The effect of ankle oedema on bone ultrasound assessment at the heel

Radiofrequency echographic multispectrometry (REMS): an innovative technique for the assessment of bone status in young women with anorexia nervosa

PURPOSE

Reduced bone mineral density (BMD) and increase risk of fragility fracture are common complication of anorexia nervosa (AN). BMD by dual-energy X-ray absorptiometry (DXA) present several limits in subjects with AN. This study aimed to evaluate the usefulness of the new Radiofrequency echographic multispectrometry (REMS) technique in the assessment of bone status in young women with AN.

METHODS

In a cohort of 50 subjects with restrictive AN and in 30 healthy controls, we measured BMD at the lumbar spine (LS-BMD), at femoral neck (FN-BMD) and total hip (TH-BMD) using both DXA and REMS technique.

RESULTS

BMD evaluated by DXA and REMS technique at all measurement sites were all significantly (p < 0.01) lower in subjects suffering from AN subjects than in controls. Good correlations were detected between BMD by DXA and BMD by REMS measurements at LS (r = 0.64, p < 0.01) at FN (r = 0.86, p < 0.01) and at TH (r = 0.84, p < 0.01) in subjects suffering from AN. Moreover, Bland-Altman analysis confirmed the good agreement between the two techniques. The subjects suffering from AN with previous vertebral fragility fractures presented lower values of both BMD-LS and BMD-TH by DXA and by REMS with respect to those without fractures; however, the difference was significant only for BMD-TH by REMS (p < 0.05).

CONCLUSIONS

Our data suggest that REMS technique due to its characteristic of precision and reproducibility may represent an important tool for the evaluation of the changes in bone status in AN young women, especially during the fertile age and in case of pregnancy and breastfeeding.

LEVEL OF EVIDENCE

Level of evidence: level III cohort study.

The quantitative ultrasound method for assessing low bone mass in women with anorexia nervosa

This study investigated the potential role of quantitative ultrasound (QUS) to assess low bone mass in anorexia nervosa patients (AN). Bone parameters from QUS and DXA were positively correlated and significantly reduced in AN compared with controls, suggesting that QUS is a pertinent technique to assess low bone mass in these patients.

PURPOSE

The aim of this study was to investigate the potential role of an alternative technique, quantitative ultrasound (QUS), to assess low bone mass in patients with anorexia nervosa (AN).

METHODS

Two hundred seven young women (134 patients with AN and 73 healthy controls) with ages ranging from 14.4 to 38.4 years participated in this observational cross-sectional study. Bone mass was concomitantly evaluated by DXA to determine areal bone mineral density (aBMD; g/cm²) at hip, lumbar spine, and radius and by QUS to determine broadband ultrasound attenuation (BUA; dB/MHz) at the heel.

RESULTS

BUA (66.5 ± 4.6 dB/MHz vs 61.0 ± 5.0 dB/MHz) and aBMD at the hip (0.916 ± 0.013 g/cm² vs 0.806 ± 0.010 g/cm²), lumbar spine (0.966 ± 0.012 g/cm² vs 0.886 ± 0.010 g/cm²), and radius (0.545 ± 0.005 g/cm² vs 0.526 ± 0.04 g/cm²) were significantly decreased (p < 0.01) in patients with AN compared with controls. When patient and control data were pooled, BUA was significantly correlated with aBMD at the hip (r = 0.60, p < 0.001), lumbar spine (r = 0.48, p < 0.001), and radius (r = 0.40, p<0.001). In patients with AN, BUA and aBMD were mainly and positively correlated with weight, lean tissue mass, body mass index (BMI), and minimal BMI life and negatively with the duration of both disease and amenorrhea. Better concordance between the two techniques was obtained when absolute BUA and aBMD values were used according to the WHO T score classification.

CONCLUSION

BUA measurement at the heel by QUS appears to be a pertinent nonionizing technique to assess low bone mass in patients with AN.

Arterial stiffness is not associated with bone parameters in an elderly hyperhomocysteinemic population

Several studies have observed positive associations between bone disease and cardiovascular disease. A potential common pathway is hyperhomocysteinemia; however, to date, there is a lack of data regarding hyperhomocysteinemic populations. Therefore, we examined both cross-sectionally and longitudinally, whether there is an association between bone parameters and arterial stiffness in a hyperhomocysteinemic population, and investigated the potential common role of homocysteine (hcy) level on these associations. Cross-sectional and longitudinal data of the B-PROOF study were used (n = 519). At both baseline and 2-year follow-up we determined bone measures-incident fractures and history of fractures, bone-mineral density (BMD) and quantitative ultrasound (QUS) measurement. We also measured arterial stiffness parameters at baseline-pulse wave velocity, augmentation index and aortic pulse pressure levels with applanation tonometry. Linear regression analysis was used to examine these associations and we tested for potential interaction of hcy level. The mean age of the study population was 72.3 years and 44.3 % were female. Both cross-sectionally and longitudinally there was no association between arterial stiffness measures and BMD or QUS measurements or with incident fractures (n = 16) within the 2-3 years of follow-up. Hcy level did not modify the associations and adjustment for hcy did not change the results. Arterial stiffness was not associated with bone parameters and fractures, and hcy neither acted as a pleiotropic factor nor as a mediator. The potential association between bone and arterial stiffness is therefore not likely to be driven by hyperhomocysteinemia.

