PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Absorptiometry, Photon”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 433 records · Page 24Linked to original sources

Radial cortical and trabecular bone densities of men and women standardized with the European Forearm Phantom.

We previously showed that it is possible to cross-calibrate peripheral bone densitometers using the European Spine Phantom (ESP). We have now performed a multinational study of cross-calibrated radius bone density based on normal subjects of both sexes in eight European centers. Six centers were equipped with machines made by Scanco or Stratec for determining distal radial trabecular bone density by quantitative computed tomography (QCT) and two were equipped with Lunar SP2 single photon absorptiometry (SPA) equipment for measuring midshaft cortical bone density. Subjects recruited ranged from 20 to over 80 years of age. Over one hundred and fifteen men were studied by QCT and a different cohort of 104 men were studied with SPA; the equivalent figures for women were 235 and 123. Reference ranges were derived for bone density against age for each of the four groups, and their applicability is discussed in relation to between-center differences in the results obtained. There were insignificant differences (P > 0.05 with Bonferroni correction) between centers in the values obtained by QCT in the different populations. However, there were considerably larger and highly statistically significant differences between midshaft cortical bone density values of about 10% of overall means between subjects from eastern Finland and central Belgium (P < 0.001), with higher Finnish values. Women had considerably lower radial trabecular bone density values than men at all ages, a result that differentiates the radius from the spine. This sex difference widened after menopause. These results have important implications for understanding the contribution of bone density to the differential risk of Colles' fracture in the two sexes and suggest that further work is needed to establish young normal reference ranges for radial bone density in Europe.

Absorptiometry, Photon↗

Effect of radiographic abnormalities on rate of bone loss from the spine.

When measured by dual-photon absorptiometry (DPA), the adjusted annual rate of change in bone mineral density (BMD) of the lumbar spine was 0.11 +/- 0.51 (SE)% in 44 healthy postmenopausal women with radiographic abnormalities in the scan field and -0.97 +/- 0.26% in 249 women with normal lateral lumbar radiographs (p = 0.046). Rates of loss of BMD from the radius were similar in the 2 groups. Spurious rates of loss of spine BMD are likely to be found in subjects with calcification of the aorta, osteophytes or other abnormalities in the spine scan field. This should be kept in mind when serial spine scans are being considered in these subjects.

Absorptiometry, Photon↗

Bone density measurements.

Early diagnosis of osteoporosis is difficult. Bone density measurements, however, are helpful in screening patients at risk. Technology now provides means of measuring densities of both peripheral and central bones. The most practical method is dual X-ray densitometry, which is of good sensitivity and accuracy. Single photon absorptiometry on peripheral bones can be used to screen populations at risk. Computed tomography is also useful but the radiation dose is relatively high. In dual X-ray densitometry, calibration methods and comparisons with reference values are fairly reliable. The best sites for measurements are the lumbar spine and proximal femur, in which osteoporotic fractures are common. In general, however, one measurement is not enough. Biological variation is great. Repeated measurements will allow estimation of the rate of bone loss. Precise location of a previous site is sometimes difficult on reexamination and extraskeletal calcifications can be sources of error. Bone densitometry in connection with the prevention and treatment of osteoporosis is fairly easily performed with a single patient. Knowledge about the correlation between bone density and fracture risk is not yet adequate. The results of measurement of bone mineral density relate only to mineral content, not bone quality, i.e., differential diagnosis of osteoporosis and osteomalacia is not possible.

Absorptiometry, Photon↗

Nondestructive measurement of bone mineral in femurs from ovariectomized rats.

