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PubMed1989

Traumatic brain swelling studied by computerized tomography and densitometry.

Two-hundred and fifty-two computerized tomography (CT) scans of 107 patients with head injuries were analyzed. The most frequent consequence of trauma was a diffuse swelling of the brain in 91% of the cases. The severity of brain swelling and its course can be estimated by the compression of (or absence of) the intracranial cerebrospinal fluid space. These observations may be of prognostic value as well. By measurement of the Hounsfield units (HU) in 52 cases the blood or water content in the brain tissues was assessed. An increase in blood content of the tissues (hyperaemia) can account for an increase in Hounsfield values. A decrease in HU suggests brain edema. The density measurements showed that in the first hours and days following head injury, the diffuse brain swelling was caused by severe cerebrovascular congestion in the majority (53%) of the cases. Immediate brain edema without a preceding hyperaemic phase occurs less frequently (32%). Between the 1st and 4th day after injury, edema started to prevail, and between the 5th and 8th day the edematous type of brain swelling was present almost exclusively.

Absorptiometry, Photon↗
PubMed1990

Parametric assessment of myocardial perfusion during interventional cardiac catheterization by means of X-ray densitometry-short-and long-term results.

X-ray densitometric evaluation of digital subtraction angiocardiograms allows an assessment of myocardial perfusion by means of the parameter 'MEAN RISE TIME' (MRT), defined as the time from the onset of local myocardial contrast medium opacification to the point of maximum opacification. Best results are obtained when the response of that parameter is compared before and after stimulation of coronary flow by papaverine. A prolongation of this parameter, especially after papaverine, was indicative of an impairment of myocardial perfusion, when compared to the results of TL-201 scintigraphy. In 50 patients with single vessel coronary artery disease the results of MRT pre and post papaverine before and after coronary angioplasty, as well as after 6 months were evaluated for 204 post-stenotic regions-of-interest. Before angioplasty papaverine induced a significant prolongation of post-stenotic MRT was measured 2.3 s +/- 0.9 s vs 3.1s +/- 0.8s; p less than 0.01), while after successful angioplasty post-stenotic MRT was measured significantly shorter after stimulation of coronary flow (2.6s +/- 1.0s vs. 1.9s +/- 0.9s; p less than 0.01). This indicated an improvement in myocardial perfusion. Nevertheless, 16/50 patients still presented pathological results of post-stenotic MRT after papaverine, although angioplasty was regarded successful. These patients presented a markedly higher rate of restenosis (14/16 patients after 6 months), a higher rate of dissections at the dilation site and a higher rate of dilated vessels, supplying myocardial areas after a Q-wave myocardial infarction. Thus, these results demonstrate the additional information about the short-and long-term outcome of an angioplasty procedure by densitometric myocardial perfusion analysis.

Absorptiometry, Photon↗
PubMed1997

[New developments in parameter-oriented roentgen densitometry perfusion analysis within the scope of heart catheter studies].

X-ray densitometric evaluation of digital subtraction coronary arteriograms allows a qualitative and quantitative detection of contrast medium propagation through the epicardial coronary arteries, the capillary system and the coronary venous system. So-called "time-density-curves" (TDCs) can be generated following Lambert-Beer's law similar to indicator dilution curves by using contrast medium as the indicator. Several time and density parameters can be derived from these TDCs, which are related to local myocardial perfusion. Different animal validation studies have shown the applicability of this concept for in-vivo evaluation of coronary blood flow and myocardial perfusion. Nevertheless, absolute measurement of volumetric coronary blood flow or myocardial perfusion failed. Therefore, relative changes in coronary blood flow or myocardial perfusion in response to pharmacologically induced maximum hyperemia were measured and coronary or myocardial perfusion reserve was calculated as the ratio of hyperemic flow or perfusion divided by baseline values. Despite theoretical attractions for an application during routine cardiac catheterization, this densitometric approach did not get a wide acceptance. Primary reason for this limited use in specialized centers was the time consuming process of densitometric evaluation of the subtraction coronary arteriograms, which require digital cine angiography and necessitates enormous computer hard ware. This main limitation has been overcome since more powerful computer hard ware (processor speed, hard disk space, digitization boards) has become rapidly available during the last years at more moderate pricing and digital techniques today are state of the art in cardiac catheterization laboratories. In addition, soft ware program packages allowed an automatization of the digitization and densitometric evaluation process. These programs include ECG triggered cine image digitization with improved temporal resolution, semiautomatic definition of regions-of-interest including definition of reference regions-of-interest for the detection of background density changes and quality-controlled densitometric parameter analysis. This progress made an application during routine cardiac catheterization feasible. In animal validation studies this improved X-ray densitometric approach for evaluation of local myocardial perfusion was validated versus colour-coded microsphere techniques. The time parameter "rise time", defined as the time from the start of local contrast medium induced density change to its maximum revealed a close correlation (r2 = 0.965) to the results of the microsphere technique over a wide range of perfusion. We have applied this technique before and after coronary interventions such as balloon angioplasty and stenting. Results documented an improvement of poststenotic myocardial perfusion reserve immediately after coronary balloon angioplasty and an additional improvement after adjunct coronary stenting. Only after stenting but usually not after coronary balloon angioplasty alone poststenotic myocardial perfusion reserve gained the intraindividual reference level, measured in a perfusion bed supplied by an epicardial coronary artery without stenoses. These results documented the functional benefit of coronary stenting on poststenotic myocardial perfusion in addition to the well known morphologic benefit with the creation of a larger and more circular conduit.