Reductions in heel bone quality across gestation are attenuated in pregnant adolescents with higher prepregnancy weight and greater increases in PTH across gestation

Few studies have examined the effect of maternal calcium intake and vitamin D status on bone health across gestation in pregnant adolescents. This study aimed to characterize maternal bone quality and determinants of bone-quality change across gestation in pregnant adolescents. Healthy pregnant adolescents (n = 156; aged 13 to 18 years) with singleton pregnancies and at 12 to 30 weeks gestation at enrollment were recruited from two urban maternity clinics in Baltimore, MD, and Rochester, NY, for this prospective longitudinal study. Maternal serum was collected at midgestation and at delivery for assessment of bone biomarkers and calcitropic hormones. Maternal bone quality (assessed by heel ultrasound) and sonographic fetal biometry were measured up to three times across pregnancy. Racially diverse teens (64.7% African American, 35.3% white) were followed from 21.0 (interquartile range [IQR] 17.3, 27.0) weeks of gestation until delivery at 40.0 (IQR 39.0, 40.7) weeks. Significant decreases in calcaneal speed of sound (SOS), broadband ultrasound attenuation (BUA), and quantitative ultrasound index (QUI) (-9.2 ± 16.1 m/s, -3.2 (-8.0, 2.1) dB/MHz and -5.3 ± 8.8, respectively) were evident across pregnancy. Multivariate analysis controlling for baseline measures and measurement intervals was used to identify independent predictors of normalized (per week) calcaneal bone loss. Weekly decreases in bone quality were not significantly associated with maternal calcium intake or 25(OH)D concentration. Greater weekly reductions in calcaneal bone quality were evident in teens with lower prepregnancy weight (BUA, p = 0.006 and QUI, p = 0.012) and among those with lower weekly increase in PTH (SOS, p = 0.046). Overall, significant decreases in calcaneal bone quality occurred across pregnancy in adolescents, but the magnitude of this loss was attenuated in those with greater prepregnancy weight and weekly increases in PTH. Further studies are needed to understand the role of elevated PTH and greater prepregnancy weight in preserving adolescent bone during pregnancy.

The association between plasma homocysteine levels and bone quality and bone mineral density parameters in older persons

INTRODUCTION

High plasma homocysteine levels have been associated with incident osteoporotic fractures, but the mechanisms underlying this association are still unknown. It has been hypothesized that homocysteine might interfere with collagen cross-linking in bone, thereby weakening bone structure. Therefore, we wanted to investigate whether plasma homocysteine levels are associated with bone quality parameters, rather than with bone mineral density.

METHODS

Cross-sectional data of the B-PROOF study (n=1227) and of two cohorts of the Rotterdam Study (RS-I (n=2850) and RS-II (n=2023)) were used. Data on bone mineral density of the femoral neck and lumbar spine were obtained in these participants using dual-energy X-ray assessment (DXA). In addition, participants of B-PROOF and RS-I underwent quantitative ultrasound measurement of the calcaneus, as a marker for bone quality. Multiple linear regression analysis was used to investigate the associations between natural-log transformed plasma levels of homocysteine and bone mineral density or ultrasound parameters.

RESULTS

Natural-log transformed homocysteine levels were inversely associated with femoral neck bone mineral density in the two cohorts of the Rotterdam Study (B=-0.025, p=0.004 and B=-0.024, p=0.024). In B-PROOF, no association was found. Pooled data analysis showed significant associations between homocysteine and bone mineral density at both femoral neck (B=-0.032, p=0.010) and lumbar spine (B=-0.098, p=0.021). Higher natural-log transformed homocysteine levels associated significantly with lower bone ultrasound attenuation in B-PROOF (B=-3.7, p=0.009) and speed of sound in both B-PROOF (B=-8.9, p=0.001) and RS-I (B=-14.5, p=0.003), indicating lower bone quality. Pooled analysis confirmed the association between homocysteine and SOS (B=-13.1, p=0.016). Results from ANCOVA-analysis indicate that differences in SOS and BUA between participants having a plasma homocysteine level above or below median correspond to 0.14 and 0.09 SD, respectively.

DISCUSSION

In this study, plasma levels of homocysteine were significantly inversely associated with both bone ultrasound parameters and with bone mineral density. However, the size of the associations seems to be of limited clinical relevance and may therefore not explain the previously observed association between plasma homocysteine and osteoporotic fracture incidence.

Calcium economy in human pregnancy and lactation

Pregnancy and lactation are times of additional demand for Ca. Ca is transferred across the placenta for fetal skeletal mineralisation, and supplied to the mammary gland for secretion into breast milk. In theory, these additional maternal requirements could be met through mobilisation of Ca from the skeleton, increased intestinal Ca absorption efficiency, enhanced renal Ca retention or greater dietary Ca intake. The extent to which any or all of these apply, the underpinning biological mechanisms and the possible consequences for maternal and infant bone health in the short and long term are the focus of the present review. The complexities in the methodological aspects of interpreting the literature in this area are highlighted and the inter-individual variation in the response to pregnancy and lactation is reviewed. In summary, human pregnancy and lactation are associated with changes in Ca and bone metabolism that support the transfer of Ca between mother and child. The changes generally appear to be independent of maternal Ca supply in populations where Ca intakes are close to current recommendations. Evidence suggests that the processes are physiological in humans and that they provide sufficient Ca for fetal growth and breast-milk production, without relying on an increase in dietary Ca intake or compromising long-term maternal bone health. Further research is needed to determine the limitations of the maternal response to the Ca demands of pregnancy and lactation, especially among mothers with marginal and low dietary Ca intake, and to define vitamin D adequacy for reproductive women.

