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PubMed2006

Quantitative ultrasound and peripheral bone densitometry in patients with genetic disorders.

The aim of the study was comparison of quantitative ultrasound and densitometric peripheral measurements in subjects with genetic disorders. The study included 52 subjects (35 boys and 17 girls) in mean age 13.1 +/- 4.8 y. Patients with following disorders were evaluated: Down syndrome (n = 21), Martin-Bell syndrome (n = 14) and other (n = 17). There were no additional factors potentially influencing bone metabolism. Bone status was assessed by quantitative ultrasound at the hand phalanges using DBM Sonic 1200 (IGEA, Italy), which measures amplitude-dependent speed of sound (Ad-SoS [m/s]) and bone densitometry at the calcaneus and forearm by the use of PIXI (GE, USA), which measures bone mineral density (BMD, g/cm2). Ad-SoS correlated significantly with forearm and calcaneus BMD in the whole group (r = 0.66, p < 0.000001 and r = 0.51, p < 0.0001, respectively), in females (r = 0.58, p < 0.05 and r = 0.5, p < 0.05) and in males (r = 0.70, p < 0.000001 and r = 0.54, p < 0.001). Calcaneus BMD correlated with wrist BMD in the whole group, in females and males: r = 0.66, p < 0.000001, r = 0.67, p < 0.01 and r = 0.75, p < 0.0001, respectively. These coefficients of correlation were compared and did not reveal significant differences in the whole group and in the gender subgroups. ROC analysis of Ad-SoS values versus calcaneus and forearm BMD showed area under curve 0.89 for forearm BMD and 0.79 for calcaneus BMD (subjects with Ad-SoS T-score below -3.2 were considered as abnormal). Age correlated significantly with Ad-SoS, forearm and calcaneus BMD (r ranged from 0.53 to 0.9, p from 0.05 to 0.000001). In all patients and males, age more strongly influenced Ad-SoS than calcaneus BMD (p < 0.05). Also, body weight and height correlated significantly with Ad-SoS, forearm and calcaneus BMD, except for correlation between forearm BMD and height in female patients (r from 0.58 to 0.84, p < 0.05). Generally, in multiple stepwise regression analysis of age and body size on skeletal parameters, age had positive influence, and body size was a positive or a negative factor. In conclusion, both quantitative ultrasound and peripheral densitometry may be recommended for the assessment of skeletal status in subjects with genetic disorders, although measurements of phalanges seem to be more sensitive for detecting age-related bone changes.

Absorptiometry, Photon↗
PubMed1997

The contribution of bone densitometry to the diagnosis and treatment of osteoporosis.

OBJECTIVE: It has recently been proposed that a specialist osteoporosis service, including bone densitometry, should be made available to those most at risk in the UK population. The aim of this study was to evaluate such a service, and in particular the role of bone densitometry, in terms of its effect on the diagnosis of osteoporosis and clinical management of the disease. METHODS: A retrospective data abstraction study was performed to investigate the diagnosis and management of patients referred to the Metabolic Clinic, City Hospital Nottingham, with a potential diagnosis of osteoporosis. Hospital records were available for 117 patients, aged between 45 and 59, who had attended the Clinic in a given time period and undergone bone mineral density measurement. RESULTS: Forty-eight patients (41.0%) had osteoporosis of the lumbar spine. The final diagnosis of osteoporosis after attending the clinic was different from that on referral in a substantial proportion (62.6%) of cases. Only 48.9% of patients with spinal osteoporosis were identified by their referring doctor. The percentage of patients receiving treatment for osteoporosis increased from 34.2% to 72.6% after attending the clinic. CONCLUSIONS: Measurement of bone mineral density identifies cases of osteoporosis who would not otherwise be detected and as a consequence contributes to the proportion of patients receiving treatment after referral. The osteoporosis service provided by the Metabolic Clinic including measurement of bone mineral density was thus found to have a considerable impact on the diagnosis and treatment of patients with osteoporosis.

Absorptiometry, Photon↗
PubMed1994

Assessment of bone density in the distal radius with computer assisted X-ray densitometry (CXD).