One hundred ninety-eight rats were ovariectomized (OX) or sham-ovariectomized (shOX) at 100 days of age. Groups were killed at 35, 70, 100, 125, 180, 270, 360, and 540 days postsurgery. Bone mineral content (BMC) of the right femur was assayed on a dual photon absorptiometer (DPA) optimized for human spine and whole body measurements. Three regions were studied: the distal measuring 0.8 cm, the proximal measuring 0.88 cm, and the diaphysis, the remainder. The DPA technique accurately showed the ash content (r = 0.96), with a precision error of 3-5%. Whole femoral BMC was 4.3-11.1% lower in OX than shOX rats, with significant differences from 35-180 days. By 35 days, distal femoral BMC declined 6% in OX rats and rose 12% in shOX rats. Distal femoral BMC was 11.3-17.5% lower in OX than shOX rats, with significant differences at all times except 540 days. Femoral diaphyseal BMC of OX and shOX rats did not differ at any time. The relative distal femoral osteopenia which appeared by 35 days in OX rats did not worsen during the next 17 months. A DPA suited for human BMC studies is also accurate for BMC determination in bones with 250-500 mg of mineral. It is less precise for this purpose than dedicated instruments using single photon absorptiometry. However, enough precision exists to monitor the development of relative osteopenia in OX rats. Osteopenia in OX rats is confined to a region containing appreciable cancellous bone. Its self-limiting nature suggests the existence of an estrogen-dependent quantum of cancellous bone in female rats. The adult rat model is accurate for cancellous bone of the adult human, but inaccurate for cortical bone.

Absorptiometry, Photon↗

Correlations between photon absorption properties and failure load of the distal radius in vitro.

The bone mineral content (BMC) and cross-sectional properties of cadaveric radii were assessed by single photon absorptiometry (SPA). A new multiple-angle scanning technique was used in conjunction with SPA to measure the area and moments of inertia of the radial cross section in intact forearms. The radii of the same forearms were then broken in a failure test to simulate a fall on the outstretched arm. Colles' fracture was produced in 16 of 18 radii tested. The BMC divided by the bone width, which is called bone mineral density (BMD) in clinical applications, did not correlate with the load at failure in cadaveric forearms. The BMC alone did correlate significantly with failure load (r2 = 0.62), and the cross-sectional properties gave the best correlation with failure load in a sequential multiple regression (r2 = 0.80). We conclude that if SPA is to be used in clinical studies to predict risk of radial fracture or of fractures at remote skeletal sites, then BMC should be used rather than BMD. An even better indicator of radial bone strength than BMC would be a biomechanical parameter derived from the cross-sectional area and moments of inertia, which can be obtained from multiple-angle SPA.

Absorptiometry, Photon↗

Prospective study of radial bone mineral density in a geographically defined population of postmenopausal Caucasian women.

The radial bone mineral density (BMD) mass of 324 Caucasian women, aged 55-80 years, from geographically defined areas was evaluated in 1983 using single photon absorptiometry; 271 of these women (86%) were reexamined 5 years later in 1988. More than 65% of women lost radial BMD in excess of 1%/year in the 5-year follow-up. Thirty percent of women lost at least 2%/year. Baseline radial BMD measures taken in 1983 were highly predictive of the 1988 radial BMD values, explaining approximately 82% of the variability. The rate of bone change, expressed as percent change or 5-year difference (g/cm2), was not associated with baseline radial BMD value. Rate of change was not strongly associated with chronologic age or years since menopause, even when data were restricted to those women who reported no previous use of perimenopausal estrogen or thiazide medication. We conclude that BMD loss in a general population may be more substantial than previously believed.

Absorptiometry, Photon↗

Bone densitometry of excised vertebrae; anatomical relationships.

Bone mineral density (BMD) was determined in 32 excised vertebrae using three methods: (1) dual-energy quantitative computed tomography (QCT), (2) dual-photon absorptiometry (DPA) with 153-Gd in an anteriorposterior projection and (3) scanning slit X-ray absorptiometry (SSXA) in both AP and lateral projections. The QCT region-of-interest in the anterior vertebral body had a lower density than that of the total trabecular portion of the body, but was highly correlated to this larger region (r = 0.96; SEE = 8 mg/cm3). The anterior QCT region also correlated moderately with BMD from DPA (r = 0.77; SEE = 18 mg/cm3). Measurements of the vertebral body in lateral projection were less well correlated (r = 0.5-0.7) to QCT densities. Both the anterior QCT region (r = 0.81; SEE = 18 mg/cm3) and the BMD from DPA (r = 0.86; SEE = 16 mg/cm3) and the BMD from DPA (r = 0.86; SEE = 16 mg/cm3) were similarly predictive of density of the integral vertebral body. Differences among densitometric methods on the spine depend on the projection used and the region examined.

Absorptiometry, Photon↗

Evaluation of bone mineral density in children with diabetes mellitus.

