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PubMed1967

Quantitative Analyses of Certain Enteric Bacteria and Bacterial Extracts: II. Discrimination of Sonic Extracts by Interfacial Densitometry of Precipitin Systems.

Bacterial extracts prepared by ultrasonic disruption were reacted with both narrow- and broad-spectrum reference (homologous) and cross-reacting (heterologous) precipitins produced in rabbits. Quantitation of the reaction was obtained by densitometry of the antigen-antibody interface. Comparisons were made of sonic extracts from various starting populations all equated to the same nitrogen concentrations, and of various nitrogen levels derived from five bacterial population levels prepared separately. Sources of error are probed to show under what circumstances cross-reactions would be of greater magnitude than reference ones. The feasibility was shown of using quantitative densitometry of the interface combined with broadly reacting precipitins to identify bacteria on an intergeneric and interspecies scale. Problems associated with the use of absorbed or monospecific precipitins are explained.

Journal Article↗
PubMed2001

Influence of age and disease severity on high resolution CT lung densitometry in asthma.

BACKGROUND: Low attenuation areas (LAA) on computed tomographic (CT) scans have been shown to represent emphysematous changes in patients with chronic obstructive pulmonary disease (COPD). However, the significance of LAA is still controversial in patients with asthma. This study was undertaken to assess the usefulness of lung CT densitometry in the detection of airspace enlargement in association with asthma severity. METHODS: Forty five asthmatic subjects and 15 non-smoking controls were studied to determine the influence of age, pulmonary function, and asthma severity on mean lung density (MLD) and the relative area of the lung showing attenuation values less than -950 HU (RA(950)) on high resolution CT (HRCT) scans. RESULTS: In asthmatic patients both MLD and RA(950) correlated with parameters of airflow limitation (%FEV(1), FEV(1)/FVC, %FEF(25-75)) and lung volume (%TLC, %FRC, %RV), but not with lung transfer factor (%TLCO, %TLCO/VA). The results of HRCT lung densitometry also correlated with patient age and severity of asthma. CONCLUSIONS: Decreased CT lung density in non-smoking asthmatics is related to airflow limitation, hyperinflation and aging, but not with lung transfer factor.

Adult↗
PubMed1996

Changes in lung volume and volume of emphysema after unilateral lung reduction surgery: analysis with CT lung densitometry.

PURPOSE: To evaluate changes in volume of the lungs and volume of emphysema after unilateral lung reduction surgery (ULRS) by using computed tomographic (CT) lung densitometry. MATERIALS AND METHODS: Twenty-eight patients underwent CT before and 3 months after ULRS. With use of a density mask software program and a three-dimensional graphics workstation, CT scans were analyzed to define the volume of the lungs and the volume of emphysema. Pre- and postoperative mean CT numbers were determined. RESULTS: After ULRS, the surgically reduced lung volume decreased 22%, and the intact opposite lung volume increased 4%. Emphysema in the surgically reduced lung decreased 14% and was unchanged in the intact opposite lung. Mean CT numbers in the surgically reduced lung increased 26 HU but were unchanged in the intact opposite lung. CONCLUSION: The effects of ULRS on each lung can be evaluated by using CT lung densitometry and a three-dimensional graphics workstation. ULRS reduces emphysema and lung volume in the surgically reduced lung without statistically significant worsening of contralateral emphysema at 3 months.

Adult↗
PubMed1998

Air trapping in children: evaluation with dynamic lung densitometry with spiral CT.

PURPOSE: To evaluate the feasibility of the use of a simple method of dynamic lung densitometry with spiral computed tomography (CT) to differentiate air trapping from compensatory hyperinflation in children. MATERIALS AND METHODS: Eight children (mean age, 4 years 2 months) who had focal areas of radiolucency on chest radiographs underwent spiral CT (5-second acquisition time, fixed table position) during quiet breathing. Data were reconstructed with 0.7-second temporally overlapping scans. Lung attenuation in selected regions of interest was plotted against time. RESULTS: In children with air trapping (n = 5), mean lung attenuation (+/- 1 standard deviation) in hyperlucent regions was -815 HU +/- 52, and mean respiratory excursion was 28 HU +/- 7. In patients with compensatory hyperinflation (n = 4), mean lung attenuation was -664 HU +/- 31, and respiratory excursion was 84 HU +/- 15. The differences were statistically significant (P = .001 for mean attenuation; P < .0005 for respiratory excursion). CONCLUSION: Dynamic spiral CT lung densitometry is a quick, simple method for quantitative confirmation of the presence of air trapping and differentiation from compensatory hyperinflation.

