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PubMed1988

Radiation dose to small infants from single-photon absorptiometry.

The radiation dose to the patient resulting from single-photon absorptiometry (SPA), now a widely used method for measuring bone mineral content (BMC) in vivo in infants and children, was evaluated. Lithium fluoride chips were placed on a phantom with a BMC in the small infant range (60 and 145 mg/cm). Measurement procedures mimicked the actual clinical sequence. The radiation exposure for a single BMC measurement is 46-70 mrad (460-700 microGy) to the forearm surface and 25-38 mrad (250-380 microGy) and 125-190 mrad (1,250-1,900 microGy) to the bone marrow and the bone, respectively. When eight repeated measurements are performed over a 1-year period, the radiation dose is about 368-560 mrad (3,680-5,600 microGy) to the forearm surface and 200-305 mrad (2,000-3,050 microGy) and 1,000-1,525 mrad (10.0-15.25 mGy) to the bone marrow and the bone, respectively. Even though the radiation dose is small, this method should be used only in well-designed clinical studies.

Body Weight↗

PubMed1983

[Clinical study on bone mineral mass in metabolic bone disorders--I-125 photon absorptiometry].

Changes in bone mineral mass were investigated by 125I-photon absorptiometry in 5 groups of patients; postmenopausal osteoporosis (n = 50), after partial or total gastrectomy (n = 54), thyroid disorders (n = 28), parathyroid disorders (n = 6) and healthy subjects (n = 214) as control. Radial bone mineral content (BMC) was measured at the distal 1/3 and 1/6 sites of the radius and the densitometric patterns were analized . The results obtained were as follows: Age variation in bone mineral mass and bone mineral change in pathological status were more sensitively detectable at the distal 1/6 site of the radius (predominantly trabecular) than the distal 1/3 site of the radius (predominantly cortical). In osteoporosis there was a diminution in radial 1/6 BMC and a significant decrease of radial trabecular bone index ( RTBI ) estimated from densitometric patterns, as compared with age-matched control. Sequential changes of bone mineral mass were evaluated during the treatment. There was no significant change in bone mineral mass during the first 3 months of 1 alpha-OH-D3 administration. Bone mineral mass then decreased about 20% in radial 1/6 BMC in the course of the treatment. An increase in bone mineral mass at the distal 1/6 site of the radius was revealed at 1 year treatment with 1 alpha-OH-D3. But at the distal 1/3 site of the radius only a little change in bone mineral mass was recognized during the treatment. Total gastrectomy caused a significant deficit of radial BMC as compared to partial gastrectomy. 1 alpha-OH-D3 was also effective on bone mineral loss after gastrectomy. Loss of radial 1/6 BMC occurred in hyperthyroidism (high turn over osteoporosis) but not in hypothyroidism. Striking bone mineral loss was observed in hyperparathyroidism, which recovered after surgical treatment.

Adolescent↗

PubMedDate not supplied

[Measurement of femoral bone density using dual photon absorptiometry. Values in osteoporosis].

X-ray absorptiometry allows measuring the density of bone in the upper end of the femur in 3 mains areas: the neck, Ward's triangle and the greater trochanter. Failin prospective data, it is not possible at present to know whether one of these areas has better performances than the others for the assessment of fracture risks. The interpretation of the measurement is based on the idea that bone demineralization is the main risk factor of osteoporotic fracture. It is carried out on the basis of reference normal values, which must be determined in the French population. More sophisticated predictive models of fracture risks are being developed. In young adults, the reproducibility of the measurements is lower than 2% for the neck and the trochanter, and around 2.5 to 3% for Ward's triangle. The density of femoral bone is not well correlated to that of the other bony sites (os calcis, ulna, vertebrae: r = 0.3 to 0.7). On the other hand, the correlation between the right and left femur is good, as well as that of the three femoral measurement areas between them. A fracture of the upper end of the femur is often associated with a decrease in femoral bone density (-12 to -15%, according to the site of measurement), while the measurement in the ulna or the spine is normal or just slightly lowered. Femoral bone rarefaction is also noted in vertebral osteoporosis. Dual photon absorptiometry allows, in most cases, an accurate and reproducible measurement of the femoral bone density. This measurement is indicated to assess the risk of osteoporosis on menopause and in elderly subjects and/or those with lumbar osteoarthritis.

