[Polychromatic photon absorptiometry (author's transl)].
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Bone and Bones↗
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Vertebral and total body bone mineral content by dual photon absorptiometry.
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Absorption↗
Measuring bone mineral content.
Orthopaedic nurses encounter many patients with fractures related to osteoporosis. This article discusses the most available methods of measuring bone mineral content (BMC) to diagnose osteoporosis. The methods include single photon absorptiometry, dual photon absorptiometry, and dual photon absorptiometry using x-rays and computerized tomography.
Absorptiometry, Photon↗
Effects on bone mass after eight years of hormonal replacement therapy.
OBJECTIVE: The purpose of this randomised double-blind placebo-controlled study over two years followed by a six year open controlled extension phase was to investigate the effects of hormonal replacement therapy (HRT) both continuous combined HRT and sequential HRT) versus no treatment on lumbar spine bone mineral density (L-BMD) and distal forearm bone mineral content (F-BMC). Further, bone mineral density of the proximal femur, lateral spine, and distal forearm was studied after eight years. DESIGN: Prospective study of normal, early postmenopausal women, initially in a double-blind, placebo controlled study, subsequently an open, controlled investigation. SETTING: Clinical physiology unit of a general second degree referral hospital. SAMPLE: Seventy-three normal, early postmenopausal women (HRT n = .47; placebo/untreated n = 26). METHODS: Dual photon absorptiometry, dual X-ray absorptiometry, single photon absorptiometry. MAIN OUTCOME MEASURES: HRT resulted in a significantly (P < 0.001) higher mean L-BMD after eight years, when it was 12.1% higher than the mean initial value and 14.8% higher than the mean bone mineral density of the untreated group. L-BMD increased by 14.6% in women receiving continuous combined HRT compared with 11.1% in those on sequential HRT but intergroup differences were not statistically significant. Mean F-BMC measured with SPA decreased in the HRT group and in the placebo/untreated group by 0.2% and 14.8% (P < 0.001), respectively. However, after eight years mean F-BMC was 14.5% higher in the HRT group than in the placebo/untreated group. The study showed after eight years for all regions of the distal radius and ulna a significantly higher bone mineral density value compared with the placebo/untreated group (P < 0.001). An especially large effect of HRT was found on the bone mineral density of the vertebral body of the 3rd lumbar vertebra (L3), this one, measured by lateral scanning, being 18.7% higher than that of the placebo/untreated group. For the proximal femur, only the bone mineral density of Ward's triangle was significantly higher in the HRT group than in the placebo/untreated group. CONCLUSION: Eight years of treatment with HRT resulted in a significant, substantial gain of bone mineral density in the lumbar spine. The distal radius, ulna and Ward's triangle showed a significantly higher bone mineral density in the HRT group compared with the placebo/untreated group.
Absorptiometry, Photon↗
Osteoporosis and bone mineral densitometry.
Osteoporosis is a common cause of vertebral and hip fractures and although their occurrence depends on a variety of factors, bone mineral density (BMD) is the most important determinant. Methods of measuring BMD are therefore pertinent to identify individuals with reduced bone mass and at increased risk of fracture, and current techniques provide accurate and precise BMD measurements with low radiation dose. The methods most widely used are single photon absorptiometry; dual photon absorptiometry, which has been replaced by dual energy x-ray absorptiometry; and quantitative CT. Dual energy x-ray absorptiometry permits BMD measurement in the lumbar spine, femoral neck, forearm, and whole body. Bone strength is also related to trabecular width and arrangement. The newer techniques of broadband ultrasound attenuation and MR imaging (T2*) offer potential for investigating both trabecular bone mass and structure, as does high-resolution CT. These methods provide powerful tools for the study of the skeleton in health and disease and have established roles in appropriate clinical circumstances. Although BMD measurement can provide an estimate of fracture risk, there are limitations to fracture prediction in an individual subject, but efforts are being made to improve the discriminatory and predictive aspects of BMD.
Absorptiometry, Photon↗
Technical aspects and clinical interpretation of bone mineral measurements.