The 25th Anniversary of BUA for the Assessment of Osteoporosis: Time for a New Paradigm?

The measurement of broadband ultrasonic attenuation (BUA) in cancellous bone at the calcaneus for the assessment of osteoporosis was first described within this journal 25 years ago. It was recognized in 2006 by Universities UK as being one of the ‘100 discoveries and developments in UK Universities that have changed the world’ over the past 50 years. In 2008, the UK's Department of Health also recognized BUA assessment of osteoporosis in a publication highlighting 11 projects that have contributed to ‘60 years of NHS research benefiting patients’. The BUA technique has been extensively clinically validated and is utilized worldwide, with at least seven commercial systems currently providing calcaneal BUA measurement. However, there is still no fundamental understanding of the dependence of BUA upon the material and structural properties of cancellous bone. This review aims to provide an ‘engineering in medicine’ perspective and proposes a new paradigm based upon phase cancellation due to variation in propagation transit time across the receive transducer face to explain the non-linear relationship between BUA and bone volume fraction in cancellous bone.

Dual-frequency ultrasound--new pulse-echo technique for bone densitometry

Quantitative ultrasound has been suggested for screening of osteoporosis. Most commercial ultrasound devices are based on the through-transmission measurement of calcaneus, which is not a typical fracture site. In contrast to through-transmission measurements, reflection and backscattering measurements may be conducted at typical fracture sites such as vertebra and proximal femur. At these regions, soft tissues overlying bones affect reliability of the measurements. In this study, a novel dual-frequency ultrasound (DFUS) pulse-echo technique is introduced for reduction of the errors induced by soft tissues. First, DFUS was validated using elastomer samples. For further validation, human trabecular bone samples (n = 25) covered with heterogeneous soft tissues were measured at frequencies of 2.25 MHz and 5.0 MHz. The DFUS technique reduced (p < 0.01) the mean error induced by soft tissue from 58.6% to -4.9% and from 127.4% to 23.8% in broadband ultrasound backscattering and integrated reflection coefficient (at 5.0 MHz), respectively. To conclude, the DFUS, being the first ultrasound technique capable of determination of the composition and thickness of the soft tissue overlying the bone, may enhance the accuracy of clinical ultrasound measurements. Thereby, DFUS shows a significant clinical potential.

Quantitative ultrasound in the management of osteoporosis: the 2007 ISCD Official Positions

Dual-energy X-ray absorptiometry (DXA) is commonly used in the care of patients for diagnostic classification of osteoporosis, low bone mass (osteopenia), or normal bone density; assessment of fracture risk; and monitoring changes in bone density over time. The development of other technologies for the evaluation of skeletal health has been associated with uncertainties regarding their applications in clinical practice. Quantitative ultrasound (QUS), a technology for measuring properties of bone at peripheral skeletal sites, is more portable and less expensive than DXA, without the use of ionizing radiation. The proliferation of QUS devices that are technologically diverse, measuring and reporting variable bone parameters in different ways, examining different skeletal sites, and having differing levels of validating data for association with DXA-measured bone density and fracture risk, has created many challenges in applying QUS for use in clinical practice. The International Society for Clinical Densitometry (ISCD) 2007 Position Development Conference (PDC) addressed clinical applications of QUS for fracture risk assessment, diagnosis of osteoporosis, treatment initiation, monitoring of treatment, and quality assurance/quality control. The ISCD Official Positions on QUS resulting from this PDC, the rationale for their establishment, and recommendations for further study are presented here.

The clinical use of quantitative ultrasound (QUS) in the detection and management of osteoporosis

For the detection and management of osteoporosis and osteoporosis-related fractures, quantitative ultrasound (QUS) is emerging as a relatively low-cost and readily accessible alternative to dual-energy X-ray absorptiometry (DXA) measurement of bone mineral density (BMD) in certain circumstances. The following is a brief, but thorough review of the existing literature with respect to the use of QUS in 6 settings: 1) assessing fragility fracture risk; 2) diagnosing osteoporosis; 3) initiating osteoporosis treatment; 4) monitoring osteoporosis treatment; 5) osteoporosis case finding; and 6) quality assurance and control. Many QUS devices exist that are quite different with respect to the parameters they measure and the strength of empirical evidence supporting their use. In general, heel QUS appears to be most tested and most effective. Overall, some, but not all, heel QUS devices are effective assessing fracture risk in some, but not all, populations, the evidence being strongest for Caucasian females over 55 years old. Otherwise, the evidence is fair with respect to certain devices allowing for the accurate diagnosis of likelihood of osteoporosis, and generally fair to poor in terms of QUS use when initiating or monitoring osteoporosis treatment. A reasonable protocol is proposed herein for case-finding purposes, which relies on a combined assessment of clinical risk factors (CR.F) and heel QUS. Finally, several recommendations are made for quality assurance and control.

