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PubMed1997

[Usefulness of bone densitometry, quantitative computed tomography and quantitative ultrasound in diagnosis and monitoring of osteoporosis treatment].

Bone densitometry is characterized by high sensitivity and specificity in osteoporosis, and new generations of densitometers enable measurements with improved intra- and inter-assay precision. The clinical potential of bone densitometry is well documented and the technique is widely used in clinical practice. It does not, however, allow for measurement of "true" bone density; instead it measures so called serial density (expressed in g/cm2) which is the distribution of bone mass over the flat projection of the skeleton. Limitations of densitometric techniques can be overcome by applying other methods, i.e. quantitative computed tomography (QCT) and ultrasound (US). QCT enables separate measurements of compact and trabecular bone density (expressed in g/cm3), as well as calculation of Strength-Strain Index (SSI), reflecting the mechanical resistance of bone to fracture. US is a non-invasive technique, providing information of fracture risk and bone tissue quality. Both techniques seem very promising and have been extensively studied recently; they are expected to move from clinical research to clinical practice soon.

Bone and Bones↗
PubMed1998

[Comparison of pulse dye densitometry and thermodilution method in cardiac output measurement].

We measured cardiac outputs at forty points from five patients by pulse dye densitometry and compared these with those measured by thermodilution method. We obtained a good correlation (y = 1.090 x = . 0.030, n = 40, 5 cases) and small mean bias (0.348 +/- 0.830 l.min-1, n = 40, 5 cases) between the two methods. We suggest that this method of cardiac output measurement by pulse dye densitometry is not invasive and may be more effective than that by thermodilution method.

Cardiac Output↗
PubMed1999

Value of morphometry, texture analysis, densitometry, and histometry in the differential diagnosis and prognosis of malignant mesothelioma.

Malignant mesothelioma is a tumour with increasing incidence due to widespread use of its causative agent, asbestos, in the past decades. The poor survival necessitates a correct differentiation from other lesions at the same site, such as hyperplastic mesothelium and carcinomas metastatic to pleura or peritoneum. Since genetic and immunohistochemical markers are not absolutely differentiating, the diagnosis is based on the histology complemented with (immuno)histochemistry. However, as the tumour presents itself in numerous heterogeneous histological forms, visual evaluation is extremely difficult. In order to evaluate the prognostic and diagnostic performance of syntactic structure analysis (SSA), chromatin texture analysis, densitometry, and morphometry, an automated KNN-classification system has been used to compare Feulgen-stained tissue sections of hyperplastic mesothelium, malignant mesothelioma, and pulmonary adenocarcinoma. In addition, we also studied most discriminative aspects in the differentiation, typing, and prediction of survival. The results indicate that for the diagnosis of malignant mesothelioma, chromatin texture parameters outperform SSA, densitometry, and morphometry (recognition score=96.8 per cent). Most discriminative parameters highlight spatial patterns of the chromatin distribution that are hard to appraise visually and directly show the benefits of a quantitative approach. Typing of the tumour is best described by SSA parameters, relating to the spatial arrangement of the cells in the tissue (recognition score=94.9 per cent). In survival time classifications, chromatin texture yields the highest recognition score (82.9 per cent), although accurate estimations are unreliable due to a large degree of misclassification.

Adenocarcinoma↗
PubMed1994

Precision of dual X-ray absorptiometry and peripheral computed tomography using mobile densitometry units.