A modified and improved radiographic absorptiometry of the distal radius which enables on-site analysis, called computer assisted X-ray densitometry (CXD), was evaluated from the viewpoint of quality assessment. Its precision and the correlation with dual energy X-ray absorptiometry (DXA) was evaluated in 12 volunteers (mean age 44.7 years). The profile of CXD-measured radial bone mineral density (RBMD) from 142 subjects (75 premenopausal and 67 postmenopausal women, mean ages 44.9 and 50.6 years, respectively) were compared with previous data by other methodologies of bone mineral analysis. The intra-assay coefficient of variation (CV) was 0.617%, the inter-assay CV was 2.064%, and the inter-observer CV was 0.673%. The correlation between CXD-measured RBMD and DXA-measured RBMD was of statistical significance (r2 = 0.733, P < 0.01). The correlation of CXD-measured RBMD with age, height or weight corresponded well with previous reports. CXD-measured RBMD and DXA-measured vertebral bone mineral density (VBMD) also had a significant positive correlation, but their correlation was not so close (r2 = 0.149, P < 0.01). The discriminative ability of osteoporosis by CXD was of acceptable level (odd's ratio = 5.72, P < 0.05), when assessed by comparison with bone dystrophy score (BDS) on the plain vertebral radiogram. Although some problems remain in technical standardization, CXD could be an easy, inexpensive, and widely applicable alternative of non-weight bearing cancellous bone densitometry.

Absorptiometry, Photon↗
PubMed1998

Applications of bone densitometry for osteoporosis.

Over the past decade, growing awareness of the impact of osteoporosis on the elderly population and the availability of new treatments to prevent fractures have stimulated the rapid development of new radiologic techniques to assist in diagnosis. With the ability to perform high precision measurements of bone mineral density (BMD) in the spine and hip, dual X-ray absorptiometry (DXA) is well suited to meet this latter need. However, there is continuing interest in smaller, cheaper systems for assessing the peripheral skeleton that include DXA scanning of the distal forearm and a variety of devices for performing quantitative ultrasound (QUS) measurements on bone. Alongside the new equipment, new guidelines have been developed to assist in the interpretation of bone densitometry studies and, following a report by a World Health Organization working group, osteoporosis is increasingly diagnosed on the basis of the patient's T-score value (difference of BMD from young adult mean normalized to the population SD). For the future, wider provision of bone densitometry services is required to properly target the new treatments now becoming available. Since it is unlikely that conventional DXA can meet these needs, QUS is an attractive alternative, especially because this technique is now proven in its ability to predict fracture risk in the elderly and FDA approval is imminent.

Absorptiometry, Photon↗
PubMed1997

Cardiac output and circulating blood volume analysis by pulse dye-densitometry.

OBJECTIVE: Pulse dye-densitometry (PDD) is a newly developed method for monitoring the indocyanine green (ICG) concentration in an artery with which cardiac output (CO) and circulating blood volume (CBV) can be determined. We evaluated its accuracy for clinical use. METHODS: In 7 patients under general anesthesia, ICG-sensitive optical probes (805 and 890 nm) were attached to a finger. Following injection of ICG, the arterial concentration of dye was recorded optically by the non-invasive test instrument and sampled arterial blood ICG concentration was also measured photometrically for comparison. In order to validate the PDD analysis, CO was also measured by both the dye dilution cuvette method and by thermodilution in 8 patients scheduled for coronary artery bypass grafting. In 30 other patients, CBV assessed by PDD was compared with its value estimated from body size. RESULTS: The blood dye concentration correlated well with the values obtained by PDD (r = 0.953, p < 0.01). Mean bias for the test PDD CO was +0.15 +/- 0.72 min l-1 (not significant (n.s.)) compared with the cuvette method while the mean bias of the thermodilution method vs the cuvette method was +0.79 +/- 0.84 min l-1 (p < 0.0001.). The average value of CBV obtained by PDD was 3.81 +/- 1.39 L compared with that estimated value, 3.72 +/- 0.77 L (n.s.). CONCLUSIONS: CO determined by PDD agrees well with cuvette densitometry, and somewhat less well with CO by thermodilution. The new method, by not requiring a pulmonary arterial catheter, is less invasive than either older method, and yields in addition a value of CBV.

Blood Volume↗
PubMed2002

Odds ratios for hip- and lower forearm fracture using peripheral bone densitometry; a case-control study of postmenopausal women.