Absorptiometry, Photon↗

PubMed1981

Total body bone mineral and lean body mass by dual-photon absorptiometry. III. Comparison with trunk calcium by neutron activation analysis.

Dual-photon absorptiometry using 153Gd (44 and 100 keV) was used to measure the bone mineral content (BMC) of the trunk and of the total body (TBBM) in 7 volunteers with no overt bone disease. These values were compared to those obtained with partial-body neutron activation of calcium (trunk Ca). The trunk Ca seemed to represent best a 60 x 30 cm area; the correlation coefficient with the corresponding BMC in that area was 0.97 (SEE congruent to 7%). Trunk Ca was also highly correlated with TBBM (r = 0.96; SEE = 8%) and with radius BMC (r = 0.92; SEE = 11%), but the correlations with the BMC of smaller subareas of the trunk were lower (r congruent to 0.9; SEE approximately 12%). The BMC of the lumbar spine was only moderately correlated with trunk Ca, radius BMC and TBBM (r approximately 0.82; SEE approximately 18%), and only slightly more associated with trunk BMC (r approximately 0.88; SEE approximately 14%). The BMC of the combined lumbar-thoracic spine showed higher correlations with trunk Ca, radius BMC and TBBM (r approximately 0.87; SEE approximately 13%), and trunk BMC (r = 0.93; SEE approximately 10%). An accurate and sensitive measure of spinal status requires a direct measurement of that area.

Adult↗

PubMed1985

Measurement of lumbar spine bone mineral: a comparison of dual photon absorptiometry and computed tomography.

A comparison of computed tomography (CT) and dual photon absorptiometry (DPA) in the measurement of spinal bone mineral was made in 44 subjects of whom 26 had vertebral crush fractures. Although CT measures only trabecular bone within the vertebral body whilst DPA measures the whole vertebral segment, a good correlation was observed (r = 0.80) when these quantities were expressed in dimensionally similar units. Trabecular bone in the distal radius measured by CT correlated less well with vertebral CT (r = 0.65). Cortical bone in the radius correlated poorly with the spinal DPA measurement (r = 0.38).

Adult↗

PubMed1978

Combined cortical thickness and bone density determination by photon absorptiometry.

Bone cortical thickness and density were measured in rat femurs in vitro by a photon absorptiometry technique. A scan perpendicular to the long bone axis using photons from highly collimated 109Cd or 125I sources yielded the bone wall thickness and attenuation at mid-shaft. A second scan after the bone was rotated axially 90 degrees was taken to measure the wall or shaft thickness identically responsible for the mid-shaft attenuation of the first scan. The mid-shaft attenuation of the second scan was due to the bone thickness derived from the first scan; thus two complementary measurements are derived by this technique. The bone density is then directly calculated with an estimated accuracy of 10% (coefficient of variation) using empirically determined mass attenuation coefficients. Measurements of mass attenuation coefficients of ashed and dried samples were compared with calculated coefficients for estimated bone composition. Results indicate that the mass attenuation coefficient for bone in vivo can be well estimated such that bone density can be accurately derived from this technique.

Animals↗

PubMed1994

Dual photon absorptiometry for bone mineral measurements using a gamma camera.

A gamma camera was equipped with a special collimator and arm assembly for bone mineral measurements with dual photon absorptiometry (DPA). The system was evaluated in vitro and in vivo and compared both with a rectilinear DPA and a dual energy X-ray (DEXA) system. All 3 systems showed a linear response in measurements of 4 vials, containing different amounts of hydroxyapatite. Phantom measurements with the gamma camera system showed a precision of 1.6% to 2.8%. Results obtained in 8 healthy volunteers with rectilinear and gamma camera systems were well correlated (R2 = 0.78). With the photon beam directed from posterior to anterior, the separation of vertebrae was easy with the gamma camera system. We conclude that bone mineral measurements can be made with a gamma camera for assessment of fracture risk and in the decision process whether a patient needs treatment or not. For follow-up, the precision of DPA with a gamma camera is inadequate.

Absorptiometry, Photon↗

PubMed1976

Bone demineralization in renal failure: a longitudinal study of the distal femur using photon absorptiometry.

