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PubMed2005

Discordance in diagnosis of osteoporosis using spine and hip bone densitometry.

BACKGROUND: Diagnostic discordance for osteoporosis is the observation that the T-score of an individual patient varies from one key measurement site to another, falling into two different diagnostic categories identified by the World Health Organization (WHO) classification system. This study was conducted to evaluate the presence and risk factors for this phenomenon in a large sample of Iranian population. METHODS: Demographic data, anthropometric measurements, and risk factors for osteoporosis were derived from a database on 4229 patients referred to a community-based outpatient osteoporosis testing center from 2000 to 2003. Dual-energy X-ray absorptiometry (DXA) was performed on L1-L4 lumbar spine and total hip for all cases. Minor discordance was defined as present when the difference between two sites was no more than one WHO diagnostic class. Major discordance was present when one site is osteoporotic and the other is normal. Subjects with incomplete data were excluded. RESULTS: In 4188 participants (3848 female, mean age 53.4 +/- 11.8 years), major discordance, minor discordance, and concordance of T-scores were seen in 2.7%, 38.9% and 58.3%, respectively. In multivariate logistic regression analysis, older age, menopause, obesity, and belated menopause were recognized as risk factors and hormone replacement therapy as a protective factor against T-score discordance. CONCLUSION: The high prevalence of T-score discordance may lead to problems in interpretation of the densitometry results for some patients. This phenomenon should be regarded as a real and prevalent finding and physicians should develop a particular strategy approaching to these patients.

Journal Article↗
PubMed1981

The radiographic detection of acute pulmonary oedema. A comparison of radiographic appearances, densitometry and lung water in dogs.

We have induced acute pulmonary oedema in upright anaesthetized dogs by increasing pulmonary microvascular permeability or by extracellular fluid volume overload in order to determine the sensitivity and specificity of the radiograph to the presence of abnormal lung water. Radiographs were taken before and after development of oedema. At the end of the experiment we removed the inflated lungs and froze them in liquid nitrogen and subsequently examined them macroscopically in the frozen state. The extravascular water/dry lung weight ratio was measured gravimetrically on seven portions of each lung. Finally without the base-line films for comparison. We directly measured the change in opacity of the films with a radiographic densitometer. When a dog's mean extravascular water/g dry lung was increased by more than 35% it was invariably recognized, in one or more zones, as definite oedema. Control dogs were reliably recognized as normal when base-line films were used but the distinction between normal and minor degrees of oedema could not be made without the base-line films. There was a positive correlation between radiological grade and lung water, but a great deal of overlap between grades. Densitometry was not a sensitive or reliable method for diagnosing or quantifying oedema. Oedema was usually associated with a decrease in volume of the lower lung zones.

Absorptiometry, Photon↗
PubMed1995

A comparison of bone densitometry measurements of the central skeleton in post-menopausal women with and without vertebral fracture.

The purpose of this investigation was to compare the ability of two different bone densitometry techniques (quantitative computed tomography and dual X-ray absorptiometry) to discriminate subjects without any vertebral fracture from those with definite vertebral fractures. Bone mineral density (BMD) was determined in 112 post-menopausal women. 83 women were classified free of vertebral fracture and 29 were considered to have definite vertebral fractures. Quantitative computed tomography (QCT) was performed using three different spinal regions of interest. Dual X-ray absorptiometry (DXA) was measured at the spine (both in posteroanterior (PA) and lateral (L-DXA) projection, and at hip (total, neck and Ward regions). An additional estimated volumetric BMD was derived from the PA and L-DXA spine scans. Individuals with definite vertebral fractures had lower bone mineral density for each of the methods and regions of interest (ROI). Spinal QCT results, total and Ward hip DXA results showed the greatest percentage decrement. Odds ratio estimates revealed a significant relationship between BMD and fracture with spinal QCT, hip, and volumetric spinal DXA. The greatest areas under the receiver operating characteristic (ROC) curves were found with results of spinal QCT, total and Ward hip DXA, and volumetric spinal DXA measurements. It is concluded that spinal QCT and femoral total DXA measurement may be preferred to PA and lateral L3 DXA measurements.

Absorptiometry, Photon↗
PubMed1996

Patient doses in bone mineral densitometry.