Four procedures--single photon absorptiometry, dual photon absorptiometry, dual energy radiography, and quantitative computed tomography--allow nontraumatic measurement of bone mineral, with high accuracy and precision, under conditions generally encountered in patient care situations. By using these procedures, almost any part of the skeleton is accessible to such measurements. Total bone is measured by the absorptiometry procedures, trabecular bone by quantitative computed tomography. Several commercial instruments are available for each technique. For clinical use, if decisions are being made based on measurements in a given patient, preferred measurement sites are the spine (for Type I osteoporosis) and hip (for Type II osteoporosis). The newly introduced dual energy x-ray absorptiometry (DEXA) procedure allows measurements of the spine and hip with the highest precision and accuracy, the lowest radiation dose, and the shortest scanning time.
Absorptiometry, Photon↗
Appropriate use of bone densitometry.
The authors discuss current capabilities of three common bone densitometry techniques--single photon absorptiometry, dual photon absorptiometry, and quantitative computed tomography--and potential capabilities of new innovations of each of these techniques. They believe that use of bone densitometry is valid in the following four clinical applications and recommend its usage to (a) assess patients with metabolic diseases known to affect the skeleton, (b) assess perimenopausal women for initiation of estrogen replacement therapy, (c) establish a diagnosis of osteoporosis or assess its severity in the context of general clinical care, and (d) monitor the efficacy of treatment interventions or the natural course of disease.
Bone Diseases, Metabolic↗
Advances in imaging of rheumatoid arthritis.
Several new imaging modalities have been found useful in clinical evaluation of patients with rheumatoid arthritis (RA). Magnetic resonance (MR) imaging has proven to be an excellent noninvasive method to evaluate the spine, shoulder, hip, and knees; its use for the evaluation of smaller joints is still being investigated. In patients with RA, MR imaging has been used to evaluate cervical spine instability, rotator cuff tear, osteonecrosis, and osteomyelitis. Patients with RA may have advanced osteoporosis, predisposing to insufficiency fractures. This includes fractures associated with increased activity after hip or knee arthroplasty. Newer methods for measuring the degree of osteoporosis include single photon absorptiometry, dual photon absorptiometry, quantitative computed tomography (CT), and dual-energy projection radiography. It has not yet been determined which of these methods will be most widely used in the future, but quantitative CT and dual-energy projection radiography currently show the most promise. Ultrasonography provides an excellent noninvasive method for the diagnosis of popliteal cysts, and color Doppler sonography can differentiate cyst and popliteal aneurysm. As compared to radiography or conventional CT, high-resolution CT provides an improved method to detect the early changes of RA in the lung parenchyma.
Arthritis, Rheumatoid↗
[Determination of bone mineral content in vivo in dialyzed patients using photon radiation absorptiometry].
In a group of 47 women and 54 men with chronic renal failure included in a regular haemodialyzation programme the mineral content of bone was assessed using the method of radiation absorption of the radioisotope americium (241Am) on a Bone mineral detector of Gambro Co. The bone mineral content was reduced in men and women by 22%, as compared with healthy subjects of the same age and sex. The reduction was more marked in patients dialyzed for longer periods and when there were lamoratory signs of activity of the process.
Absorptiometry, Photon↗
New perspectives on bone densitometry.
Methods of bone mineral density measurement are presented. Radiological photogrammetry, single photon absorptiometry, dual photon absorptiometry and dual energy X-ray absorptiometry are described. Mode of work of densitometers and their characteristics ares presented. Modern development of densitometric equipment and possible application in diagnosing of osteoporosis is discussed.
Adult↗
Methods of measurement of bone turnover and clinical evaluation of osteoporosis: relevance to asthma and corticosteroid therapy.
Bone turnover can be assessed by measurements of biochemical markers. Serum alkaline phosphatase and osteocalcin can be used as indices of bone formation, and hydroxyproline and pyridinium crosslinks in urine can be used to assess bone resorption. These markers are able to detect changes induced by high-dose corticosteroid therapy given by the oral or inhaled route. However, a clinical diagnosis of osteoporosis requires, in addition, the presence of at least one relatively atraumatic fracture. Fracture risk may be assessed by in vivo measurement of bone density, for which a number of new techniques, including single-photon absorptiometry, dual-photon absorptiometry, dual-energy X-ray absorptiometry, and quantitative computed tomography, have been developed and are now in clinical use.
Absorptiometry, Photon↗
Current status of physical measurements of the skeleton.