The measurement of broadband ultrasonic attenuation in cancellous bone--a review of the science and technology

The measurement of broadband ultrasonic attenuation (BUA) in cancellous bone at the calcaneus was first described in 1984. The assessment of osteoporosis by BUA has recently been recognized by Universities UK, within its EurekaUK book, as being one of the "100 discoveries and developments in UK Universities that have changed the world" over the past 50 years, covering the whole academic spectrum from the arts and humanities to science and technology. Indeed, BUA technique has been clinically validated and is utilized worldwide, with at least seven commercial systems providing calcaneal BUA measurement. However, a fundamental understanding of the dependence of BUA upon the material and structural properties of cancellous bone is still lacking. This review aims to provide a science- and technology-orientated perspective on the application of BUA to the medical disease of osteoporosis.

Instrumentation for in vivo ultrasonic characterization of bone strength

Although it has been more than 20 years since the first recorded use of a quantitative ultrasound (QUS) technology to predict bone fragility, the field has not yet reached its maturity. QUS has the potential to predict fracture risk in several clinical circumstances and has the advantages of being nonionizing, inexpensive, portable, highly acceptable to patients, and repeatable. However, the wide dissemination of QUS in clinical practice is still limited and suffering from the absence of clinical consensus on how to integrate QUS technologies in bone densitometry armamentarium. Several critical issues need to be addressed to develop the role of QUS within rheumatology. These include issues of technologies adapted to measure the central skeleton, data acquisition, and signal processing procedures to reveal bone properties beyond bone mineral quantity and elucidation of the complex interaction between ultrasound and bone structure. This article reviews the state-of-the art in technological developments applied to assess bone strength in vivo. We describe generic measurement and signal processing methods implemented in clinical ultrasound devices, the devices and their practical use, and performance measures. The article also points out the present limitations, especially those related to the absence of standardization, and the lack of comprehensive theoretical models. We conclude with suggestions of future lines and trends in technology challenges and research areas such as new acquisition modes, advanced signal processing techniques, and modelization.

Bone properties in patients with acromegaly: quantitative ultrasound of the heel

Growth hormone (GH) deficiency and acromegaly serve as good models for investigating the effects of GH on bone remodeling. However, the results from various studies are rather conflicting. The aim of our study was to estimate the potential role of gender, disease activity, and duration on both calcaneus quantitative ultrasound (QUS) parameters and bone turnover markers in patients with acromegaly. Thirty-six acromegalic patients (17 men, 19 women) and 3 age- and gender-adjusted controls for every patient were included in the study. The disease was active in 22 patients, and was considered cured in 14 of them. In each subject, QUS of the heel and parameters of bone turnover (bone alkaline phosphatase, beta-crosslaps, and osteocalcin) were measured. The results demonstrated lower QUS values in acromegalic patients compared with the controls. When stratified by gender, the differences in QUS parameters were significant in men, but not in women. Male patients with active disease had significantly lower QUS values than those in remission. Such differences were not observed among women. Multiple regression model indicated strong association between disease activity and the QUS parameters. The group of patients with active disease had a higher level of serum beta-crosslaps, whereas osteocalcin concentration was significantly increased only in male patients with active disease. The results of our study suggest significantly lower QUS values and increased bone turnover in male patients with active acromegaly. The disease activity is the strongest predictor of the QUS parameters in acromegalic patients.

Cross-sectional reference data for phalangeal quantitative ultrasound from early childhood to young-adulthood according to gender, age, skeletal growth, and pubertal development

Bone mineral status by phalangeal quantitative ultrasound (QUS, DBM Sonic, IGEA, Carpi, Modena, Italy) was examined in 3044 (1513 males and 1531 females) healthy subjects, aged 2-21 years. The aim of the study was to provide a reference database for phalangeal QUS parameters, amplitude-dependent speed of sound (AD-SoS) and bone transmission time (BTT), both expressed as centiles and Z score, according to gender, age, height, weight, body mass index (BMI), and pubertal stage to be used for estimating bone mineral status in patients with disorders of growth or of bone and mineral metabolism. In both sexes, AD-SoS and BTT increased significantly (P<0.0001) according to all the anthropometric variables. Females showed higher values than males in the age groups 9-14 for AD-SoS (P<0.04-P<0.0001) and in the age groups 11-13 for BTT (P<0.02). Males had higher BTT values than females in the age groups 6-8 and 15-21 (P<0.04-P<0.0001). AD-SoS was higher (P<0.02-P<0.0001) in females than in males at pubertal stages 2, 3, and 4, but it was higher (P=0.001) in males compared with females at pubertal stage 5. BTT was higher in males than females at pubertal stages 1 (P<0.0001), 2 (P<0.01), and 5 (P<0.0001). In both sexes, AD-SoS and BTT were significantly correlated between them (r=0.92, P<0.0001) and with all the anthropometric variables (r=0.53-r=0.85, P<0.0001). Age, weight, BMI, and pubertal stage were independent predictors of AD-SoS in males; age and pubertal stage were independent predictors of AD-SoS in females. In both sexes, height and pubertal stage, and also age only in females, were independent predictors of BTT. In conclusion, our data show that gender, age, height, and timing of sexual maturation are main determinants of bone structure and geometry, and that both these two processes may be captured by phalangeal QUS. It may be a useful tool to assess bone mineral status from early childhood to young-adulthood with a very small confounding effect related to bone sizes and without exposing the subjects to a source of radiation.