Absorptiometry, Photon↗
PubMed2005

[Bone mineral turnover and bone densitometry in patients with a high-risk diet: hyperphenylalaninemia and galactosemia].

INTRODUCTION: Patients with any type of congenital metabolism error are at risk for developing osteoporosis. To gain further insight into the physiopathology of this disease, we studied bone mineral turnover in 10 children with hyperphenylalaninemia, seven with phenylketonuria and six with galactosemia. Oral intake was strictly controlled and the children followed recommendations for physical exercise. MATERIAL AND METHOD: Markers of bone resorption (hydroxyproline and pyridinoline in urine samples) and markers of bone formation (levels of osteocalcin and C-terminal procollagen peptide type I) were analyzed. Bone mineral density was analyzed by ultrasound densitometry. RESULTS: A non-significant reduction in bone densitometry with respect to the normal population was observed. Bone mineral turnover was slightly diminished in patients with phenylketonuria but was within the normal range in patients with hyperphenylalaninemia and galactosemia. CONCLUSION: Adequate control of dietary intake of both proteins and minerals, as well as a healthy lifestyle, can prevent the development of significant alterations in bone mineralization.

Adolescent↗
PubMed1996

Digital ventriculography: valid on-line calculation of cardiac volumes by corrected computer densitometry in coronary artery disease.

Cardiac catheterization facilitates the assessment of left ventricular function in coronary artery disease (CAD). Digital left ventriculography offers the potential for an on-line quantitative determination of left ventricular end-diastolic volume (LVEDV) and left ventricular end-systolic volume (LVESV). These are routinely evaluated by the area-length method (ALM), which is considered as a standard. Densitometry (DENS) is an alternative method but may lead to calculated underestimations. The purpose of this study was to investigate the accuracy of corrected DENS for LVEDV and LVESV in comparison with ALM in single-plane 30 degrees right anterior oblique (RAO) projection. The computer densitometric correction equation was adapted from the linear regression analysis (y = 0.86x + 2.73) in cardiac models and applied to the analysis of digital left ventriculograms in patients suffering from CAD. The study of cardiac models yielded highly significant correlations (r > or = 0.9; P < or = 0.001) between true volumes and both DENS and ALM. DENS and ALM correlated highly significantly (r > or = 0.9; P < or = 0.001) with a low standard error of estimate (SEE) of +/-9.5 mL. The comparison of DENS and ALM in 44 patients' digital ventriculograms exhibited highly significant (r = 0.74; P < or = 0.001) correlations for noncorrected and corrected LVEDV. Systematic underestimation by DENS of LVEDV disappeared after correction and SEE decreased from +/-23.7 to +/-19.2 mL. DENS and ALM correlated highly significantly for LVESV (r = 0.78; P < or = 0.001; SEE +/- 15.6 mL +/- 13.5 mL, respectively) after correction. Following correction, mean values for DENS increased from 116 +/- 32 to 132 +/- 37 mL (LVEDV) and 50 +/- 22 to 55 +/- 25 mL (LVESV). For ALM, mean values decreased from 159 +/- 35 to 127 +/- 28 mL (LVEDV) and 55 +/- 25 to 46 +/- 21 mL (LVESV). This study shows that LVEDV and LVESV can be reliably analyzed on-line by corrected computer densitometry. Method-related errors of both DENS and ALM are present and account for minor volume deviations.

Aged↗
PubMed2002

Bone strength at clinically relevant sites displays substantial heterogeneity and is best predicted from site-specific bone densitometry.

In this study we test the hypotheses that mechanical bone strength in elderly individuals displays substantial heterogeneity among clinically relevant skeletal sites, that ex situ dual-energy X-ray absorptiometry (DXA) provides better estimates of bone strength than in situ DXA, but that a site-specific approach of bone densitometry is nevertheless superior for optimal prediction of bone failure under in situ conditions. DXA measurements were obtained of the lumbar spine, the left femur, the left radius, and the total body in 110 human cadavers (age, 80.6 +/- 10.5 years; 72 female, 38 male), including the skin and soft tissues. The bones were then excised, spinal and femoral DXA being repeated ex situ. Mechanical failure tests were performed on thoracic vertebra 10 and lumbar vertebra 3 (compressive loading of a functional unit), the left and right femur (side impact and vertical loading configuration), and the left and right distal radius (fall configuration, axial compression, and 3-point-bending). The failure loads displayed only very moderate correlation among sites (r = 0.39 to 0.63). Ex situ DXA displayed slightly higher correlations with failure loads compared with those of in situ DXA, but the differences were not significant and relatively small. Under in situ conditions, DXA predicted 50-60% of the variability in bone failure loads at identical (or closely adjacent) sites, but only around 20-35% at distant sites, advocating a site-specific approach of densitometry. These data suggest that mechanical competence in the elderly is governed by strong regional variation, and that its loss in osteoporosis may not represent a strictly systemic process.

