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At least 1,351 records · Page 75Linked to original sources
PubMed1992

[Densitometry determination of coronary flow rates using digital subtraction angiography (DSA). Methods, multiple examinations and interobserver comparison].

In invasive diagnostics of coronary heart disease (CHD), three each DSA examinations of the left coronary artery were performed at 2-minute intervals in ten patients subsequent to conventional examination by means of a left-side cardiac catheter and coronary angiography. While placing the patient in left anterior oblique (60 degrees) position, 6 ml each of ionic contrast medium were injected mechanically with a flow of 4 ml/sec at a pacemaker-induced heart rate of 100/min. Examinations were performed according to a standard mode and were evaluated via the image analysing computer APU of the Philips DVI-DSA system. The purpose of this approach was to analyse the examination conditions and a new improved evaluation algorithm in respect of stability, feasibility and sensitivity. 17 series were evaluated by two examiners who were independent of each other. The interobserver differences obtained were between 5% at the time of maximum density (Tmax) and 25% with exponential downward slope of the curve (lambda), with reference to the median value in each case. Scatter of the individual examinations around the median value of all the three DSA runs is 11 to 17% with the exception of lambda. A significant rise can be proven in the RCX region for the curve slope rise parameters "slope" and "RFL2". We interpret this as a genuine 1.2 to 1.3 fold regional flow increase due to the residual effect of the contrast medium. At the same time, this can be interpreted as an indicator for the good sensitivity of the method.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

[A comparison between quantitative computed tomography and dual-energy densitometry in the study of patients at risk for postmenopausal osteoporosis].

A comparison was made of the densitometric values of the lumbar vertebrae obtained using quantitative Computed Tomography, and those measured with dual energy X-ray absorptiometry. A selected group of patients at increased risk of developing postmenopausal osteoporosis was chosen: women who had undergone bilateral oophorectomy in child-bearing years. The densitometric data recorded revealed a considerable decrease in bone mass, in particular in the cancellous portion of the vertebrae (a 17% change in the quantitative Computed Tomography value and a 13% decrease in that of dual energy X-ray absorptiometry a one year after oophorectomy). Although quantitative Computed Tomography and dual energy X-ray absorptiometry demonstrated a similar trend in bone mass reduction, given the marked and unexplained variability of both absolute values and percent variations, it was impossible to establish a clinically useful mathematical correlation between the two sets of data. Quantitative Computed Tomography is the densitometric procedure of choice to study metabolic bone disorders that involve mainly tha cancellous portion, such as postmenopausal osteoporosis. Nevertheless, given its accuracy, short execution time, lower radiation dose required, as well as good sensitivity in the measurement of bone mass variations, it would seem that dual energy X-ray absorptiometry could also find a place in clinical studies on postmenopausal osteoporosis.

Absorptiometry, Photon↗
PubMed2004

[Bone mineral density in patients with Crohn's disease. Contribution of bone densitometry in 53 cases].

Fifty-three patients with Crohn disease were included in a prospective study. Bone mineral density was measured at the femoral neck and lumbar spine by dual-energy X-ray absorptiometry. Ten variables were analyzed in search of an association with bone demineralization; Age, sex, nutritional state, smoking, duration of the disease, hormonal status, inflammatory syndrome, site of disease: ileal, colic or ileocolic, accumulated doses of corticoids and intestinal resection. A bone demineralization was observed in 58.5% of cases. The ileum location and the corticothérapie were predictives of bone demineralization. Crohn disease is a disease at high risk of bone demineralization. Predictors of the bone loss were smoking, long duration of the disease, ileal site and systematic corticotherapy.

Absorptiometry, Photon↗
PubMed2004

Efficiency of polylactide/polyglycolide copolymers bone replacements in bone defects healing measured by densitometry.

Healing of bone defects is the most frequent cause of failure in surgical treatments of an odontogenic ostitic processes. The aim of this study was to determine successfulness in healing of bone defects after implantation of alloplastic co-polymer-polyglycol bone implant. A group of 45 cases with periradicular ostitic processes were examined. The densitometric measurements were taken from radiovisiographic dental x-ray images. Patients were observed throughout a period of one year. The results obtained were analyzed and presented graphically. Thirty-eight patients (84%) were treated successfully, and seven patients (16%) showed unsuccessful healing of the bone defects. The results obtained indicate that polyglycol copolymer bone implants can be successfully used in a treatment of odontogenically caused bone defects. Their fundamental advantage is a slow biodegradation, which ensures a more suitable area for the apposition of a new bone in the defect, simple application in clinical work and the possibility of a mutual combination of all three available forms.

Absorptiometry, Photon↗
PubMed2000

Periprosthetic bone densitometry of the hip: influence of prosthetic design and hydroxyapatite coating on regional bone remodelling.

