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PubMed1990

Heterotopic ossification. Effect on dual-photon absorptiometry of the hip.

Dual-photon absorptiometry (DPA) is now widely used to determine bone mineral density of the lumbar spine and hips. Because the resulting images are often not of sufficient resolution to identify many bone or soft tissue abnormalities that may influence results, clinical and radiographic correlation is necessary. Presented are two cases in which results of DPA of the hips were elevated because of the presence of heterotopic ossification.

Absorptiometry, Photon↗
PubMed1991

Stone fragility--measurement of stone mineral content by dual photon absorptiometry.

We measured the mineral content of urinary tract stones by dual photon absorptiometry, which is widely used for the analysis of bone mineral content, and compared the values of the stones by dual photon absorptiometry (DPA values) with the results of an in vitro fracture study as well as those of an in vivo extracorporeal shock wave lithotripsy treatment study. The results of a preliminary experiment showed that the DPA values of 20 urinary tract stones reflected actual stone mineral content. As a result of the in vitro fracture study, the DPA value calculated by volume of a struvite stone, which was the most easily disintegrated, was the lowest (0.53 g/cm3). The DPA values of calcium oxalate monohydrate and apatite stones, which poorly disintegrated, were the highest (0.98, 1.01 g/cm3). The DPA value of calcium oxalate dihydrate, which moderately disintegrated, was 0.86 g/cm3. By the in vivo extracorporeal shock wave lithotripsy treatment study, the total DPA values of stones measured before extracorporeal shock wave lithotripsy treatment in 12 patients were 0.73 +/- 0.34 g in successful cases and 1.92 +/- 0.43 g in unsuccessful cases with a significant difference between the two (p less than 0.05). These results showed that the measurement of stone mineral content by dual photon absorptiometry was useful in predicting the fragility of stones against shock waves before performing extracorporeal shock wave lithotripsy treatment for patients with urinary tract stones.

Absorptiometry, Photon↗
PubMed1988

[Clinical usefulness of a dual photon absorptiometry system using X-ray for peripheral bone--comparison with a single photon absorptiometric system].

A newly developed dual photon absorptiometry system (DCS-600, ALOKA Co., LTD.) using two monochromatic X-rays for the determination of bone mineral in the peripheral bone was fundamentally studied, in comparison to single photon absorptiometry system (SPA). The accuracy and precision in DCS-600 were equal to or better than SPA system. Furthermore, in DCS-600 the forearm could be imaged, and the manipulation was easy. Thus DCS-600 was found to be a good instrument as a quantifying system of bone mass.

Bone and Bones↗
PubMed1989

Effect of source strength and attenuation on dual photon absorptiometry.

A systematic error in dual photon absorptiometry (DPA) measurements of bone mineral density (BMD) related to source strength has been previously described and attributed to an erroneous algorithm for deadtime correction. Since detected counts (or photon flux) is a product of source strength and attenuation, the effect of various source activities and attenuation depths on BMD calculations were evaluated using a phantom. Ten DPA scans were acquired at two source strengths, 0.3 and 1.0 Ci, and at each of two water depths, 16.4 and 24.5 cm. These activities and depths are within the range encountered clinically. Scans were acquired and processed using a commercially available lumbar spine scanner and software, and were reanalyzed with two upgraded versions of software. Mean BMD obtained with the initial software varied by 2 to 14% with changes in both sources strength and attenuating depth. Software revisions reduced but did not entirely eliminate these differences. The remaining 6% discrepancy is of sufficient magnitude to influence both patient management and research investigations.

Absorptiometry, Photon↗
PubMed1988

Nuclear medicine studies of aging--III. Radial bone mineral content by single and dual photon absorptiometry.

Measurement of bone mineral content of the radius has been possible by single photon absorptiometry. Recently, dual photon devices have become widely used for measuring the quantity of lumbar vertebral bone mineral. Therefore, we studied the utility of a dual beam machine for quantifying the bone mineral content of the radius, and compared results with those obtained by single photon absorptiometry in the same patient on the same day. There was an excellent correlation between single and dual beam measurements of the radius. The present study indicates that a dual photon machine can be used for assessing not only vertebral, but radial bone mineral content as well. This may facilitate studies of the two sites by use of one machine.

Adolescent↗
PubMed1988

Precision of dual-photon absorptiometry.