Absorptiometry, Photon↗
PubMed2000

[CT-assisted volumetry and densitometry of distraction osteogenesis lengthened mandibular areas].

Gradual callus distraction in the correction of hypoplastic areas in the viscerocranial skeleton is an established method due to its efficacy. Whereas functional and esthetical improvements can be seen easily, it is impossible to get the increase of the bony mass right using the distractor scale or by clinical investigation. Only in animal studies can volumetric and densitometric measurements be done directly. By permission of the local ethics commission, in a clinical study, CT data of 24 children (12 unilateral and bilateral hypoplasias each) taken before and after mandibular distraction osteogenesis were used to get information on the amount of created bone and the grade of ossification of the callus at the time of the distractor removal. The CT data were prepared for computer evaluation using software which had been especially developed for this investigation. The quality of the investigation was influenced by disturbed data acquisition (insufficient sedation, Gantry deviation, different axial cuts). Therefore, the estimation of the real increase of bone was not possible, but all in all an increase of the volume could be seen. Using a grey scale analysis, the grade of new bone ossification was over 90% at the time of distractor removal. In our opinion, these results argue against the use of CT scans for the validation of a mandibular distraction. The estimation of the volume is very imprecise, the grade of ossification of the new bone very constant.

Absorptiometry, Photon↗
PubMed1999

[Clinical application of densitometry].

An early diagnosis of osteoporosis and an accurate estimation of treatment outcome are the focus of the radiological efforts. The most commonly applied methods for the evaluation of the peripheral and axial skeleton are dual x-ray absorptiometry, quantitative computed tomography, and quantitative ultrasound. Data of an individual are generally compared to an age-, sex-, and ethically-matched control population. The bone mass measurement predict a patients future risk of fracture and the presence of osteoporosis can be diagnosed even in the absence of prevalent fractures. Fracture risk increases approximately 1.5-2.5 times for every 1.0 standard deviation an individual's bone mass is below the mean peak mass of healthy young individuals (T-score). The choice of the appropriate measurement sites may vary depending on the specific circumstances of the patient. The choice of the appropriate technique in any given clinical circumstance should be based on the strength and limitations of the different techniques.

Absorptiometry, Photon↗
PubMed2001

[Bone densitometry and ultrasound studies of the bone: methods, indications and efficacy].

The amount of calcium-containing crystals in bone tissue can be determined by osteodensitometry. The most common methods use X-ray energy. Two-dimensional approaches (dual-energy X-ray absorptiometry, DXA) have to be distinguished from volumetric measurements (quantitative computed tomography, QCT). Using ultrasound, broadband ultrasound attenuation (BUA) and ultrasound transmission velocity (SOS) can be measured. The results measured are correlated to fracture risk. Thus, considering the criteria of evidence-based medicine, these measurements are suitable for estimating the individual risk for osteoporotic fractures. Measurements can be recommended to persons with evidence for an increased osteoporosis risk based on the patient's clinical data and family history. According to a recommendation of a WHO working group in 1994, definition of osteoporosis can be based on osteodensitometry, which has now been widely accepted. Nowadays, we are able to evaluate the usefulness of osteodensitometry using X-ray energy for patient follow-up and treatment monitoring. However, not enough data are available with regard to ultrasound measurements. The correct use of these methods implies the observance of and attention to quality standards as defined by a working group of the Osteology Association ("Dachverband Osteologie" in the German-speaking countries).

