Osteoporosis: Barkmann R

Krieg MA, Barkmann R, Gonnelli S, Stewart A, Bauer DC, Del Rio Barquero L, Kaufman JJ, Lorenc R, Miller PD, Olszynski WP, Poiana C, Schott AM, Lewiecki EM, Hans D. · Lausanne University Hospital, Lausanne, Switzerland. <> · J Clin Densitom. · Pubmed #18442758 No free full text.

Abstract: 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.

Glüer CC, Barkmann R, Hahn HK, Majumdar S, Eckstein F, Nickelsen TN, Bolte H, Dicken V, Heller M. · Medizinische Physik, Klinik für Diagnostische Radiologie, Universitätsklinikum Schleswig-Holstein, Kiel. · Rofo. · Pubmed #17136644 No free full text.

Abstract: Quantitative parametric imaging approaches provide new perspectives for radiological imaging. These include quantitative 2D, 3D, and 4D visualization options along with the parametric depiction of biological tissue properties and tissue function. This allows the interpretation of radiological data from a biochemical, biomechanical, or physiological perspective. Quantification permits the detection of small changes that are not yet visually apparent, thus allowing application in early disease diagnosis and monitoring therapy with enhanced sensitivity. This review outlines the potential of quantitative parametric imaging methods and demonstrates this on the basis of a few exemplary applications. One field of particular interest, the use of these methods for investigational new drug application studies, is presented. Assessment criteria for judging the quality of quantitative imaging approaches are discussed in the context of the potential and the limitations of these methods. While quantitative parametric imaging methods do not replace but rather supplement established visual interpretation methods in radiology, they do open up new perspectives for diagnosis and prognosis and in particular for monitoring disease progression and therapy.

Barkmann R, Glüer CC. · Klinik für diagnostische Radiologie, Universitätsklinikum Schleswig-Holstein, Kiel. · Radiologe. · Pubmed #16896637 No free full text.

Abstract: Methods of quantitative ultrasound (QUS) can be used to obtain knowledge about bone fragility. Comprehensive study results exist showing the power of QUS for the estimation of osteoporotic fracture risk. Nevertheless, the variety of technologies, devices, and variables as well as different degrees of validation of the single devices have to be taken into account.Using methods to simulate ultrasound propagation, the complex interaction between ultrasound and bone could be understood and the propagation could be visualized. Preceding widespread clinical use, it has to be clarified if patients with low QUS values will profit from therapy, as it has been shown for DXA. Moreover, the introduction of quality assurance measures is essential. The user should know the limitations of the methods and be able to interpret the results correctly. Applied in an adequate manner QUS methods could then, due to lower costs and absence of ionizing radiation, become important players in osteoporosis management.

Glüer CC, Barkmann R. · Medical Physics, Department of Diagnostic Radiology, University Hospital Schleswig-Holstein, Campus Kiel, Michaelisstrasse 9, D-24105 Kiel, Germany. · Curr Osteoporos Rep. · Pubmed #16036071 No free full text.

Abstract: Quantitative ultrasound (QUS) techniques have found widespread clinical use, but their specific role in clinical practice needs further refinement. This review discusses the ability of QUS approaches to predict the risk for prevalent vertebral fractures and the risk for future fractures. QUS approaches perform as well as central dual x-ray absorptiometry devices but with some disadvantages (at least for older QUS approaches) with regard to the predictive power for hip fractures. Technologic diversity of QUS approaches may lead to differences in performance. QUS also has the potential for assessing bone mineral density-independent aspects of bone composition that are relevant for bone strength. For measurements at the calcaneus, it is evident that bone microstructure is the key determinant of QUS variables obtained. However, in most cases, microstructure is so highly correlated with bone mineral density that no separate assessment can be performed in clinical practice. At cortical sites, a selective assessment of bone properties is easier. Technologies need to be adapted to this purpose because requirements differ significantly from those desired for optimum fracture risk assessment. More importantly, multiple partially independent QUS variables need to be defined to assess complementary aspects of bone tissue.

Mohr A, Barkmann R, Mohr C, Römer FW, Schmidt C, Heller M, Glüer CC. · Klinik für Diagnostische Radiologie, Universitätsklinikum Schleswig-Holstein, Campus Kiel, Arnold-Heller-Strasse 9, 24105 Kiel, Deutschland. · Rofo. · Pubmed #15088189 No free full text.

