Bone quality assessed by phalangeal quantitative ultrasonography in children and adolescents with isolated idiopathic growth hormone deficiency

Imaging methods for bone mass evaluation during childhood and adolescence: an update

The objective of the work was to prepare an update on imaging methods for bone evaluation during childhood and adolescence. The text was based on original and review articles on imaging methods for clinical evaluation of bone mass in children and adolescents up to 20 years old. They were selected from BIREME and PUBMED by means of the following keywords: bone density; osteoporosis/diagnosis; densitometry; tomography; ultrasonography; magnetic resonance imaging; and radiogrammetry and published in Portuguese or English, in the last 10 years (2006-2016). The article was organized into topics with the description of peculiarities, advantages and disadvantages of each imaging method and their possible clinical applicability. Despite the emergence of new technologies, dual energy X-ray absorptiometry (DXA) remains the gold standard method for low bone mass diagnosis in all age groups. However, interpretation is complex in children and adolescents and demands skilled people. Quantitative computed tomography (QCT) [central QCT, peripheral QCT (pQCT) and high resolution-pQCT (HR-pQCT)] and magnetic resonance imaging (MRI) evaluate real bone density, but are not yet available for routine use. Quantitative bone ultrasound (QUS) shows good perspectives for its use in primary prevention actions. Automated radiogrammetry shows promise as a method able to flag individuals who might benefit from a complete bone assessment, but the clinical value of the measures still needs to be established.

Phalangeal quantitative ultrasound in 1,719 children and adolescents with bone disorders

SUMMARY

We measured bone properties by phalangeal quantitative ultrasound in 1,719 pediatric patients with bone disorders, classifying them according to fracture status. Quantitative ultrasound discriminated fractured and nonfractured pediatric patients and enabled us to stratify fractured patients into classes according to the severity of the causative trauma (spontaneous, minimal trauma, appropriate trauma fractures).

INTRODUCTION

The correlation between quantitative bone measurements and fractures is poorly established in pediatric patients with bone disorders. We correlated phalangeal quantitative ultrasound (QUS) and fracture history in children and adolescents with bone disorders and evaluated the ability of QUS to recognize fractured patients.

METHODS

Amplitude-dependent speed of sound (AD-SoS) and bone transmission time (BTT) were measured in 1,719 pediatric patients with bone disorders and related to fracture history. The patients were classified as (1) spontaneously (77), (2) minimal trauma (101), or (3) appropriate trauma fractured (206), and (4) nonfractured (1,335). The likelihood of fracture according to QUS was calculated as odds ratio per SD decrease (OR/SD), and the effectiveness in discriminating fractured patients was evaluated by receiver operating characteristic (ROC) analysis. The influence of age, sex, puberty, height, and BMI was explored by respective adjustments and multiple logistic regression.

RESULTS

Fractured patients showed significantly reduced AD-SoS and BTT standard deviation score (-0.32 ± 1.54 and -0.78 ± 1.49) compared to nonfractured subjects (0.43 ± 1.63 and -0.11 ± 1.34). QUS measurements paralleled the causative trauma severity, ranging from the lowest values in spontaneously fractured patients to normal values in appropriate trauma fractured subjects. The OR/SD were increasingly higher in appropriate trauma fractured, minimal trauma fractured, and spontaneously fractured patients. At ROC analysis, both parameters proved to have significant discrimination power in recognizing spontaneously and minimal trauma-fractured patients.

CONCLUSIONS

QUS identifies fractured pediatric patients with bone disorders, reflecting the severity of the causative trauma with a high discrimination power for fragility fractures.

Impact of metabolic control on bone quality in phenylketonuria and mild hyperphenylalaninemia

OBJECTIVES

A reduction of bone mineral density of unknown etiology has been reported in phenylketonuria (PKU) by radiological techniques, whereas no data on bone density in mild hyperphenylalaninemia (HPA) are available. We aimed to assess bone condition in PKU and HPA by quantitative ultrasound (QUS), taking into account patients' clinical and biochemical features.

PATIENTS AND METHODS

Phalangeal QUS has been used for bone assessment in 78 patients affected by PKU (n = 42) or mild HPA (n = 36). For each patient, blood phenylalanine concentrations in the 2 years before the study have been recorded and related to bone assessment.

