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At least 1,261 records · Page 70Linked to original sources
PubMed1999

Aortic calcification contributing to bone densitometry measurement.

A 75-yr-old glucocorticoid-dependent asthmatic male had a bone mineral density study to assess possible osteoporosis prior to initiating therapy. A radiograph of the lumbar spine revealed an asymmetrical compression of the second lumbar vertebra, marked scoliosis, vertebral osteopenia, and a highly calcified abdominal aorta. Bone mineral density (dual X-ray absolptiometry [DXA]) revealed low bone mass in L2-L4 and a markedly abnonrnal pattern, with a linear central density representing a calcified aorta. Posterior-anterior measurements of the midlumbar region with and without the overlying aorta indicated that the calcified vessel contributed up to 33% of the measured density. This was a far higher contribution than reported in other studies. Lateral DXA measurements of the L2 vertebra and the overlying aorta were performed to validate this finding. The density of the L2 vertebra was 0.215 g/cm(2), and that of the overlying calcified aorta was 0. 210 g/cm(2). This case suggests that aortic calcifications may contribute sign)ficantly to overall lumbar bone density and, unless recognized, can inadvertently lead to misclassification of osteoporosis.

Absorptiometry, Photon↗
PubMed2000

A simple method of computing hip axis length using fan-beam densitometry and anthropometric measurements.

Hip axis length (HAL), a simple measure obtained from dual X-ray absorptiometry (DXA) scans of the proximal femur, predicts hip fracture, independent of bone mineral density and age. Owing to a magnification error associated with newer fan-beam DXA, automatic calculation of HAL, which is available in pencil-beam DXA, is inaccurate. The purpose of this study was to model HAL, measured from a pencil-beam DXA, as a function of HAL from a fan-beam DXA combined with other anthropometric measures. Proximal femur scans were performed using pencil- and fan-beam DXA in 21 women (ages 24-60). Height, weight, hip circumference, subject thickness, height of the greater trochanter and anterior superior iliac spine from the scanning table, and HAL as measured by a ruler from the scan printouts were recorded. Anthropometric measurements were taken by two researchers; all but the greater trochanter were reproducible (r > or = 0.92). A simple linear model using the manual measurement of HAL from the fan-beam scan, height, weight, body mass index, and hip circumference was able to predict HAL measured using the pencil-beam DXA with a high degree of accuracy (R(2) > or = 0.96). The fan-beam-acquired values of HAL using our model are nonbiased and accurate estimates of the "gold standard" pencil-beam method. This model may provide researchers and clinicians with a simple method of calculating HAL using fan-beam DXA.

Absorptiometry, Photon↗
PubMed2001

Peripheral or central densitometry: does it matter which technique we use?

Over the past decade, bone density scans have assumed an essential role in the diagnosis of osteoporosis. Although dual X-ray absorptiometry (DXA) scans of the central skeleton remain widely used, a variety of different types of equipment for measuring peripheral sites is now available. However, the poor correlation between different types of measurement and a lack of consensus on how results from peripheral sites should be interpreted have proved a barrier to the more widespread use of these devices. These issues prompt the following questions: Which technique best identifies patients at risk of fracture? What approaches to scan interpretation ensure the closest agreement among different methods? Does it matter if different patients are selected for treatment on the basis of different techniques? The relative risk (RR)of fracture derived from prospective studies is a key parameter for comparing the clinical value of different techniques. Recent reports confirm the advantages of hip bone mineral density compared with peripheral measurements for predicting hip fracture risk, although for fractures at other sites the differences are inconclusive. Using receiver operating characteristic curves, we show that the guidelines adopted for scan interpretation are of crucial importance for ensuring that the information provided is used effectively. The closest agreement among different techniques is achieved by setting thresholds for peripheral devices that target either the same percentage of the population or the same percentage of future fracture cases as femur DXA. Different methods select different groups of individuals from the total pool of patients who will later sustain a fracture, with the most successful technique being the one with the largest RR value. The emphasis placed by many studies on validating new techniques by studying their correlation with DXA may lead to the clinical value of peripheral devices being underestimated when the key datum is the RR value inferred from prospective fracture studies.

Absorptiometry, Photon↗
PubMed2002

Centile curves for bone densitometry measurements in healthy males and females ages 5-22 yr.

Normative pediatric bone measurement data are necessary for defining osteopenia in children and for identifying factors associated with normal bone growth. The LMS statistical method is used to produce centile curves plotting a growth characteristic as a function of age. The purpose of this study was to provide centile curves of bone measurements using peripheral quantitative computed tomography (pQCT) and dual X-ray absorptiometry (DXA) in 231 (107 male) healthy individuals ages 5 22 yr using the LMS method. pQCT (Norland XCT 2000; Norland, Ft. Atkinson, WI) was used to image a single slice at the 20% distal tibia. Periosteal circumference, endosteal circumference, and cortical density measurements were used to obtain centile curves. Whole-body DXA (Hologic QDR 4500; Hologic, Bedford, MA) was obtained and scans were analyzed using adult whole-body software for total body bone mineral content (BMC) and total body bone area. pQCT measurements showed prepubertal expansion of the tibia that plateaued in females at age 14 and continued in males until age 18. Tibia cortical density increased during the age of puberty more gradually in females than in males. DXA measurement curves showed that total body BMC and total body bone area plateaued in females at approximately age 15, whereas male curves of the same measurements showed a continued increase.