The bone mineral content (BMC) of the lower end of the femur was measured by photon absorptiometry in 87 patients with chronic renal failure. The gamma-ray photon source was Am241. Serial measurements were obtained for up to two years. The mean BMC of the adult patients, comprising: 18 pre-dialysis (CRF), 41 chronic haemodialysis (CHD) and 19 renal transplant (RT) patients were all significantly lower than controls with the exception of the male CRF group. Two adults and one child on chronic haemodialysis showed a significant rate of bone loss (less than 2% per year). In one of these adults the addition of daily oral 1 alpha hydroxycholecalciferol was associated with no further reduction in BMC. Two children and one adult on chronic haemodialysis showed a significant rate of increase in BMC (less than 2% per year). This adult had had a tendency to loss of BMC on standard CHD treatment but after receiving parenteral 1,25 dihydroxycholecalciferol three times weekly showed a significant rate of loss of BMC on serial measurement. Two adults and one child with CRF had a significant rate of increase in BMC on standard treatment.

Adolescent↗

PubMed1988

Sensitivity of dual-photon absorptiometry in spinal osteoporosis.

Lumbar spine bone mass and density were measured with Dual photon absorptiometry (DPA) in 60 patients with crush fractures and 60 age-matched normal women. Short-term reproducibility of bone mineral density (BMD) was 1.3% in normal women and 2.5% in osteoporotic women; long-term reproducibility in normal women was 2.2%. The reproducibility of bone mineral content (BMC) seemed to be poorer than that of BMD. In this study, aortic calcifications had no effect on BMD, and one or two crush fractures in the L2-L4 region increased BMD by an average of 3% (0-10%). Lumbar spine DPA provided high sensitivity for these younger crush fracture osteoporotic patients (x = 65 years). The sensitivity at 95% specificity was 74% for BMD and 73% for BMC. This sensitivity is substantially better than that reported for DPA instruments giving higher variances or for quantitative computed tomography.

Aged↗

PubMed1981

Bone mineral content measured with photon absorptiometry - a methodological study carried out on normal individuals.

Bone mineral content (BMC) was measured by photon absorptiometry in 136 adults and 14 children in order to obtain a reference group. The radiation source was 241 Am (45 mCi) and measurements were made on the midshafts of both forearms. The baseline level for measurements was the photon absorption through a waterfilled rubber cuff applied around the arm. Positive correlations were found between BMC and body parameters such as weight, body surface area, height, arm length and bone width. Negative correlations were found between BMC and fat parameters such as the size of a hump adjacent to the bone in the photon absorption profile, skin fold thickness, body mass index and the photon absorption between the bones. Therefore the measured BMC should be corrected for one of the fat parameters and probably also for a body parameter. As a means to correct for fat tissues a baseline level for photon absorption through soft tissue between the bones was compared to the use of a baseline level through water. BMC seemed to be higher in the dominant than in the non-dominant arm. However, after correction for fatty tissue there was no significant difference. BMC seemed to increase with intake of milk products. No correlation could be shown to physical exercise, pregnancies, duration of lactation, or smoking.

Adult↗

PubMed1984

Total body bone mineral in vivo by dual photon absorptiometry. II. Accuracy.

We investigated the accuracy of total body mineral (TBBM) measured by dual photon absorptiometry (1 Ci 153Gd source, 44 and 100 KeV) using skeletons, soft tissue equivalent materials and whole cadaver extremities. The accuracy was assessed on five skeletons (r = 0.99, SEE = 1.5%). The influence of the soft tissue composition on the TBBM measurement was investigated in the same five skeletons. They were scanned in a 16 cm thickness of ethanol solutions of different concentration (0, 20, 40, 60, 80, 100% ethanol) and only a 2% difference (non-significant) was found between measuring 100% ethanol and 100% water. Furthermore, seven whole cadaver extremities were scanned before and after removal of the soft tissues (r = 0.995, SEE = 6.3%). The slope was not different from one and the intercept not different from zero. Equipment at the University of Wisconsin, Madison, and at Glostrup Hospital, Denmark, was compared by measuring the same healthy subjects and skeletons on both scanners. The Glostrup and Madison TBBM values correlated well (r = 0.99, SEE = 5.8%) and the intercept (345 Glostrup arbitrary units) was not significantly different from zero (P greater than 0.05). The TBBM results were calibrated into total body calcium (TBCa) and no significant difference was found between Glostrup and Madison TBCa values (P greater than 0.20).

Bone and Bones↗

PubMed1989

Body fat from body density: underwater weighing vs. dual-photon absorptiometry.