Abstract: Quantitative ultrasound (QUS) methods are promising tools for the assessment of the bone status in osteoporosis. The techniques are based on changes in speed and amplitude of a broadband ultrasound signal propagating through the bone. However, ultrasound propagation through the anisotropic bone is complex and cannot be described in a simple way. The devices are easy to use, inexpensive, portable, do not use ionizing radiation, and therefore have advantages compared to conventional densitometry. This review discusses the technical basics, current research, clinical applications, points of weakness, and future prospects of QUS. For better understanding ultrasound propagation through bone is visualized with a simulation software.

Glüer CC, Barkmann R, Heller M. · Arbeitsgruppe Medizinische Physik, Universitätskrankenhaus Kiel. · Z Arztl Fortbild Qualitatssich. · Pubmed #10996935 No free full text.

Abstract: In recent years Quantitative Ultrasound (QUS) approaches have increasingly been used for the assessment of osteoporosis. Extensive study results exist for the estimation of osteoporotic fracture risk. Also, results exist for the analysis of properties which characterize osteoporosis--low bone mass and deterioration of bone architecture. However, the existence of different methods, devices and parameters has to be taken into account. Moreover, the status of the evaluation is different for each type of device. Measures of quality assurance and in-depth knowledge about limitations of the approach are of substantial importance for clinical use. Because of the lack of ionising radiation and their lower cost, QUS approaches--if used appropriately--can play an important role in the assessment of osteoporotic fracture risk.

Glüer CC, Eastell R, Reid DM, Felsenberg D, Roux C, Barkmann R, Timm W, Blenk T, Armbrecht G, Stewart A, Clowes J, Thomasius FE, Kolta S. · Medical Physics, Department of Diagnostic Radiology, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany. · J Bone Miner Res. · Pubmed #15068502 No free full text.

Abstract: We compared the performance of five QUS devices with DXA in a population-based sample of 2837 women. All QUS approaches discriminated women with and without osteoporotic vertebral fractures. QUS of the calcaneus performed as well as central DXA. INTRODUCTION: Quantitative ultrasound (QUS) methods have found widespread use for the assessment of bone status in osteoporosis, but their optimal use remains to be established. To determine QUS performance for current devices in direct comparison with central DXA, we initiated a large population-based investigation, the Osteoporosis and Ultrasound Study (OPUS). MATERIALS AND METHODS: A total of 463 women 20-39 years of age and 2374 women 55-79 years of age were measured on five different QUS devices along with DXA of the spine and the proximal femur. Their vertebral fracture status was evaluated radiographically. The association of QUS and DXA with vertebral fracture status was evaluated using logistic regression. RESULTS: All QUS approaches tested discriminated women with and without osteoporotic vertebral fractures (20% height reduction), with age-adjusted standardized odds ratios ranging 1.2-1.3 for amplitude-dependent speed of sound (AD-SOS) at the finger phalanges, 1.2-1.4 for broadband ultrasound attenuation (BUA) at the calcaneus, and 1.4-1.5 for speed of sound (SOS) at the calcaneus, 1.4-1.6 for DXA of the total femur, and 1.5-1.6 for DXA at the spine. For more severe fractures (40% height reduction), age-adjusted standardized odds ratios increased to up to 1.9 for DXA of the spine and 2.3 for SOS of the calcaneus. CONCLUSIONS: In conclusion, all five QUS devices tested showed significant age-adjusted differences between subjects with and without vertebral fracture. When selecting the strongest variable, QUS of the calcaneus worked as well as central DXA for identification of women at high risk for prevalent osteoporotic vertebral fractures. QUS-based case-finding strategies would allow halving the number of radiographs in high-risk populations, and this strategy works increasingly well for women with more severe vertebral fractures. It is likely that the good performance of QUS was in part achieved by rigorous quality assurance measures that should also be used in clinical practice.

Hans D, Srivastav SK, Singal C, Barkmann R, Njeh CF, Kantorovich E, Glüer CC, Genant HK. · Osteoporosis and Arthritis Research Group, University of California, San Francisco, USA. · J Bone Miner Res. · Pubmed #10234587 No free full text.

