Use of quantitative ultrasound to assess bone status in children with juvenile idiopathic arthritis: a pilot study

"Which skeletal imaging modality is best for assessing bone health in children and young adults compared to DXA? A systematic review and meta-analysis"

BACKGROUND

Skeletal imaging techniques have become clinically valuable methods for measuring and assessing bone mineral density in children and young people. Dual-energy X-ray absorptiometry (DXA) is the current reference standard for evaluating bone density, as recommended by the International Society for Clinical Densitometry (ISCD). Various bone imaging modalities, such as quantitative ultrasound (QUS), peripheral quantitative computed tomography (pQCT), high-resolution peripheral quantitative computed tomography (HR-pQCT), magnetic resonance imaging (MRI), and digital X-ray radiogrammetry (DXR) have been developed to further quantify bone health in children and adults. The purpose of this review, with meta-analysis, was to systematically research the literature to compare the various imaging methods and identify the best modality for assessing bone status in healthy papulations and children and young people with chronic disease (up to 18 years).

METHODS

A systematic computerized search of Medline, PubMed, and Web of Science databases was conducted to identify English-only studies published between 1st January 1990 and 1st December 2019. In this review, clinical studies comparing imaging modalities with DXA were chosen according to the inclusion criteria. The risk of bias and quality of articles was assessed using the Quality Assessment Tool for Diagnostic Accuracy Studies (QUADAS-2). The meta-analysis to estimate the overall correlation was performed using a Fisher Z transformation of the correlation coefficient. Additionally, the diagnostic accuracy measures of different imaging methods compared with DXA were calculated.

RESULTS

The initial search strategy identified 13,412 papers, 29 of which matched the inclusion and exclusion criteria. Of these, twenty-two papers were included in the meta-analysis. DXA was compared to QUS in 17 papers, to DXR in 7 and to pQCT in 4 papers. A single paper compared DXA, DXR, and pQCT. The meta-analysis demonstrated that the strongest correlation was between DXR and DXA, with a coefficient of 0.71 [95%CI: 0.43; 1.00, p-value < 0.001], while the correlation coefficients between QUS and DXA, and pQCT and DXA were 0.57 [95%CI: 0.25; 0.90, p-value < 0.001] and 0.57 [95%CI: 0.46; 0.67, p-value < 0.001], respectively. The overall sensitivity and specificity were statistically significant 0.71 and 0.80, respectively.

CONCLUSION

No current imaging modality provides a full evaluation of bone health in children and young adults, with each method having some limitations. Compared to QUS and pQCT, DXR achieved the strongest positive relationship with DXA. DXR should be further evaluated as a reliable method for assessing bone health and as a predictor of fractures in children and young people.

Clinical utilities of quantitative ultrasound in osteoporosis associated with inflammatory rheumatic diseases

Secondary osteoporosis is an important co-morbidity related to inflammatory rheumatic diseases that is attributed to several factors including inflammatory cytokines, inactivity and glucocorticoid treatment. Quantitative ultrasound (QUS) has been utilized in osteoporosis research due to its detectability of bone density as well as bone quality. The current narrative review is to address the potential utilities of QUS in secondary osteoporosis of inflammatory rheumatic diseases, focusing on the clinical aspects of QUS in these diseases, based on the conformity of QUS with dual emission X-ray absorptiometry (DXA), the relationship with disease characteristics, and its capability of fracture prediction. Although limited data demonstrate that QUS had moderate to strong correlation with DXA, and might be useful as a potential imaging tool to screen for osteoporosis, further research is still required for QUS to be utilized effectively for the best outcome in these patients with rheumatic diseases.