Irrespective of the method used for noninvasive bone mass determination, data comparison between different centers is a major problem as significant interunit variation may occur. We, therefore, have employed mobile densitometry units to reduce interunit variability in two large epidemiologic studies in Germany. Two cars were equipped with either two dual X-ray absorptiometry (DXA) instruments (QDR 1000 Hologic, USA) (car I) or a special purposed scanner for peripheral quantitative computed tomography (pQCT) (XCT 900, Stratec, FRG) (car II). The cars were moved across Germany 11,090 km and 1651 km during the studies over a period of 30 and 7 months, respectively. Precision in vitro was determined using hydroxyapatite phantoms. Forty-eight patients underwent duplicate measurements at the lumbar spine (n = 22) and hip (n = 26) for assessing reproducibility in vivo. Between the two series of scans, the car was moved 63 km. Long-term precision in vitro of the QDR 1000 instruments were 0.41% and 0.59% for BMD with no evidence of machine drift (rate of change per year 0.04% and 0.05%, respectively). Short-term reproducibility in vivo showed a coefficient of variation (cv) of 1.02% for spinal BMD (L2-L4) and 1.72% for femoral neck. Long-term precision in vitro of the pQCT scanner was 0.9%. Our study shows precision in vivo and in vitro and stability of the mobile densitometers similar to that achieved with stationary equipment. In conclusion, mobile densitometry may become a useful tool not only for epidemiologic surveys and clinical trials but also for routine evaluation in less densely populated areas.

Absorptiometry, Photon↗
PubMed1992

Morphometry versus densitometry--a comparison by use of casts of human coronary arteries.

Geometric and densitometric methods for quantitative coronary arteriography have generally been compared by use of phantoms simulating arteries with circular lumina ('Hole phantoms'). We have used more adequate phantoms obtained by casting disease-free and atheromatous human coronary arteries. The phantoms, filled with contrast medium, were imaged digitally (1024 x 1024 x 10 matrix) under experimental conditions simulating routine coronary angiography. The angiographic 'diameters' and the densitometric cross-sectional areas of 59 marked lumina were determined in single plane and orthogonal biplane raw images. Geometric calibration was performed by help of a 7F coronary catheter. For the densitometric calibration, we used a 'hole phantom' attached to the image intensifier. The obtained luminal areas were compared to their true values determined previously by planimetry. The mean absolute error of single plane cross-sections obtained geometrically was 1.53 mm2. Biplane imaging reduced it by a factor 2.4 to 0.64 mm2. The corresponding mean absolute errors for densitometry were 0.56 mm2 and 0.51 mm2. Single plane 'diameter' measurements appear thus of very limited value for hemodynamic conclusions. In contrast, biplane geometric quantification was not markedly inferior to single plane and biplane densitometry.

Absorptiometry, Photon↗
PubMed1997

Ex vivo estimation of thoracolumbar vertebral body compressive strength: the relative contributions of bone densitometry and vertebral morphometry.

The estimation of vertebral fracture risk in individuals with suspected osteopenia is commonly based on measurements of lumbar spine bone density. The efficacy of vertebral size and deformity, as assessed by vertebral morphometry, in the prediction of fractures has been less studied. In an ex vivo investigation the regional relationships between vertebral size, vertebral deformity, bone density and compressive strength throughout the thoracolumbar spine were examined. In 16 vertebral columns (T1-L5) the bone mineral content (BMC) and bone mineral density (BMD) of each segment were measured using lateral projection dual-energy X-ray absorptiometry, and the vertebral cancellous density (VCD) and mid-vertebral cross-sectional area (CSA) measured using quantitative computed tomography. Vertebral body heights were determined from mid-sagittal CT scans, and vertical height ratios calculated for each segment. The failure load and failure stress of the isolated vertebral bodies were determined using a material testing device. Separate analyses were performed for the upper (T1-4), middle (T5-8) and lower (T9-12) thoracic, and lumbar (L1-5) segments. In all regions, failure load was strongly correlated with BMD (r = 0.82-0.86), moderately correlated with VCD (r = 0.60-0.71) and vertebral height (r = 0.22-0.49), and poorly correlated with the height ratios (r = 0.04-0.33). Failure stress was best predicted by BMD (r = 0.73-0.78) and VCD (r = 0.70-0.78) but was poorly correlated with all morphometric variables (r = 0.01-0.33). The segmental correlations between BMD and VCD ranged form r = 0.49 to r = 0.79. For all regions, BMD and VCD were included in the stepwise regression models for predicting failure load and failure stress. Either the mid-vertebral height or CSA were included in all the failure load models, while mid-vertebral height was included in only one of the failure stress models. The results suggest that vertebral deformity and size (as assessed by vertebral morphometry) make only a minor contribution to the prediction of vertebral strength additional to that provided by bone densitometry alone. The consistent regional relationships between variables appear to support the practice of global fracture risk assessment based on lumbar spine densitometry.