Absorptiometry, Photon↗
PubMed2004

Accuracy and precision of PIXImus densitometry for ex vivo mouse long bones: comparison of technique and software version.

Many densitometric studies in mice assess bone mineral density (BMD) at specified regions of interest, often using ex vivo specimens. In the present study, we sought to determine the precision and accuracy of ex vivo densitometry of mouse bones, comparing two software versions and two data acquisition techniques. The newer software allows manual adjustment of the threshold value for bone, improving the ability to analyze bone edges correctly. Root mean square standard deviations were 2-3 mg/cm2, with coefficients of variation ranging between 3% and 5% for femora and humeri and between 6% and 7% for radii. The regression coefficients for bone mineral content as a function of ash mass were near 1 for femora and humeri, but considerably lower for radii. Coefficients of determination were inversely related to bone size, with R2 values exceeding 0.9 at the femur, 0.8 at the humerus, and ranging between 0.3 and 0.6 at the radius. We found that our instrument has a position artifact, with BMD and bone mineral content dependent on the specimen's coordinates in the scanned field. Our findings establish the limitations of ex vivo densitometry with the PIXImus and support our recommendation that investigators seek position artifacts in their instruments.

Absorptiometry, Photon↗
PubMed1996

The effects of age, sex, lung size, and hyperinflation on CT lung densitometry.

OBJECTIVE: To test our proposal that, on high-resolution CT scans, the relative area of the lung with attenuation values lower than -950 H (RA950) can be a measurement of pulmonary emphysema, we examine the possible influences of sex, age, lung size, and hyperinflation on CT lung densitometry. SUBJECTS AND METHODS: The RA950 and the mean lung density (MLD) were measured in 42 healthy subjects (21 men, 21 women) from 23 to 71 years old, in 10 patients with asthma before and after a bronchial challenge test, and in seven patients with asthma who have irreversible hyperinflation (defined as an increased total lung capacity). RESULTS: In the healthy subjects, we found no significant difference between sexes and no significant correlation between age and the MLD, but we found a significant correlation between age and the RA950. In addition, we found a significant correlation between the total lung capacity expressed as absolute values and both the RA950 and the MLD. We did not observe any effect of acute airflow limitation either on the MLD or on the RA950 in the asthmatic subjects after the bronchial challenge test. Likewise, we observed no change in either the MLD or the RA950 in the asthmatic subjects with chronic hyperinflation. CONCLUSION: This study shows that CT lung densitometry is influenced by total lung capacity and, to a lesser degree, by age. Thus, this study suggests that normal CT attenuation values for the lung should be established.

Absorptiometry, Photon↗
PubMed2002

Use of computed tomographic densitometry to quantify contrast enhancement of compressive soft tissues in the canine lumbosacral vertebral canal.

OBJECTIVES: To evaluate computed tomography (CT) densitometry as a technique for quantifying contrast enhancement of compressive soft tissues in the canine lumbosacral vertebral canal and to determine whether the degree of contrast enhancement can be used to help predict tissue type or histopathologic characteristics. ANIMALS: 29 large breed dogs with lumbosacral stenosis. PROCEDURE: Contrast-enhanced CT of L5-S3 was performed by use of a previously described protocol. At each disk level, CT densities of a water-filled syringe, epaxial muscles, and 4 vertebral canal locations were measured. Mean tissue enhancement was calculated by vertebral canal location, using water-filled syringe enhancement as a correction factor. Corrected CT enhancement was compared with tissue type, degree of tissue inflammation, and degree of tissue activity. RESULTS: Intravenous contrast administration of contrast medium significantly increased CT densities of water-filled syringes and epaxial muscles. Corrected CT enhancement of vertebral canal soft tissues at stenotic sites was greater than at nonstenotic sites. There was no association between enhancement and tissue type for any vertebral canal location. There was no correlation between enhancement and degree of tissue inflammation. There was a correlation between enhancement and tissue activity in the dorsal vertebral canal only. CONCLUSIONS AND CLINICAL RELEVANCE: A water-filled syringe is a useful calibration tool for CT density measurements. The degree of tissue contrast enhancement, measured by CT densitometry, can be helpful for predicting the location of compressive soft tissues in dogs with lumbosacral stenosis. However, it is of limited value for predicting compressive soft-tissue types or histopathologic characteristics.