Precision of dual-photon absorptiometry (DPA) measurements was determined in a lumbar spine phantom and in humans. Approximately half of the measurements were made before and half after a 153gadolinium source change. The phantom was measured with different amounts of acrylic, which simulates human soft tissue, in order to evaluate the influence of body thickness on bone mineral density (BMD). Results of scans analyzed with two software versions from Lunar Radiation Corp., the widely used 08B and a prototype 08C, are compared. DPA with a cold source significantly overestimated BMD in the phantom in the presence of large amounts (more than 25 cm) of soft tissue equivalent with version 08B but not with the newer version 08C. Similarly, in nine subjects, there was a significant decrease in spine BMD after a source change when scans were analyzed with version 08B (mean difference 0.026 g/cm2, P = 0.002) but not with 08C (0.01 g/cm2, P = 0.234). No systematic effect of source change on femoral BMD measurements was observed. The SD of the mean difference of two measurements of the nine subjects was 0.019 g/cm2 (1.6% of the mean value) for the spine with software version 08B and 0.024 g/cm2 (2.0%) with version 08C, 0.03 g/cm2 (3.3%) for the femur neck, 0.03 g/cm2 (4.0%) for the greater trochanter, and 0.04 g/cm2 (4.9%) for Ward's triangle region of the proximal femur. The spine phantom was scanned on two other commercial bone densitometers in order to assess inter-instrument variation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

[A clinical study evaluating bone mineral mass in the radius during skeletal growth--single photon absorptiometry].

Using 125-I single photon absorptiometry, bone mineral measurements were performed on 206 healthy Japanese children (2 to 19 years of age). Bone mineral content (BMC), bone width (BW) and BMC/BW values were determined for the radius at distal 1/6 site (metaphysis) and distal 1/3 site (diaphysis). BMC/BW values at both sites correlated well with body height and weight. Bone mass in the diaphysis (distal 1/3 site) increased linearly during the 2-19 years of skeletal growth, but bone mass in the metaphysis (1/6 site) increased steeply during the pubertal period. In children receiving glucocorticoid therapy, bone mass was reduced in proportion to the duration of drug administration. In children under anticonvulsant therapy, the yearly increase in bone mass was significantly low especially in those patients with poor physical activity levels. Bone mineral decrease in the radius occurred in the children with hypopituitalism, hypothyroidism (cretinism), hyperthyroidism and Turner's syndrome.

Adolescent↗
PubMed1990

Structural changes of the femoral shaft with age measured by dual photon absorptiometry.

During measurements of bone mineral content with dual photon absorptiometry the external and internal diameters of the femoral shaft were determined from the attenuation curves. Measurements on aluminium cylinders demonstrated a precision error on such determinations of 2-3%. Repeated determinations of the external and internal diameter on the femoral shaft in vivo showed an average difference between two measurements of 2.1 and 4.2%, respectively. Determinations on the femoral shaft in vivo of 101 normal women aged 20-90 years and 41 normal men aged 20-85 years showed that the external and internal diameter increased significantly with age in both women and men, but more pronouncedly in women. The cortical width and the density of the cortical bone, g/cm3, decreased significantly in women. In men neither the cortical width nor the bone density of the femoral shaft changed significantly with age.

Absorptiometry, Photon↗
PubMed1990

Accuracy and reproducibility of lumbar bone mineral status determined by dual photon absorptiometry in live male cynomolgus macaques (Macaca fascicularis).

Dual photon absorptiometry (DPA) was used to determine the in vivo bone mineral content (BMC) and bone mineral density of lumbar vertebrae (L2-4) in feral adult male cynomolgus macaques (Macaca fascicularis, n = 20). Following in vivo DPA scans, all animals were euthanized and the lumbar spine segment excised. The excised lumbar vertebrae, plus spinal cord, were formalin-fixed and measured three times by ex vivo DPA. The first ex vivo scan matched the monkey's own in vivo soft tissue beam attenuation ratio (Rs, ranging from 1.38 to 1.45). The second ex vivo scan was made creating a constant obese-like condition (Rs = 1.38), and the third creating a constant lean-like condition (Rs = 1.45). All scans were taken at a 1.0 mm point resolution, 1.0 mm line spacing, a 6 cm width, and a scan speed of 5 mm/sec. The second lumbar vertebra (L2) was ashed and the ash weight was compared to the measured L2BMC of the in vivo and ex vivo DPA analyses. Noninvasive in vivo DPA proved to be adequate in measuring the lumbar bone mineral content in male cynomolgus macaques. Ex vivo DPA at a high and constant Rs value of 1.45 provided for the best accuracy of formalin-fixed wet bone tissue when compared to the bone ash weight.

Absorptiometry, Photon↗
PubMed1989

Quantitative dual-energy radiographic absorptiometry of the lumbar spine: in vivo comparison with dual-photon absorptiometry.

Quantitative dual-energy radiographic absorptiometry (DRA) and dual-photon absorptiometry (DPA) were compared to determine the best means of assessing bone density. Both methods were used to evaluate the lumbar spine in 107 women (aged 35-84 years [mean, 64 years]) referred for evaluation of osteoporosis risk. High correlation was documented between measurements derived by the two techniques, with a .95 linear regression coefficient for the total spine density measurement. Age-related regression equations were similar in slope but manifested different intercepts. Bone mineral density values derived with DRA were consistently lower than those obtained with DPA (conversion equation: DPA density = [1.067 X DRA density] + 0.163). Besides the inherent imperfections of each system, it was found that inaccurate identification of intervertebral spaces on the low-resolution DPA images introduced errors in patient data. DRA may replace DPA as the dedicated projectional densitometric procedure of choice for technical reasons, but at present a conversion equation must be used to compare DRA data to DPA data.