An overview is presented of some of the major methods of measuring the skeleton in the past 30 years. These include single photon absorptiometry (SPA), dual photon absorptiometry (DPA), quantitative computed tomography (QCT), and recently dual energy radiographic absorptiometry (DRA), also called DEXA (dual energy x-ray absorptiometry). In addition to these methods, all attempting to measure bone mineral density, regional and total body calcium have been determined by in vivo neutron activation analysis (IVNAA). An attempt to determine bone quality as contrasted with bone quantity has been made using ultrasound, with measurements of speed of sound and of attenuation as useful parameters to characterize bone tissue. While the various methods for measuring bone density have been most useful, no one method includes all the features required to be entirely satisfactory: excellent precision and accuracy and the ability to measure volumetric density in gm/cm3. Least successful has been the ability to predict fracture risk, an essential goal in helping the patient.
Absorptiometry, Photon↗
Noninvasive measurements of bone mass, structure, and strength: current methods and experimental techniques.
Current methods for assessing osteoporotic fracture risk involve measuring the content and/or density of bone at a number of skeletal sites and relating the measurement to that in either age-matched or young control subjects measured at the same site with the same technique. These densitometric methods have been used to predict several types of fractures; however, engineering principles verify that the bone structure and loading conditions also affect skeletal strength. Many densitometric measurements inherently contain information about skeletal structure and bone distribution, yet this information is not clinically used. In this paper, the currently available techniques for assessing bone content and density, namely, single-photon absorptiometry, dual-photon absorptiometry, dual-energy X-ray absorptiometry, and quantitative CT, and their usefulness in assessing fracture risk and distinguishing between patients with and without osteoporosis are reviewed. Extensions of conventional densitometry that have been developed by several researchers to include information in addition to bone mass also are presented. Results from recent studies using new applications of ultrasound techniques and MR imaging are reviewed. Preliminary studies show the value of these new techniques in noninvasive measurement of bone structure in order to estimate bone strength and assess fracture risk more accurately. However, to become clinically useful, many of these methods require further investigation to increase their ease of use and decrease their cost.
Absorptiometry, Photon↗
Indexes of bone mineral content on second metacarpal bone roentgenogram analyzed by digital image processing: a comparison with other bone mass quantifying methods.
A new photodensitometric technique (digital image processing, DIP) was performed to assess the bone mineral content of the metacarpal bone as a screening test for bone loss in 340 healthy or osteoporotic women as well as 35 steroid-dosed patients and 46 patients with chronic renal failure on hemodialysis. This procedure was compared with single photon absorptiometry and dual photon absorptiometry in terms of clinical value. Two bone mineral indexes, metacarpal index and sigma GS/D (the integrated bone mineral density of cortical and trabecular bone on a cross section in the middle of the second metacarpal bone), were equal to other methods in the quantification of decreases in bone mineral content due to aging in healthy or osteoporotic women. In addition, sigma GS/D was sensitive enough to detect decreases in bone mineral content in patients with vertebral fractures, on steroid therapy, and with chronic renal failure. Thus, sigma GS/D measured by DIP was shown to have clinical value as a tool in screening for decreased bone mineral content.
Absorptiometry, Photon↗
[Evaluation of optimal measuring site and index by QDR4500A for postmenopausal bone loss].
As the function of most bone mineral measuring machine is limited, either by single photon absorptiometry (SPA), dual photon absorptiometry (DPA), speed of sound (SOS), or dual energy x-ray absorptiometry (DEXA), it is hard to evaluate the best place and index of postmenopausal bone loss at many positions by one machine at the same time. So we used QDR4500A, one of the best advanced DEXA which has a good repeatability, to search the best place and index for postmenopausal bone loss. The results showed that (1) bone mineral density (BMD) was better than bone mineral content (BMC) and Area to reflect this kind of bone loss; (2) lumber BMD was a better place than the forearm BMD, total spine BMD and other places; and (3) midlateral L3, 4 BMD was a best index for postmenopausal bone loss.
Absorptiometry, Photon↗
Prevention and management of osteoporosis: consensus statements from the Scientific Advisory Board of the Osteoporosis Society of Canada. 2. The use of bone density measurement in the diagnosis and management of osteoporosis.