Animals↗
PubMed1999

[Quality control in bone densitometry].

Bone densitometry is a biological measurement which must comply to the usual rules of quality control. Calibration phantoms are available and must be regularly measured. Results may be interpreted by visual inspection or by estimating drift percentage. Different calculation methods have been proposed. A rigorous procedure is required when replacing densitometry devices. Simple and regular controls can assure the reliability of the technique.

Absorptiometry, Photon↗
PubMed2000

[Acoustic densitometry for quantification of renal allografts microcirculation and microstructure].

OBJECTIVE: To establish a new method for observing renal allografts microcirculation and microstructure with acoustic densitometry (integrated backscatter, contrast, second harmonics). METHODS: 27 patients with renal allografts were investigated by Doppler, IBS, contrast and second harmonics. Renal allografts failed age in 5 patients 20-61 years. Intravenous injection of SHU-508A was given, compared with pre-injection by quantitative assessment of acoustic densitometry (AD) of renal microstructure. RESULTS: There was a significant difference in the peak intensity, the area under the curve and the half-time of wash-out between pre-injection and injection contrast agent. The wish-in and wish-out curve was shown in a peak shape. The renal allografts with acute rejection were significantly lower than the control group in AD (P < 0.05). No contrast opacification of renal microstructure was present in 5 failed renal allografts and the wish-in and wish-out curve appeared in a straight line shape. CONCLUSION: AD is safe, and efficient in assessing renal allografts microstructure. It more sensitive in detecting allograft complication such as rejection than Doppler.

Adult↗
PubMed2003

[Results of bone scintigraphy, densitometry and radiography in secondary hyperparathyroidism in patients with chronic renal failure].

UNLABELLED: Secondary hyperparathyroidism occurs frequently in patients with chronic renal failure (CRF). Cardinal manifestations in patients with secondary hyperparathyroidism involve also skeletal changes. Hence the aims of our studies were detailed investigations of bones using isotope scintigraphy (99mTc-MDP), densitometry (DEXA-Lunar) and radiography, in a group of 34 patients with advanced secondary hyperparathyroidism with very high PTH serum concentrations. Bone mineral density of radius amounted to 74.14 +/- 14%, and 29 cases had osteoporosis, and 5 cases osteopenia. Bone mineral density of vertebral bodies was 85.6 +/- 10.5% was within osteopenia range in 16 cases, osteoporosis in 11 cases and was normal in 6 cases. Bone scintigraphy revealed: excessive tracer uptake in cranial vault, mandible, spine and lateral parts of the sacral bone. Tracer accumulation was decreased in soft tissues and absent in kidneys. Roentgen studies revealed changes typical to secondary hyperparathyroidism: acroosteolysis in 60% of cases, subperiosteal resorption in 43% of cases, calcifications in 20% of cases, cortical fibrosis in 35% of cases and osteoporosis in 85% of cases. CONCLUSIONS: 1. Bone mineral density is markly decreased in the radius and to a lower extent in the vertebral bodies, hence DEXA studies of radius are most appropriate for evaluation of mineral bone density. The differences in BMD are characteristic of hyperparathyroidism, both primary and secondary. 2. In most patients bone scintigraphy shows characteristic abnormalities, thus scintigraphy is helpful in the diagnosis of advanced secondary hyperparathyroidism. 3. In x-ray studies osteoporosis is frequently observed, other signs of secondary hyperparathyroidism are not so common and appear in later stage of disease than decreased bone mineral density in densitometry.

Absorptiometry, Photon↗
PubMed2005

[Quantitative computerized tomographic densitometry for the evaluation of osteoporosis risk in menopausal women].

