Quantitative evaluation of muscle quality and quantity using an ultrasound radio frequency signal

We aimed to investigate the utility of quantitative ultrasonographic (QUS) parameters derived from radio frequency (RF) signals for the assessment of muscle quality and quantity.

A total of 200 hospitalized patients (102 men, 98 women; mean age: 59.11 ± 27.58 years) were prospectively enrolled in the study. Their skeletal muscle density (SMD) and skeletal muscle index (SMI) were calculated from computed tomography images, as the gold-standard methods of evaluating muscle quality and quantity, respectively. At the L3 vertebral level, the paraspinal muscle (PSM) thickness was measured by ultrasound, and the RF signals of the PSM were recorded, from which QUS parameters were obtained. Univariate and multivariate logistic regression analyses were performed to identify independent predictors of SMD and SMI. Receiver operating characteristic curves were used to evaluate the predictive performance of combination of parameters for low SMD and low SMI.

The RF signals-based QUS parameters MusQBOX.NNM(C), MusQBOX.NNM(L), MusQBOX.Nα(C), and MusQBOX.NK(L) were identified as independent predictors of low SMD (all P < 0.05). The PSM thickness and the parameter MUSQBOX.NMI(L) were independent predictors of low SMI (both P < 0.05). The combination of MusQBOX.NNM(C), MusQBOX.NNM(L), MusQBOX.Nα(C), and MusQBOX.NK(L) had high diagnostic efficiency in the prediction of low SMD [area under the curve (AUC): 0.899 [95% confidence interval (CI): 0.852-0.945), P < 0.001]. In addition, the combination of PSM thickness and MUSQBOX.NMI(L) showed moderate efficacy for the prediction of low SMI [AUC: 0.779 (95% CI 0.714-0.836), P < 0.001].

The RF signals-based QUS parameters derived from PSM are effective means of assessing both low SMD and low SMI and provide an alternative noninvasive method of evaluating muscle quality and quantity.