Abstract: There is a growing interest in the use of quantitative ultrasound (QUS) measurements as an alternative to current radiation-based bone densitometry techniques for the noninvasive assessment of fracture risk. While most of the commercialized ultrasound devices measure only single predefined peripheral skeletal sites, the Omnisense prototype (Sunlight Ltd., Israel) can be used on multiple bones, including the spinous processes. In this study, we examined the ability of speed of sound measured at the calcaneus, distal third and ultradistal radius, proximal third phalanx, metacarpal, capitate, patella, and the posterior process of the thoracic spine to differentiate subjects with hip fractures from normal controls. Seventy-nine postmenopausal Caucasian Israeli women who had sustained an atraumatic fracture of the proximal femur within the last 6 months were recruited from the local population (mean age 80 +/- 8.9 years). As controls, 295 postmenopausal Caucasian Israeli women without osteoporotic fractures were also included (mean age 70 +/- 8.7 years). Discrimination of hip fractures with QUS at all ultrasound sites was highly statistically significant (p < 0.01) (odds ratios [ORs] = 1.4-3.0; area under the ROC curve [AUC] 77-92%), except for the hand metacarpal. Distal radius and calcaneus measurements (ORs = 2.4 and 3.0) were the best discriminators of hip fracture patients from controls. Using a forward selective linear regression model, the discriminator values of combined assessment at two sites were investigated. There was moderate improvement in diagnostic value, but the best combination was the calcaneus with the distal radius, which improved the AUC by 3% and raised both the sensitivity and specificity to 94%. These data demonstrate the encouraging potential of improving discrimination of hip fracture by using multiple-site ultrasonic measurements.

Barkmann R, Laugier P, Moser U, Dencks S, Klausner M, Padilla F, Haiat G, Heller M, Glüer CC. · Medizinische Physik, Diagnostische Radiologie, Universitätsklinikum Schleswig-Holstein, Kiel, Germany. · Ultrasound Med Biol. · Pubmed #18294756 No free full text.

Abstract: Quantitative ultrasound (QUS) measurements can be used to estimate osteoporotic fracture risk. The commonly used variables are the speed of sound (SOS) and the frequency dependent sound attenuation (broadband ultrasound attenuation, [BUA]) of a wave propagating through the bone, preferably the calcaneus. The technology, so far, is less suitable for direct measurement in vivo at the spine or the femur for prediction of bone mineral density (BMD) or fracture risk at the main osteoporotic fracture sites. To improve the clinical performance of QUS, we built a device for direct QUS measurements at the human femur in vivo. In vivo images of ultrasound transmission at one of the main fracture sites, the proximal femur, could be acquired. The estimated precision of SOS measurements of 0.5% achieved at the femur is comparable with the precision of peripheral QUS devices.

Scholz-Ahrens KE, Delling G, Stampa B, Helfenstein A, Hahne HJ, Açil Y, Timm W, Barkmann R, Hassenpflug J, Schrezenmeir J, Glüer CC. · Institute of Physiology and Biochemistry of Nutrition, Federal Research Centre for Nutrition and Food-Location Kiel, Hermann-Weigmann-Str. 1, D-24103 Kiel, Germany. · Am J Physiol Endocrinol Metab. · Pubmed #17456640 links to  free full text