Adult↗
PubMed1993

Quality assurance for bone densitometry research studies: concept and impact.

A concept for quality assurance (QA) in bone densitometry has been developed for clinical multicenter studies. Major elements provided by a coordinating center comprise (1) consulting services and certification of participating centers in the start-up phase of the study, (2) review of scan data acquired on QA standards for cross-calibration and longitudinal assessment of scanner stability, (3) review of selected patient data as well as of problem cases during the study, and (4) comprehensive review and correction of patient results based on QA data after conclusion of the study. Limitations of phantom-based QA data should be acknowledged. Typical problems encountered during research studies and guidelines for solutions are presented. Successful implementation of QA measures may yield substantial enhancement of statistical power. Depending on the study design and the variability of response within patient groups, improvement in precision due to QA measures may reduce the smallest detectable difference between subject groups or, alternatively, sample size by a few to more than 50%, and thus may contribute to a substantial reduction in study cost. Formulae for calculation of the magnitude of these effects are presented. To maximize the net benefit, QA efforts have to be limited to levels that assure reliability of the data at acceptable QA cost. While QA programs at individual clinical sites or for local practitioners may not need to be as extensive as for multicenter clinical trials, awareness of the potential problems and implementation of basic QA measures will help in obtaining high-quality bone densitometry results.

Bone Density↗
PubMed2000

Axial and total-body bone densitometry using a narrow-angle fan-beam.

We assessed a new dual-energy bone densitometer, the PRODIGY, that uses a narrow-angle fan-beam (4.5 degrees) oriented parallel to the longitudinal axis of the body (i.e., perpendicular to the usual orientation). High-resolution scans across the body can be stepped at 17 mm intervals. The energy-sensitive array detector uses cadmium zinc telluride, which allowed rapid photon counting. Spine and femur scans required 30 s, and total-body scans required 4-5 min; the dose was only 3.7 mrem and 0.04 mrem respectively, or about 5 to 10 times lower than conventional fan-beam densitometry. We found only a small influence of soft-tissue thickness on bone mineral density (BMD) results. There was also a small (+/- 1%) influence of height above the tabletop on BMD results. A software correction for object height allowed a first-order correction for the large magnification effects of position on bone mineral content (BMC) and area. Consequently, the results for BMC and area, as well as BMD, with PRODIGY corresponded closely to those obtained using the predecessor DPX densitometer, both in vitro and in vivo; there was a generally high correlation (r = 0.98-0.99) for BMD values. Spine and femur values for BMC, area and BMD averaged within 0.5% in vivo (n = 122), as did total-body BMC and BMD (n = 46). PRODIGY values for total-body lean tissue and fat also corresponded within 1% to DPX values. Regional and total-body BMD were measured with 0.5% precision in vitro and 1% precision in vivo. The new PRODIGY densitometer appears to combine the low dose and high accuracy of pencil-beam densitometry with the speed of fan-beam densitometers.

Absorptiometry, Photon↗
PubMed1999

[Bone densitometry by dual energy methods].

Osteoporosis is mainly diagnosed by means of bone densitometry. Dual X-ray absorptiometry examinations represent the basis for a highly reproducible and correct measurement. At present, densitometry is the only method at our disposal capable of assessing material-related fracture risk. The calculation of general fracture risk is dependent on a number of varios factors and is, therefore, not to be deduced from bone density values only. Reference values are necessary in order to estimate bone strength. The most sensible way to achieve this is to compare measured values with a normal, healthy population (T score). Material-related fracture risk increases with the decrease of bone density.