Multiple studies have documented reduction in peripheral bone mass in children with insulin dependent diabetes mellitus (IDDM). In this study, the bone mineral density (BMD) of the lumbar vertebrae (L2-L4) was measured by dual photon absorptiometry in 14 female and 16 male diabetic patients of age 11 to 16 years with varying clinical duration. Twenty three children between 11 to 16 years with normal anthropometric measurements between 10th and 97th percentile and no known history of metabolic bone disease served as a control group. BMD values, weight, height, body mass index, metabolic, biochemical and growth parameters of the study group were compared with those of the control group. BMD (L2 AP 0.732 +/- 0.15 gm/cm2, L2 lateral 0.534 +/- 0.09 gm/cm2 in the study group and 0.812 +/- 0.63 gm/cm2 and 0.619 +/- 0.20 gm/cm2 in the control group) and osteocalcin (10.10 +/- 3.40 ng/ml and 23.12 +/- 2.74 ng/ml in diabetes and control respectively) levels were significantly lower in diabetic patients (p < 0.05, p < 0.01 respectively). Within the study group BMD correlated positively with age but not with the duration of the disease nor with the level of metabolic control.

Absorptiometry, Photon↗

Factors affecting bone mineral density in renal transplant patients.

Bone disease is a major cause of morbidity in end stage renal failure. This study is aimed to assess the prevalence of abnormal bone mineral density (BMD), measured by dual photon absorptiometry (DPA) in the renal transplant population. Subjects consisted of 110 patients followed up after transplantation for between 1 and 17 years. Variables analyzed included age, sex, ethic origin, years and type of dialysis prior to transplantation, date of transplant, total steroid dose, number of rejection episodes, use of Cyclosporin, and biochemical/hormonal variables such as serum calcium, phosphate, magnesium, alkaline phosphatase, creatinine, FSH, LH and PTH. Analysis of variance and chi square tests were performed to assess the differences between groups and Pearson correlation coefficients were obtained. The total steroid dose, year of birth, PTH level and duration since transplantation were correlated with BMD (p < 0.05). Despite the statistical significance, the degree of variability indicated by each of these variables was low revealed by multiple regression analysis. We conclude that although steroid therapy is a major contributor to the increase in osteoporosis in renal transplant patients, about two thirds of the parameters that can influence bone metabolism remain unexplained.

Absorptiometry, Photon↗

Total body and regional bone mineral content in hemodialysis patients.

Bone mineral content (BMC) in the total body and lumbar spine was evaluated in 126 hemodialysis patients (60 males, 66 females) by dual photon absorptiometry with the Norland DBD 2600. Measurements of: 1) total body BMC divided by lean body mass (BMCTB/LBM), 2) bone mineral density (BMD) of total body, 3) BMD of four regional sections (head, trunk, pelvis, and legs), and 4) BMD of lumbar spine, generally showed a significant decrease in the hemodialysis patients compared to the reference population. However, arm BMD did not show a significant difference between patients and control populations. The z-score of BMCTB/LBM declined significantly throughout the duration of hemodialysis, although that of the lumbar spine BMD did not. It should be noted that the degree of decrease in BMC was more prominent in the total body measurement than in the lumbar spine measurement. There was preferential osteopenia of the total body in the hemodialysis patients. Although the lumbar spine BMD showed a lower value than the control population, the lumbar spine is not the recommended region to monitor the BMD change in hemodialysis patients.

Absorptiometry, Photon↗

The effect of androstenedione/estrone supplementation on cortical and cancellous bone in the young intact female monkey: a model for the effects of polycystic ovarian disease on the skeleton?