Bone loss after stroke over 52 weeks at os calcis: influence of sex, mobility and relation to bone density at other sites

BACKGROUND

As life expectancy increases after stroke, skeletal consequences become increasingly important, and patients at risk of fracture require identification. We have investigated peripheral bone mineral density (BMD) measurement at the heel as a possible surrogate for hip dual energy X-ray absorptiometry measurement and we have related bone loss over 52 weeks to balance and mobility.

METHODS

BMD at the heel (PIXI), proximal femur and whole body (QDR4500A), Tinetti (a measure of mobility and balance) and Barthel (a measure of activities of daily living) scores were measured in 52 patients (27 males and 25 females) within 8 weeks of stroke and repeated in 27 (15 males and 12 females) after 52 weeks.

RESULTS

BMD was not initially low at the femoral neck (FN). A significant fall occurred on the stroke side (SS) over 52 weeks at the heel, FN and total hip (TH), in both sexes, but was greater in women. On the non-SS, women lost bone at the TH and heel. Patients who were in the lowest Tinetti score tertile initially, showed significant loss of bone in the FN (14.5%) and at the heel (12.2%) on the SS. BMD at the SS heel correlated with the FN at 8 weeks (r = 0.64, P<0.01) and at 52 weeks (r = 0.60, P<0.01) after stroke. Women lost more bone than men on SS but also lost bone on the non-SS at the same sites, suggesting that SS bone loss may result from factors additional to stroke.

CONCLUSION

Heel BMD was a useful surrogate for hip BMD. Low initial Tinetti scores were an indicator of bone loss and, together with initial BMD measurements, provide a useful indication for those needing early prophylaxis against bone loss.

Evaluation of skeletal status by quantitative ultrasonometry in postmenopausal women without known risk factors for osteoporosis

The objective of our study was to evaluate bone density in Italian postmenopausal women without clinical risk factors for osteoporosis resident in the Naples area using quantitative ultrasonometry of bone (QUS). Subjects were 1149 Italian postmenopausal women (age: 54.9 +/- 5.0 years (mean +/- standard deviation); range: 45-74 years) resident in the Naples area. Clinical risk factors for osteoporosis resulting in exclusion from the study were family history of osteoporosis, dietary, smoking and alcohol habits, personal history of fractures and/or metabolic diseases. The following QUS parameters were calculated: amplitude-dependent speed of sound (AD-SoS), T-score and Z-score. We found significant inverse correlations between AD-SoS and age (r = - 0.23), time since menopause (r = - 0.25) and body mass index (BMI) (r = - 0.16). The same was observed for T-score. In contrast, Z-score showed a significant positive correlation with age and time since menopause, and a negative correlation with BMI. A T-score suggestive of high risk for osteoporosis (less than -3.2) was found in 1.6% of subjects, while a T-score suggestive of moderate risk for osteoporosis (between -3.2 and -2) was found in 19.3% of patients. In this group of women without clinical risk factors for osteoporosis we found a very low prevalence of QUS results suggesting a high risk for osteoporosis. However, a condition of 'moderate' risk for osteoporosis was present in a remarkable percentage of these women.

Impact of anthropometric, lifestyle, and body composition variables on ultrasound measurements in school children

Quantitative ultrasound (QUS) measurement at hand phalanges was demonstrated to be a reliable method to assess skeletal maturation during childhood and adolescence. The aim of the study was to evaluate the influence of age, gender, puberty, lifestyle factors, and body composition on QUS parameters and to provide a normative database for QUS in school children in Lebanon. Measurements of phalangeal osteosonography were examined in 256 healthy subjects (132 boys and 124 girls) aged 11-18 years using an ultrasound device. In both genders, amplitude-dependent speed of sound (AD-SoS) and bone transmission time (BTT) increased significantly with age and pubertal stages. Girls had higher AD-SoS values than boys between 11 and 15 years of age and at Tanner stages III and IV; however, no differences were detected in the older age groups. AD-SoS and BTT showed a significant positive correlation with age and height in both genders (R = 0.41-0.66, P < 0.01). There was no correlation between physical activity, calcium intake, sun exposure, and any of the QUS parameters in either gender. Weight showed moderate positive correlation with AD-SoS in boys and with BTT in both genders (R = 0.31-0.47, P < 0.01). Lean mass showed significant positive correlation with AD-SoS and BTT (R = 0.2-0.68, P < 0.01) in both genders. Percentage body fat showed significant negative correlation with BTT and AD-SoS in boys (R = -0.25 to -0.37, P < 0.01). In the linear regression analyses, there was a significant negative correlation between percentage fat mass and both AD-SoS and BTT in both genders. In conclusion, QUS parameters of the phalanges in Lebanese children are related to growth variables such as height, age, and puberty in healthy children. The impact and magnitude of body composition variables and lifestyle factors on ultrasonometry derived variables differ from their effect on dual energy X-ray absorptiometry derived parameters.