Absorptiometry, Photon↗
PubMed2004

Timing of follow-up densitometry in hormone replacement therapy users for optimal osteoporosis prevention.

The objectives of the study were (1) to determine the time interval for repeat dual-energy X-ray absorptiometry (DXA) to detect significant bone loss, i.e., greater than the coefficient of variation (CV) of the center (2.8 x CV%) and (2) to assess how long hormone replacement therapy can be maintained to avoid undetected development of low bone mass and to not unduly delay appropriate treatment. A total of 3,826 healthy women, aged 40-65 years, participated in a prospective cohort study, 807 of whom were treated with transdermal estrogen replacement therapy and 626 with transdermal estrogen/progesterone regimens. The untreated group included the remaining 2,393 women. Between 1996 and 2002 they underwent a baseline DXA scan, and DXA scans were then repeated annually. There were no differences among the study groups at entry into the study. Treatment with estrogen was a protective factor for loss of bone mass at the lumbar spine (odds ratio [OR] =0.431, 95% confidence interval [CI] 0.344 to 0.522) and at the femoral neck (OR =0.433, 95% CI 0.352 to 0.521). Treatment with estrogen/progesterone also showed a protective effect against significant changes in follow-up BMD (>2.8 x 1.05% CV of densitometry at L1-L4, >2.8 x 2.3% CV at the femoral neck). In the treated group, significant differences in BMD at the lumbar spine (OR =1.593, 95% CI 1.423 to 2.355) did not appear within the first 3 years, and differences in BMD at the femoral neck (OR =3.555, 95% CI 2.782 to 4.905) did not appear within the first 4 years. It is concluded that in women aged 45-65 years, receiving transdermal hormone replacement therapy without risk factor for loss of bone mass, such as age < 55 years and body mass index <25 kg/m(2), periodical follow-up densitometries would not be necessary, provided that the duration of estrogen or estrogen/progesterone therapy is shorter than 3 years.

Absorptiometry, Photon↗
PubMed2002

Interest of a prescreening questionnaire to reduce the cost of bone densitometry.

Bone mineral density (BMD) measurement is widely recognized as the best single tool to identify patients with a high lifetime risk of developing an osteoporosis-related fracture. However, the cost/benefit value of screening the whole population has been repeatedly challenged and demonstrated to be rather poor. In many countries, BMD scan is not or no longer reimbursed because of lack of validated criteria to identify patients who should benefit from this procedure. Based on the proposals of a nationwide expert panel, a simple questionnaire identifying historical, clinical and behavioral risk factors for osteoporosis was developed. The aim of this study was to assess the diagnostic accuracy of the proposed criteria; to determine the extent to which this questionnaire could be useful for optimizing the use of densitometry tests; and, more specifically, to estimate the diagnostic costs per osteoporotic or osteopenic patient detected. For this purpose, we applied the questionnaire to 3998 consecutive individuals at least 20 years old, of both genders, either consulting spontaneously or referred for a BMD measurement to an outpatient osteoporosis center. BMD was measured by dual-energy X-ray absorptiometry (DXA) at the lumbar spine and at the hip (both total hip and femoral neck). Diagnostic accuracies were evaluated through measures of sensitivity, specificity, and positive and negative predictive values. After determining a benchmark value for age, different strategies were compared in order to identify the most cost-effective one in terms of cost per patient detected. According to the WHO operational definition of osteoporosis (T-score <-2.5), 31% of the subjects were classified as osteoporotic at one or more of the measured sites. If only patients with at least one of the proposed risk factors had been referred for scans, 33.3% of the BMD measurements would have been avoided. Among those, less than 5% were missclassified as they did have osteoporosis at the total hip and up to 23% at one or more of the considered sites. On the other hand, of the subjects who would be recommended for a densitometry test, only a small fraction were identified correctly (the positive predictive values varied from 11.3% at the total hip to 34.8% at any site). In this first setting, the suggested criteria seem useful chiefly for excluding subjects who do not need a DXA scan rather than selecting osteoporotic patients. When applied only to patients aged 61 years or more, the positive predictive values rose to 15.1% (total hip) and 42.9% (any site), whereas the corresponding negative predictive values were set at 93% and 68.6%. In comparison, with a mass screening scenario the estimated diagnostic costs (costs associated with the DXA procedure) per osteoporotic patient detected at any of the considered sites would be reduced by more than 9% (59.4 instead of 65.3 Euros) if the suggested indications are taken into account for prescreening patients. And when the questionnaire is applied only to women over the age of 60 years these costs would be further reduced to 50.6 Euros, representing a 23% decrease. Then, a prescreening strategy based on these indications concomitantly with an age-selective criterion could represent a promising way toward a more rational use of BMD measurement.