The impact of underlying disease on fracture risk and bone mineral density in children with rheumatic disorders: A review of current literature

Childhood rheumatic diseases are associated with negative impacts on the skeleton, related to both the underlying illness and complications of therapy. The effects of medications like corticosteroids are well recognized, leading to reductions in bone mineral density and bone strength and concomitant increases in bone fragility and fracture risk. The impact of factors directly attributable to the underlying disease is not as well recognized. In this article, we review relevant literature to identify data which can contribute to an understanding of the impact of childhood rheumatic disease on the skeleton. We conclude that childhood rheumatic diseases are associated with reductions in bone mineral density and increased risk of vertebral and non-vertebral fractures. These data are strongest for juvenile arthritis, while conclusions are more limited for other rheumatic illnesses, like juvenile systemic lupus erythematosus or juvenile dermatomyositis, due to small numbers of patients studied. Finally, we make recommendations for areas in need of further research. These include the need for long-term longitudinal studies and for data to be collected in patients who have not been treated with corticosteroids.

Evidence-based outcomes on diagnostic accuracy of quantitative ultrasound for assessment of pediatric osteoporosis - a systematic review

BACKGROUND

Dual-energy absorptiometry (DXA) is the current reference standard for assessing pediatric osteoporosis; however due to its areal nature, it has limitations. Thus, quantitative ultrasound (QUS), a modality free of ionizing radiation, has been proposed as a potential surrogate for DXA.

OBJECTIVE

To semi-quantitatively assess the diagnostic accuracy of QUS for evaluating pediatric osteoporosis according to the U.S. Preventive Services Task Force guidelines.

MATERIALS AND METHODS

We retrieved articles on the diagnostic accuracy of quantitative US for assessing abnormal bone quality or quantity in patients of mean age ≤19 years from MEDLINE, EMBASE and Cochrane Library CCTR databases. Evidences were analyzed for reliability, construct and criterion validity, and responsiveness of quantitative US, according to the following questions: (1) How reliable is the acquisition of QUS measurements? (2) Is QUS diagnostically accurate to characterize bone strength and quality in osteoporotic children? (3) Is QUS sensitive to detect changes in bone status over time? (4) Is QUS able to predict future skeletal fractures/degeneration? Three reviewers independently evaluated the quality of reporting and methodological quality using the Standards for Reporting of Diagnostic Accuracy (STARD) and the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tools.

RESULTS

Out of 262 retrieved references (215 unique), we included 28 studies (1,963 patients; 807 reported boys and 761 girls, others unspecified; reported mean age, 0-19 years). The mean quality of reporting score was "excellent" in 24/28 (86%) studies; 11/28 (39%) studies had "adequate" research design quality.

CONCLUSION

There is no evidence of the diagnostic value of QUS at the present time despite the overall excellent and adequate research design quality of primary studies. Although QUS can produce reliable measurements, insufficient evidence has been reported to support other clinimetric properties of this technique.

Bone status of children born from mothers with autoimmune diseases treated during pregnancy with prednisone and/or low molecular weight heparin

BACKGROUND

To evaluate bone status in children born from mothers followed for autoimmune diseases and treated during pregnancy with low molecular weight heparin (LMVH) and/or prednisone.

FINDINGS

History, physical examination, laboratory tests and phalangeal ultrasonography were performed. Demographic, clinical, and laboratory data were entered into a customized database, and results were analyzed with SPSS software. In children whose mothers were treated with LMWH, we retrieved dried blood spots taken for newborn screening, and analyzed the presence of heparin with tandem mass spectrometry. We enrolled 27 females and 14 males born from 31 mothers with SLE or connective tissue diseases. These women were continuously treated during pregnancy with LMWH (n = 10), prednisone (n = 16), or both (n = 15). Bone ultrasound revealed low values (≤ 3 centile for age) in ten patients. In a multistep regression analysis, age at examination resulted the single predictor of low ultrasound values (p < 0.004). Tandem mass spectroscopy failed to determine traces of heparin in newborn blood.

CONCLUSIONS

Children born from mothers with autoimmune diseases are at risk to develop reduced bone mass. The administration of LMWH and of prednisone seems to be safe with regard to children's bone health.

A survey of steroid-related osteoporosis diagnosis, prevention and treatment practices of pediatric rheumatologists in North America

BACKGROUND

The purpose of our study is to assess practices of North American pediatric rheumatologists regarding monitoring, prevention, and treatment of low bone mineral density (BMD) in children on long-term glucocorticoid treatment. Long-term glucocorticoid therapy is associated with accelerated bone loss. Children with JIA and lupus have low baseline BMD and incident vertebral fractures commonly occur in these groups of patients even after a relatively short period of time being on systemic glucocorticoids. There are no established guidelines for identification, prevention, and treatment of glucocorticoid-induced bone loss in children.