Adult↗
PubMed1989

The reproducibility of single photon absorptiometry in a clinical setting.

The reproducibility of single photon absorptiometry (SPA) results for detection of changes in bone mineral content (BMC) was evaluated in a clinical setting. During a period of 18 months with 4 different sources, the calibration scans of an aluminium standard had a variation of less than 1% unless the activity of the 125I source was low. The calibration procedure was performed weekly and this was sufficient to correct for drift of the system. The short term reproducibility in patients was assessed with 119 duplicate measurements made in direct succession. The best reproducibility (CV = 1.35%) was found for fat corrected BMC results expressed in g/cm, obtained at the site proximal to the 8 mm space between the radius and ulna. Analysis of all SPA scans made during 1 year (487 scans) showed a failure of the automatic procedure to detect the space of 8 mm between the forearm bones in 19 scans (3.9%). A space adjacent to the ulnar styloid was taken as the site for the first scan in these examinations. This problem may be recognized and corrected relatively easy. A significant correlation was found between BMC of the lower arm and BMC of the lumbar spine assessed with dual photon absorptiometry. However, the error of estimation of proximal BMC (SEE = 20.0%) and distal BMC (SEE = 19.4%) made these measurements of little value to predict BMC at the lumbar spine in individuals. The short term reproducibility in patients combined with the long term stability of the equipment in our clinical setting showed that SPA is a reliable technique to assess changes in bone mass at the lower arm of 4% between 2 measurements with a confidence level of 95%.

Bone and Bones↗
PubMed1995

Comparison of speed of sound ultrasound with single photon absorptiometry for determining fracture odds ratios.

The purpose of this study was to compare the ability of ultrasound velocity measurement with that of single photon absorptiometry to determine the odds of history of fracture since age 40, for a population-based study. To do this we computed odds ratios and 95% confidence intervals for 809 women and 502 men, aged 50 years and older, who are participants in the prospective phase of the Saunders County Bone Quality Study. These participants received both the ultrasound and single photon absorptiometry bone measurements at the initiation of the study. In addition, a history of all fractures that had occurred to participants since age 40 was obtained. The two bone assessment methods were compared by examining the magnitude of the odds ratios, to determine which produces the highest estimate of the probability of odds of fracture, and by examining widths of the respective confidence intervals to show which estimate of odds ratio is the most precise. Ultrasound velocity estimates a higher probability of odds of both low-trauma fractures and all fractures than distal radius and ulna bone mineral content, but lower than bone mineral density at the same sites for both women and men. However, the ultrasound measure is more precise than bone mineral density, but less precise than bone mineral content. We conclude that ultrasound velocity is as good as single photon absorptiometry in estimating odds of fracture.

Absorptiometry, Photon↗
PubMed1988

Determination of radial bone mineral content in low birth weight infants by photon absorptiometry.

Studies at the University of Wisconsin have demonstrated that photon absorptiometry is a precise, accurate, and reproducible technique for measuring bone mineral content in premature infants and can be used to establish an "intrauterine" curve of bone mineralization in the fetus. Photon absorptiometry can also be used to measure bone width, thereby documenting appositional bone growth. The bone mineral content/bone width ratio may be helpful in identifying disorders of bone mineral metabolism in premature infants. The technique has been used to demonstrate that relatively poor bone mineralization (compared with the intrauterine curve) occurs in very low birth weight infants after birth, regardless of the type of feeding or the presence or absence of bronchopulmonary dysplasia.

Bone Development↗
PubMed1990

Factors affecting the precision of bone mineral measurements. Part 1: Review of experimentally derived results obtained from single photon absorptiometry.

An evaluation of the factors which influence the precision of bone mineral measurements using single photon absorptiometry (SPA) is presented. This incorporates several techniques which have been developed over the past few years to improve the reliability of such measurements. As such, the figures obtained should provide an objective and up-to-date basis for critical comparison with other modalities such as quantitative computerized tomography (QCT), dual photon absorptiometry (DPA) using Gd-153, and quantitative digital radiography (QDR). Under optimum conditions, a precision of 0.3% was achievable for in vitro phantom measurements. Under realistic working conditions, however, a precision of 1.0% for phantoms and 1.4% for clinical studies was found to be more typical for bone mineral content (BMC) measurements. Derived parameters such as bone mineral density (BMD) were generally less reliable, with a precision of 4.7%. It is unlikely that these values can be improved upon substantially with current SPA technology.

Absorptiometry, Photon↗