We measured fat in 286 healthy volunteers by underwater weighing (FUWW) and dual-photon absorptiometry (FDPA) to develop a translation table for the differing results from these entirely different techniques and to study the sources of these differences. In 99 males and 187 females aged 19-94 yr, fatness was 7-47%. Prediction equations are presented for FUWW-FDPA (delta F), density of lean body mass (DLBM), and FDPA. FUWW and FDPA were significantly different from each other (P less than 0.01). Calculated DLBM is less than the assumed constant of 1.10 (P less than 0.01), ranging widely from 1.05 to 1.13 and being highly correlated with the ratio of total body bone mineral to lean body mass (TBBM/LBM). delta F, the differences between FUWW and FDPA measurements in individual subjects, varied widely (-7 to +11% in males and -18 to +13% in females). The difference was positively correlated with the DLBM. FUWW was no better than anthropometrics in equations for predicting FDPA. The FDPA predicted from anthropometrics showed smaller standard errors than when FUWW was used. Neither anthropometrics nor FUWW equations are clearly superior to those previously available.

Adipose Tissue↗

PubMed1988

[Dual-photon absorptiometry: a new method of determining bone mineral content. I. Basic principles].

Today dual-photon absorptiometry (DPA) is recommended as the best procedure for diagnosing osteoporosis at an early stage considering its low cost, low radiation exposure and reasonable reliability. Cortical (neck of femur) and trabecular (L 2-4) bone mass has been determined repeatedly with DPA using 153Gd (NOVO Lab 22 a) in 545 females and 112 males with no evidence of bone diseases. Measured "normal" (age- and sex-related average) values for bone mineral content (BMC) differed significantly (p less than 0.01) from those of US inhabitants determined by the same equipment, i.e., they were on average about 30% lower, but matched well with corresponding results from Belgium. BMC-area was found the most suitable parameter both for cross-sectional and longitudinal studies, since it is independent of height and weight. But there is still need to reduce the overlap and improve accuracy and reproducibility for making decisions after shorter intervals. Assessment of the individual mineral loss and fracture risk by comparison with average values remains problematical due to the wide range of "normal" BMC values, and in women additionally due to the variable onset of menopause. For estimations of the individual fracture risk of elderly patients BMC should not be normalized on age, because at the age of 65 half of the women had "pathologic" values, i.e. were below the so-called "osteoporosis threshold". Comparison of the individually measured postmenopausal BMC with average values of premenopausal women and with BMC values normalized to their menopausal age may be helpful approaches to overcoming these difficulties.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗

PubMed1986

Age-, sex-, and menopause-related changes of vertebral and peripheral bone: population study using dual and single photon absorptiometry and radiogrammetry.

Vertebral and peripheral bone mass have been measured with single and dual photon absorptiometry and radiogrammetry in 146 male and 220 female volunteers ranging in age from 20 to 85 yr. One hundred four subjects with interfering diseases, treatment, or x-ray manifestations of lumbar osteoarthritis were excluded for purposes of this study. Patterns of age-related bone gain and diminution differed between sexes and measuring sites. The effect of menopause on the peripheral and vertebral skeleton also differed. Men, at all measured sites, have more bone than women. In the fifth decade, however, women's lumbar bone mineral content was almost equal to the value found in men. Bone loss associated with aging was more marked in women than in men and started, for the lumbar spine, at about the age of 25 yr in both women and men and, for the peripheral bones, at the age of 55 in women and 65 in men. Bone loss in the spine in women was not linear. Women in the fifth and sixth decade, who still had menstruation, differed significantly from those who had not menstruated for at least the last 6 mo. Bone diminution at menopause was twice as great in the lumbar spine than elsewhere in the peripheral skeleton, 15% versus 7%. Of the 25% total bone loss of the spine during adult life in women, 60% was lost within 10 yr after menopause. Estrogen deficiency, not aging, is the predominant cause of bone loss in the spine. For the peripheral skeleton, there is a two-component decrease, a rapid loss induced by the menopause superimposed on a slower age-related loss. Although there was a significant correlation between peripheral and vertebral bone mass indices, it was clear that observations made at one site will not necessarily reflect changes observed at another site.

Adult↗

PubMed1993

Intramedullary nailing and cortical bone mineral content. Photon absorptiometry measurements in vitro.

