Standards and guidelines for technologists performing central dual-energy X-ray absorptiometry

Bone parameters in T1D and T2D assessed by DXA and HR-pQCT - A cross-sectional study: The DIAFALL study

INTRODUCTION/AIM

People with type 1 diabetes(T1D) and type 2 diabetes(T2D) have an increased risk of fractures due to skeletal fragility. We aimed to compare areal bone mineral density(aBMD), volumetric BMD(vBMD), cortical and trabecular measures, and bone strength parameters in participants with diabetes vs. controls.

METHODS

In a cross-sectional study, we included participants with T1D(n = 111), T2D(n = 106) and controls(n = 328). The study comprised of whole-body DXA and HR-pQCT scans, biochemistry, handgrip strength(HGS), Timed Up and GO(TUG), vibration perception threshold (VPT), questionnaires, medical histories, alcohol use, and previous fractures. Group comparisons were performed after adjustment for sex, age, BMI, diabetes duration, HbA1c, alcohol, smoking, previous fractures, postmenopausal, HGS, TUG, and VPT.

RESULTS

We found decreased aBMD in participants with T1D at the femoral neck(p = 0.028), whereas T2D had significantly higher aBMD at peripheral sites(legs, arms, p < 0.01) vs. controls. In T1D we found higher vBMD(p < 0.001), cortical vBMD (p < 0.001), cortical area(p = 0.002) and thickness(p < 0.001), lower cortical porosity(p = 0.008), higher stiffness(p = 0.002) and failure load(p = 0.003) at radius and higher vBMD(p = 0.003), cortical vBMD(p < 0.001), bone stiffness(p = 0.023) and failure load(p = 0.044) at the tibia than controls. In T2D we found higher vBMD(p < 0.001), cortical vBMD(p < 0.001), trabecular vBMD(p < 0.001), cortical area (p < 0.001) and thickness (p < 0.001), trabecular number (p = 0.024), lower separation(p = 0.010), higher stiffness (p < 0.001) and failure load (p < 0.001) at the radius and higher total vBMD(p < 0.001), cortical vBMD(p < 0.011), trabecular vBMD(p = 0.001), cortical area(p = 0.002) and thickness(p = 0.021), lower trabecular separation(p = 0.039), higher stiffness(p < 0.001) and failure load(p = 0.034) at tibia compared with controls.

CONCLUSION

aBMD measures were as expected but favorable bone microarchitecture and strength parameters were seen at the tibia and radius for T1D and T2D.

New Horizons for Hydroxyapatite Supported by DXA Assessment-A Preliminary Study

Dual Energy X-ray Absorptiometry (DXA) is a tool that allows the assessment of bone density. It was first presented by Cameron and Sorenson in 1963 and was approved by the Food and Drug Administration. Misplacing the femoral neck box, placing a trochanteric line below the midland and improper placement of boundary lines are the most common errors made during a DXA diagnostic test made by auto analysis. Hydroxyapatite is the most important inorganic component of teeth and bone tissue. It is estimated to constitute up to 70% of human bone weight and up to 50% of its volume. Calcium phosphate comes in many forms; however, studies have shown that only tricalcium phosphate and hydroxyapatite have the characteristics that allow their use as bone-substituted materials. The purpose of this study is aimed at analyzing the results of hip densitometry and hydorxyapatite distribution in order to better assess the structure and mineral density of the femoral neck. However, a detailed analysis of the individual density curves shows some qualitative differences that may be important in assessing bone strength in the area under study. To draw more specific conclusions on the therapy applied for individual patients, we need to determine the correct orientation of the bone from the resulting density and document the trends in the density distribution change. The average results presented with the DXA method are insufficient.

Quality in dual-energy X-ray absorptiometry scans

Dual-energy X-ray absorptiometry (DXA) is the gold standard for measuring bone mineral density (BMD), making the diagnosis of osteoporosis, and for monitoring changes in BMD over time. DXA data are also used in the determination of fracture risk. Procedural steps in DXA scanning can be broken down into scan acquisition, analysis, interpretation, and reporting. Careful attention to quality control pertaining to these procedural steps should theoretically be beneficial in patient management. Inattention to procedural steps and errors that may occur at each step has the possibility of providing information that would inform inappropriate clinical decisions, generating unnecessary healthcare expenses and ultimately causing avoidable harm to patients. This article reviews errors in DXA scanning that affect trueness and precision related to the machine, the patient, and the technologist and reviews articles which document problems with DXA quality in clinical and research settings. An understanding of DXA errors is critical for DXA quality; programs such as certification of DXA technologists and interpreters help in assuring quality bone densitometry. As DXA errors are common, pay for performance requiring DXA technologists and interpreters to be certified and follow quality indicators is indicated.