Osteoporosis: What a clinician expects to learn from a patient's bone density examination

Osteoporosis has lately become recognized as an important disease on two accounts. On one hand, demographic change has resulted in a greatly increased and increasing burden of morbidity and mortality due to osteoporotic fracturing. On the other hand, lifestyle changes and preventive measures have become recognized as important factors in prevention of both osteoporosis and osteoporotic fractures, while several effective drug treatments have recently become available to treat osteoporosis by increasing bone density and reducing fracture incidence. Because bone density is, with age, the best predictor of fracture risk, its measurement has become central to the care of those potentially at risk. When a clinician refers a person for a bone density examination, the clinician should be concerned less with an "imaging diagnosis" than with the requirement that the laboratory has procedures in place for rigorous quality assurance and precision measurements, as well as for education of the staff involved. Implementation of these measures and an understanding of their clinical relevance in diagnosis and follow-up, as well as communication with clinicians in this context, are more important than any diagnostic insight that might be provided by "interpreting" a bone density study.

Quantitative ultrasound of the calcaneus and dual X-ray absorptiometry of the lumbar spine in assessment and follow-up of skeletal status in patients after kidney transplantation

Bone loss after kidney transplantation is a significant complication of immunosuppressive treatment leading to a high prevalence of bone fracture in these patients. The purpose of this study was to determine the usefulness of quantitative ultrasound (QUS) of the calcaneus in comparison with dual X-ray absorptiometry (DXA) of the lumbar spine in determining bone status and mineral changes in patients in the first 6 months after transplantation. Forty-six patients participated in the study (25 men and 21 women; age range 26-62 years, 102+/-66 months previously on dialysis). They were treated with cyclosporine, methylprednisolone, mycophenolate mofetil, and basiliximab. The 6-month cumulative steroid dose was 24.9+/-3.7 mg/kg body weight. Calcaneal QUS (Sahara, Hologic, Waltham, Mass.) and DXA (Hologic QDR 4500) of the lumbar spine were done in all patients within 3 weeks after transplantation and 6 months thereafter. Bone mineral density (BMD) of the lumbar spine measured by DXA decreased from 0.892+/-0.137 to 0.837+/-0.126 g/cm2 (p<0.0001) and the T score decreased from 1.84+/-1.29 standard deviation (SD) to 2.35+/-1.19 SD (p<0.0001) in the first 6 months after transplantation. The QUS parameters of the calcaneus were broadband ultrasound attenuation (BUA), speed of sound (SOS), and quantitative ultrasound index (QUI). The QUS parameters did not change significantly after the first 6 months. All QUS parameters correlated significantly with DXA BMD of the lumbar spine immediately after transplantation and 6 months thereafter. Significant decrease of the lumbar spine BMD in the first 6 months after transplantation was not accompanied by significant changes of calcaneal QUS parameters. The calcaneal QUS does not reflect bone mineral changes occurring in the lumbar spine and could not be a substitute for a direct-site DXA of the lumbar spine in the early period after kidney transplantation.

Bone mineral density, ultrasound velocity, and broadband attenuation predict mechanical properties of trabecular bone differently

Measurement of areal bone mineral density (BMD(areal)), broadband ultrasound (US) attenuation (BUA), and speed-of-sound (SOS) are widely used ways to perform clinical assessment of bone quality. In this study, bovine (n = 37) and human (n = 32) trabecular bone was investigated in vitro and in vivo to reveal relationships between mechanical properties, mineral density, and US parameters BUA and SOS. To fulfill these aims, clinical US and dual-energy X-ray absorptiometry (DXA) techniques, as well as dynamic and destructive mechanical testing, were utilized. BUA correlated positively and linearly with BMD(areal) only in human calcaneus of low or moderate density (r = 0.849, n = 32, p < 0.01). When calcaneal areas with high BMD(areal) were included in the analysis, however, the in vivo study revealed that the BUA-BMD(areal) relationship could be described by a second-order polynomial fit (r(2) = 0.618, n = 408). In high-density human or bovine bone, the BUA-bone density relationship was negative. In the in vitro assessment, BUA correlated linearly and negatively with volumetric BMD (BMD(vol)) (r = -0.540, n = 29, p < 0.01) and with storage modulus, as measured at 1 Hz (r = -0.505, n = 28, p < 0.01). A weak positive correlation was found between BUA and mechanical loss tangent (r = 0.322, n = 28, p < 0.1). SOS correlated strongly positively with BMD(vol) (r = 0.888, n = 29, p < 0.01), as well with storage modulus (r = 0.649, n = 28, p < 0.01). In contrast, SOS correlated negatively with loss tangent (r = -0.417, n = 28, p < 0.05). When tested dynamically in the frequency range of 0.01-22.7 Hz, bovine trabecular bone was only slightly viscoelastic. In summary, the most accurate parameters for measuring storage modulus and strength of bovine trabecular bone were SOS and BMD(vol), respectively. BUA failed to predict the mechanical properties of high-density trabecular bone. In vivo mapping of the calcaneus revealed the importance of standardized and reproducible localization of the measurement site for the validity of BUA values.