METHODS

A cross-sectional online survey was conducted with 199 physicians who were listed in the ACR database as practicing pediatric rheumatology in North America.

RESULTS

86 physicians (43%) responded; 87% were board-certified in pediatric rheumatology. 95% used dual energy X-ray absorptiometry as their primary modality for assessing BMD. 79% "rarely" or "never" obtained a baseline BMD measurement prior to initiation of glucocorticoid therapy. 42% of respondents followed BMD annually. 93% "frequently" or "always" prescribed calcium for patients on long-term corticosteroid therapy; 81% "frequently" or "always" prescribed vitamin D. In patients diagnosed with osteoporosis, 35%-50 % of the practitioners "sometimes", "frequently" or "always" prescribed bisphosphonates. Bisphosphonates are prescribed at similar rates for male and female patients, and slightly more frequently for pubertal than for pre-pubertal patients. 96% of respondents "rarely" or "never" prescribed calcitonin for patients on long-term glucocorticoid therapy; 92% "rarely" or "never" prescribe this medication for patients with known osteopenia or osteoporosis.

CONCLUSIONS

Utilization of DXA in children on long-term corticosteroid therapy varies greatly among North American pediatric rheumatologists. Most respondents do not screen for low BMD on a regular basis despite acknowledging the risks of bone loss in this population. Broad consensus appears to be present among practitioners favoring the prescription of calcium and vitamin D for patients receiving long-term corticosteroid therapy. Relatively few respondents consistently recommend bisphosphonate therapy, even for patients with known low bone density; calcitonin is rarely used. These data underscore the need for studies to acquire specific data on bone loss, and its prevention and treatment in young patients on long-term glucocorticoid therapy.

Can ultrasound be used to estimate bone mineral density in children with growth problems?

AIM

To assess predictability of bone mineral density (BMD) of the lumbar spine (LS) determined by dual-energy x-ray absorptiometry (DXA) using by ultrasound speed of sound of the right and left radii (SOS-R and SOS-L) in patients with growth problems.

METHODS

Ultrasound and DXA were compared in patients with advanced, normal and delayed bone ages assessed by Greulich and Pyle (GP) and Tanner and Whitehouse (TW3) methods.

RESULTS

There was a strong correlation (r), of raw scores, between SOS-R and SOS-L, r = 0.81, p = 0.000 and their respective Z-scores, r = 0.78, p = 0.000. Z-score correlations were poor between SOS-R or SOS-L and LS-BMD. Sensitivity, specificity, positive and negative predictive values of SOS-R and Z-scores for predicting normal (>-1 to <1) and low (<-1) LS-BMD were poor. For high (>1) LS-BMD, Z-scores were 22%, 93%, 29% and 90%, respectively, for SOS-R and for SOS-L, 25%, 89%, 20% and 91%. For very low (<-2) LS-BMD, SOS-R and SOS-L were the same, respectively, 29%, 91%, 40% and 86%.

CONCLUSION

Ultrasound of the radius is a poor predictor of radiologically assessed BMD at the LS, especially with delayed bone age.

Probing heterogeneity of cortical bone with ultrasound axial transmission

In clinical examination of long cortical bones based on ultrasound axial transmission, the parameter currently used as indicator of bone fragility is the velocity of the first arriving signal (VFAS). VFAS is inherently related to the material properties of the bone site. However, experimental uncertainties may hide the true sensitivity of VFAS to elastic characteristics of bone. Measurements are performed with a multi-element compact array placed in contact with the bone. Therefore, VFAS measurements may be biased by variability imposed by geometrical irregularities of the sample below the probe and/or by probe misalignment. In this paper, we test the assumption that despite experimental errors, VFAS variations resulting from material properties can be measured. The methodology was to compare VFAS and velocities of compression bulk waves (VBWs) on carefully matched sites around the circumference of a test sample (bovine femur). VBW was mapped on bone cross-sections using a through-transmission technique. VBW and VFAS were highly correlated [R² = 0.80, root mean square error = 23 m·s⁻¹, p < 10⁻⁵] and the slope of the linear regression was close to 1 except in a part of the circumference with a pronounced curvature. In measurements performed with the same protocol as for clinical measurements, regions with different material properties (reflected by VBW) could be identified. This work demonstrates that within-specimen variations of material properties can be assessed with a technique available for in vivo measurements.