The goal of this study was to determine the effects of chronically elevated blood androstenedione and estrone levels on the quality and quantity of both cancellous (trabecular) and cortical bone in a young (mean age 9.4 years) female primate model (M. fascicularis). Thirteen intact female monkeys received continuous androstenedione/estrone supplementation via subcutaneous implants over a 24-month period to simulate the human condition known as polycystic ovarian disease (PCOD). A group of 16 untreated intact age-matched female monkeys served as controls. Lumbar spine and whole body bone mineral density (BMD) status was determined mid-study by dual photon absorptiometry (DPA); subsequent analysis of the bone related to data obtained following the 2-year treatment period without further BMD measurement. Bone markers, including serum acid phosphatase, total bone alkaline phosphatase, bone gla protein and tartrate-resistant acid phosphatase were measured at the end of the study. At necropsy, the lumbar vertebrae and femora were recovered in order to analyze the bone mineral quality and quantity of cancellous and cortical bone respectively and to compare these with the control group. Mineralization profiles of the vertebrae and femora were obtained using the density fractionation technique. Chemical analysis of the three largest fractions retrieved by density fractionation was performed to evaluate differences in %Ca, %P, Ca/P ratio and mineral content (%Ca + %PO4) between control and experimental groups. In addition, unfractionated bone powder was examined by X-ray diffraction to identify any changes in crystal size. Coronal sections of vertebrae were analyzed for structural parameters using histomorphometry and image analysis. Cross-sections taken at the midshaft diaphyseal femora were analyzed for structural macroscopic and intracortical parameters. There was a significant increase in BMD at the L2-L4 region in the treatment group compared with the control groups (p < 0.005) as measured at 1 year into the trial. Serum acid phosphatase was significantly lower (p < 0.05) in the treatment group compared with the controls near study termination. A nonsignificant shift in the mineralization profile of the vertebrae towards less dense bone was observed in the treatment group, while there was a significant shift in the mineralization profile towards more dense bone in the treated femora compared with controls (p < 0.05) after a 2-year period. There was no difference between treatment and control groups in terms of size/strain of the cortical or cancellous bone crystal as detected by X-ray diffraction. There was a significant increase in cancellous bone area (B.Ar.) (p < 0.02) and a significant increase (p < 0.05) in mean trabecular width with a corresponding decrease in trabecular separation (p < 0.03) in the experimental group compared with the controls. There were no significant changes in osteoid parameters (perimeter, area or width) or eroded perimeter measurements in the experimental group compared with the controls. In the experimental group, trabecular strut analysis showed a significant increase in the number of nodes (p < 0.02) and in the total strut length (p < 0.003) compared with the controls. There was also a significant increase in the node to node (p < 0.04) and node to terminus (p < 0.004) strut length in the treatment group compared with the controls. A significant increase in B.Ar. without concurrent indices of ongoing remodelling differing from controls suggests that cancellous bone of the vertebral body in the treated young female primate had been receptive to the anabolic stimulus of androstenedione/estrone supplementation over the 2-year period. In contrast, macroscopic parameters of cortical bone such as perimeter, area and width were preserved over the 2-year course, while intracortical remodeling was evident with increased percent porosity (p < 0.001), osteonal bone (p < 0.01) and osteonal density (p < 0.01) observed in the treatment group compared with the controls. The endocrine profile of both elevated androstenedione and estrone levels in an intact female primate of reproductive age may identify differential effects of the condition known as polycystic ovarian disease on the skeletal compartments.

Absorptiometry, Photon↗

Prediction of bone loss rate in healthy postmenopausal women.

Prevention of fractures is the only way to drastically reduce osteoporosis-related health expenditures. In order to optimize the cost/benefit ratio of a strategy of prevention, it is essential to identify, as early as possible, women who will develop fractures later in their life. Therefore, and since postmenopausal bone loss is an asymptomatic process, screening procedures should detect, at the time of the menopause, women whose postmenopausal bone loss is higher than the mean, and will, a couple of years later, exhibit a low mineral content and a subsequent high risk for fractures. For 3 years we have followed a cohort of 92 healthy women who had undergone menopause less than 36 months previously. By a multivariate discriminant analysis based on the differences in lumbar bone density, assessed by dual photon absorptiometry, and in a few routine biochemical parameters (serum phosphorus, estrone, androstenedione, and urine calcium) observed during the first 6 months of the study, we have been able to correctly predict the rate of spinal bone loss, observed at the end of the 3 years, in 76% of the subjects. All of the women who presented a bone loss higher than 10% over the 3 years were correctly isolated by our discriminant functions after 6 months of follow-up. We conclude that a measurement of lumbar bone mineral density coupled with a few routine biochemical determinations, repeated twice at a 6-month interval in healthy postmenopausal women, can isolate 100% of postmenopausal "fast bone losers" with an overall specificity of 76%.