OBJECTIVES: The aim of the study was retrospective analysis of osteoporosis risk in menopausal women. DESIGN: Retrospective analysis of bone mineral density of 2733 women was performed between 1997 - 1999 year. MATERIAL AND METHODS: Retrospective analysis of bone mineral density of 2733 women aged 16 to > 68 by quantitative computer tomography densitometry of L2-L4 vertebrae. RESULTS: The most rapid bone mineral density loss concerns postmenopausal women aged 59 to 63. By 18.7% comparing to the group 54-58 years and 59-63. CONCLUSIONS: 82% women who undergo densitometry is in the group over 44 years old. Bone mineral density loss is depending on age and concerns postmenopausal women, mainly.

Absorptiometry, Photon↗
PubMed2005

[Verification of the indication for densitometry examination in the population of patients referred by the home doctors].

In the paper we present the analysis of the women population referred to the specialist center by the home doctors. In the population due to the indication: age more then 50, menopause or recent bone fracture densitometry examination of the lumbar spine in screening for osteoporosis was performed. Along with the examination the women completed the self reported questioner, with the questions addressing epidemiological data being referred in the literature to be osteoporosis related. The aim of the study is the revision of the indication for the osteoporosis screening. The acquired data were verified and analyzed as for it's relation to the densitometry outcomes. In the analyzed indication for osteoporosis screening only two factors (age above 50 and resent fractures) showed the statistical correlation with the osteoporosis.

Absorptiometry, Photon↗
PubMed2006

[Bone densitometry for the diagnosis of osteoporosis: the Belgian reimbursement paradox].

Osteoporosis is considered as a major Public Health issue, in most developed countries. Bone mineral density assessment is the single best predictor of the future fracture risk for an individual. Belgium has the highest number of bone densitometers, per million habitants, in Europe. However, densitometry is not yet reimbursed in Belgium. This situation is rather paradoxical since the demonstration of a prevalent vertebral fracture or of a low bone mineral density is requested to obtain the reimbursement of drugs to be used for the management of osteoporosis. Hopefully, Belgium will soon be online with the requirement s of the European Commission, suggesting to make bone densitometry accessible, through reimbursement.

Absorptiometry, Photon↗
PubMedDate not supplied

[Relation between laboratory tests and densitometry values: characterization of the baseline profile in a perimenopausal population at anamnestic risk for osteoporosis].

The relationship between usual laboratory indexes of bone metabolism and dual photon densitometry in perimenopausal women at anamnestic risk for osteoporosis are studied. One hundred and twenty five women, with one or more risk factors for osteoporosis, have been investigated by: plasma calcium, phosphorus, osteocalcin, ALP-bone-isoenzyme, PTH, and 24 hours urinary calcium and hydroxyproline, besides dual photon densitometry of lumbar spine. Laboratory indexes are indicated as "above normal values" and, within the range of normality, "at lower limits", "average values", and "at upper limits". More than 90% of patients show laboratory findings at the upper limits. Furthermore, 46% of them show both hydroxyproline greater than 20 mg/24 h and urinary calcium greater than 200 mg/24 h; 81.7% osteocalcin greater than 7.00 ng/ml and plasma calcium greater than 4.9 mEq/l; 87.9% osteocalcin greater than 7.00 ng/ml and urinary calcium greater than 200 mg/244; 86.4% densitometric values less than 0.700 g/cm2 and osteocalcin greater than 7.00 ng/ml. Our at risk population shows a wide agreement among the laboratory indexes, to indicate an increased bone metabolism.

Absorptiometry, Photon↗
PubMed1991

Morphometry, densitometry and pattern analysis of plastic-embedded histologic material from urothelial cell carcinoma of the bladder.

An image analysis method of grading histologic sections of bladder carcinoma was tested. The method was new in four respects. First, for fixation of the biopsies a coagulant fixative was used. Second, 2-microns plastic sections were used to ensure the reproducibility of nuclear imaging. Third, a new stereologic approach was used for calculation of the nuclear volume and DNA content. Fourth, for the classification rule the morphometric, densitometric and texture features were used in concert. The IBAS 2000 instrument was used for the measurements. Texture analysis of the chromatin patterns was performed using Markovian texture features. Using discriminant analysis, of 22 parameters, 2 morphometric, 2 densitometric and 3 texture features were selected for the classification rule. With them, 89% of the bladder carcinomas were correctly classified into the three grades. All grade III tumors were classified correctly. Among the features tested, the densitometry of the DNA had the highest F values. All of the grade III tumors and 45% of the grade II tumor group had DNA histograms indicating aneuploidy. This study showed that plastic-embedded material is well suited to morphometry and densitometry and can be used for quantitative grading of bladder carcinoma.

Carcinoma, Transitional Cell↗