Absorptiometry, Photon↗
PubMed2004

Fundamentals and pitfalls of bone densitometry using dual-energy X-ray absorptiometry (DXA).

Measurement of bone mineral density (BMD) with central dual-energy X-ray absorptiometry (DXA) is the current "gold standard" for diagnosing osteoporosis and for monitoring patients. Errors in demographic information, improper patient positioning, incorrect scan analysis, and mistakes in interpretation can all lead to a wrong clinical decision or action. This paper reviews the fundamentals of positioning, scan analysis, and interpretation for central DXA and highlights some of the common pitfalls that may lead to erroneous results.

Absorptiometry, Photon↗
PubMed2004

A population-based study of osteoporosis testing and treatment following introduction of a new bone densitometry service.

Bone density measurement plays a key role in the initial diagnostic assessment of osteoporosis and in targeting pharmacologic therapies. The impact of access to dual-energy X-ray absorptiometry (DXA) on physician prescribing habits is unclear, however. We were able to directly evaluate the change in physician osteoporosis testing and prescribing following introduction of a DXA testing service in a geographic region that had previously had very limited access. This evaluation was conducted in the province of Manitoba, Canada, which has a provincially based bone density testing program and maintains a population-based bone density database that can be linked with administrative health data sources including drug prescriptions. The province of Manitoba was geographically partitioned into the urban and rural health regions serviced by the new program (urban(new )and rural(new)) and the remaining urban and rural health regions which had relatively unchanged DXA access during this period (urban(control) and rural(control)). Regression models of DXA testing rates and osteoporosis prescription rates were created for all older women in these regions. There was a statistically significant increase in bone density testing and BMD-guided osteoporosis treatment in the urban(new) and rural(new) regions following introduction of the DXA testing service, relative to the control regions. Although the overall rate of empiric postfracture and preventive osteoporosis treatment did not show a specific region effect, when analysis was limited to nonhormonal agents there was a significant reduction in preventive and empiric postfracture treatment in some subgroups of women. These results suggest that the local availability of the bone density testing service led to an increase in objective test-guided therapy with some reduction in the use of empiric and preventive strategies and had a neutral effect on overall use of these agents.

Absorptiometry, Photon↗
PubMed2005

Comparison of quantitative ultrasound of the phalanges with conventional bone densitometry in healthy postmenopausal women.

The objective of this study was to evaluate the utility of the quantitative ultrasound (QUS) technique for the identification of subjects with spine fracture or low bone mineral density (BMD) previously determined by dual energy X-ray absorptiometry (DEXA). QUS of the phalanges in 1,350 postmenopausal women (60-83 years old) was compared with DEXA measurements of four skeletal sites (lumbar spine, total hip, femoral neck, and distal radius) of the same subjects. The contribution of body mass index (BMI) was also assessed. Amplitude dependent speed of sound (AD-SoS), ultrasound bone profile index (UBPI), and BMD of all anatomical regions, except for the spine, decreased significantly with increasing age quartiles. QUS parameters correlated weakly but significantly with BMD ( r =0.21-0.31, p <0.01). After adjustment for BMI, the association between QUS parameters and BMD remained unchanged. UBPI was found to be independent of BMI. All techniques and all sites were able to significantly discriminate fractured from non-fractured subjects by receiver operating characteristic (ROC) analysis (area under the curve [AUC]> or =0.60, p <0.0001). AD-SoS and UBPI showed similar fracture discrimination ability of spine, distal radius and total body BMD in terms of odds ratios, but BMD of the total hip and femoral neck showed the best performance in discriminating fractured from non-fractured subjects. In conclusion, QUS assessment of the phalanges correlates moderately with BMD of all skeletal sites and is able to effectively discriminate fractured from non-fractured subjects.

Absorptiometry, Photon↗
PubMed2000

An update on the diagnosis and assessment of osteoporosis with densitometry. Committee of Scientific Advisors, International Osteoporosis Foundation.

