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PubMed2000

An audit of current clinical practice in the management of osteoporosis in Nottingham.

BACKGROUND: Osteoporosis is now recognized by the World Health Organization and the Department of Health as a major public health problem. In 1994, the Advisory Group on Osteoporosis (AGO), set up by the Department of Health, recommended that Health Authorities and general practitioner fundholders should purchase bone densitometry services for the management of osteoporosis. The aims of this study were to assess the criteria for requests for bone densitometry from primary care in comparison with the AGO recommendations and to compare the numbers of patients referred with a low-trauma osteoporotic fracture with the expected number of fractures in the Nottingham area. METHODS: Patient referral data and requests for bone densitometry were collected by case note review of all new patients referred to the Nottingham Osteoporosis Clinic over a 12 month period and then compared with the AGO recommendations. The patients referred with a history of a low-trauma fracture were then compared with the expected incidence of fractures, calculated using age-sex-specific fracture incidence data applied to the Nottingham population Census statistics. RESULTS: A total of 413 patients were referred to the Osteoporosis Clinic for bone densitometry. Almost two-thirds of the patients had no clinical indicators for requests for scanning, in comparison with the AGO recommendations. Seventy-seven patients were referred with vertebral fracture, 12 hip, 20 colles and 26 other fractures. Using age-sex-specific fracture incidence data applied to the Nottingham population Census statistics, it was estimated that the expected incidence of hip fractures would be 812, distal forearm fractures 514 and vertebral fractures presenting to clinical attention 625. This represents 1.5 per cent of the total hip fractures, 3.9 per cent distal forearm and 12.3 per cent vertebral actually presenting to the Osteoporosis Clinic. CONCLUSION: Bone densitometry was requested in up to 60 per cent of the patients with no clinical risk factors to warrant bone densitometry. Osteoporosis-related fractures remain unrecognized in clinical practice. The majority of patients do not receive specialist assessment despite being at high risk of future fracture. Further steps are necessary to educate health care professionals in primary and secondary care, but more importantly, to direct services more proactively in those at high risk of future fracture.

Absorptiometry, Photon↗
PubMed2006

Osteoporosis assessment and treatment in older patients who have sustained a hip fracture.

BACKGROUND AND AIMS: Currently fracture sufferers are not being assessed or treated for osteoporosis. Osteoporosis guidelines differ in their secondary prevention recommendations, with the Scottish Intercollegiate Guideline Network (SIGN) advocating bone densitometry in all fracture patients and anti-resorptive treatment only if evidence-based criteria are confirmed, but the National Institute of Clinical Excellence (NICE) technology appraisal recommends treatment for all older females without this bone densitometry confirmation. We aimed to determine the rate of referral for bone densitometry, the numbers achieving SIGN criteria for anti-resorptive therapy, and the rate of osteoporosis treatment in patients with hip fracture METHODS: A retrospective review of all patients older than 65 years who had sustained a hip fracture in Tayside between April 2003 and July 2005 was performed RESULTS: Only 8.6% of hip fracture patients underwent bone densitometry, of which 90.6% of females older than 75 years met SIGN criteria for anti-resorptive treatment. 74.3% of all patients referred for bone densitometry were treated with an anti-resorptive agent, compared to only to 12.7% of the large majority group who were not assessed for osteoporosis CONCLUSION: Osteoporosis investigation and therefore treatment remains sub-optimal in hip fracture patients. Almost all females, older than 75 years, with a hip fracture met evidence-based criteria for anti-resorptive treatment. NICE guidance, recommending anti-resorptive treatment without bone densitometry confirmation of reduced bone mineral density, should maybe be implemented for this specific group of patients in an attempt to increase osteoporosis treatment rates.

Absorptiometry, Photon↗
PubMed1984

Quantitation of type I and III collagens using electrophoresis of alpha chains and cyanogen bromide peptides.

The methods of quantitating the relative amounts of type I and III collagens in samples containing crosslinked collagen chains were evaluated using electrophoresis of alpha chains and cyanogen bromide peptides. The densitometry areas of the alpha I(I) chains from type I collagen and the alpha I(III) chains from type III collagen were reduced because of the failure of the crosslinked chains to dissociate. However, the ratios of the unit densitometry areas of these chains (area of chain/micrograms type I or III collagen loaded) were constant for type I and III collagens prepared from the same samples of tissue. A calibration factor, which was the same for dermis and mitral valve, was derived to convert the densitometry area ratios to the weight ratios of type I to III collagens. In contrast, the densitometry areas of the alpha I(I) CB8 (type I collagen marker) and the alpha I(III) CB5 (type III collagen marker) were not reduced by crosslinked collagen chains. A calibration factor was also derived to convert the ratios of the densitometry areas of the marker peptides to weight ratios of type I to type III collagens. Almost identical results were obtained when electrophoresis of alpha chains and of cyanogen bromide peptides was used with these calibration factors to quantitate the relative amounts of type I and III collagens in tissue extracts which contained different amounts of crosslinked chains.

