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PubMedDate not supplied

CT densitometry of the cochlear capsule in otosclerosis.

Cochlear otosclerosis can be recognized in most cases by high-definition axial and coronal CT images. However, routine technique does not allow a quantitative measurement of the changes. Reported here is a study of cochlear CT densitometry. The densitometric profile of the cochlear capsule was obtained in 10 ears with normal hearing and 50 ears in 27 patients with known clinical otosclerosis and progressive mixed-type hearing loss. Patients with hearing loss had decreased absorption of as much as 60% in comparison to the normal range. In 42 ears with abnormal densitometric profiles, the changes were visibly apparent on the CT images, whereas in eight others, the densitometric profile alone demonstrated decreased absorption.

Adult↗
PubMed1983

Micro-analysis for quinidine in serum by thin-layer chromatography followed by fluorescence densitometry.

We report a thin-layer-chromatographic micro-analysis for quinidine in serum, with detection by fluorescence densitometry. Quinidine is extracted from 20 microL of serum at pH 13 into 3 mL of hexane/acetone solution (80/20 by vol) containing N-(1-naphthyl)ethylenediamine as internal standard. The extract is concentrated and applied to silica-gel-impregnated plates for conventional thin-layer chromatography. Quinidine is identified from its RF value and quantified from the peak-height ratio between quinidine and the internal standard, relative to that of simultaneously extracted serum standards. The proposed assay is sensitive (to 0.2 mg/L), specific for unmetabolized quinidine, precise (between-run coefficients of variation less than 6%), and readily adaptable to large-scale "batch" analysis. Peak-height ratio is linearly related to concentration to at least 20 mg/L. Quinidine concentrations in the serum of patients, as measured by the proposed method (x) and by a traditional double-extraction spectrofluorometric assay (y), were related as follows: y = 0.994x + 0.276 (r = 0.989, n = 20).

Chromatography, Thin Layer↗
PubMed1983

Cooperative effects in the interaction between melittin and phosphatidylcholine model membranes. Studies by temperature scanning densitometry.

The interaction between the peptide melittin from bee venom with multilamellar liposomes of dipalmitoylphosphatidylcholine or egg yolk phosphatidylcholine has been studied by the method of temperature scanning densitometry, yielding information on the specific volume of the association products and on the changes during the thermotropic transition of the lipids. The effects of the interaction were found to be biphasic with respect to melittin concentration; below 10(-3) mol per mol of phospholipid, an increase in transition temperature, abolition of the pretransition, a reduction in the transition volume of the lipids by about 25%, and a nonadditive increase in apparent specific volume of the complexes were observed. Only minor changes in these parameters could be detected between molar ratios of 10(-3) and 10(-2). Above 1 mol % melittin, the transition temperature decreased and the transition volume approached zero around 10 mol %. Since the effects in the low concentration range cannot be accounted for only by local perturbations around the actual sites of interaction, it is concluded that the interaction involves long range effects of melittin affecting several hundreds of phospholipid molecules. The results are discussed in terms of a phospholipid cluster model, whereby the interaction with melittin leads to a cooperative transition of entire clusters to a state of expanded volume. It is suggested that this transition may be important to the activating effect of melittin on membrane enzymes and to enhanced membrane permeability and lysis.

Bee Venoms↗
PubMed1981

A new method for measurement of bone mineral deposition pattern--using dual energy radiographic densitometry method in a single exposure.

Quantitative observations of bone mineral distribution in the maxillo-mandibular bone are of great interest in the clinical field. Radiographic densitometry is the most simple method but the film density is influenced by the X-ray exposure and processing conditions and by the soft tissue layers. This fluctuation can be corrected from the image of the wedge of the reference material simultaneously projected with the object on the same film. There is no other method than the dual energy technique to correct the effect of the soft tissue layer to be applicable in the maxillo-mandibular region. Two radiograms of the object obtained by a different beam quality represent the different X-ray contrast. When the penetrated fractions of the incident X-rays through the object at different energies are obtained from the film density and the characteristic curve of the film and substituted for the first order simultaneous equation whose coefficients are the mass attenuation coefficients of the bone mineral and soft tissue to the X-rays of the respective energy, the bone mineral content is obtained as the solution of the equation in the form of the product of the mineral density and the thickness of the bone (mg/cm2). This paper shows the principle of the method and the results of the experiment which agreed closely with the data obtained by the chemical assessment.