Common Mistakes in the Dual-Energy X-ray Absorptiometry (DXA) in Turkey. A Retrospective Descriptive Multicenter Study

BACKGROUND

Osteoporosis is a widespread metabolic bone disease representing a global public health problem currently affecting more than two hundred million people worldwide. The World Health Organization states that dual-energy X-ray absorptiometry (DXA) is the best densitometric technique for assessing bone mineral density (BMD). DXA provides an accurate diagnosis of osteoporosis, a good estimation of fracture risk, and is a useful tool for monitoring patients undergoing treatment. Common mistakes in BMD testing can be divided into four principal categories: 1) indication errors, 2) lack of quality control and calibration, 3) analysis and interpretation errors, and 4) inappropriate acquisition techniques. The aim of this retrospective multicenter descriptive study is to identify the common errors in the application of the DXA technique in Turkey.

METHODS

All DXA scans performed during the observation period were included in the study if the measurements of both, the lumbar spine and proximal femur were recorded. Forearm measurement, total body measurements, and measurements performed on children were excluded. Each examination was surveyed by 30 consultants from 20 different centers each informed and trained in the principles of and the standards for DXA scanning before the study.

RESULTS

A total of 3,212 DXA scan results from 20 different centers in 15 different Turkish cities were collected. The percentage of the discovered erroneous measurements varied from 10.5% to 65.5% in the lumbar spine and from 21.3% to 74.2% in the proximal femur. The overall error rate was found to be 31.8% (n = 1021) for the lumbar spine and 49.0% (n = 1576) for the proximal femur.

CONCLUSION

In Turkey, DXA measurements of BMD have been in use for over 20 years, and examination processes continue to improve. There is no educational standard for operator training, and a lack of knowledge can lead to significant errors in the acquisition, analysis, and interpretation.

The role of DXA in sarcopenia

Sarcopenia is a condition characterized by progressive and generalized reduction in skeletal muscle mass and muscle strength, associated with an increased risk of adverse outcomes (disability, hospitalization, death). The growing attention in the last years, aiming to establish a consensus definition and treatment, reflects the interest of the scientific community toward this complex condition, which has many implications in clinical practice and public health. Dual-energy X-ray absorptiometry (DXA) is the gold-standard technique in the analysis of body composition at molecular level, providing assessment and quantification of fat mass, lean mass and bone mineral content, both in a single body region of interest and at whole-body level. In particular, through the assessment of non-bone lean mass parameters, such as appendicular lean mass adjusted for BMI or height (ALM/BMI and ALM/ht², respectively), it is possible to discriminate subjects with "physiological" loss of muscle mass from those with "pathological" impoverishment of this compartment, referring to specific cutoff values validated in the literature, but keeping in mind the lack of standardization of DXA measures. In addition, it is useful in treatment planning, estimating resting energy expenditure, and in follow-up, because it allows quantifying with high reproducibility the modifications in BC, distinguishing when the change is biological (deterioration due to a progression of the disease or improvement due to treatment). Due to DXA favorability in terms of accuracy, simplicity, availability, low cost and low radiation exposure, its role in sarcopenia diagnosis is becoming increasingly important, emerging as reference assessment technique in muscle mass evaluation.

DXA: Technical aspects and application

The key role of dual-energy X-ray absorptiometry (DXA) in the management of metabolic bone diseases is well known. The role of DXA in the study of body composition and in the clinical evaluation of disorders which directly or indirectly involve the whole metabolism as they may induce changes in body mass and fat percentage is less known or less understood. DXA has a range of clinical applications in this field, from assessing associations between adipose or lean mass and the risk of disease to understanding and measuring the effects of pathophysiological processes or therapeutic interventions, in both adult and paediatric human populations as well as in pre-clinical settings. DXA analyses body composition at the molecular level that is basically translated into a clinical model made up of fat mass, non-bone lean mass, and bone mineral content. DXA allows total and regional assessment of the three above-mentioned compartments, usually by a whole-body scan. Since body composition is a hot topic today, manufacturers have steered the development of DXA technology and methodology towards this. New DXA machines have been designed to accommodate heavier and larger patients and to scan wider areas. New strategies, such as half-body assessment, permit accurate body scan and analysis of individuals exceeding scan field limits. Although DXA is a projective imaging technique, new solutions have recently allowed the differential estimate of subcutaneous and intra-abdominal visceral fat. The transition to narrow fan-beam densitometers has led to faster scan times and better resolution; however, inter- or intra-device variation exists depending on several factors. The purposes of this review are: (1) to appreciate the role of DXA in the study of body composition; (2) to understand potential limitations and pitfalls of DXA in the analysis of body composition; (3) to learn about technical elements and methods, and to become familiar with biomarkers in DXA.