Reference values for quantitative ultrasonography (QUS) of radius and tibia in healthy greek pediatric population: clinical correlations

The aim of this study was to provide reference standards for measurements of quantitative ultrasonography (QUS) of radius and tibia in normative Greek pediatric population. Analysis was performed in 1549 healthy subjects (814 girls and 735 boys) with a mean decimal age of 11.41+/-3.52 yr (range: 3.78-18.33 yr). Results showed a gradual increase of absolute values of radial and tibial speed of sound (SOS), with aging and with pubertal progressing, in both girls and boys. Gender comparison showed significantly increased SOS values measured both at radius and at tibia in girls more than 13 yr of age compared with aged-matched boys. Significant but mild correlation was noted between standard deviation scores (SDS) of SOS at radius and at tibia (r = 0.259, p < 0.001). Additionally, tibial SOS SDS were significantly negatively correlated with body mass index (BMI) SDS (r = -0.230, p < 0.001). Finally, subjects that spend more than 3h of daily "screen time" (television and personal computer) showed significantly decreased SOS values measured both at radius and at tibia. On the contrary, no correlation was observed between SOS values and the amount of physical activity reported.

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.

Vitamin D receptor polymorphism among rickets children in Mongolia

BACKGROUND

It was reported that 32% of children under five years old in Mongolia had symptoms of rickets. Vitamin D receptor (VDR) gene polymorphism has received attention in relation to bone metabolism. We therefore investigated whether VDR polymorphism is related to high prevalence of rickets in Mongolia and to bone properties in childhood.

METHODS

We conducted a case-control study in Ulaanbaatar involving 80 children aged 7-10 years with a history of rickets (cases) and 72 children with no history of rickets (controls). VDR polymorphism was assessed using BsmI, ApaI, and TaqI, and bone properties were determined by measuring age-standardized midtibial cortical speed of sound (TCSOS).

FINDINGS

Each allelic frequency was verified to satisfy the Hardy-Weinberg equilibrium in cases, controls, and the total sample. The VDR polymorphisms among cases (BB 3%, Bb 18%, bb 80%; AA 15%, Aa 38%, aa 47%; and TT 81 %, Tt 17%, tt 3%) did not differ significantly from those among controls (BB 1%, Bb 13%, bb 86%; AA 16%, Aa 46%, aa 38%; and TT 86%, Tt 13%, tt 1%). There were no significant differences in TCSOS according to the VDR genotype among either cases or controls.

CONCLUSIONS

The VDR polymorphism does not play a major role in the development of rickets in Mongolia and has no effect on TCSOS in childhood.

Longitudinal measurements of bone status in preterm infants

BACKGROUND

Quantitative ultrasound measurement of the speed of sound (SOS) through bone has been investigated as a means of assessing bone status in preterm infants. Few studies report longitudinal measurements.

OBJECTIVE

To assess longitudinal changes in bone SOS in preterm infants.

METHODS

Sixty preterm infants with gestational ages of < 33 weeks and with birth weight appropriate for gestational age (AGA), and 48 healthy, term AGA infants were enrolled. SOS measurements of the tibia were made within the first week of life in the preterm infants, and within the first 72 hours of life in the term infants. During their hospital stay, weekly measurements of tibial SOS were made in 29 of the preterm infants, who were divided into three gestational age groups: Group 1: 24-26 weeks (n = 8), Group 2: 27-29 weeks (n = 9), and Group 3: 30-32 weeks (n = 12).