Absorptiometry, Photon↗
PubMed1995

Flow measurements with digital subtraction densitometry in a steady flow experimental model.

Computerized densitometry was applied on digital subtraction series for measuring flow rates, 600 to 2,000 ml/min, in model experiments, using contrast medium as indicator substance. A total of 962 measurements were performed, employing the Stewart-Hamilton dilution technique, as well as direct measurements of velocity of the indicator bolus between 2 measuring sites. Results with the dilution technique were closely correlated with true values, but slightly lower (mean 8%), presumably because of sedimentation of contrast medium. Measurements based on bolus velocity were most accurate when the bolus passage was defined by points near the gravity line of the area under the concentration curve. Use of more easily identified curve points, e.g. the time of curve maximum, tended to yield too high values due to flow laminarity with a high-velocity leading edge of the indicator. Variation in repeated measurements on any single image series was attributed to the low sampling rate.

Absorptiometry, Photon↗
PubMedDate not supplied

[Use of x-ray scanning densitometry and computerized tomography in the evaluation of the effect of tumor treatment].

The paper considers the ways of quantitative assessment of changes occurring in the density and size of a tumorous focus during its treatment (radiation, chemical and hormonal therapies). They are based on scanning densitometric techniques by identifying quantitative integral and differential parameters. The parameters are used to assess tissue alterations by applying computerized tomography. The investigations into the impact of radiation and chemotherapy on tumor tissue in breast and lung cancers have indicated that scanning densitometry and computerized tomography may be used to evaluate therapeutical effects.

Absorptiometry, Photon↗
PubMed1995

[Mass-screenings for osteoporosis using computed X-ray densitometry (CXD): in a mobile unit].

The early diagnosis and treatment of osteoporosis is considered to be important for the prevention of fractures which often cause elderly to become bed-ridden. Computed X-ray densitometry (CXD), a method to measure bone mineral content in the metacarpus II utilizing a simple X-ray image, has been used for mass-screening of osteoporosis, because of its utility and reliability. However, due to its requiring adequate X-ray equipment, this method is often unsuitable for use in small facilities in a remote mountain areas. The use of CXD for osteoporosis screening, was attempted in a mobile unit for tuberculosis screening, by our public health center. The results showed that it is possible to use CXD in combination with a mobile unit, correcting the obtained values according to the radiographic conditions. With this set-up, CXD was used for mass-screening of osteoporosis in a total of 1150 subjects living in mountainous areas of Yoshino-gun, Nara prefecture, and CXD was found to be convenient and effective for mass-screening. The use of CXD in a mobile chest X-ray unit can be expected to be useful for mass-screening of osteoporosis especially in remote mountainous areas having inadequate X-ray equipment.

Absorptiometry, Photon↗
PubMed1995

[Prevention of osteoporosis and role of densitometry].

Osteoporosis is a major public health problem in countries with aging populations, resulting in excess morbidity and mortality. Osteoporosis is defined as a systemic skeletal disease characterized by low bone mass and micro-architectural deterioration of bone tissue, with the consequent increase in bone fragility and susceptibility to fractures. Therefore, the bone loss that precedes fractures is a continuous process that is often mostly irreversible in the aging. The most efficient method of preventing fractures is the prevention of bone loss. The measurement of bone mass and other skeletal characteristics can effectively identify women at high risk for fractures. The measurement of bone mass which can be carried out by osteo-densitometry is now widely available. It is the only clinical data that can provide accurate assessment of individual fracture risk. Treatments exist that will preserve bone mass and presumably reduce fracture risk; therefore there is a place for screening of patients at high risk of fractures. Many studies have shown recently that a reduced bone mass (at least 1 standard deviation below normal) was associated with a more than 100% increased risk of fracture. Thus the initial assessment of bone mass can be used to estimate future fracture risk and to start prevention measures for high risk patients. Primary prevention can be initiated during the adolescence to optimize peak bone mass. Later in life, secondary prevention can prevent excessive bone loss and more specific treatments can prevent postmenopausal and age related bone demineralization. Strategies of prevention should be promoted and validated as general health care strategies.