Abstract: Information on the pathophysiology of glucocorticoid-induced osteoporosis (GIO) is limited, since its clinical picture often reflects a combined effect of glucocorticoids (GC) and the treated systemic disease (i.e., inflammation and immobility). In 50 healthy adult (30-mo-old) primiparous Göttingen minipigs, we studied the short-term (8 mo, n = 30) and long-term (15 mo, n = 10) effect of GC on bone and mineral metabolism longitudinally and cross-sectionally compared with a control group (n = 10). All animals on GC treatment received prednisolone orally at a dose of 1.0 mg x kg body wt(-1) x day(-1) for 8 wk and thereafter at 0.5 mg/kg body wt(-1) x day(-1). In the short term, GC reduced bone mineral density (BMD) at the lumbar spine by -47.5 +/- 5.1 mg/cm(3) from baseline (P < 0.001), which was greater (P < 0.05) than the loss [not significant (NS)] in the control group of -11.8 +/- 12.6 mg/cm(3). Calcium absorption decreased from baseline by -2,488 +/- 688 mg/7 days (P < 0.001) compared with -1,380 +/- 1,297 mg/7 days (NS) in the control group. Plasma bone alkaline phosphatase (BAP) decreased from baseline by -17.8 +/- 2.2 U/l (P < 0.000), which was significantly different (P < 0.05) from the value of the control group of -1.43 +/- 4.8 U/l. In the long term, the loss of BMD became more pronounced and bone mineral content (BMC), trabecular thickness, mechanical stability, calcium absorption, 25-hydroxyvitamin D(3), 1,25-dihydroxyvitamin D(3), and parathyroid hormone tended to be lower compared with the control group. There was a negative association between the cumulative dose of GC and BMD, which was associated with impaired osteoblastogenesis. In conclusion, the main outcomes after GC treatment are comparable to symptoms of GC-induced osteoporosis in human subjects. Thus the adult Göttingen miniature pig appears to be a valuable animal model for GC-induced osteoporosis.

Dencks S, Barkmann R, Padilla F, Haïat G, Laugier P, Glüer CC. · Medizinische Physik, Klinik für Diagnostische Radiologie, Universitätsklinikum Schleswig Holstein, Kiel, Germany. · Ultrasound Med Biol. · Pubmed #17445965 No free full text.

Abstract: To estimate osteoporotic fracture risk, several techniques for quantitative ultrasound (QUS) measurements at peripheral sites have been developed. As these techniques are limited in the prediction of fracture risk of the central skeleton, such as the hip, we are developing a QUS device for direct measurements at the femur. In doing so, we noticed the necessity to improve the conventional signal processing because it failed in a considerable number of measurements due to multipath transmission. Two sets of excised human femurs (n = 6 + 34) were scanned in transmission mode. Instead of using the conventional methods, the radio-frequency signals were processed with the continuous wavelet transform to detect their time-of-flights for the calculation of speed-of-sound (SOS) in bone. The SOS-values were averaged over a region similar to the total hip region of dual X-ray absorptiometry (DXA) measurements and compared with bone mineral density (BMD) measured with DXA. Testing six standard wavelets, this algorithm failed for only 0% to 6% of scan in test set 1 compared with 29% when using conventional algorithms. For test set 2, it failed for 2% to 12% compared with approximately 40%. SOS and BMD correlated significantly in both test sets (test set 1: r2 = 0.87 to 0.92, p < 0.007; test set 2: r2 = 0.68 to 0.79, p < 0.0001). The correlations are comparable with correlations recently reported. However, the number of evaluable signals could be substantially increased, which improves the perspectives of the in vivo measurements.

Glüer CC, Scholz-Ahrens KE, Helfenstein A, Delling G, Timm W, Açil Y, Barkmann R, Hassenpflug J, Stampa B, Bauss F, Schrezenmeir J. · Medical Physics, Department of Diagnostic Radiology, University Hospital Schleswig-Holstein, Campus Kiel, Germany. · Bone. · Pubmed #17174621 No free full text.

Abstract: The Göttingen minipig is one of the few large animal models that show glucocorticoid (GC)-induced bone loss. We investigated whether GC-induced loss of bone mineral density (BMD) and bone strength in minipigs can be recovered by treatment with the bisphosphonate ibandronate (IBN). 40 primiparous sows were allocated to 4 groups when they were 30 months old: GC treatment for 8 months (GC8), for 15 months (GC15), GC treatment for 15 months plus IBN treatment for months 8-15 (GC&IBN), and a control group without GC treatment. Prednisolone was given at a daily oral dose of 1 mg/kg body weight for 8 weeks and thereafter 0.5 mg/kg body weight. IBN was administered intramuscularly and intermittently with an integral dose of 2.0 mg/kg body weight. BMD of the lumbar spine (L1-3) was assessed in vivo by Quantitative Computed Tomography (QCT) at months 0, 8, and 15. Blood and urine samples were obtained every 2-3 months. After sacrificing the animals lumbar vertebrae L4 were tested mechanically (Young's modulus and ultimate stress). Histomorphometry was performed on L2 and mineral content determined in ashed specimens of T12 and L4. In the GC&IBN group, the GC associated losses in BMD of -10.5%+/-1.9% (mean+/-standard error of the mean, p<0.001) during the first 8 months were more than recovered during the following 7 months of IBN treatment (+14.8%+/-1.2%, p<0.0001). This increase was significantly larger (p<0.0001) than the insignificant +2.1%+/-1.2% change in group GC15. At month 15, the difference between groups GC&IBN and GC15 was 22% (p<0.01) for BMD, 48% (p<0.05) for Young's modulus, and 31% (p<0.14) for ultimate stress; bone-specific alkaline phosphatase showed trends to lower values (p<0.2) while deoxypyridinoline was comparable. This minipig study demonstrates that GC-induced impairment of bone strength can be effectively and consistently treated by IBN. GC&IBN associated alterations in BMD and bone turnover markers can be monitored in vivo using QCT of the spine and by biochemical analyses, reflecting the changes in bone strength.