RESULTS

The median SOS value for the 60 newborn preterm infants was significantly lower than that for the 48 newborn term infants (2,924 versus 3,036 m/sec, p < 0.001). At each time point, SOS values for each of the preterm infant gestational age groups were significantly lower than the term newborn infant SOS values. SOS values decreased significantly over time for the entire cohort of 29 preterm infants (p < 0.001), and for Groups 1 (p = 0.015) and 2 (p = 0.003). At several time points, there was a significant negative correlation between serum alkaline phosphatase levels and SOS values, and a significant positive correlation between serum phosphorus levels and SOS values.

CONCLUSION

SOS measurements of the tibia decline during hospitalization in preterm infants, suggesting a progressive loss of bone strength. Longitudinal measurements of bone SOS in combination with serum alkaline phosphatase and serum phosphorus levels may identify infants at risk of developing osteopenia of prematurity.

Imaging of juvenile idiopathic arthritis

Over the past decade there have been considerable changes in the classification and imaging of juvenile idiopathic arthritis (JIA). Radiology now has a considerable role in the management of JIA, the differential diagnosis, monitoring disease progression and detecting complications. The different imaging modalities available, their role and limitations are discussed in this article and the various disease features that the radiologist should be aware of are described. An approach to the imaging of the child with joint disease and in the monitoring of disease complications are also discussed.

[Diagnosis and treatment of juvenile osteoporosis]

Bone mass is primarily genetically determined, but exogenous factors also play a major role. The prevention of osteoporosis can start from childhood, and optimal achievement of peak bone mass during childhood and adolescence is important in order to minimise future fracture risks. Chronic inflammatory diseases can have a detrimental effect on bone mass, by means of several mechanisms. Different diagnostic methods for detection and monitoring of osteoporosis are in use or under investigation. The role of calcium and vitamin D supplementation for the prevention and treatment of osteoporosis associated with paediatric rheumatic diseases remains to be established. New treatments such as bisphosphonates and calcitonin are now available, although their use in the paediatric age has been limited.

Bone status over 1 yr of etanercept treatment in juvenile idiopathic arthritis

OBJECTIVE

To evaluate bone mineral status over 1 yr of etanercept treatment in juvenile idiopathic arthritis (JIA).

METHODS

Twenty children (13 female, 7 male) aged 5.2-11.4 yr, with active polyarticular JIA were prospectively enrolled to receive etanercept (0.4 mg/kg, twice weekly). Responders were defined according to the American College of Rheumatology Pediatric 50 definition of improvement. Broadband ultrasound attenuation (BUA) by bone was determined at the left calcaneus to assess bone status at baseline and at 1-yr follow-up.

RESULTS

After 12 months of treatment, 15 (75%) patients were considered as responders. At baseline, responders and non-responders did not differ with regard to age, disease duration, core-set variables or BUA and Z-score values (patient's value--age specific normal value/normal group's s.d.). At 6-month and 1-yr follow-up in the whole group, BUA and Z-score values were not significantly different compared with baseline. At 1-yr follow-up, but not at 6 months, all 15 responders, differently from non-responders, showed a significant increase in both BUA and Z-score values: BUA at 1 yr 55.2 +/- 3.3 vs baseline 43.5 +/- 3.2 dB/MHz, P<0.001; Z score at 1 yr -0.3 +/- 0.2 vs baseline 1.5 +/- 0.4, P<0.002.

CONCLUSION

For the first time in childhood rheumatic disease this pilot prospective study, although in a small group, shows evidence that 1 yr of etanercept therapy by controlling the underlying disease activity induces a sustained benefit on JIA bone loss. Prospective studies in larger patient samples are needed to confirm these data.

Three-dimensional simulations of ultrasonic axial transmission velocity measurement on cortical bone models