Absorptiometry, Photon↗
PubMed1994

X-ray bone densitometry in the diagnosis and followup of reflex sympathetic dystrophy syndrome.

OBJECTIVE: To establish bone involvement in reflex sympathetic dystrophy syndrome (RSDS). METHODS: Bone mineral density (BMD g/cm2) and bone mineral content (BMC g) were measured by dual X-ray absorptiometry. We studied 12 patients with phase I RSDS and 18 controls. RESULTS: BMD and BMC were significantly lower in the involved side of patients (28.4 and 45.1%, respectively) compared with the contralateral normal limb. Controls only showed a minimal variation of 2.17% in BMD and 4.38% in BMC between right and left measures. The difference between patients and controls was highly significant (p < 0.001). A second measurement of BMD and BMC was made in 8 patients following treatment (prednisone or calcitonin) and showed increments in both variables, which was significant in the affected limbs (20.1%). CONCLUSION: We believe that X-ray bone densitometry is a highly sensitive and specific technique to evaluate bone mass in patients with RSDS and aid in diagnosis and treatment monitoring.

Absorptiometry, Photon↗
PubMed1994

[Osteoporosis screening--indications for bone densitometry].

Osteoporosis is a major public health problem because of increasing prevalence and the cost of related morbidity, especially fractures of the spine and hip. The perimenopausal evaluation of risk patients by assessment of clinical risk factors and bone-mass measurements are used to select patients for prevention of postmenopausal and age-associated bone loss. The value of bone-mass for prediction of fracture-risk and the clinical significance of bone-densitometry for patient management is reviewed. Four essential clinical indications for bone mass assessment are discussed.

Absorptiometry, Photon↗
PubMedDate not supplied

A fundamental study of a computed X-ray densitometry system for bone mineral measurement in the second metacarpal bone.

The effect of radiographic exposure factors such as the photographic film density, X-ray tube voltage, and focus-film distance on the indices of bone mineral obtained by computed X-ray densitometry (CXD), a newly developed X-ray microdensitometric system, was investigated. sigma GS/D, which corresponded to the bone mineral density divided the integrated bone mineral by the bone width of the second metacarpal bone, was influenced by these exposure factors, whereas MCI, which represented the ratio of the cortical bone to whole bone, was independent of them. Present results indicated that the focus-film distance between 85 and 115 cm, the X-ray tube voltage in 45-60 kV, and a photographic density of lower than 1.82-1.86 of the screen-film combination should be used to assess quantitatively bone mineral of the second metacarpal bone using the CXD system.

Absorptiometry, Photon↗
PubMed1977

[Precision bone densitometry using films without screens (author's transl)].

The new method of indirect bone densitometry proposed evaluates a coefficient of reduction related to the minerals of bone tissue (M.C.R.) by measurement of the blackness of a film without creen exposed to a well-defined monochromatic ray. The M.C.R. is closely related (R=0.98) to the mineral content measured experimentally in bone fragments. It represents a precise evaluation of the "quality" of bone tissue. A.M.C.R. less than normal is seen in hyperosteoidosis syndromes or in the case of increased intraosseous resorption. This relatively simple and cheap method is particularly useful in the detection and observation of osteomalacia, and in bone disorders associated with haemodialysis and hyperparathyroidism.

Absorptiometry, Photon↗
PubMedDate not supplied

The role of DEXA bone densitometry in evaluating renal osteodystrophy in continuous ambulatory peritoneal dialysis patients.