Bone quality assessment by quantitative ultrasound of proximal phalanxes of the hand in healthy subjects aged 3--21 years

Bone quality by quantitative ultrasound was assessed in 1083 (587 males) healthy white subjects aged 3--21 y. Amplitude-dependent speed of sound (AD-SoS) through the distal end of the first phalanx diaphysis of the last four fingers of the hand was measured by an ultrasound device (DBM Sonic 1200, IGEA, Carpi, Italy). Mean AD-SoS values increased progressively from 3 to 21 y (males, 1845.9--2119.1 m/s, p < 0.0001; females, 1842.3--2098.8 m/s, p < 0.0001). They did not differ (p = NS) between sexes up to age 11, but females showed higher (p < 0.05 - p < 0.0001) AD-SoS values than males in age groups 12, 13, and 14 y. There was no difference (p = NS) of AD-SoS values between sexes in pubertal stages 1, 2, and 5, but females had higher mean AD-SoS values than males in stages 3 (p < 0.01) and 4 (p < 0.001). Independent predictors of AD-SoS were weight, body mass index, pubertal stage, and mean width of fingers in males, and age, pubertal stage, and mean width of fingers in females (p < 0.01 - p < 0.0001). However, 7.8% in males and 3.6% in females of the increment of AD-SoS values can be related to the finger anatomy alone. AD-SoS values probably reflect the architectural organization of growing bone or changes in bone elasticity. Increased bone density and size may be additional factors influencing AD-SOS: Measurement of AD-SoS at the hand phalanxes may be a simple, noninvasive, and radiation-free technique to assess bone quality in children.

Quantitative ultrasound and dual X-ray absorptiometry measurements of the calcaneus in patients on maintenance hemodialysis

It has been suggested that quantitative ultrasound measurements (QUS), which reflect mainly bone density, could be influenced by bone micro-architecture. The aim of the study was to assess whether the relationship of QUS to dual X-ray absorptiometry (DXA) would reflect abnormalities of bone structure observed in renal osteodystrophy. QUS and bone mineral density of the calcaneus (BMDc) were measured by DXA in 30 patients on maintenance hemodialysis and 34 age- and gender-matched controls. QUS parameters and BMDc were significantly lower in hemodialysis patients than in controls (speed of sound [SOS] and broadband ultrasound attenuation [BUA], p = 0. 030; stiffness, p = 0.003; BMDc, p = 0.006). Bone measurements were not correlated with serum parathyroid hormone (PTH). The regression lines of SOS, BUA, and stiffness to BMDc were not significantly different from that of the controls. When dividing the patients into two subgroups according to their median PTH (203 pg/mL), the slopes of the regression lines of BUA to BMDc were significantly different between these two subgroups (p = 0.052). The slope of the subgroup with PTH </= 203 pg/mL was significantly different from that of the controls (p = 0.030). In conclusion, QUS of the calcaneus can be used for bone assessment in patients on maintenance hemodialysis. The differences in the slopes of patients with a less pronounced degree of hyperparathyroidism compared with patients with a higher degree of hyperparathyroidism and to controls suggest that BUA of the calcaneus contains information on bone complementary to DXA measured at the same site. The clinical relevance of this finding is presently unclear.

Quantitative ultrasound in postmenopausal osteoporosis

Ultrasound has been proposed as a low-cost, radiation-free method for osteoporosis assessment in postmenopausal women. Large prospective studies have shown that ultrasound parameters can be used for fracture risk estimate in this population, providing that adequate quality control is performed. The places of both ultrasound and the current gold standard method for bone assessment, dual energy x-ray absorptiometry, are still to be determined. Further studies are needed on the diagnosis of osteoporosis using ultrasound, because current diagnostic thresholds, designed by the World Health Organization, do not apply to this-new technology. Monitoring of skeletal changes and treatment effects by ultrasound cannot be recommended.

Evaluation of error bounds on calcaneal speed of sound caused by surrounding soft tissue

For absorptiometry measurements, soft tissue may have an impact on quantitative ultrasound (QUS) measurements. In the present study, we focused primarily on the quantification of measurement error on speed of sound (SOS) caused by surrounding soft tissue. The relevant soft tissue parameters affecting the inherent SOS inaccuracies are thickness and sound velocity. To meet our goal, SOS measurements were taken at the right heel using a QUS imaging device in 21 healthy subjects. Site-matched measurements of soft tissue thickness (STT) and bone width were performed using magnetic resonance imaging of the heel. Several bone velocities were calculated either by accounting for bone width (SOSBW) only or by taking into account the exact path lengths of all major components traversed by ultrasound &lapr;V(b)). Given that soft tissue composition is difficult to determine in vivo, we chose to estimate lower and upper error bounds on bone velocity (V(b lower) and V(b upper)) by spanning the full range of available values in the literature. The mean BW was 30.7 +/- 2.7 mm and the mean medial and external STTs were 8.8 +/- 1.7 and 8.5 +/- 1.5 mm, respectively. Accounting for true BW only resulted in no significant difference between SOS (1533 +/- 37) and SOSBW (1531 +/- 33). By contrast, accounting for both true BW and surrounding soft tissue resulted in an increase in the calculated bone velocity and statistically significant differences between SOS and V(b upper) (1568 +/- 36) and V(b lower) (1542 +/- 34). Root mean square errors between SOS and the calculated velocities were 0.34, 2. 32, and 0.70% for SOSBW, V(b upper), and V(b lower), respectively. We report here measurement errors caused by soft tissue to be 3 to 20 times higher than the SOS short-term precision (SOS coefficient of variation of 0.1%). Our results suggest that inaccuracies in SOS measurement caused by overlying soft tissue cannot be neglected. Overlying soft tissues may influence outcomes of longitudinal studies, especially if variations in tissue thickness and composition occur during the longitudinal follow-up. A practical way of minimizing the measurement error could be to perform an adequate correction for the overlying soft tissue. However, ideally, this should require knowing both the thickness and sound velocity in soft tissue. One might preferably conduct experimental investigations that directly control soft tissue thickness and composition to resolve this problem.