Absorptiometry, Photon↗
PubMed2001

Use of quantitative ultrasound densitometry (QUS) in male osteoporosis.

Bone densitometry is a key factor in the early diagnosis of osteoporotic bone disorders. Cut-off values for WHO classification for male osteoporosis and all densitometry techniques such as dual x-ray absorptiometry (DXA), quantitative ultrasound (QUS), and quantitative computed tomography (QCT) need to be developed. Hereby, QCT, DXA, and QUS are equivalent methods in the prospective assessment of fracture risk. Where men and women have similar BMD values, they also have similar fracture probability. QUS has several advantages compared to the radiological devices. The QUS systems, which are commercially available at present, are non-invasive methods, which are safe, simple, free of radiation, portable, and relatively inexpensive. QUS can be measured at the calcaneus and phalanges or with multi-site systems. Phalangeal ultrasound is especially useful as being easily accessible.

Adult↗
PubMed1999

Bone densitometry: influence of prosthetic design and hydroxyapatite coating on regional adaptive bone remodelling.

The objective of this prospective study was to determine if bone densitometry can detect disparities in regional adaptive bone remodelling surrounding the cementless porous-coated femoral component of a hip prosthesis in two titanium alloy implants of different design . These prostheses were the S-ROM (n=69) and the Multilock (n=65). The Multilock implants consisted of two groups; 25 had a 50 micron layer of hydroxyapatite (HA) sprayed over the porous surface of the femoral component and the remaining 40 femoral components were not coated with HA. Densitometry was performed with dual energy X-ray absorptiometry (DXA) utilizing the LUNAR ORTHO software to analyse the seven Gruen zones. Bone mineral density measurements were obtained within a week of surgery as a baseline reference and at 6, 12, 24, 36 and 48 months thereafter. At 6 months there was significant mineral loss in all Gruen zones in the three prostheses. By 48 months there were differences in mineral loss between the three prostheses. In the zones adjacent to the porous surface, predominantly zones 1 and 7, the S-ROM exhibited 60% less mineral loss than the Multilock in zone 1, and there was no significant difference in zone 7. Compared to the Multilock-HA, the S-ROM lost 35% less mineral in zone 1, but the Multilock lost 70% less mineral than the S-ROM in zone 7. The Multilock-HA lost 37% and 75% less mineral than the Multilock in zones 1 and 7, respectively, i.e., hydroxyapatite coating tended to preserve bone stalk. Using the Gruen zone area measurements provided by the software, the S-ROM had significantly greater bone resorption in zone 7 at 24 months than either of the Multilocks, which did not differ from each other. In conclusion, DXA has shown differences in periprosthetic adaptive bone remodelling between implants of different design and composition as a function of time.

Absorptiometry, Photon↗
PubMed2006

[Methods of imaging and bone densitometry in osteoporosis of patients with inflammatory rheumatoid diseases].