Adolescent↗
PubMed2003

Bone densitometry of a patient with osteosclerosis.

A 30-yr-old Caucasian man with a history of dorsal and lumbar back pain, which responded partially to antiinflammatory agents, was seen at our Unit. The biochemical bone markers showed an increment in bone alkaline phosphatase and urinary CTX. Serum phosphate tended to be low. Radiographic abnormalities were marked osteosclerosis in the pelvis and vertebral bodies without changes in size. Bone scintigraphy results were normal. The increase in bone mineral density (BMD) was greater in L2-L4 (+ 3.9 SDs) than in total skeleton (+ 1.4 SDs). Analysis of skeletal subareas showed a marked increase in axial skeleton BMD: trunk, +4.0 SDs; spine, +2.5 SDs and pelvis, +4.5 SDs. BMD of the remaining subareas was found to be normal: skull, +0.04 SDs; arms, -0.3 SDs and legs, -0.05 SDs. The patient refused to have a bone biopsy. The radiologic, densitometric, and biochemical findings in the patient presented herein are compatible with axial osteomalacia. Evaluation of total skeleton BMD, and especially skeletal subareas, clearly indicated that the abnormal BMD was restricted to the spine and pelvis whereas the rest of the skeleton was not affected.

Absorptiometry, Photon↗
PubMed2003

Serial bone densitometry during mandibular distraction osteogenesis.

The purpose of this study was to obtain serial measurements of bone mineral density (BMD) of the mandible during distraction osteogenesis. Fourteen skeletally mature male rabbits were subjected to unilateral mandibular osteodistraction at a defined rate. Two animals were sacrificed each week after surgery for 7 wk. The mandible and overlying soft tissue were resected and the BMD measured using dual-energy X-ray absorptiometry (DXA). Measurements obtained from the generate bone were compared to the contralateral (control) hemi-mandible. In the control hemi-mandible, BMD remained stable throughout the distraction protocol at 0.5 gm/cm2. In the distracted hemi-mandible, BMD sharply decreased to 0.35 gm/cm2 by the second week of distraction but steadily increased starting the third week of distraction. BMD surpassed control levels by wk 7. BMD measurements may provide a noninvasive assessment of bone mineralization and strength during distraction osteogenesis.

Absorptiometry, Photon↗
PubMed2004

Bone densitometry in premenopausal women: synthesis and review.

Bone loss prior to menopause is being increasingly identified in women. Clearly, low bone mineral density (BMD) is a significant risk factor for fracture in the estrogen-deficient female postmenopause. The significance of low bone density prior to menopause needs to be addressed. Low bone density in the premenopausal female may reflect attainment of a lower peak bone mass. It may also be secondary to progressive bone loss following achievement of peak bone density. The etiology of low bone density in the premenopausal female needs to be clarified with meticulous exclusion of secondary causes of bone loss. Menstrual status is an important determinant of peak bone mass as well as the development of bone loss in women prior to the onset of menopause. Subclinical decreases in circulating gonadal steroids may be associated with a lower peak bone mass as well as progressive bone loss in otherwise reproductively normal women. Elevations of follicle-stimulating hormone (FSH) of greater than 20 miu/L are associated with evidence of increased bone turnover marker activity and correlate with progressive bone loss in perimenopausal women. This transitional period requires further study with respect to the magnitude of bone loss experienced and the potential benefits of antiresorptive therapy. Detailed assessment of menstrual status is necessary in the evaluation of low bone density in premenopausal women. The majority of the cross-sectional and longitudinal studies completed evaluating BMD in the premenopausal years suggest that minimal bone loss does occur prior to menopause after attainment of peak bone mass. The magnitude of premenopausal bone loss, however, is controversial and may be site-dependent. More rapid rates of bone loss are seen in the transitional period beginning 2-3 yr prior to the onset of menopause. Prospective data are needed to understand further the relationship between BMD and fracture in the premenopausal period. Women with steroid-induced bone loss as well as other secondary causes of osteoporosis respond to antiresorptive therapy with documented improvements in BMD. Biomarkers can identify perimenopausal women with increased bone turnover. Lifestyle modification can improve BMD in the pre- and the perimenopausal period. Antiresorptive therapy has not been evaluated in pre- or perimenopausal women with low BMD in the absence of secondary causes of osteoporosis. As new treatment options are evaluated and become available, biomarker assessment may be of value in identifying women at risk of fracture.