In 1994 the WHO proposed guidelines for the diagnosis of osteoporosis based on measurement of bone mineral density. They have been widely used for epidemiological studies, clinical research and for treatment strategies. Despite the widespread acceptance of the diagnostic criteria, several problems remain with their use. Uncertainties concern the optimal site for assessment, thresholds for men and diagnostic inaccuracies at different sites. In addition, the development of many new technologies to assess the amount or quality of bone poses problems in placing these new tools within a diagnostic and assessment setting. This review considers the recent literature that has highlighted the strengths and weaknesses of diagnostic thresholds and their use in the assessment of fracture risk, and makes recommendations for actions to resolve these difficulties.

Absorptiometry, Photon↗
PubMed2000

Quantitative ultrasound and bone densitometry to evaluate the risk of nonspine fractures: a prospective study.

The ability of quantitative ultrasound (QUS) to estimate the risk of osteoporotic fractures was evaluated in a prospective study over a mean time of 5.47 years in 254 postmenopausal women (mean age 58.06+/-7.67 years). Baseline measurements of ultrasound transmission velocity (UTV) and bone mineral density (BMD) were taken at the distal radius (DR). UTV was also measured at the patella (P). Fifty nonspine fractures due to minor trauma were detected during annual check-ups with an incidence of 3.59/year. Fractures occurred in older women with a lower BMD and QUS. Using Cox regression analysis the relative risk (RR) per 1 standard deviation (SD) decrease in the unadjusted QUS and BMD measurements was: BMD-DR = 3.56, 95% confidence interval (CI) 1.57-8.09; 95% CI 2.08-9.68. The relationship between BMD and QUS variables and fracture risk persisted after adjusting for potential confounders apart from previous fractures, giving the following RR: BMD-DR = 2.99, 95% CI 1.06-8.41; UTV-DR = 3.69, 95% CI 1.18-11.49; UTV-P = 3.89, 95% CI 1.53-9.90. Correcting also for previous fractures, only UTV-P remained an effective predictor of fracture risk even after QUS measurement correction for BMD. Wrist fractures were best related to BMD-DR (RR 7.33, 95% CI 1.43-37.50) and UTV-DR (RR 10.94, 95% CI 1.10-108.45), while hip and ankle fractures were significantly associated only with UTV-P (hip: RR 32.14, 95% CI 1.83-562.80; ankle: RR 17.60, 95% CI 1.78-173.79). The combined use of BMD and QUS is a better predictor of fracture risk than either technique used separately. Comparison of the areas under the receiver operating characteristic (ROC) curves did not show differences in the ability of BMD and QUS to correctly distinguish fractures. In conclusion, QUS predicts fracture risk in osteoporotic women at least as well as BMD. UTV-DR and BMD-DR are good predictors of wrist fractures, while UTV-P is strongly related to hip and ankle fractures. QUS and BMD combined improve the diagnostic ability of each technique individually.

Absorptiometry, Photon↗
PubMed2001

DXA of the hip and heel ultrasound but not densitometry of the fingers can discriminate female hip fracture patients from controls: a comparison between four different methods.

Dual-energy X-ray absorptiometry (DXA) of the proximal femur and in more recent years quantitative ultrasound (QUS) of the heel are the most established methods for assessing hip fracture risk. Measurement of the fingers offers a new approach. We performed DXA of the proximal femur, QUS of the heel and fingers, and radiographic absorptiometry (RA) of the fingers in 87 non-institutionalized women, 65-85 years of age, with a first hip fracture and compared them with 195 randomly selected age-matched controls. Bone mineral density (BMD) of the femoral neck and heel Stiffness Index were significantly lower among cases than among controls (by 15% and 17%, respectively; p < 0.0001), whereas no significant differences were found for finger measurements. When applying the WHO criterion of osteoporosis, 62-98% of the patients were classified as osteoporotic, compared with 19-85% of the controls, depending on method and site. The risks of hip fracture, estimated as odds ratios for every 1 SD reduction in femoral neck BMD, heel Stiffness Index, finger QUS and finger RA, were: 3.6 (95% CI 2.4-5.5), 3.4 (95% CI 2.2-5.0), 1.0 (95% CI 0.7-1.3) and 1.2 (95% CI 0.8-1.6), respectively. Compared with women with normal BMD of the femoral neck, those classified as osteopenic had an odds ratio of hip fracture of 14 (95% CI 2-110), whereas those classified as osteoporotic had an odds ratio of 63 (95% CI 8-501). We conclude that hip DXA and heel QUS have similar capacities to discriminate the risk of a first hip fracture, whereas QUS and RA of the phalanges seem inferior techniques for differentiating female hip fracture patients from controls.

