Analysis of quantitative ultrasound graphic trace and derived variables assessed at proximal phalanges of the hand in healthy subjects and in patients with cerebral palsy or juvenile idiopathic arthritis.: A pilot study

Abstract

Amplitude-dependent speed of sound (AD-SoS) and bone transmission time (BTT) are the quantitative ultrasound (QUS) variables usually assessed at proximal phalanges of the hand to estimate bone mineral status. The aim of the study was to provide a reference database for some additional QUS variables reflecting morphology of the ultrasound graphic trace according to gender, age, height, weight, and body mass index (BMI), and to assess their clinical usefulness. Fifty-two patients (age 3.1–20.9 years) affected by cerebral palsy with spastic tetraplegia (CPST, n = 38) or polyarticular active juvenile idiopathic arthritis (JIA, n = 14) were examined. In addition to AD-SoS and BTT, two QUS variables derived from the morphological analysis of ultrasound graphic trace, such as energy, extrapolated from the area under the ultrasound signal received, and weighted-slope (W-slope), derived from the angular coefficient of the regression line fitting the top point of the peaks of the ultrasound signal, were measured by phalangeal QUS (DBM Sonic, IGEA). The values of all the QUS variables measured in the patients were compared with our own sex- and age-reference values ( n = 1083, 587 males and 496 females, aged 3–21 years). The mean values of AD-SoS, BTT, energy, and W-slope were reduced ( P < 0.0001) in patients as a whole compared with normative data (− 2.4 ± 1.2, − 2.7 ± 1.5, − 2.5 ± 1.1, − 2.5 ± 1.1 Z-score, respectively). Fractured patients showed lower ( P < 0.001– P < 0.0001) values of the QUS variables than fracture-free patients (AD-SoS, − 3.3 ± 1.2 and − 1.8 ± 0.9; BTT, − 3.9 ± 1.7 and − 1.8 ± 1.1; energy, − 3.2 ± 1.2 and − 2.2 ± 0.7; W-slope, − 3.4 ± 1.4 and − 2.2 ± 0.9 Z-score, respectively). There was no difference ( P = NS) between patients with CPST and those with JIA. Age and height were positively correlated with all the QUS variables ( r = 0.55–0.79, P < 0.01– P < 0.0001). QUS variables were positively correlated among them ( r = 0.74–0.94, P < 0.0001). Age and number of fractures were independent predictors of the QUS variables (coefficients: AD-SoS, 11.466 and − 17.642; BTT, 0.049 and − 0.045; energy, 1.072 and − 1.303; W-slope, 0.046 and − 0.067; respectively). In conclusion, measurement of QUS variables derived from the morphological analysis of the ultrasound signal could give additional information in estimating bone mineral status in children and adolescents, probably reflecting some aspect related to bone structure.