Procedures were developed to compute effective dose equivalent (H(E)) values for patients undergoing bone mineral densitometry (BMD) measurements such as dual energy X-ray absorptiometry (DEXA) and quantitative computed tomography (QCT). Representative values of H(E) were determined for patients undergoing each type of BMD procedure. Typical DEXA measurements are associated with an H(E) of about 2.5 microSv. For QCT, the values of H(E) are 300 microSv for single energy techniques and 1 mSv for dual energy techniques, respectively. By comparison, a single well collimated abdominal X-ray examination often taken in conjunction with DEXA studies results in an H(E) of about 100 microSv. BMD patient doses are at the lower end of the exposure range encountered in diagnostic radiology. As a result, radiation dose is not a primary factor in choosing the method for BMD determination.

Absorptiometry, Photon↗
PubMed1997

A suggested methodology for the construction of national bone densitometry reference ranges: 1372 Caucasian women from four UK sites.

This paper presents a simple methodology for combining bone densitometry data from different sites in the UK, having instruments from the same manufacturer (LUNAR Radiation). Additive normalization factors were used on all data prior to inclusion in a reference database which ultimately included data on 1372 Caucasian women, aged 20-70 years, of whom 749 were post-menopausal. Reference data for spine (L2-L4) and femoral neck bone mineral density are given in tabular form as 3 year moving averages for: (1) all women; (2) perimenopausal women grouped by menopausal status; and (3) post-menopausal women with respect to years since menopause. These data may be used to construct Z-score. T-score or percentile reporting ranges and may be adopted as the core for a UK reference range.

Adult↗
PubMed2001

Bone densitometry in the management of Colles' fractures: which site to measure?

This study assessed whether patients with Colles' fractures can be evaluated by measurement of peripheral bone mineral density (BMD) instead of the more established axial BMD technique. 205 consecutive patients who had sustained a recent Colles' fracture were invited to attend for BMD measurement at the lumbar spine, hip and forearm by dual energy X-ray absorptiometry (DXA) using a Hologic QDR4500C instrument. Hologic normal reference ranges were used for spine and ultradistal radius BMD, and the NHANES 111 reference range was used for the femoral neck. 158 patients attended, of whom only 61 had a T-score below -2.5 at one of the three measured sites (84 T<-2.0, 112 T<-1.5). 36 patients had bilateral forearm fractures and did not undergo a forearm measurement. After excluding these patients and using a T-score of -2.5 as a diagnostic threshold, a spine and hip measurement strategy missed 26% of osteoporotic patients and a forearm only strategy missed 33%. If a forearm strategy is adopted, with axial BMD performed only on those patients with an ultradistal radial T-score of <-1.5 and >-2.5, 27 further scans would be required and only four patients with T<-2.5 at the spine or hip would be undetected. Where axial BMD measurement is performed, this should be accompanied by forearm BMD measurement in some patients with Colles' fractures. A peripheral bone mineral densitometry strategy using forearm BMD alone will miss many individuals with osteoporosis. Therefore where forearm, and probably any peripheral scanning method, only is used for patient assessment there should be close liaison with an axial BMD centre with agreed joint protocols, as some patients should be advised to have an additional axial BMD measurement following their peripheral BMD measurement.

Aged↗
PubMed2006

Heel bone densitometry: device specific thresholds for the assessment of osteoporosis.

A diagnosis of osteoporosis is facilitated by bone mineral density (BMD) measurement of the lumbar spine and hip using dual energy X-ray absorptiometry (DXA), interpreted in accordance with criteria published by the World Health Organization (WHO). The use of peripheral DXA is growing in primary care and guidance on its use has recently been published by the National Osteoporosis Society (NOS), recommending a triage approach using thresholds specific to each type of peripheral device. However, no data currently exist for the Norland Apollo heel densitometer (Cooper Surgical, Trumbull, USA). 215 women between 50 years and 75 years of age (mean age 64.6 years) referred for hip and spine BMD measurements also had a heel BMD measurement. Device specific upper and lower thresholds were calculated for the Norland Apollo heel densitometer to give a 90% sensitivity and 90% specificity for osteoporosis at the hip or spine. Patients with a heel T-score of above -1.2 are very likely to have normal bone density on axial densitometry, whilst patients with heel T-score of below -2.2 are very likely to have osteoporosis at the hip or spine. Patients whose measurements lie between the thresholds should be referred for axial DXA.

Absorptiometry, Photon↗
PubMed1994

Bitewing-based alveolar bone densitometry: digital imaging resolution requirements.