Child, Preschool↗
PubMed2001

Body fat measurement among Singaporean Chinese, Malays and Indians: a comparative study using a four-compartment model and different two-compartment models.

This cross-sectional study compared body fat percentage (BF%) obtained from a four-compartment (4C) model with BF% from hydrometry (using 2H2O), dual-energy X-ray absorptiometry (DXA) and densitometry among the three main ethnic groups (Chinese, Malays and Indians) in Singapore, and determined the suitability of two-compartment (2C) models as surrogate methods for assessing BF% among different ethnic groups. A total of 291 subjects (108 Chinese, seventy-six Malays, 107 Indians) were selected to ensure an adequate representation of age range (18-75 years) and BMI range (16-40 kg/m2) of the general adult population, with almost equal numbers from each gender group. Body weight was measured, together with body height, total body water by 2H2O dilution, densitometry with Bodpod and bone mineral content with Hologic QDR-4500. BF% measurements with a 4C model for the subgroups were: Chinese females 33.5 (sd 7.5), Chinese males 24.4 (sd 6.1), Malay females 37.8 (sd 6.3), Malay males 26.0 (sd 7.6), Indian females 38.2 (sd 7.0), Indian males 28.1 (sd 5.5). Differences between BF% measured by the 4C and 2C models (hydrometry, DXA and densitometry) were found, with underestimation of BF% in all the ethnic-gender groups by DXA of 2.1-4.2 BF% and by densitometry of 0.5-3.2 BF%). On a group level, the differences in BF% between the 4C model and 2H2O were the lowest (0.0-1.4 BF% in the different groups), while differences between the 4C model and DXA were the highest. Differences between the 4C model and 2H2O and between the 4C model and DXA were positively correlated with the 4C model, water fraction (f(water)) of fat-free mass (FFM) and the mineral fraction (f(mineral)) of FFM, and negatively correlated with density of the FFM (D(FFM)), while the difference between 4C model and densitometry correlated with these variables negatively and positively respectively (i.e. the correlations were opposite). The largest contributors to the observed differences were f(water) and D(FFM). When validated against the reference 4C model, 2C models were found to be unsuitable for accurate measurements of BF% at the individual level, owing to the high errors and violation of assumptions of constant hydration of FFM and D(FFM) among the ethnic groups. On a group level, the best 2C model for measuring BF% among Singaporeans was found to be 2H2O.

Absorptiometry, Photon↗
PubMed2000

Myocardial architecture, texture and left ventricular heterogeneity in the pulsed Doppler tissue imaging pattern.

The regional contribution for the global ventricular functional performance is complex and heterogeneous, the myocardial texture could reflect this particular aspect, during the phases of myocardial contraction and relaxation. The objective of our clinical study was to evaluate the relationship between the segmental myocardial velocity pattern by Doppler tissue imaging and the ultrasound characteristics of the left ventricular myocardium analysed by computerized ultrasound densitometry with the calculation of its intensity (dB), in a population of 22 subjects without clinical history of cardiovascular pathology, 50% female gender, mean age 43 +/- 11 years (19-66 years). In the methodology of study, the left ventricular myocardium was divided in 16 segments, according with the transthoracic echocardiographic recommendations of the American Society of Echocardiography (A.S.E.). During one cardiac cycle interval, the ultrasound characteristics of the left ventricular myocardium were evaluated continuously and in a quantitative manner, applying the computerized ultrasound densitometry method on the gray scale images of the ventricular myocardium, with the sample size identical to the myocardial wall thickness. The peak (Vmax-cm/sec) and mean (Vm-cm/sec) pulsed Doppler tissue imaging velocities, individuals, segmental and a total velocities, contraction and relaxation velocities of the left ventricular myocardium were obtained immediately after the computerized ultrasound densitometry analysis. Ultrasound densitometry and Doppler tissue imaging data were obtained in a total number of 352 left ventricular myocardial segments. Using the multiple linear correlation matrix analysis, the ultrasound intensity registered inverse significant correlation's with the Doppler tissue imaging Vmax and Vm for the systolic "s" wave in the total segments and each one of them (r = -0.66; p = 0.001; interval 2-18 cm/sec; r = -0.52 to -0.70) and with the early diastolic "e" wave (r = -0.42; p = 0.01; interval 2-19 cm/sec; r = -0.35 to -0.55). Direct correlation's were obtained for the computerized ultrasound densitometry intensity and Doppler tissue imaging Vmax and Vm of the late diastolic "a" wave in the total number of the left ventricular myocardial wall segments and in each one of them (r = 0.51; p = 0.01; interval 1-17 cm/sec; r = 0.42 a 0.66). We conclude that in our study and under physiological conditions of myocardial performance, a direct correlation was obtained between the ultrasound characteristics of the ventricular myocardial imaging and its velocities of contraction and relaxation. These facts reflect the close relationship between left ventricular myocardial structure and function, analyzed by the new ultrasound Doppler technologies.