BACKGROUND: Dual-energy X-ray absorptiometry (DXA) measured at the lumbar spine and particularly at the hip remain the gold-standard for diagnosing osteoporosis. However, devices for assessing the peripheral skeleton present several advantages in terms of lower price and portability. A major concern when using peripheral densitometry is the poor correlation with the central measurements. The main aim of this study is, therefore, to assess the possibility of expressing ultrasound measurements at the heel and bone mineral density (BMD) measured at the distal forearm as fracture odds ratios rather than an absolute measure of bone mass. METHODS: A total of 76 women with lower forearm fracture, 47 women with hip fracture and 231 age-matched women (controls) were included. All had broadband ultrasound attenuation (BUA) and speed of sound (SOS) measured at the heel using the DTU-one ultrasound scanner as well as BMD measured by dual X-ray absorptiometry on the DTX-200 at the distal forearm. RESULTS: BUA, SOS and BMD at the distal forearm were all significantly lower in fracture patients compared with their respective control groups. The odds ratio for lower forearm fracture was 3.1 (95% CI: 1.8; 5.2) for heel-BUA (T-score cutoff: -2.3), 4.1 (2.3; 7.4) for heel-SOS (-2.1) and 2.2 (1.3; 3.7) for lower forearm BMD (-2.7). The odds ratio for hip fracture was 3.4 (1.5-7.7) for heel-BUA (-2.7), 3.6 (1.6; 8.1) for heel-SOS (-2.6) and 3.2 (1.4; 7.4) for lower forearm BMD (-2.9). CONCLUSION: Peripheral densitometry can discriminate between hip- and lower forearm fracture patients and age-matched controls. Significantly elevated odds ratios for incurring these fractures can be calculated using device- and site specific t-score cutoff values. The results from this case-control study need to be confirmed by prospective cohort studies.

Absorptiometry, Photon↗
PubMed1978

[Attenuation values of normal and pathological liver tissue as a basis for computer tomographic densitometry of fatty livers (author's transl)].

Measurements of the density of normal and diffusely disease liver parenchyma show a significant difference only in the presence of fatty livers. A linear relationship between the fat content and density (g/cm3) has been demonstrated. Computer tomographic densitometry of liver tissue correlates well with physical in vitro measurements and permits measurements of fat content which are sufficiently accurate for clinical use. Other types of liver disease cannot be differentiated by densitometry.

Absorptiometry, Photon↗
PubMedDate not supplied

[Quantifying mineralization processes in post-traumatic algodystrophy using computerized tomography densitometry].

Computed tomography examinations have been made in 12 patients with posttraumatic algodystrophy. Significant differences of sides were found to be a measure of demineralisation by CT densitometry. 7 patients could be repeatedly examined during up to 60 weeks after the trauma. CT-integrated densitometry enables to quantify the process of de- and remineralisation and to objectify the disease according to the spongiosa bone. It seems to be possible to value the process of mineralisation by this method.

Absorptiometry, Photon↗
PubMed1983

[Computer tomographic densitometry of primary liver tumors].

The dynamic computed tomography (CT) densitometry is defined as the combination of rapid bolus injection of urographic contrast medium and timed sequential computed tomography scan permitting recognition of different patterns of enhancement. The results of this method on fifty patients with histologically proofed hepatic tumors (focal nodular hyperplasia n = 12, cavernous hemangioma n = 13, liver cell carcinoma in cirrhotic liver n = 10, primary liver cell carcinoma n = 6, bile duct carcinoma n = 4, others n = 5) are demonstrated. CT-densitometry offers valuable aid for the differential diagnosis of focal liver lesions, i.e. cavernous hemangioma, focal nodular hyperplasia of the liver.

Adenoma, Bile Duct↗
PubMed1995

Bone scintigraphy and densitometry in children with osteopetrosis.

Bone scintigraphy and dual x-ray absorptiometry were performed in 18 children (8 males, 10 females) with clinical and radiologic diagnoses of osteopetrosis in order to demonstrate the scintigraphic features of this rare disorder and to measure the bone mineral density. Their mean age was 9 years (range, 3-16 years). Bone scintigraphy demonstrated characteristic features of a widened metaphysis of all long bones that showed increased tracer uptake, particularly in the distal femur and proximal tibia. Dual x-ray absorptiometry of the lumbar spine, three femoral sites, and total body showed a marked increase in bone mineral density. The mean values for bone density of the lumbar spine and greater trochanter were markedly elevated than were other sites. Compared with a normal group matched for age and gender, the increase in bone mineral density was 181% for the lumbar spine and 193% for the greater trochanter. The authors concluded that bone imaging and bone densitometry are useful in establishing the diagnosis of osteopetrosis by demonstrating increase tracer uptake in the widened metaphysis and increased bone density. Bone densitometry may be of prognostic value in follow-up, especially in monitoring the response to therapy.

Absorptiometry, Photon↗
PubMed1999

Sources of error in lung densitometry with CT.