Absorptiometry, Photon↗

Comparison of calcitriol treatment with etidronate-calcitriol and calcitonin-calcitriol combinations in Turkish women with postmenopausal osteoporosis: a prospective study.

Calcitriol has been widely used in the management of osteoporosis, but its efficiency is a matter of controversy. It is not known whether combinations of calcitriol and antiresorptive agents such as etidronate and calcitonin are superior to calcitriol alone in the treatment of postmenopausal osteoporosis. To make this determination, 30 Turkish women with postmenopausal osteoporosis between 45 and 68 years of age were randomized to receive either intermittent cyclical etidronate (400 mg/day, for 14 days) followed by 60 days of cyclical calcitriol therapy 0.25 microg twice daily (group 1; n = 10), or calcitriol 0.25 microg twice daily (group 2; n = 10), or calcitriol 0.25 microg/day in combination with 100 IU intranasal salmon calcitonin taken every other day (group 3; n = 10) through a 1-year period. Bone mineral density (BMD) of lumbar spine (L2 to L4) was determined for each patient by dual-photon absorptiometry (153Gd) at baseline, after 6 months, and at the end of the study. There was no significant difference among groups with respect to mean spinal BMD at baseline, after 6, and after 12 months. No significant spinal BMD changes occurred in any group from baseline, after 6 months, and after 12 months. Four patients in groups 1 and 2 and five patients in group 3 developed hypercalcemia at least once during therapy. Hypercalciuria occurred at least once in 9, 10, and 7 patients in groups 1, 2, and 3, respectively. One patient in group 2 developed a renal stone at the end of the study. Mean urine hydroxyproline levels did not change significantly in any group with respect to baseline. The data suggest that one-year treatment with calcitriol, given either alone or in combination with antiresorptive agents, does not improve spinal BMD in Turkish women with postmenopausal osteoporosis, and is associated with a high rate of adverse events.

Absorptiometry, Photon↗

Prevention of corticosteroid-induced osteoporosis with alendronate in sarcoid patients.

Prolonged corticosteroid administration, as often required in the treatment of sarcoidosis, increases the risk of osteoporosis and fracture. The aim of the present study was to evaluate the usefulness of alendronate, a third generation bisphosphonate, in preventing corticosteroid-induced osteoporosis. Forty-three consecutive, previously untreated, sarcoid patients (17 men and 26 premenopausal women) were included in the study: 13 needed no treatment and served as controls (Group 1) and 30 needed glucocorticoids (prednisone) and were randomly selected to also receive either placebo (n = 15, Group 2) or alendronate 5 mg/day (n = 15, Group 3). Bone mineral density (BMD) at the ultradistal radius by dual photon absorptiometry (Osteograph 1000, NIM, Verona, Italy) and biochemical markers of bone turnover were measured at baseline and after 6 and 12 months of glucocorticoid therapy. No significant difference was found between Groups 2 and 3 in the mean cumulative dose of prednisone (4945 +/- 1956 mg and 5110 +/- 2013 mg, respectively). At the end of the study period, BMD increased by 0.8% in the alendronate-treated group; in the placebo-treated group, BMD decreased by 4.5%. The difference between groups was significant (P < 0.01, ANOVA). A significant decrease in markers of bone formation was found in all patients treated with prednisone (Groups 2 and 3), independently of alendronate. Alendronate, however, counteracted the increase in markers of bone resorption induced by glucocorticoid therapy. Our data suggest that alendronate is effective in preventing glucocorticoid-induced bone loss in sarcoid patients. Further studies on alendronate use in steroid-induced osteoporosis are needed.

Absorptiometry, Photon↗

Efficacy of ipriflavone in established osteoporosis and long-term safety.