The resolution requirements were determined for detection of incremental alveolar bone loss from digitized Ektaspeed radiographs. Ten clinical radiographs were examined with a calibrated optical microscope to measure the smallest feature of interest discernible for alveolar bone. Images of trabeculae > 100 microns in diameter could be identified, but smaller ones could not be resolved. The Nyquist Criterion requires sampling with 50 microns (or smaller) pixels to measure such features. Numerous 25 microns Ag aggregates were present. Fifty microns resolution is a practical compromise between noise level and feature resolution. In another example of 10 bitewings digitized at 8 bit grey scale, about half the available range was used for alveolar bone, resulting in uncertainty, over a range of 2 optical density (OD) units, of about 1.42% at the average OD for alveolar bone (1.1). With the same radiographs digitized at 12 bit resolution, over 2000 of 4096 grey scales were used with a corresponding uncertainty of about 0.09%. Twelve-bit precision was also able to resolve smaller increments in an aluminium stepwedge than was 8 bit precision. Twelve-bit grey scale and 50 microns spatial resolution are recommended for alveolar bone densitometry performed with Ektaspeed radiographs.

Absorptiometry, Photon↗
PubMed1997

A preliminary evaluation of the lunar expert-XL for bone densitometry and vertebral morphometry.

We have evaluated the Lunar Expert-XL for standard bone mineral densitometry (BMD) and for morphometric imaging of the spine in the lateral projection. The short-term precision in vitro of the Expert-XL for BMD measurements was 0.7% for the Hologic and European spine phantoms, and the long-term stability (15-month) measurements had a 1.1% coefficient of variation. The precision in vivo for three operators examining a group of 10 premenopausal women was 0.9-1.5% for lumbar spine (L2-L4), 1.7-2.2% for the femoral neck, and 0.9% for the total hip region of interest. For a group of nine postmenopausal women, the lumbar spine, femoral neck, and total femur precision ranges were 2.0-2.4, 1.2-2.9, and 1.6-1.7% respectively. For L2-L4, BMD comparison between the Expert-XL and DPX-L yielded a correlation coefficient of r = 0.98, a slope of 0.86, and an intercept of 0.139 g/cm2. The femoral neck results were r = 0.92, slope = 1.00, and intercept = 0.03 g/cm2. In an evaluation of the Expert-XL for lateral morphometry, we employed a group of 16 postmenopausal women. Comparison of vertebral dimensions between the Expert-XL and radiographic morphometry showed strong agreement (r = 0.97), but the interobserver variability for vertebral height was higher for the Expert-XL than for radiographs (3-5% vs. 1-2%). In a subset of four women who had repeat scans, the interscan precision for measuring vertebral dimensions was 1.9, 4.1, and 43% for the L1-L4, T12-T8, and T7-T5 levels respectively. In the Expert-XL images, it was possible to identify clearly L4-T4 in 10 of 16 patients and L4-T6 in 15 of 16, indicating potential utility for vertebral fracture prescreening.

Absorptiometry, Photon↗
PubMed1989

Computerized tomographic densitometry of the solitary pulmonary nodule using a nodule phantom.

The successful application of computerized tomographic density analysis for evaluating the solitary pulmonary nodule has previously been described and the technique has since been simplified by using a calcium-equivalent nodule reference phantom. Because published experience with this technique remains limited, the current research reports the Cleveland Clinic experience with the CIRS model III pulmonary nodule reference phantom. Without knowledge of the final diagnosis, the nodule phantom was used as the standard for categorizing 31 nodules in 29 patients as either benign or indeterminate. Secure diagnoses were obtained in all cases. Eleven nodules were called benign and ten proved so, whereas 20 nodules were classified as indeterminate. One lesion, an adenocarcinoma, was falsely called benign using this technique. The excellent density discrimination achieved with CT makes this a superior tool for analysis of the solitary pulmonary nodule, and the nodule reference phantom has greatly simplified the technique of CT densitometry. As demonstrated by this and prior studies, calcification is not a unique feature of the benign lesion and successful clinical application of this technique requires cautious interpretation of results.

Adult↗
PubMed1998

Gall stones detected on lumbar bone densitometry examination.

A dual-energy X-ray bone densitometry study, in a 73-yr-old woman, detected gall stones in the right upper quadrant of the abdomen. These showed a rim of higher density. The density of the region was 0.550 g/cm2, or 70% of the value found in the L1 vertebra.

Journal Article↗
PubMed2002

Dual X-ray absorptiometry of hip, heel ultrasound, and densitometry of fingers can discriminate male patients with hip fracture from control subjects: a comparison of four different methods.