Adult↗
PubMed1991

Osteoporosis and bone density measurement methods.

Recent technologic advances in bone mineral densitometry have resulted in increasingly precise and accurate methods of estimating bone mineral density. Dual-photon absorptiometry has been made obsolete by the introduction of dual-energy radiography, a development that is likely to result in more widespread use of densitometry. The technique allows a reproducible, low dose examination of the spine, hip, and total body. Although capable of selectively measuring trabecular bone, quantitative computed tomography is currently limited to the spine, and the reliability of the technique varies from center to center. Single-photon absorptiometry and ultrasound experimental methods are of limited value because only peripheral skeletal sites can be examined by these techniques. Although invaluable in epidemiologic research and in limited clinical situations, the role of densitometry in the management and prevention of involutional osteoporosis has not been established. The evidence indicates that densitometry is unlikely to be effective as a selective screening procedure. Long-term prospective studies are needed to clarify the role of densitometry in osteoporosis management.

Bone Density↗
PubMed2002

Management of glucocorticoid-induced osteoporosis in patients with rheumatoid arthritis: rates and predictors of care in an academic rheumatology practice.

OBJECTIVE: To examine rheumatologists' management practices for patients with rheumatoid arthritis (RA) taking glucocorticoids seen at one academic medical rheumatology practice. METHODS: All patients diagnosed with RA making at least 2 visits to the practice who were noted to be taking glucocorticoids on an index visit in January or February 1999 were included in a retrospective chart review. RESULTS: Of the 623 eligible patients identified with RA, 236 patients were taking glucocorticoids at their index visit and were included in this study. The mean daily dosage of prednisone (or its equivalent) was 8.8 mg and the mean duration of use during the 2-year chart review was 15.4 months. Twenty-three percent of the study population underwent bone densitometry, and 42% were prescribed a medication that reduces bone loss (not including calcium and/or vitamin D). Calcium and/or vitamin D were noted on the medication lists of 25% of patients. Factors associated with not undergoing bone densitometry in adjusted logistic models included male patient sex and premenopausal status in women. No physician factors were significantly related to performing bone densitometry. Variables associated with not receiving prescription treatment of osteoporosis were male patient sex, premenopausal status, and having at least 1 comorbid condition. CONCLUSION: Patients with RA taking oral glucocorticoids did not routinely undergo bone densitometry and/or receive prescription medications for osteoporosis. Men and premenopausal women were less likely to undergo bone densitometry and to receive a prescription medication for osteoporosis than postmenopausal women. Interventions to improve detection and prevention of glucocorticoid-induced osteoporosis are necessary.

Academic Medical Centers↗
PubMed2004

Regional volumetric coronary blood flow measurement by digital angiography: in vivo validation.

RATIONALE AND OBJECTIVES: There are well-known limitations to the use of visual estimation to assess the severity of coronary artery disease and luminal stenosis. This is especially true in the case of an intermediate coronary lesion (30%-70% diameter stenosis), where coronary arteriography is very limited in distinguishing ischemia-producing intermediate coronary lesions from non-ischemia-producing ones. For this reason, a functional measure of stenosis severity is desirable. The goal of this study is to validate a video densitometry technique for quantitative assessment of regional volumetric coronary blood flow. MATERIALS AND METHODS: Coronary arteriography was performed in eight swine (body weight, 25-50 kg) after power injection of contrast material into the left main coronary artery. Phase-matched subtracted images were used to quantify regional coronary blood flow using a video densitometry technique. The in vivo regional flow measurements were validated using a transit time ultrasound flow probe. RESULTS: In 44 measurements, the ultrasound (Q(US)) and video densitometry (Q(VD)) regional flow measurements were related by Q(VD) = 0.98 Q(US) + 0.11 mL/min (r = 0.98). The results of mean regional coronary blood flow measurements for repeated coronary arteriograms of the first (Q(VD1)) and second (Q(VD2)) measured flows were related by Q(VD1) = 1.04 Q(VD2) + 0.05 mL/min (r = 0.97). CONCLUSIONS: A video densitometry technique for quantification of regional coronary blood flow was validated using a swine animal model. The results demonstrated the feasibility and potential utility of the video densitometry technique for accurate measurement of regional coronary blood flow, in vivo. This study provides an angiographic method that can potentially be used to evaluate intermediate coronary lesions during routine coronary arteriography.