Haïat G, Padilla F, Barkmann R, Gluer CC, Laugier P. · Laboratoire d'Imagerie Paramétrique, CNRS UMR 7623, Université Paris 6, Paris, France. · Ultrasonics. · Pubmed #16859726 No free full text.

Abstract: Finite-difference numerical simulation of ultrasound propagation in complex media such as cancellous bone represents a fertile alternative to analytical approaches because it can manage the complex 3D bone structure by coupling the numerical computation with 3D numerical models of bone microarchitecture obtained from high-resolution imaging modalities. The objective of this work was to assess in silico the sensitivity of ultrasound parameters to controlled changes of microarchitecture and variation of elastic constants. The simulation software uses a finite-difference approach based on the Virieux numerical scheme. An incident plane wave was propagated through a volume of bone of approximately 5 x 5 x 8 mm(3). The volumes were reconstructed from high-resolution micro-computed tomography data. An iterative numerical scenario of "virtual osteoporosis" was implemented using a dedicated image processing algorithm in order to modify the initial 3D microstructures. Numerical computations of wave propagation were performed at each step of the process. The sensitivity to bone material properties was also tested by changing the elastic constants of bone tissue. Our results suggest that ultrasonic variables (slope of the frequency-dependent attenuation coefficient and speed of sound) are mostly influenced by bone volume fraction. However, material properties and structure also appear to play a role. The impact of modifications of the stiffness coefficients remained lower than the variability caused by structural variations. This study emphasizes the potential of numerical computations tools coupled to realistic 3D structures to elucidate the physical mechanisms of interaction between ultrasound and bone structure and to assess the sensitivity of ultrasound variables to different bone properties.

Haïat G, Padilla F, Barkmann R, Kolta S, Latremouille C, Glüer CC, Laugier P. · Laboratoire d'Imagerie Paramétrique, Université Paris VI, Paris, France. · Ultrasound Med Biol. · Pubmed #15972205 No free full text.

Abstract: Quantitative ultrasound has been recognized as a useful tool for fracture risk prediction. Current measurement techniques are limited to peripheral skeletal sites. Our objective was to demonstrate the in vitro feasibility of ultrasonic velocity measurements on human proximal femur and to investigate the relationship between velocity and bone mineral density (BMD). Sound velocity images were computed from 2-D scans performed on 38 excised human femurs in transmission at 0.5 MHz. Different regions-of-interest were investigated. Dual x-ray absorptiometry scans have been achieved for BMD measurements in site-matched regions. Our study demonstrates the feasibility of ultrasonic velocity measurements at the hip with reasonable precision (coefficient of variation of 0.3%). The best prediction of BMD was reached in the intertrochanter region (r(2) = 0.91, p < 10(-4)), with a residual error of 0.06 g/cm(2) (10%). Because BMD measured at the femur is the best predictor of hip fracture risk, the highly significant correlation and small residual error found in this study suggest that speed of sound measurement at the femur might be a good candidate for hip fracture risk prediction.