OBJECTIVE: The aims of this study were to assess the clinical utility of total and regional bone densitometry in a large continuous ambulatory peritoneal dialysis (CAPD) population and to determine the clinical, biochemical, and radiographic variables that best identified osteopenic CAPD patients. DESIGN AND PATIENTS: A cross-sectional study was performed on 45 CAPD patients (19 males, 26 females), comprising the total CAPD population at the Princess Alexandra Hospital. MAIN OUTCOME MEASURES: Total body (TB), anteroposterior lumbar spine (APL), femoral neck (FN), Ward's triangle (WT), and skull bone mineral densities (BMDs) were measured using dual-energy x-ray absorptiometry (DEXA) and then correlated with clinical, biochemical, and radiographic indices of uremic osteodystrophy. RESULTS: BMDs were not significantly different from age- and sex-matched reference population data. Considerable regional variation of BMD Z scores were noted between FN (-0.11 +/- 0.23), WT (-0.11 +/- 0.22), and APL (1.22 +/- 0.04) (p = 0.003). APLZ scores were significantly reduced in patients with a previous history of fracture (-1.36 +/- 1.07 vs 0.89 +/- 0.31), bone pain (-0.72 +/- 1.08 vs 1.01 +/- 0.31), or steroid treatment (-0.62 +/- 0.39 vs 1.16 +/- 0.35). Increased BMD Z scores for APL (1.82 +/- 0.57 vs 0.38 +/- 0.29, p < 0.05), FN (0.32 +/- 0.36 vs -0.38 +/- 0.29, p = 0.014), and WT (0.45 +/- 0.38 vs -0.45 +/- 0.26, p < 0.05) were found in patients with radiographic hyperparathyroid bone disease. Both APL BMD Z scores and skull BMDs were weakly correlated with PTH (r = -0.33, p < 0.05 and r = -0.33, p < 0.05, respectively) and with CAPD duration (r = 0.30, p < 0.05 and r = -0.30, p < 0.05). Generally, however, total body and regional BMDs were poorly related to age, renal disease type, dialysis duration, renal failure duration, serum aluminum, calcium, phosphate, alkaline phosphatase, osteocalcin, and parathyroid hormone. CONCLUSIONS: We conclude that the prevalence of osteopenia is not increased in CAPD patients. Clinical and biochemical parameters do not reliably predict BMD measurements, but prior steroids and bone symptoms are major risk factors for important bone loss. Although DEXA can reliably detect osteopenia in different skeletal regions, its usefulness in detecting osteodystrophy is limited by the confounding effects of superimposed hyperparathyroid osteosclerosis, which increases BMD.

Absorptiometry, Photon↗
PubMed1996

[Bone densitometry].

Recently, several methods for measurement of bone density have been developed. Among them, dual X-ray absorptiometry (DXA) is now considered to be a standard method in bone densitometry. In most cases, values by DXA measurement reflect bone strength and thus measurements of lumbar spine and femoral neck by DXA are used for diagnosis of osteopenia or osteoporosis. In several clinical trials of new drugs, measurement of DXA proved to be very useful. Other methods such as DXA for os radius or os calcaneus are also useful for screening of general osteopenia and quantitative ultrasound is widely used for mass-screening of osteoporosis because of its convenience. Radiographic absorptiometry is also a convenient method, which can be performed only by taking an X-ray photograph with an aluminum phantom. Quantitative computed tomography (QCT) is a method which enables measurement of trabecular true bone density as well as an analysis of trabecular structure and peripheral QCT, aimed for measurement of peripheral bones, is also expected to be a sensitive method to monitor therapeutic responses. Since several methods are now available, it is important to choose a method which is the most suitable for the purpose of each bone mineral measurement.

Absorptiometry, Photon↗
PubMed1996

[Importance of the clinical profile in the postmenopausal osteoporosis screening by densitometry].