Bone Density↗
PubMed2004

Densitometry in glucocorticoid-induced osteoporosis.

Bone density measurement is a critical tool in the management of glucocorticoid-induced osteoporosis (GIOP). This review addresses the utility of various measurement devices (dual-energy X-ray absorptiometry [DXA], quantitative ultrasound [QUS], quantitative CAT scanning [QCT]), their role in monitoring changes in bone mineral density (BMD), and the relationship of BMD and fracture risk in GIOP. A higher BMD threshold should be utilized for estimating fracture risk in patients on glucocorticoids.

Absorptiometry, Photon↗
PubMed2005

Construction and validation of a population-based bone densitometry database.

Utilization of dual-energy X-ray absorptiometry (DXA) for the initial diagnostic assessment of osteoporosis and in monitoring treatment has risen dramatically in recent years. Population-based studies of the impact of DXA and osteoporosis remain challenging because of incomplete and fragmented test data that exist in most regions. Our aim was to create and assess completeness of a database of all clinical DXA services and test results for the province of Manitoba, Canada and to present descriptive data resulting from testing. A regionally based bone density program for the province of Manitoba, Canada was established in 1997. Subsequent DXA services were prospectively captured in a program database. This database was retrospectively populated with earlier DXA results dating back to 1990 (the year that the first DXA scanner was installed) by integrating multiple data sources. A random chart audit was performed to assess completeness and accuracy of this dataset. For comparison, testing rates determined from the DXA database were compared with physician administrative claims data. There was a high level of completeness of this database (>99%) and accurate personal identifier information sufficient for linkage with other health care administrative data (>99%). This contrasted with physician billing data that were found to be markedly incomplete. Descriptive data provide a profile of individuals receiving DXA and their test results. In conclusion, the Manitoba bone density database has great potential as a resource for clinical and health policy research because it is population based with a high level of completeness and accuracy.

Absorptiometry, Photon↗
PubMed2005

Postmenopausal women with colles' fracture have lower values of bone mineral density than controls as measured by quantitative ultrasound and densitometry.

Measurement of ultrasonographic parameters provides information concerning not only bone density but also bone architecture. We investigated the usefulness of ultrasonographic parameters and bone mineral density (BMD) to evaluate the probability of Colles' fracture. Two-hundred eighty-nine postmenopausal women (62.3 +/- 8.7 yr) with (n = 76) and without (n = 213) Colles' fracture were studied. BMD of lumbar spine and proximal femur was evaluated in all women by dual-energy X-ray absorptiometry (DXA) and speed of sound (SOS), broadband ultrasound attenuation (BUA), and stiffness in the calcaneus were measured by a Sahara ultrasonometer (Hologic). Patients suffering from Colles' fracture had lower values of BMD adjusted by height at the lumbar spine, L2-L4 (0.797 g/cm2 vs 0.860 g/cm2), femoral neck (0.685 g/cm2 vs 0.712 g/cm2 ), SOS (1518 m/sg vs 1525 m/sg), and stiffness (74.6 vs 77.7) (p < 0.05). Nevertheless, BUA values were similar in both groups. After stepwise logistic regression analysis, the area found under receiver operating characteristic (ROC) curves was 0.60 for L2L4 and 0.63 for a formula combining L2L4 and height. Our data suggest that patients suffering from Colles' fracture have lower values of BMD by DXA, SOS, and stiffness. However, the ability of these techniques to discriminate is low because the values for the area under ROC curve are 0.60 for L2-L4 and 0.63 for a formula derived of the combination of L2-L4 and height.

Absorptiometry, Photon↗
PubMed2006

Peripheral bone densitometry: Clinical applications.

Technologies for the measurement of bone mineral density and other parameters of bone strength at peripheral skeletal sites have been studied since the 1960s. Single-energy Photon Absorptiometry (SPA), Radiographic Absorptiometry (RA), Radiogrametry (RG), Single-energy X-ray Absorptiometry (SXA), Peripheral Dual-energy X-ray Absorptiometry (pDXA), and Quantitative Ultrasonometry (QUS) have been successively evaluated. These technologies and their clinical applications are discussed in this article. The available scientific evidence supports the clinical use of these technologies at peripheral skeletal for assessment of fracture risk. Peripheral measurements other than the 33% (one-third) radius by DXA cannot be used to diagnose osteoporosis according to current standards. Peripheral skeletal sites are not clinically useful for monitoring changes in BMD with natural evolution of the disease and its treatment. Peripheral BMD measurement can theoretically be used to screen patients for selection to central DXA testing, although device-specific cut-points should be developed before this is implemented. When central DXA testing is not available, peripheral BMD testing may be considered to identify individuals who might benefit from pharmacological intervention.

Absorptiometry, Photon↗