OBJECTIVE: To determine the best method of diagnosing osteoporosis and determining fracture risk and to promote standards in the use of bone densitometry and the reporting of results. OPTIONS: Methods of bone mineral density measurement: dual-energy x-ray absorptiometry (DXA), radiographic absorptiometry, single-photon absorptiometry, dual-photon absorptiometry, quantitative computed tomography, quantitative ultrasound, neutron activation analysis. The options of using bone densitometry in individual patient management and as a mass screening tool are also considered. OUTCOMES: Appropriate use of densitometry to promote accurate diagnosis and assessment of fracture risk and timely, appropriate treatment. EVIDENCE: Relevant clinical studies and reports were examined. Clinical practice in Canada was also considered. VALUES: Accurate assessment of osteoporotic fracture risk and diagnosis of osteoporosis and assuring low exposure to medical radiation were given a high value. BENEFITS, HARMS AND COSTS: Early diagnosis through bone density measurement allows proper management of osteoporosis to minimize injury and disability, improve quality of life and reduce the personal and social costs associated with the condition. Potential harms include radiation exposure and cost. The harms and costs of appropriate use of DXA are minimal compared with the harms and costs associated with osteoporosis. RECOMMENDATIONS: Bone mineral density should be measured only to assist in making a clinical management choice. DXA is the best method of measuring bone density and, thus, the best available indicator of osteoporotic fracture risk. Plain radiographs may supplement DXA if there is a specific reason for their use. Measurement of the lumbar spine and femoral neck is standard, but a different site or a single measurement is recommended in specific cases. Unless accelerated bone loss is suspected, DXA should be repeated every 2 to 4 years for patients receiving ovarian hormone therapy and 1 to 2 years for patients undergoing bisphosphonate therapy. Measurements and reporting of results must be standardized. Reports should refer to the World Health Organization's recommended definitions of osteopenia and osteoporosis and provide actual measurement and its relation to peak bone mass.
Aged↗
The state of the art of non-invasive diagnostics for bone densitometry. Methods of photonic absorption.
The authors examine densitometric diagnostics by photonic absorption for the in-vivo determination of bone mass. Based on an analysis of the literature a comparison is made for values for accuracy, repeatability, and dosimetry offered by techniques such as single-energy photon absorptiometry (SPA), dual photon absorptiometry (DPA), dual-energy X-ray absorptiometry (DXA), or quantitative computer tomography (QCT). Also discussed are economic aspects and daily management, recent developments and future possibilities. None of the densitometric diagnostics examined is capable of entirely satisfying the different needs of measurement, and nearly all of the methods of photonic absorption reported here have specific indications. The coexistence of different systems will increase the priority of the definition of standardized protocols of calibration, so as to obtain densitometric data that may be compared.
Absorptiometry, Photon↗
Discontinuous calcitonin treatment of established osteoporosis--effects of withdrawal of treatment.
PURPOSE: The purpose of this study was to examine the effects of discontinuous treatments with intranasal salmon calcitonin on bone and calcium metabolism in postmenopausal women and to establish the effects of withdrawing treatment. PATIENTS AND METHODS: This report presents data from 26 postmenopausal women with established osteoporosis (forearm fracture) 12 months after withdrawal of a 1-year double-blind, placebo-controlled therapy with intranasal calcitonin. The women then resumed treatment with calcitonin 200 IU plus calcium 500 mg daily in an open design for an additional 1-year period. A control group of 19 age-matched women (no forearm fracture) did not receive any treatment. RESULTS: At the end of the 3 years, the control group had lost significantly more bone in the forearm (single photon absorptiometry) and spine (dual photon absorptiometry) than had the group treated with intranasal calcitonin for 2 years, whereas the group receiving calcitonin for 1 year had intermediate values. During the year of withdrawal, the rate of bone loss was similar in the women who had received calcitonin and those who had received placebo. Calcitonin was especially effective in women with initially high bone turnover and low bone mass. The bone response in the spine could, furthermore, be estimated by the changes in bone turnover. CONCLUSION: Discontinuous treatment with intranasal calcitonin affects bone and calcium metabolism in established osteoporosis. In women with high-turnover osteoporosis, therapy results in a net gain of bone in both the peripheral and axial skeleton. Response to treatment may be monitored by changes in bone turnover.
Absorptiometry, Photon↗