The ultrasonic axial transmission technique, used to assess cortical shells of long bones, is investigated using numerical simulations based on a three-dimensional (3D) finite difference code. We focus our interest on the effects of 3D cortical bone geometry (curvature, cortical thickness), anisotropy, and microporosity on speed of sound (SOS) measurements for different frequencies in the MHz range. We first show that SOS values measured on tubular cortical shells are identical to those measured on cortical plates of equal thickness. Anisotropy of cortical bone is then shown to have a major impact on SOS measurement as a function of cortical thickness. The range of SOS values measured on anisotropic bone is half the range found when bone is considered isotropic. Dependence of thickness occurs for cortical shell thinner than 0.5 x lambda(bone) in anisotropic bone (lambda(bone): wavelength in bone), whereas it occurs for cortical shell thinner than lambda(bone) when anisotropy is neglected. Sensitivity of SOS along the bone axis to intracortical microporosity is shown to be approximately -20 m s(-1) per percent of porosity. Using homogenized porous bone, we finally show that the cortical depth that contributes to lateral wave SOS measurement is approximately 1-1.5 mm for frequencies ranging from 500 kHz to 2 MHz under classical in vivo measurement conditions.

Bone disease in pediatric rheumatologic disorders

Children with rheumatic disorders have multiple risk factors for impaired bone health, including delayed growth and development, malnutrition, decreased weight-bearing activity, inflammation, and glucocorticoid therapy. The impact of rheumatic disease during childhood may be immediate, resulting in fragility fractures, or delayed, because of suboptimal peak bone mass accrual. Recent years have seen increased interest in the effects of pediatric rheumatic disorders on bone mineralization, such as juvenile rheumatoid arthritis, systemic lupus erythematosus, and juvenile dermatomyositis. This review outlines the expected gains in bone size and mass during childhood and adolescence, and summarizes the advantages and disadvantages of available technologies for the assessment of skeletal growth and fragility in children. The varied threats to bone health in pediatric rheumatic disorders are reviewed, with emphasis on recent insights into the molecular mechanisms of inflammation-induced bone resorption. The literature assessing bone deficits and risk factors for impaired bone health in pediatric rheumatic disorders is reviewed, with consideration of the strengths and limitations of prior studies. Finally, future research directions are proposed.

Use of quantitative ultrasound to assess osteopenia in children with Crohn disease

BACKGROUND AND AIMS

Children with Crohn disease are at increased risk for osteopenia and osteoporosis. Early development of osteopenia can increase the lifetime risk for fractures and may be amenable to early intervention. The gold standard for measuring bone mineral density (BMD) and fracture risk is dual x-ray absorptiometry (DXA), but this involves some radiation and specialized programs for measuring BMD in children. Bone density Z scores were evaluated with quantitative ultrasound (QUS) using a novel portable device and were compared with DXA in children with Crohn disease.

METHODS

Thirty-five children with documented Crohn disease (mean age 14.3 +/- 2.3 years) had speed of sound measured at the left radius and left tibia. Normative values for QUS Z scores were calculated from a cohort of 1,110 healthy children. A subgroup of 26 children with Crohn disease underwent both QUS and DXA. Z scores were calculated and compared for both groups.

RESULTS

The mean Z score using lumbar spine DXA was -1.04 +/- 1.51 SD, compared with -0.15 +/- 1.49 SD, using the lowest Z score for QUS ( < 0.05). Using height adjusted DXA, 50% of children with Crohn disease had osteopenia, whereas QUS detected only 19.2% of these children ( < 0.05). Significantly fewer cases of osteopenia were detected using QUS at Z scores up to -2 SD.

CONCLUSIONS

Quantitative ultrasound performed on the radius and tibia may not be sensitive enough to pick up osteopenia in children with Crohn disease.

Osteoporosis in juvenile idiopathic arthritis

Osteoporosis is characterized by loss of both bone mass and microarchitectural integrity, resulting in an increased risk of fractures with associated morbidity and mortality. Awareness of this condition is increasing in pediatrics, including pediatric rheumatology. Reduced bone mineral density is now well recognized in children and young adults with juvenile idiopathic arthritis and is multifactorial in origin. The problems of interpretation of bone analysis techniques during childhood and adolescence are highlighted. Recent studies have reported on the use of newer methods of imaging, including quantitative ultrasound and bone single photon emission computed tomography techniques. Attempting to disentangle the relative effects of disease activity, corticosteroids, nutrition, and physical activity in the development of osteoporosis in juvenile idiopathic arthritis is the focus of several studies. Finally, early optimistic reports of the use of bisphosphonates in juvenile idiopathic arthritis are welcome additions to the growing body of literature in this area.