Few studies have examined different bone densitometry techniques to determine male hip fracture risk. We conducted a case-control study of 31 noninstitutionalized men, mean age 77 yr, with a first hip fracture and compared the results with 68 randomly selected age-matched control subjects. The methods used were dual X-ray absorptiometry (DXA) of the proximal femur, quantitative ultrasound (QUS) of the heel and fingers, and radiographic absorptiometry of the fingers. Case patients had significantly lower values (4-17%; p < 0.01) for all methods. The odds ratios for every SD reduction in bone values were 4.8 (95% confidence interval [CI]: 2.3-9.9) for DXA of the femoral neck, 2.2 (95% CI: 1.2-3.9) for QUS of the heel, 2.0 (95% CI: 1.2-3.3) for QUS of the phalanges, and 3.1 (95% CI: 1.5-6.6) for radiographic absorptiometry of the phalanges. The results indicate a strong capability of DXA of the femoral neck to distinguish between men with a first hip fracture and control subjects. Furthermore, ultrasound of the heel and fingers as well as radiographic absorptiometry proved capable of discriminating men with hip fractures from control subjects.

Absorptiometry, Photon↗
PubMed2002

Prevalence of vertebral compression fracture deformity by X-ray absorptiometry of lateral thoracic and lumbar spines in a population referred for bone densitometry.

The presence of a vertebral compression fracture has been demonstrated to be a predictor of future fracture independent of bone mineral density in prospective cohort studies. Fan-beam densitometers are now available that can image the thoracic and lumbar spines and detect deformities consistent with fracture. We report a pilot study of 342 patients referred for bone densitometry who had lateral vertebral imaging performed. Fifty patients (14.6%) of the entire cohort had one or more vertebral deformities identified on lateral vertebral imaging. Seventy-three patients (21.3%) of the entire cohort were 60 or more years of age and had osteopenia by World Health Organization (WHO) criteria (T-score: -1.0 to -2.4 at the spine, total hip, or femoral neck). Twenty of these patients (27.4%) had one or more vertebral deformities. Without identifying prevalent vertebral deformities, these individuals at high risk for fracture may not be offered pharmacologic therapy to reduce fracture risk. Therefore, it may be reasonable to obtain lateral vertebral imaging at least for individuals age > or =60 yr who have mild to moderate bone loss at the spine or hip.

Absorptiometry, Photon↗
PubMed2002

Effects of radioisotopes on the accuracy of dual-energy X-ray absorptiometry for bone densitometry.

Nuclear medicine procedures are often performed in close-time proximity to bone densitometry studies. The purpose of this study was to determine the effects of various radioisotopes on the accuracy of bone mineral density (BMD) measurements performed using dual-energy x-ray absorptiometry (DEXA) systems. We evaluated two DEXA scanners: the Hologic QDR4500 and the Lunar Prodigy. The effects of various activities of Tc-99m, Tl-201, Ga-67 and I-131 on BMD were assessed by placing vials or syringes containing the appropriate isotope above or below a simulated spine (average BMD = 1.1 g/cm2) embedded in a lucite block. We also placed a spine phantom (average BMD = 2.0 g/cm2) in a water bath containing various concentrations of Tc-99m. Maximum activities evaluated were as follows: Tc-99m, 80 mCi; I-131, 50 mCi; Tl-201, 66 mCi; Ga-67, 20 mCi. For the Hologic QDR4500 system, irrespective of the radioisotope or activity, we found no significant effect of adjacent activity on measured BMD on this system. For the Lunar Prodigy system, the effects of adjacent activity on BMD were found to be dependent on source location, strength, and radioisotope. For sources placed beneath the solid lucite phantom, BMD decreased by approx 0.5%/10 mCi of activity for all isotopes. In general, for sources placed above the lucite phantom, the BMD decreased by 1.6-4.0%/10 mCi of activity, depending on location. The exception was Tl-201, where BMD increased by 0.5-2.5%/10 mCi, depending on location. With the high-density spine in the water phantom, the effects of adjacent activity were more pronounced than in the standard density spine in the lucite block. For a distributed Tc-99m source, the BMD decreased by 1.7%/10 mCi. The effect of radioactivity on DEXA measurements is system dependent. In general, adjacent activity results in a reduction in apparent BMD. The magnitude of the effect increases with increasing BMD and is dependent on the location of the activity.

Absorptiometry, Photon↗
PubMed2002

Assessment of forearm volumetric bone mineral density from standard areal densitometry data.