Absorptiometry, Photon↗
PubMed2006

Application of a triage approach to peripheral bone densitometry reduces the requirement for central DXA but is not cost effective.

A method proffered for the interpretation of measurements from peripheral dual energy X-ray absorptiometry (pDXA) is a triage approach to stratify patients into one of three risk categories; (i) high-treat, (ii) medium-refer for central DXA and (iii) low-reassure. The aim of this study was to apply the triage approach to measures from peripheral scanners and risk indices and stratify patients into one of three risk categories (i), (ii) or (iii). 207 post-menopausal women had central DXA from which they were categorised as non-osteoporotic or osteoporotic. Additional peripheral scans of the left calcaneus were performed on three scanners (GE Lunar Achilles and PIXI, McCue CubaClinical). From demographic details four risk indices were calculated and algorithms combining measures from peripheral scanners and one risk index were obtained. All peripheral measures, risk indices and combination algorithms were good at identifying women at risk of osteoporosis (ROC areas: 0.67-0.82). Each tool stratified varying numbers of osteoporotic and non-osteoporotic women into each risk category using the triage approach. One combination algorithm (PIXI & osteoporosis indices of risk (OSIRIS)) performed best by minimising misclassification (10% non-osteoporotic, 10% osteoporotic) and reducing requirement for central DXA to 36%. However the cost of implementing the triage approach for PIXI & OSIRIS was greater (263%) than central DXA (100%) scanning all women. Although the triage approach was an effective tool at identifying women at risk of osteoporosis the unnecessary treatment of non-osteoporotic women in the high risk category make it impractical. Therefore an alternative more cost-effective method has been suggested.

Absorptiometry, Photon↗
PubMed2000

Ultrasound and X-ray-based bone densitometry in patients with anorexia nervosa.

In 20 patients (mean age 23+/-5 years) with anorexia nervosa (AN), bone mass was evaluated by broadband ultrasound attenuation (BUA) of the calcaneus, peripheral quantitative computed tomography (pQCT) of the distal radius, and dual X-ray absorptiometry (DXA) of the lumbar spine and the hip. Compared with 20 age- and sex- matched healthy controls, patients with AN showed marked osteopenia at all measuring sites. Values of BUA (33.0+/-9 dB/MHz vs. 51.0+/-5.7 dB/MHz; P<0.0001) and of BMD of all regions of the hip (e.g., femoral neck: 0.71+/-0.13 g/cm(2) versus 0.89+/-0.07 g/cm(2); P<0.001), lumbar spine (0.82+/-0.15 g/cm(2) versus 1.24+/-0.06 g/cm(2); P<0.003) and total BMD of the peripheral radius (303.2+/-75 g/cm(3) versus 369.4+/-53.2 g/cm(3), P<0.001) were significantly reduced. Calculating a Z-score we found the most prominent differences between AN and controls by BUA of the calcaneus (-3.2+/-1.6), followed by DXA at the lumbar spine (-2.9+/-2.2) and the hip (femoral neck -2.1+/-1.7) and by pQCT at the distal radius (total BMD -1.2+/-2.0). There were highly significant correlations between BUA of the calcaneus and BMD of the femoral neck (r = 0.78, P<0.0001) and lumbar spine (r = 0.75, P<0.0001) as well as between BMD values of the femoral neck and lumbar spine (r = 0.95; P<0.0001). In addition, there were significant correlations (P<0.001) between body mass index (BMI) and the three different measuring sites and between the duration of the disease and BUA (r = 0.5, P<0.05). Our data suggest that BUA of the calcaneus is a valuable tool in the management of osteoporosis. Being a fast, radiation-free investigation method of good acceptance, it may be well suited for an assessment of the skeletal status in patients with AN.

Absorptiometry, Photon↗