Röben P, Barkmann R, Ullrich S, Gause A, Heller M, Glüer CC. · Arbeitsgruppe Medizinische Physik, Universitätsklinikum Kiel, Germany. · Ann Rheum Dis. · Pubmed #11406521 links to  free full text

Abstract: OBJECTIVE: Periarticular osteopenia is an early radiological sign of rheumatoid arthritis (RA). Quantitative ultrasound (QUS) devices have recently been shown to be useful for assessing osteoporosis. In this study the capability of a transportable and easy to use QUS device to detect skeletal impairment of the finger phalanges in patients with RA was investigated. METHODS: In a cross sectional study 83 women (30 controls, 29 with glucocorticosteroid (GC) treated RA, and 24 with GC treated vasculitis) were examined. QUS measurements were obtained at the metaphyses of the proximal phalanges II-V and directly at the proximal interphalangeal joints II-IV with a DBM Sonic 1200 (IGEA, Italy) QUS device. Amplitude dependent speed of sound (AD-SoS) was evaluated. In 23 of the patients with RA, hand radiographs were evaluated. RESULTS: Significant differences between patients with RA and the other groups were found for AD-SoS at both measurement sites. Compared with age matched controls, the AD-SoS of patients with RA was lowered by two and three standard deviations at the metaphysis and joint, respectively. Fingers of patients with RA without erosions (Larsen score 0-I) already had significantly decreased QUS values, which deteriorated further with the development of erosions (Larsen II-V). CONCLUSION: This study indicates that QUS is sensitive to phalangeal periarticular bone loss in RA. QUS is a quick, simple, and inexpensive method free of ionising radiation that appears to be suited to detection of early stages of periarticular bone loss. Its clinical use in the assessment of early RA should be further evaluated in prospective studies.

Barkmann R, Kantorovich E, Singal C, Hans D, Genant HK, Heller M, Glüer CC. · Medizinische Physik, Diagnostische Radiologie, CAU Kiel, Germany. · J Clin Densitom. · Pubmed #10745297 No free full text.

Abstract: We investigated a new multisite quantitative ultrasound device that measures the acoustic velocity in axial transmission mode along the cortex. Using a prototype of the Omnisense (Sunlight Ultrasound Technologies, Rehovot, Israel), we tested the performance of this instrument at four sites of the skeleton: radius, ulna, metacarpal, and phalanx. Intraobserver (interobserver) precision errors ranged from 0.2% to 0.3% (0.3% to 0.7%) for triplicate measurements with repositioning. Fracture discrimination was tested by comparing a group of 34 women who had previously suffered a fracture of the hip, spine, ankle, or forearm to a group of 28 healthy women who had not suffered a fracture. Age-adjusted standardized odds ratios ranged from 1.6 to 4.5. Except for the ulna the sites showed a significant fracture discrimination (p < 0.01). The areas under the receiver operating curves (ROC) curves were from 0.88 to 0.89 for radius, metacarpal, and phalanx. A combination of the results from the three sites showed a significant increase of the ROC area to 0.95 (p < 0. 05). Our results show promising performance of this new device. The ability to measure a large variety of sites and the potential to combine these measurements are promising with regard to optimizing fracture risk assessment.

Glüer CC, Barkmann R, Heller M. · Klinik für Diagnostische Radiologie, Christian-Albrechts-Universität zu Kiel. · Radiologe. · Pubmed #10218214 No free full text.

Abstract: In recent years Quantitative Ultrasound (QUS) approaches have increasingly been used for the assessment of osteoporosis. The development of new technologies has accelerated, and today a number of different devices are commercially available. For a balanced evaluation of the approaches one needs to recognise two issues: There are different applications for QUS, and there are different QUS approaches and devices. Regarding the applications, today the main area for use of QUS approaches is the assessment of a fracture risk. For use in monitoring and diagnosis, further advances and studies are required. Regarding the various approaches, one needs to recognise the differences between the measurement parameters Speed Of Sound (SOS) and Broadband Ultrasound Attenuation (BUA), the different measurement sites and the different technologies employed. Moreover, some of the earlier devices are very well validated whereas newer machines may feature more advanced technology--which, however, needs to be tested and validated. Whatever the choice of a device will be, adequate and regularly performed measures for quality assurance and in-depth knowledge on the general and device specific limitations of the approach are of substantial importance. When used appropriately, QUS devices can play an important role in the assessment of osteoporosis.