RATIONALE AND OBJECTIVES: To determine and analyze the most important error sources in lung CT densitometry in vivo. METHODS: The authors examined the influences of CT acquisition errors, physiologic changes, and image segmentation errors on lung densitometry. Among others, spatial dependency and long-term reproducibility of the density measurements of blood and air were examined over a period of 4 years in a group of 28 patients with pulmonary emphysema. These results were related to the measured lung densities in this group. RESULTS: The density measurement of blood and air is strongly dependent on the position in the thorax. Despite full-scanner calibrations, x-ray tube replacement can induce a significant increase in measured blood density. CONCLUSIONS: A change in a lung density parameter over time can actually be the result of tube replacement or changing blood density. A simple postprocessing technique can correct for these changes.

Absorptiometry, Photon↗
PubMed2004

Optimization and standardization of lung densitometry in the assessment of pulmonary emphysema.

Currently, lung densitometry for the assessment of pulmonary emphysema has been fully validated against pathology, pulmonary function, and health status, and it is therefore being applied in pharmacotherapeutic trials. Nevertheless, its application for the early detection of emphysema has not yet been introduced in daily clinical practice. The main reason for this is the fact that it is not yet regarded a fully optimized and standardized technique. In this work, an overview is given on the current status of different standardization aspects that play an important role in this, ie, image acquisition, choice of densitometric parameter and image processing. To address these issues, solutions have been sought from the literature and from original data from previous studies. Standardization and optimization of lung densitometry has reached a more advanced stage than has been reported so far. If normal values will become available, this technique will be feasible for clinical practice. As a result, standardization for the detection and assessment of other density-related lung diseases can be achieved in a shorter period of time.

Absorptiometry, Photon↗
PubMedDate not supplied

CT densitometry of the lungs: scanner performance.

OBJECTIVE: Our goal was to establish the reproducibility and accuracy of the CT scanner in densitometry of the lungs. MATERIALS AND METHODS: Scanner stability was assessed by analysis of daily quality checks. Studies using a humanoid phantom and polyethylene foams for lung were performed to measure reproducibility and accuracy. The dependence of the CT-estimated density on reconstruction filter, zoom factor, slice thickness, table height, data truncation, and objects outside the scan field was determined. RESULTS: Stability of the system at air density was within approximately 1 HU and at water density within approximately 2 HU. Reproducibility and accuracy for densities found for lung were within 2-3%. Dependence on the acquisition and reconstruction parameters was neglible, with the exceptions of the ultra high resolution reconstruction algorithm in the case of emphysema, and objects outside the scan field. CONCLUSION: The performance of the CT scanner tested is quite adequate for densitometry of the lungs.

Absorptiometry, Photon↗
PubMedDate not supplied

CT lung densitometry: dependence of CT number histograms on sample volume and consequences for scan protocol comparability.

PURPOSE: Our goals were to determine the dependence of CT number histograms of the lung on section thickness and reconstruction filter and to evaluate the consequences for scan protocol conformity required for universally comparable densitometry of the lungs. METHOD: The effects of section thickness and reconstruction filter were parameterized with the CT's sample volume [V approximately (section thickness x in-plane resolution2)]. In a study of 31 patients, we determined as a function of V the following CT number histogram parameters: percentiles P(10) and P(90), pixel indexes PI(-905) and PI(-950), and standard deviation. RESULTS: Patient histogram parameters depended strongly on sample volume. Large differences were found between protocols using 1 and 10 mm sections. For small variations in somewhat larger sample volumes (> 8 mm3), discrepancies were much smaller. CONCLUSION: To obtain comparable histogram parameters, nearly identical sample volumes (> or = 8 mm3) should be used. When this condition is satisfied, available data suggest that universally comparable densitometry is feasible.

Absorptiometry, Photon↗
PubMed1996

Evaluation of bone density in newborn infants by computed x-ray densitometry.

We evaluated bone density in term and preterm infants using computed x-ray densitometry, which permits measurement of bone density with minimal disturbance to the infants in their incubators. Bone density, bone width, and bone length of the right radius were determined in 155 infants of appropriate weights for their gestational ages (23 to 41 weeks). A curve for intrauterine bone growth was extrapolated from these data. The mean coefficients of variations for variabilities for intra- and interobserver error for all measurements were < 3.5%. In 18 infants, measurements of the right forearm were obtained in two positions to confirm the validity of densitometric measurements. The mean coefficients of variation were 3.42% for bone density, 3.48% for bone width, and 0.21% for bone length. Bone density was significantly correlated with gestational age (r = 0.924) and birth weight (r = 0.921). Bone width and length were also correlated with gestational age (r = 0.866 and 0.937) and birth weight (r = 0.878 and 0.954). Our results suggest that computed x-ray densitometry is a useful method for evaluation of bone density in preterm infants, including those in an intensive care environment.