Besides clinical history and clinical findings conventional X-ray is important in the evaluation of osteoporosis as the third diagnostic tool. Its purpose is mainly excluding other diseases and proof of fractures as well as their follow up. Also X-ray is able to demonstrate complications of osteoporosis such as insuffiency fractures and effects of therapy as for example fluorosis. For very early diagnosis bone densitometry is used. Today the improved methods deliver fracture prediction percentages of high value. As a planar measurement method DXA of the spine and of the femoral neck can be used. Volumetric tools, which can measure trabecular bone, without overlying cortical bone, are computed tomography of the spine and of the distal radius. Quantitative ultrasound is an interesting approach, but which does not really measure bone densitometry and which is net yet suited for clinical follow up. Quantitative Magnetic Resonance is far from routine clinical application.

Absorptiometry, Photon↗
PubMed1995

Maxillary sinus aspergillosis: diagnosis and differentiation of the pathogenesis based on computed tomography densitometry of sinus concretions.

PURPOSE: The efficacy of preoperative computed tomography (CT) densitometry in evaluating the origin of sinus concretions (SC) in sinus aspergillosis (SA) and its value for differentiation between a dental (endodontic) and an aerogenic pathogenesis were examined. PATIENTS AND METHODS: Thirty-two patients who demonstrated radiodense maxillary sinus concretions in standard radiography underwent an additional preoperative CT examination of the maxillary sinus and the SC. The density of the SC and the root canal filling materials was assessed. The SC were subdivided into organic (< 1,500 HU) and inorganic (> 1,500 HU) masses; this classification was useful in the differentiation between a dental and an aerogenic pathogenesis of SA. RESULTS: SA was diagnosed in 22 patients (68.8%). The SC of SA patients had a density of 2,566.5 +/- 713.6 HU, whereas those of patients without SA had a density of 1,159.9 +/- 1,008.4 HU (P < .01). A correlation between the density of inorganic SC and that of root filling materials was found (r = .78, P < .01). CONCLUSION: CT densitometry allows a classification of SC into two subgroups. The correlation between the density of root filling materials and that of radiodense sinus concretions seems to point to a "dental" origin of some concretions in SA. However, "organic" masses found in CT densitomentric examinations represent endogenous fungal products, which indicate an aerogenic pathogenesis of SA. Additional CT examinations of radiodense sinus concretions may thus be of some value for diagnosing SA and differentiating their pathogenesis.

Administration, Topical↗
PubMed1996

Bone densitometry of the forearm: comparison of single-photon and dual-energy X-ray absorptiometry.

Forearm bone mineral densitometry was performed initially by single-photon absorptiometry (SPA), but is now achievable by dual-energy X-ray absorptiometry (DXA) as well, with a good correlation between both measurements. However, it is still unknown whether: (1) short-term precision of DXA is superior to SPA and (2) identical regions of interest (ROI) are mandatory to correlate SPA with DXA. The aim of this study was to answer these questions using a commercial system for DXA (DXA-FAS) and to test an in-house system using spine DXA and a soft-tissue compensator (DXA-STC). In ten subjects, four measurements on the same day showed significantly lower (p < 0.05) coefficients of variation (CV) for bone mineral density (BMD) by DXA-FAS (proximal site: 0.74%; ultradistal site: 1.20%) than by SPA (1.26% and 2.25%). However, the CV for bone mineral content (BMC) were similar for DXA-FAS (0.73% and 1.58%) and SPA (0.79% and 1.34%). The significant difference (p < 0.05) for surface calculation by DXA-FAS (1.24% and 0.93%) compared with SPA (2.36% and 1.28%) explains all the advantages of DXA-FAS for short-term precision. The measurements taken on the same day on the ulna and the radius or on the radius alone by SPA, DXA-FAS, and DXA-STC on 108 subjects aged 18-80 years were highly correlated [r ranging from 0.925 to 0.995 (p < 0.0001) and standard error of the estimate from 3.15% to 8.89%]. The need for a manual adjustment of the ROI was found to be mandatory for BMC but not BMD assessment. The use of DXA-STC is a fast method for forearm bone densitometry and its correlation with SPA is very high. However, its short-term precision for BMC (3.00% and 1.54%), BMD (2.15% and 1.12%), and surfaces (1.99% and 1.12%) is significantly higher (p < 0.05) than that of DXA-FAS. We conclude that short-term precision of DXA is better than that of SPA only for BMD and surface measurement but not for BMC. ROI should be adjusted manually for the assessment of BMC but not for that of BMD.

