 47–49 …”

“…In our in vivo investigation, only OC excitation yielded CK reaction rates (Figure 9E) that align well with the existing literature. [47][48][49]…”

Time-efficient relaxation measurements by 31P MR fingerprinting in human brain at 7T

“…MRF has been extensively studied to further reduce scanning duration and computational load for dictionary matching and to improve accuracy (9; 10; 11; 12). Even though MRF technique has proven its robustness and time-efficiency in human MRI studies, there are sparse studies focusing on spectroscopic MRF for both proton and X-nuclei (13; 14; 15).…”