Absorptiometry, Photon↗
PubMed2003

Bone histopathology and densitometry comparison between cyclosporine a monotherapy and prednisolone plus azathioprine dual immunosuppression in renal transplant patients.

BACKGROUND: No study has compared the bone histopathologic findings in renal transplant patients receiving cyclosporine A (CsA) monotherapy with those in patients receiving a non-CsA regimen. The aim of this study was to compare bone densitometry and histomorphometry findings in patients receiving CsA monotherapy versus those receiving azathioprine + prednisolone dual therapy. METHODS: A bone biopsy and densitometry were performed in 13 patients receiving CsA monotherapy and 12 patients receiving azathioprine + prednisolone, who had been on these regimens since the time of transplantation. Fourteen men and 11 women, age 51+/-12 years, with 140+/-75 months since transplantation, were included. RESULTS: A low bone mineral density (BMD) was observed in patients on both immunosuppressive schemes-most notably at the distal radius and less significantly at the lumbar spine. No significant differences in BMD were observed between immunosuppressive groups. Histopathologic analysis of the group as a whole revealed mixed uremic bone disease in 42%, adynamic bone in 29%, hyperparathyroid disease in 17%, and normal bone in 12%. Patients showed a slight increase in osteoclast number and function, decreased osteoblast number and function, and retardation of dynamic parameters. No differences in histopathologic diagnosis or histomorphometric findings were observed between the immunosuppressive therapy groups. In addition to the immunosuppressive drugs, male gender and old age negatively affected bone mass. CONCLUSIONS: Both prednisolone and CsA were associated with slight osteoclast stimulation and osteoblast suppression and marked retardation of mineral apposition and bone formation rates. Both drugs were also associated with reduced BMD at the axial and appendicular skeleton, even though a nonsignificant trend to a better-preserved lumbar spine BMD was observed in the CsA group.

Absorptiometry, Photon↗
PubMed2004

Investigation of physical image quality indices of a bone densitometry system.

Osteoporosis is a disease characterized by a loss of bone mass and a deterioration of bone structure. Bone mineral density (BMD) measures bone mass and is currently the method used to diagnose osteoporosis, while computerized radiographic texture analysis (RTA) is being investigated as a measure of bone structure. The GE/Lunar PIXI peripheral bone densitometer (PD) system, which uses dual-energy subtraction to measure BMD, also provides a digital image of the heel or forearm. The goal of our current research was to evaluate the physical imaging properties of the PIXI system (pixel size of 0.2 mm) compared to a Fuji computed radiography (CR) system (pixel size of 0.1 mm) to determine its suitability for texture analysis from image data. Contrast was measured using a series of uniform images covering the useful clinical exposure range. Spatial resolution was characterized by the presampling modulation transfer function (MTF) determined by an edge method. Noise power spectra (NPS) for different exposures were calculated using a two-dimensional Fourier analysis method. The expectation modulation transfer function was measured and combined with the NPS data to calculate the noise-equivalent number of quanta. The slope of the characteristic curve of the peripheral densitometer (PD) system was found to be position dependent across the image, although this dependence was substantially reduced by use of the system's clinical-settings corrections. An MTF value of 0.5 was found at 0.5 cycles/mm for the densitometry system compared to the same value at 1.6 cycles/mm for the CR system. Unlike the CR system, the NPS of the densitometry system was found not to be directionally dependent and did not drop off at higher spatial frequencies.

Absorptiometry, Photon↗
PubMedDate not supplied

Compton scatter with polychromatic sources for lung densitometry.

A mobile lung densitometer using conventional x-ray tubes, NaI detectors, and principles of two-source, two-detector Compton scattered densitometry, is described. The device is capable of one to two per second density measurements from a 45-cm3 volume with a precision of 5%. The expected in vivo accuracy (2%-3%) is determined by using an anthropomorphic phantom with replaceable lung inserts. The unintentional detection of multiple-scattered x rays results in a small density-dependent error. This error is predictable and relatively insensitive to differences in surrounding absorbers such as the chest wall. With this device, dynamic in vivo densitometry of the lung in the clinical laboratory and intensive care unit will be possible.

Absorptiometry, Photon↗