Ipriflavone (i.p.), an isoflavone derivative, is currently used in several countries for prevention and treatment of osteoporosis. Recently, 149 elderly, osteoporotic women (65-79 years) with prevalent vertebral fractures were enrolled in two Italian, multicenter, double-blind, 2-year studies. Women were randomly allocated to receive either oral i.p. (200 mg T.I.D. at meals) or matching placebo, plus 1 g oral calcium daily. One hundred eleven subjects completed the 2-year treatment period. A significant increase in forearm bone mineral density (BMD), measured by dual photon absorptiometry (DPA), was obtained after i.p. treatment. Women receiving the placebo showed only a limited bone loss during the treatment period, probably due to calcium supplement; however, a significant between-treatment difference was obtained in both studies. Urinary hydroxyproline was significantly decreased in i.p.-treated patients, suggesting a reduction in bone turnover rate. A reduction of incident vertebral fractures was observed in i.p.-treated women compared with control subjects. A significant improvement of bone pain and mobility has also been pointed out in one of the studies. To date, 2769 patients have been treated with i.p., for a total of 3132 patient/years, in 60 clinical studies performed in Italy, Japan, and Hungary and reviewed for long-term safety assessment. The incidence of adverse reactions in ipriflavone-treated patients (14.5%) was similar to that observed in subjects receiving the placebo (16.1%). Side effects were mainly gastrointestinal. Few patients presented reversible modifications of laboratory parameters. The data from the above studies show that long-term treatment with i.p. may be considered safe, and may increase bone density and possibly prevent fractures in elderly patients with established osteoporosis.

Absorptiometry, Photon↗

A prospective study of bone mineral density change in Taiwan.

In 1989, a cross-sectional study was carried out in Lin-Kou Township, Taiwan, to determine the distribution of bone mineral density (BMD) in the lumbar spine of Chinese people. Lumbar spine BMD was measured using dual-photon absorptiometry in 404 healthy volunteers (266 women and 138 men, aged 15 to 83 years). In 1994-1995, 318 of the same volunteers were reexamined for the present study. Except for there being fewer males and smokers present, there were no significant differences between the second survey respondents and nonrespondents. Spine BMD decreased at over 1% per year in Chinese women over age 50, which was somewhat higher than reported for caucasian women. Since there was a loss of BMD in Chinese women after their 20s, a case can be made for starting preventive activities for female adolescents. There were no differences in the mean BMD change rates among the different age groups of Chinese men. Baseline BMD, menopause, and weight change were associated with the lumbar spine BMD change rates in Chinese women. Body mass index was the only variable significantly associated with BMD change in Chinese men. The rate of BMD change was not associated with diet.

Absorptiometry, Photon↗

Possible predisposing factors for the second hip fracture.

Among 1685 patients who sustained a hip fracture at the island of Crete (Greece) in a 4-year period we found 106 patients with bilateral noncontemporary hip fractures. Pathologic hip fractures and fractures that emerged from high energy trauma were excluded. To investigate the possible factors predisposing to the later fracture in the sound hip, we studied these 106 patients and compared them with the 1579 patients who sustained a single hip fracture (control group). There was no significant difference between the mean age of the bilateral group at the time of the first hip fracture (78.3 +/- 7.4 years, range 52-94 years) and the mean age of the control group (77.3 +/- 11.9 years, range 50-101 years). We found no significant difference in the bone status between the two groups, using both lumbar spine dual photon absorptiometry (DXA) and calcaneus broadband ultrasound attenuation (BUA). Falls, which were the main cause of all the hip fractures, were much more common in the bilateral group. The second hip fracture was of the same location (trochanteric or cervical) in 92% of the trochanteric and 68% of cervical fractures and a tendency to greater displacement or instability was observed. Of the second hip fractures 75% happened in the first 48 months after the first one. The mean interval time was much longer (160 months) when a neck fracture was followed by a trochanteric one.

Absorptiometry, Photon↗

Radial and lumbar bone mineral density after wrist synovectomy in rheumatoid arthritis. A minimum 2-year follow-up in 10 unilaterally operated patients.

Bone mineral density (BMD) of both radii and lumbar vertebrae was measured by single-photon absorptiometry and dual X-ray absorptiometry, respectively, before and 2.1-4.8 years after a unilateral wrist synovectomy in 10 patients with rheumatoid arthritis. Radial BMD on the operated side significantly increased after synovectomy, while that on the non-operated side did not change. Lumbar BMD significantly decreased after the operation. The grip strength of the operated side increased significantly after synovectomy, while there were no changes in the grip strength on the non-operated side. These findings suggest that wrist synovectomy results in pain relief and improves use, thereby increasing the BMD of the operated radius.

Absorptiometry, Photon↗