Bone properties as estimated by mineral density, ultrasound attenuation, and velocity

Quantitative ultrasound (QUS) analysis of bone has been suggested to have a level of performance equal to dual-energy X-ray absorptiometry (DXA) for the assessment of fracture risk. In this study, QUS and DXA measurements were conducted on bovine trabecular bone in vitro using commercially available clinical instruments. The samples were then mechanically tested to obtain Young's modulus and ultimate strength. In addition, QUS and DXA parameters of the human calcaneus (n = 34) were measured in vivo. The measurements revealed a significant effect of bovine bone size on broadband ultrasound attenuation (BUA) and speed of sound (SOS) in vitro. By normalizing the DXA and QUS results with bone thickness we could systematically improve their ability to predict bone strength. However, in bovine trabecular bone, BUA showed no significant linear correlation with either bone mineral density (BMD), Young's modulus, or ultimate strength. This finding may be typical of only high-density and low-porosity bovine bone. We significantly improved prediction of ultimate strength by combining density and ultrasound velocity results as compared with assessments of volumetric BMDvol (p < 0.05) or SOS (p < 0.001) alone. However, the improvement was not significant if BMDvol, instead of wet density, was used. Altogether, 88% of the variation in the ultimate strength of bovine bone could be explained by combined density and ultrasound velocity. In vivo, SOS showed a weak negative correlation with heel width (r = -1.350). The in vivo measurements also showed a close correlation for BUA with BMD in the human calcaneus. This suggests that BUA is more suitable for quantitative analysis of low-density trabecular bone.

Factors influencing the speed of sound through the proximal phalanges

The amplitude-dependent speed of sound (AD-SOS) in the proximal phalanges is reported to be sensitive to osteoporotic changes. We investigated the influence of bone thickness and cortical thickness on AD-SOS. Phantoms made of Perspex were designed to simulate different bone width (11-16 mm) and cortical thickness (3-7.5 mm). The phantoms were designed with two opposing flat and cylindrical surfaces. The effect of cortical thickness was examined by drilling holes (simulating the medullary canal) of different diameters (1-7 mm) in the middle of the Perspex cylinders. The effect of sample thickness was investigated on solid Perspex phantoms of varied lengths. The standardized precision errors of AD-SOS measurement in vivo and in vitro on volunteers and phantoms were 2.8 and 0.9%, respectively. AD-SOS was influenced by the bone width, cortical thickness, and location along the phalanx. A decrease in either cortical width or cortical thickness resulted in a decrease in AD-SOS. The effect is dependent on whether the contact surface is curved or flat. It is possible that a curved surface has a focusing effect on the wave through the porous core, whereas for a flat surface, the path of the waves might not pass through the center. When cortical thickness and bone width were expressed as a ratio, there was a linear relationship between this ratio and AD-SOS through the phantoms. AD-SOS was independent of thickness for samples greater than 11 mm.

Prediction of vertebral strength in vitro by spinal bone densitometry and calcaneal ultrasound

Spinal bone mineral density (BMD) measurements and calcaneal ultrasound were compared in terms of their ability to predict the strength of the third lumbar vertebral body using specimens from 62 adult cadavers (28 females, 34 males). BMD was measured using dual X-ray absorptiometry (DXA) in both vertebra and calcaneus. Quantitative computed tomography (QCT) was used to determine trabecular BMD, cortical BMD, cortical area, and total cross-sectional area (CSA) of the vertebral body. Bone velocity (BV) and broadband ultrasonic attenuation (BUA) were measured in the right calcaneus. Vertebral strength was determined by uniaxial compressive testing. Vertebral ultimate load was best correlated with DXA-determined vertebral BMD (r2 = 0.64). Of the QCT parameters, the best correlation with strength was obtained using the product of trabecular BMD and CSA (r2 = 0.61). For vertebral ultimate stress, however, the best correlation was observed with QCT-measured trabecular BMD (r2 = 0.51); the correlation with DXA-determined BMD was slightly poorer (r2 = 0.44). Calcaneal ultrasound correlated only weakly with both ultimate load and stress with correlation coefficients (r2) of 0.10-0.17, as did calcaneal BMD (r2 = 0.18). Both spinal DXA and spinal QCT were significantly (p < 0.001) better predictors of L3 ultimate load and stress than were either calcaneal ultrasound or calcaneal DXA. Multiple regression analysis revealed that calcaneal ultrasound did not significantly improve the predictive ability of either DXA or QCT for L3 ultimate load or stress. Calcaneal DXA BMD, bone velocity, and BUA correlated well with each other (r2 = 0.67-0.76), but were only modestly correlated with the DXA and QCT measurements of the vertebra. These data indicate that spinal DXA and spinal QCT provide comparable prediction of vertebral strength, but that a substantial proportion (typically 40%) of the variability in vertebral strength is unaccounted for by BMD measurements. Ultrasonic measurements at the calcaneus are poor predictors of vertebral strength in vitro, and ultrasound does not add predictive information independently of BMD. These findings contrast with emerging clinical data, suggesting that calcaneal ultrasound may be a valuable predictor of vertebral fracture risk in vivo. A possible explanation for this apparent discrepancy between in vivo and in vitro findings could be that current clinical ultrasound measurements at the calcaneus reflect factors that are related to fracture risk but not associated with bone fragility.