Best Practices for Dual-Energy X-ray Absorptiometry Measurement and Reporting: International Society for Clinical Densitometry Guidance

Dual-energy X-ray absorptiometry (DXA) is a technology that is widely used to diagnose osteoporosis, assess fracture risk, and monitor changes in bone mineral density (BMD). The clinical utility of DXA is highly dependent on the quality of the scan acquisition, analysis, and interpretation. Clinicians are best equipped to manage patients when BMD measurements are correct and interpretation follows well-established standards. Poor-quality acquisition, analysis, or interpretation of DXA data may mislead referring clinicians, resulting in unnecessary diagnostic evaluations, failure to evaluate when needed, inappropriate treatment, or failure to provide medical treatment, with potentially ineffective, harmful, or costly consequences. Misallocation of limited healthcare resources and poor treatment decisions can be minimized, and patient care optimized, through meticulous attention to DXA instrument calibration, data acquisition and analysis, interpretation, and reporting. This document from the International Society for Clinical Densitometry describes quality standards for BMD testing at DXA facilities worldwide to provide guidance for DXA supervisors, technologists, interpreters, and clinicians. High-quality DXA testing is necessary for correct diagnostic classification and optimal fracture risk assessment, and is essential for BMD monitoring.

Creatinine and myoglobin are poor predictors of anaerobic threshold in colorectal cancer and health

AIMS

Myoglobin is a haem protein produced in skeletal muscles. Serum concentrations of myoglobin have been proposed as a surrogate marker of muscle mass and function in both cachectic cancer patients and healthy non-cancer individuals. Creatinine, a metabolite of creatine phosphate, an energy store found in skeletal muscle, is produced at a constant rate from skeletal muscle. Urinary and plasma creatinine have been used in clinical practice as indicators of skeletal muscle mass in health and disease. Our study aimed to test the hypothesis that plasma myoglobin and creatinine concentration could accurately predict skeletal muscle mass and aerobic capacity in colorectal cancer (CRC) patients and matched healthy controls and thereby an indicative of aerobic performance.

METHODS

We recruited 47 patients with CRC and matching number of healthy volunteers for this study. All participants had their body composition measured by dual-energy X-ray absorptiometry scan, aerobic capacity measured to anaerobic threshold (AT) by cardiopulmonary exercise testing and filled in objective questionnaires to assess the qualitative functions. This study was carried out in accordance with the Declaration of Helsinki, after approval by the local National Health Service (NHS) Research Ethics Committee.

RESULTS

Age-matched groups had similar serum myoglobin and creatinine concentrations in spite of differences in their aerobic capacity. AT was significantly lower in the CRC group compared with matched controls (1.18 ± 0.44 vs. 1.41 ± 0.71 L/min; P < 0.01). AT had significant correlation with lean muscle mass (LMM) among these groups, but myoglobin and creatinine had poor correlation with LMM and AT.

CONCLUSIONS

Serum myoglobin is a poor predictor of muscle mass, and serum myoglobin and creatinine concentrations do not predict aerobic performance in CRC patients or healthy matched controls.

Bone mineral density changes after total knee replacement in women over the age of 65

Background

There are few reports on bone mineral density (BMD) changes of axial bones after total knee replacement (TKR) due to severe osteoarthritis (OA) of the knee joint and its results are controversial. The purpose of our study was to measure the BMD changes of hip and spine in patients receiving TKR due to severe OA and to identify clinical factors relating BMD changes.

Methods

Among 66 female patients above 65 years old who underwent TKR due to severe OA and checked preoperative BMD, 52 patients who checked 1 year follow up BMD were enrolled. We investigated the association of the BMD changes with bilaterality of operation, obesity, preoperative knee functional scores, bisphosphonate medication, and diagnosis of osteoporosis.

Results

We found no correlation between BMD changes and bilaterality of operation, obesity, preoperative knee functional scores and diagnosis of osteoporosis. Spine BMD increased in non-treatment and bisphosphonate treatment group but total hip BMD significantly increased in bisphosphonate treatment group.

Conclusions

Bisphosphonate treatment for 1 year prevents early reduction of hip BMD just after TKR regardless osteoporosis diagnosis. We considered that the bisphosphonate medication would be beneficial to prevention of later hip fracture in elderly patient receiving TKR due to severe OA of knee joints.

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.