OBJECTIVE: To determine the influence of femoral hip prosthesis design and composition on regional periprosthetic bone remodelling as a function of time in asymptomatic patients. MATERIALS AND METHODS: Bone mineral density (BMD) changes surrounding two differently designed porous-coated femoral prostheses (S-ROM, n=111; and Multilocki, n=62) were determined serially over a 24 month interval. There was a subset of patients with Multilock implants that were coated with a 50 micron film of hydroxy-apatite (n=23) over the porous surface. Seven Gruen zones defined the periprosthetic bone regions (LUNAR ORTHO software). Inclusion criteria were primary implants, Harris hip scores >or=95 and no radiographic evidence of loosening. RESULTS: For the S-ROM femoral component, at 6 months all zones showed a significant decrease in BMD relative to the immediate postoperative baseline measurements; mean loss varied from 4.3% to 17.4%. At 24 months mineral change varied from -10.8% to +1% for Gruen zones 1 to 6. Gruen zone 7, the calcar, differed in that it was the site of greatest mineral loss, attaining a mean of 17% at 24 months, and it was also significantly greater than the losses registered in the other zones at that time point. For the Multilock, maximal mineral losses were registered at zones 1 and 7. There were significant differences in mineral losses between the S-ROM and Multilock implants in zones 1, 2 and 3 at 24 months; S-ROM losses of 7.3%, 10.8% and 3.5% respectively, compared to Multilock losses of 23.8%, 15.9% and 6.9% respectively. Comparison of hydroxyapatite coated and uncoated Multilock implants demonstrated significantly less loss in the coated implants in zones 1 (greater trochanter) and 7 at 24 months. Coated losses were -16.9% and 11.3% for zones 1 and 7, respectively, whereas uncoated losses were 23.8% and 20.5% respectively.

Journal Article↗
PubMed2005

Cost effectiveness analysis of using quantitative ultrasound as a selective pre-screen for bone densitometry.

It has been suggested that quantitative ultrasound (QUS) could be used as a selective population pre-screen, to maximise the cost effectiveness of referral for dual energy X-ray absorptiometry (DXA) assessment of bone mineral density (BMD). We set out to examine how such an approach might perform in the assessment of women who were referred by general practitioners for DXA via the open access service in Cardiff. In 115 women aged 40-80 (mean 69) years we used DXA to measure BMD at lumbar spine and hip, and QUS to measure broadband ultrasound attenuation (BUA) in the heel. A bottom-up approach was used to estimate the costs of DXA and QUS. We examined the cost effectiveness of using QUS as a pre-screen, only referring subjects for the more expensive DXA assessment if BUA were less than a pre-determined threshold. The unit costs of pencil-beam DXA and QUS were approximately 44 UK pounds and 16 UK pounds respectively. We identified a BUA threshold of 60 dB/MHz as the most cost effective, and calculated a sensitivity of 81% and specificity of 89% in identifying those subjects whom DXA assessment subsequently identified as having osteoporosis. At the BUA threshold of 60 dB/MHz, pre-screening saved 969 UK pounds at the expense of missing ten women with osteoporosis as diagnosed by DXA. Therefore the cost per additional woman with osteoporosis identified using DXA alone was only 97 UK pounds. QUS assessment does not appear to have a significant cost effective benefit as a pre-screen for DXA in the studied population. A QUS pre-screen would be cost effective only if this investigation could be performed at a substantially lower cost.

Absorptiometry, Photon↗
PubMed2006

Spine bone densitometry in asthmatic children treated with high dose corticosteroids: correcting for racial discrepancies.

PURPOSE: Our hypothesis is that the use of standards based on Caucasian children will under-estimate the incidence of abnormal bone density in African American children. MATERIALS AND METHODS: Eighty-two African American and 80 Caucasian asthmatic children classified as high-dose inhaled corticosteroid users comprised the study population. Bone mineral density measurements were compared to reference standards, based on Caucasians, to calculate Z-values. Regression analysis was used to compare Z-values derived from the race-specific and Caucasian standards for 32 African American children. The derived regression analysis equation was then applied to the entire African American population to determine the incidence of abnormal bone density. RESULTS: The asthmatic Caucasian mean spine bone density was significantly less than the normal standards (p < .001), but the African American mean spine bone density was not, despite the high-dose steroid use. Using the Caucasian standards, Caucasians were significantly more likely to have abnormal bone density detected (p < 0.015). Regression analysis of the 32 children with available race specific standards resulted in the following equation: Z African American= Z Caucasian-0.86. The number of African Americans with abnormal bone density detected using the regression equation was not significantly different than the Caucasian children (p > 0.12). CONCLUSIONS: Asthmatic African Americans treated with high-dose inhaled corticosteroids had denser bones than Caucasians. Caucasian standards can be adjusted using a regression equation.

Absorptiometry, Photon↗
PubMed1991

[Standardization of bone tissue densitometry].

Traditional X-ray technique have proved be scarcely reliable in determining bone tissue mineral status especially when comparing X-rays made at different times. The use of ergal or hydroxylapatite samples has been put forward to resolve this problem since, when used together with computerised imaging techniques, they allow a more precise and quantitative analysis to be made. The velidity of tyhis technique is confirmed by an experimental trial on animal bone.

Absorptiometry, Photon↗
PubMedDate not supplied

[X-ray bone densitometry. Study of in vitro and in vivo reproducibility].

We studied the reproducibility in vitro and in vivo of a new bone densitometer (HOLOGIC QDR-1000, software version 4.03) which uses an x-ray source at two different levels of energy. Short and long term coefficient of variation (c.v.) in vitro is less than 0.5%. In vivo c.v. is less than 1% in normal body weight subjects and less than 3% in obese subjects. The ingestion of 500 mg of calcium element did not modify bone mineral density (BMD), while 1000 mg determined an increase of BMD equal to 2.6% and 1.5% in the two subjects examined. The increase of water thickness on a three femoral heads phantom caused a progressive reduction of bone mineral content (BMC) and BMD until 12.1% less than basal value and an increase of c.v. from 0.1% to 1%. The addition of oil to water at different percentages determined a slight increase of both BMC and BMD, till 3.5% with 66% of oil in water, if compared with the values obtained with water alone. The reduction of soft tissue around the bone determined a progressive decrease of BMD reaching 3.4% less than basal value when the reduction was 30%.

Absorptiometry, Photon↗