In order to test the impact of a given risk profile on the incidence of osteoporosis which could justify BMD measurement, and that of a low risk profile which could render it unnecessary, BMD was measured in 217 women under 72 in whom menopause had occurred at least 6 years previously and who corresponded to one of the two following profiles: high risk (A, n = 102) = BMI < 27 kg/m2, with no estrogen replacement treatment, and with at least one of the following risk factors: BMI < 20, early menopause, positive family history, no dairy products associated with tobacco consumption (> 10 cigarettes/day for > 20 years and/or alcohol consumption of > 0.5 l wine/day during > 10 years, corticotherapy of > 6 months, rickets, anorexia nervosa. Low risk (B, n = 115) = absence of characteristics of group A, BMI > 27 kg/m2 with (B+, n = 24) or without estrogen therapy (B-, n = 91). BMD was measured by DXA in 4 centers using Lunar or Hologic equipment. Results were expressed in % of the mean of the respective young adult control groups. As expected, BMD was significantly different in these two subgroups of the population. Osteoporosis was diagnosed (BMD < 75% = < -2.5 SD, according to WHO) in 72% of group A, and in 17% (B+) and 19% (B-) respectively of group B. There was no difference between the various risk factors in group A concerning their impact on BMD, but concerning incidence, low BMI and early menopause were the most frequent. The high risk profile of group A seems to justify densitometry, since it leads to the diagnosis of osteoporosis in over 70%. However, the protective profile of group B does not exclude osteoporosis (risk still 20%); only in severe obesity (BMI > 33) does it drop to 1%.

Absorptiometry, Photon↗
PubMed1996

[Evaluation of linear attenuation coefficients for enamel and dentin using film densitometry].

The linear attenuation coefficient (mu) is an important coefficient in the study of diagnostic radiology. The mu values of dentin and enamel were rarely reported because they are thin and tightly connected to each other and are difficult to measure by thermoluminescent dosimeters or ion chambers. In this work, we used film densitometry to measure the radiation dose before and after they transmitted the 2 mm thickness tooth slice and used this data to calculate the mu values of enamel and dentin. The results show that the mu values of enamel at 70, 80, 90kVp are 2.97 +/- 0.71, 2.85 +/- 0.07, 2.70 +/- 0.16 cm-1, respectively. The mu values of dentin at 70, 80, 90kVp are 2.12 +/- 0.92, 1.81 +/- 0.23, 1.89 +/- 0.42 cm-1, respectively. The mu values may be affected by the equivalent energy of an x-ray generator operated under different kVp conditions and also by the density and calcification degree of the enamel and dentin. Nevertheless, the results obtained in this study still can severe as a reference for researchers.

Dental Enamel↗
PubMed1977

[Standard linear x-ray densitometry as a method of intravital determination of the mineral saturation of bone tissue].

The method of standard linear roentgenodensitometry represented in the work in comparison with other methods of photo- and densitometry eliminates, to a certain extent, the influence of many side factors affecting the investigation results and allows to establish a real intravital content of phosphorous calcium salts in the bone tissue. The method in question gives an objective quantitative information on the condition of mineral saturation in the human skeleton, can and must find a wide application both for elucidation of the limits of, so called, normal mineral saturation of human bones at different ages and to study bone system adaptation for different environment influences.

Absorptiometry, Photon↗
PubMed1996

[Cross sectional study of the relationship between bone density to diet and life style using ultrasound bone densitometry].

The relationship between bone density to diet and life style was investigated in pre- and postmenopausal women in Kyoto Prefecture in 1994 by a cross-sectional study. Bone densities of 453 women aged 30-86 years were measured by ultrasound bone densitometry. History of pregnancy and delivery, menstruation, medical history, bone and arthral symptoms, life style, food intake frequency, current and past intake of dairy products, and physical activity were examined by self-administered questionnaire. Analysis of covariance and multiple-regression analysis were performed to determine the relation between bone density and life style adjusted for age and obesity index among 151 premenopausal women (PRE), 244 postmenopausal but not sedentary (under 65 years of age) women (POST), and 58 sedentary (older than 65 years of age) women (SED). The results were as follows; 1) A marked age-related decline in bone density was observed at 45-55 years of age. The correlation coefficient between age and bone density was significant at -0.65 (p < 0.01). 2) Obesity index and bone density were positively correlated in each group. 3) Among the PRE group women, there was no relation between life style and bone density. Those who experienced bone fractures tended toward low bone density. Among the POST group, time since menopause, exercise, and current milk intake were significantly correlated with bone density. In the SED group, women with arthralgia showed significantly lower densities. 4) From multiple-regression analysis, age, obesity index, and milk intake during childhood were shown to be related to bone density in each group.

Adult↗