A transverse diaphyseal osteotomy of the tibia was stabilized using rigid intramedullary nailing in rabbits. In a 2nd group, nailing was performed without osteotomy. The rabbits were sacrificed 3 to 24 weeks postoperatively, and the nails were removed. The mineral content (BMC) was measured by dual photon absorptiometry and the mineral density (BMD) was calculated. At 24 weeks the osteotomized bones had significantly lower BMC values than did the respective nonosteotomized bones or the intact bones. The BMC of the nonosteotomized bones remained above the control level throughout the experiment. The minimum BMD values of the osteotomized bones were detected at 3 weeks, whereafter they gradually approached the control level over time. The results suggest that rigid intramedullary nailing in connection with osteotomy causes a significant decrease in cortical bone mineral mass, seen at 24 weeks postoperatively. The photon absorption method used seemed sensitive enough to detect changes in cortical bone mineral quantity in these experimental conditions.

Absorptiometry, Photon↗

PubMedDate not supplied

Vertebral bone mineral measurement using dual photon absorptiometry and computed tomography.

The lumbar spine of 14 cadavers was studied both by 153Gd dual photon absorptiometry (DPA) and quantitative computed tomography (QCT) at 96 and 125 kVp. The intact spine and the individual vertebrae were analyzed. After these measurements the ash content of the vertebral body, the posterior elements, and the transverse processes was determined. The fat content of the vertebral body as well as its volume was also measured. With DPA, the bone mineral content (BMC) determined in situ as well as on excised spine specimens correlated highly with the amount of total vertebral ash (r greater than 0.92, SEE less than 3.2 g). The bone mineral density (BMD, area density) of 3 lumbar vertebrae correlated accurately with the mean ash density of the vertebral body (r greater than 0.81, SEE less than 0.015 g/cm3). The so-called corpus density and central density determinations were less accurate. No difference in accuracy was found between measurements when using 3 mm and 4.5 mm step intervals. Variations in the distribution of mineral between the vertebral body and the posterior elements contribute to the error in predicting vertebral body mineral with DPA. QCT gave a smaller error when a cylindric portion of the vertebral body with a 20 mm diameter was measured compared with one with a 9 mm diameter, when the dual energy technique was used (p less than 0.01). With dual energy QCT a correlation was found between a center segment of 3 vertebrae in the lumbar spine and the mean ash density of the vertebral body of r = 0.92 (SEE = 0.010 g/cm3).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1988

Comparison of bone mass measured by histomorphometry on iliac biopsy and by dual photon absorptiometry of the lumbar spine.

In a prospective study we compared bone mass measured independently by dual photon absorptiometry (DPA) on lumbar spine and by histomorphometry on transiliac biopsy. Measurements were done in 83 patients (23 males, 60 females) with various generalized bone diseases, including spinal osteoporosis, primary hyperparathyroidism and osteopetrosis. Iliac bone density was analyzed on bone biopsy with an automatic image analyzer and expressed as the trabecular bone volume (TBV), the cortical thickness (CT) and the total bone density (TBD) which includes the density of both spongy and cortical bone within the periosteal envelope. The bone mineral content (BMC) and density (BMD) were measured from L2 to L4 with a Novo Lab 22a device. For the 83 patients, there were significant correlations between values given by both methods, with r values ranging from 0.74 to 0.43, according to the bone mass parameters analyzed. In the 37 patients with untreated vertebral osteoporosis, the TBV--but not the CT nor the TBD--correlated significantly with the BMD of the spine (r = 0.53, p less than 0.001). In conclusion, there is a significant correlation between bone density of the iliac crest assessed histomorphometrically and spinal density measured by DPA. Despite the fact that DPA measures both trabecular and cortical bone of the spine, it correlates better with iliac trabecular bone mass than with the overall iliac bone density.

Adolescent↗

PubMed1988

Accuracy of dual photon absorptiometry in excised femurs.

We investigated the accuracy of assessment of bone mineral content (BMC) by dual photon absorptiometry (DPA). Measurements were compared between BMC and ashed weight using two related scanners. The BMC in different locations of the femur was determined. Twelve cadaver femurs were cleaned of all soft tissue, divided into four parts (head, neck, trochanteric region, and shaft), and measured for BMC in an ethanol/water solution. The bones were then ashed and weighed. Volumetric density was also determined. The correlation coefficient between ash weight and BMC was 0.99 with an s.e.e. of 0.51 g and relative error of 4.8%. Similar correlations were seen within each region. The correlation between the machines was 0.99. Differences in volumetric density were found, with the density of the shaft greater than other regions, and the neck greater than the head or trochanteric regions.

Female↗