The common bone density measurement procedures produce areal bone mineral density data (BMD) alone. Volumetric bone density is thought to offer a different diagnostic perspective and is usually measured by peripheral quantitative computed tomography. We developed a calculation procedure for radial and ulnar volumetric densities based on single X-ray absorptiometry. The study consisted of 418 healthy Bulgarian females (ages 20 83 yr). Forearm bone density was measured on a DTX-100 densitometer at the 8-mm distal site, and the total volumetric bone densities of radius and ulna were calculated. The accuracy error determined on cadaveric bones was 10 14%. The in vivo precision error was 1.0 1.1%. Age-matched reference curves for volumetric BMD (vBMD) were built. Peak values were registered in the age 30 34 group: 0.403 (radius) and 0.469 g/cm(3) (ulna). Ulnar volumetric density exceeded the radial one, representing an interesting finding to be further investigated. For the age 70 74 group, vBMD was reduced by approx 30% compared with the age 30 34 group. Our data confirmed the fact that volumetric density was much less affected by age and menopause. Correlations between forearm vBMD and axial BMD were moderate. The proposed calculation procedure could become an extra option in forearm bone densitometry to be applied in pediatric populations or adults of extremely large or small body size.

Absorptiometry, Photon↗
PubMed2003

A comparison of calcaneal dual-energy X-ray absorptiometry and calcaneal ultrasound for predicting the diagnosis of osteoporosis from hip and spine bone densitometry.

Peripheral densitometry is increasingly being used in the management of osteoporosis, but the optimal diagnostic thresholds have not been defined. The aim of this study was to determine the optimal T-score for peripheral dual-energy X-ray absorptiometry (pDXA) of the heel using a GE Lunar PIXI and quantitative ultrasound (QUS) of the heel using a GE Lunar Achilles Plus when compared with dual-energy X-ray absorptiometry (DXA) of central sites (spine, femoral neck, or total hip). Ninety-nine women (mean age 69 +/- 8, range 33-86 yr) referred from the metabolic bone clinic were studied. The optimal T-score for pDXA from ROC analysis was -1.7 and for QUS was -2.5. The pDXA T-score that defined the same prevalence of osteoporosis at any central site was also -1.7 and for QUS was -2.4. These results are similar to the manufacturer's recommendations. There is no significant difference in performance between the PIXI and QUS.

Absorptiometry, Photon↗
PubMed2004

Position statement : executive summary. The Writing Group for the International Society for Clinical Densitometry (ISCD) Position Development Conference.

The International Society for Clinical Densitometry (ISCD) held a Position Development Conference in July 2003, at which time positions developed and researched by the organization's Scientific Advisory Committee were presented to a panel of international experts in the field of bone density testing. This panel reached agreement on a series of positions that were subsequently approved by the Board of Directors of the ISCD and are now official policy of the ISCD. These positions, which are outlined in this article and discussed in greater detail in subsequent articles in this journal, include (1) affirmation of the use of the World Health Organization classification for the diagnosis of osteoporosis in postmenopausal women; (2) the diagnosis of osteoporosis in men; (3) the diagnosis of osteoporosis in premenopausal women; (4) the diagnosis of osteoporosis in children; (5) technical standards for skeletal regions of interest by dual-energy X-ray absorptiometry (DXA); (6) the use of new technologies, such as vertebral fracture assessment; (7) technical standards for quality assurance, including phantom scanning and calibration; (8) technical standards for the performance of precision assessment at bone density testing centers, and for cross-calibration of DXA devices; (9) indications for bone density testing; (10) appropriate information for a bone density report; and (11) nomenclature and decimal places for bone density reporting.

Absorptiometry, Photon↗
PubMed2005

Fan-beam densitometry of the growing skeleton: are we measuring what we think we are?

Magnification error in fan-beam densitometers varies with distance from the X-ray source to the bone measured and might obscure bone mineral changes in the growing skeleton. Magnification was examined by scanning aluminum rods of different shapes (square, rectangular, solid round, and hollow round) at four distances above the X-ray source in two orientations, with rods aligned parallel (SI) and perpendicular (ML) to the longitudinal axis of the scanning table. Measured area (cm(2)) decreased linearly with distance above the X-ray source for all rods in the SI orientation (p < 0.005). Measured mineral content (g) decreased linearly with distance but only for SI round rods (p < 0.0001) and for ML hollow round rods (p < 0.005). Area and mineral content decreased 1.6-1.8% per centimeter above the source for round rods. Measured mineral density (g/cm(2)) decreased linearly with distance from the source only for ML hollow round rods (p < 0.005). Variation in area, mineral content, and mineral density measurements was 6.6-6.9%, 6.9-7.5%, and 1.9-2.3%, respectively, for SI round rods. Magnification errors of this magnitude are problematic for clinical studies using fan-beam densitometry. Particularly in pediatric subjects, increases in soft tissue during normal growth could increase a bone's distance from the fan-beam source and result in apparent reductions in area and bone mineral content.

Absorptiometry, Photon↗