Absorptiometry, Photon↗
PubMed2003

Screening for asymptomatic celiac disease among patients referred for bone densitometry measurement.

Celiac disease (CD) is a relatively common gastrointestinal disorder that can be asymptomatic. An increased prevalence of subclinical CD has been reported in many populations. Even among asymptomatic patients a reduction in bone mineral density (BMD) has been observed. The aim of this study was to evaluate the prevalence of silent CD in a cohort of consecutive individuals referred for bone densitometry measurement. Serum samples were taken from 454 women attending for bone densitometry (mean age: 56 +/- 11 years). Of the individuals evaluated, 89 had normal BMD and 365 had low BMD (T score < -1.0). Subjects were screened for the presence of serum IgA anti-endomysial antibodies (EMA) and IgA tissue transglutaminase (tTG) antibodies by indirect immunofluorescence and enzyme-linked immunosorbent assay (ELISA), respectively. BMD was measured by dual X-ray absorptiometry (DEXA) at the lumbar spine and femoral neck. Eight EMA tTG-positive individuals were identified in this population (1.8% or 1:57). Serologically positive women had a lower mean Z score at both the lumbar spine and femoral neck than EMA tTG-negative women. But this did not approach significance. There was no significant difference in the incidence of CD between the normal- and low-BMD groups in this dataset (P = 0.365). In conclusion, our study indicates that the prevalence of CD in our dataset is high. However, the frequency of asymptomatic CD among low-BMD individuals is similar to that among normal-BMD individuals in our population. These observations do not support the hypothesis that serological testing for CD may be a good accompaniment to DEXA scanning.

Absorptiometry, Photon↗
PubMed2006

Comparative evaluation of local and international reference databases for forearm densitometry: different impacts on diagnostic decisions.

Reference databases play a key role in the management of osteoporosis. The aim of this preliminary study was to compare the diagnostic consequences of using either an international or a local reference database in peripheral densitometry. For this purpose, standard curves for bone mineral density (measured by dual-energy X-ray absorptiometry at the distal and proximal forearm) were generated for healthy Hungarian men and women. In total, 303 healthy volunteers of both sexes (age range: 20-94 yr) were recruited from four osteoporosis centers. Subjects with medical conditions or taking medication affecting the bone metabolism were excluded. Bone densitometry was performed with pDEXA (Norland-Stratec, Fort Atkinson, WI) devices in each center after cross-calibration of the machines. The precision error of the forearm measurement was also determined (<1% in vitro, and 1.2-2.5% in vivo). In females, the peak forearm density was detected in the 30-39-yr group. The density decreased by 8% per 5 yr in early postmenopausal females, and by 10% per 10 yr in late postmenopausal females. In males, the highest bone mineral density was found in the 30-39-yr group for the distal forearm, but 1 decade later for the proximal site. Subsequently, a 5% decrease in density occurred per 10 yr, except in the 8th decade, in which a 20% decrease was demonstrated. One thousand four hundred thirty-four patients with suspected osteoporosis were classified according to the forearm density T-scores using both the new Hungarian reference database and the international database provided by the manufacturer. Comparison of the results measured at the distal forearm with the two different databases led to similar outcomes. However, at the proximal site, one fifth of the female patients were reclassified from the low-density group to the normal group using the domestic normative database. An opposite difference was observed for the males: use of the Hungarian reference data resulted in 40% more men being categorized in the low-density group than when the international normal database was applied. Our results suggest that not only geographic differences, but also the reference database used, can influence the prevalence of the diagnosis of osteoporosis. Further data are currently being collected to increase the statistical power of the study.

Absorptiometry, Photon↗