RESULTS

Overall normal bone quality has been observed in the whole study group (AD-SoS standard deviation score [SDS] 0.25 ± 1.29; BTT SDS -0.13 ± 1.08). PKU adolescents (age older than 15 years, AD-SoS SDS -0.54 ± 1.33; BTT SDS -0.85 ± 1.21) and patients with poor compliance with treatment (blood phenylalanine >10 mg/dL, AD-SoS SDS -0.47 ± 1.39; BTT SDS -0.97 ± 1.14) showed lower BTT SDS with respect to normal population (P = 0.003 and P < 0.001, respectively). Patients with PKU with good compliance with treatment (blood phenylalanine < 10 mg/dL, AD-SoS SDS 0.65 ± 1.33; BTT SDS 0.15 ± 0.94) and patients with mild HPA (AD-SoS SDS 0.44 ± 1.06 and BTT SDS 0.19 ± 0.85) showed normal bone mineral density and cortical thickness.

CONCLUSIONS

Good compliance with treatment in PKU during adolescence and adulthood is desirable because diet discontinuation is associated with bone loss. Mild HPA seems not to be complicated by bone damage.

Bone quantitative ultrasound in congenital and acquired childhood multiple pituitary failure

The aim of the present study is to investigate bone status by phalangeal quantitative ultrasound (QUS) in a cohort of hypopituitaric pediatric subjects, and to relate measurement outcome to their clinical, laboratory, and therapeutical features. Forty-three hypopituitaric children were submitted to bone measurement by QUS with DBM sonic bone profiler 1200 (IGEA, Carpi, Modena, Italy). This method measures bone transmission time (BTT) and amplitude-dependent speed of sound (AD-SoS) of an ultrasound beam crossing the first four phalanges of the hand and provides respective standard deviation scores (SDS). These two parameters provide information on bone mineral density and structure. Clinical, laboratory and therapeutical features were considered to look for correlations. Overall BTT and AD-SoS SDS were significantly reduced (-0.87 +/- 1.52, p = 0.001, and -0.97 +/- 1.56, p = 0.001) as well as respective height- or bone age-corrected SDS. Bone condition proved significantly worse in subjects with higher number of hormonal deficiencies (p = 0.001 for both parameters) and in those with acquired hypopituitarism (p = 0.020 for BTT and p = 0.010 for AD-SoS) than in those with congenital forms. In participants under growth hormone (GH) treatment, regression analysis revealed that QUS measurement outcome was significantly associated with age at GH therapy start (p = 0.001), time interval before therapy initiation (p = 0.011), treatment duration (p = 0.007) and administered dosage (p = 0.036). Our data show that childhood hypopituitarism is associated with bone morbidity, detectable at QUS measurement independently of potential confounders as stature and bone age. Skeletal impairment is related to acquired hypopituitarism, number of hormonal deficiencies and duration of disease before replacement therapies, whereas GH treatment duration and doses are associated with a better skeletal condition. Phalangeal QUS measurements of BTT and AD-SoS promise as a reliable method for obtaining quantitative measurements of bone disease in individuals with hypopituitarism but more studies are needed for verification.

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

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.

Quantitative ultrasound methods to assess bone mineral status in children: technical characteristics, performance, and clinical application

Measurement of bone mineral status may be a useful tool in identifying the children who could be exposed to an increased risk of osteoporosis in adulthood. Dual energy x-ray absorptiometry and peripheral quantitative computed tomography may be used to this purpose, but the exposure to ionizing radiation is a limiting factor for preventive studies in large populations of children. In the last years, quantitative ultrasound (QUS) methods have been developed to assess bone mineral status in some peripheral skeletal sites such as calcaneus, phalanges of the hand, and tibia. QUS techniques are safe, easy to use, radiation-free, and devices are portable, so that they are particularly indicated to assess bone mineral status in children. This review will concentrate on the main methodological principles of ultrasounds and the QUS variables derived from their application to bone tissue, technical differences and performance of QUS methods, factors influencing QUS measurements, normative data and results obtained in children with disturbances of growth or affected by disorders of bone and mineral metabolism, including the assessment of fracture risk, and comparison among QUS, dual energy x-ray absorptiometry, and peripheral quantitative computed tomography methods.