Absorptiometry, Photon↗
PubMed2003

Unresectable pulmonary malignancies: CT-guided percutaneous radiofrequency ablation--preliminary results.

PURPOSE: To assess whether percutaneous radiofrequency (RF) ablation of unresectable pulmonary malignancies is safe and technically feasible and to evaluate the usefulness of computed tomographic (CT) nodule densitometry as a tool for following up tumors after ablation. MATERIALS AND METHODS: Twelve patients (seven men and five women; mean age, 60.6 years) with unresectable disease (because of poor lung reserve or multifocality) underwent nodule CT densitometry and CT-guided percutaneous RF ablation of 19 lung tumors (six [32%] tumors were adenocarcinoma, one (5%) was large cell carcinoma, two (10%) were bronchoalveolar carcinoma, four (21%) were colorectal carcinoma, and six (32%) were sarcoma less than 50 cm2 in area (range, 0.25-35.00 cm2). No patients had symptoms of their disease before RF ablation. Follow-up CT densitometry was scheduled for 1, 3, 6, and 12 months after RF ablation. Lesions were evaluated for change in area and contrast enhancement at follow-up CT. RESULTS: RF ablation was well tolerated by all patients. Intraprocedural complications included 12 cases of pneumothoraces (two patients required chest tube placement, while 10 were asymptomatic and required no further treatment), two cases of pleural effusion, and two cases of moderate pain (one case during and one case both during and after the procedure). Mean follow-up was 4(1/2) months (range, 1-12 months). In the eight patients with 3-month follow-up, lesion size increased in two and remained stable in six. Mean contrast enhancement, however, decreased from 46.8 HU (range, 19-107 HU) at baseline to 9.6 HU (range, 0-32 HU) at 1-2-month follow-up. In the one patient with 12-month CT densitometry follow-up, lesion enhancement was less than 50% of that at baseline, and lesion diameter remained stable. CONCLUSION: These preliminary results show that percutaneous RF ablation is a safe and technically feasible management option for unresectable pulmonary malignancies. CT densitometry may have potential for future use as a noninvasive method of following up tumors after RF ablation.

Adenocarcinoma↗
PubMed2005

Does a distal forearm fracture lead to evaluation for osteoporosis? A retrospective cohort study in 147 Danish women.

In postmenopausal women, a low-trauma distal forearm fracture is a risk factor for osteoporosis and future fracture, which indicates osteoporosis follow-up according to prevailing guidelines. We decided to determine how often women over 45 yr presenting with a low-trauma distal forearm fracture to a Danish emergency department during a 1-yr period were followed up for osteoporosis. We performed a retrospective review of hospital records and we sent the women and their general practitioners (GPs) questionnaires regarding the follow-up undertaken in primary care. Finally, we invited the women for a densitometry to estimate the prevalence of osteoporosis. From May 1, 2001 to April 30, 2002, 147 women presented with a low-trauma distal forearm fractures. According to the review of hospital records, none of the women was referred for bone densitometry or spine X-rays. One woman had calcium and vitamin D supplementation (CVDS) prescribed and two were recommended to consult their GPs for osteoporosis follow-up. In primary care, 12 women were referred for densitometry or spine X-rays, and 11 women started CVDS after the fracture. Women with risk factors for osteoporosis in addition to the forearm fracture were not more likely to be referred for densitometry or spine X-rays (p = 0.10). The prevalence of osteoporosis was 24% among the 79 women who underwent densitometry. Our study demonstrates a low use of available measures to reduce the risk of future fracture in women with a low-trauma distal forearm fracture, and it emphasizes the need to decide on a local level how to provide osteoporosis follow-up for women with fragility fractures.

Absorptiometry, Photon↗
PubMed2001

[Diagnosis of osteoporosis in the elderly; an overview.].

Measurement of bone mineral density (BMD) is the basis of the diagnosis of osteoporosis. WHO classification of osteoporosis is based on dual energy X-ray absorptiometry (DEXA) using the BMD of young women (20-30 years) as the reference value (T-score). For clinical purpose it is better to use age-matched control (Z-score) to evaluate future fracture risk in relation to other individuals of the same age. A further facility of the new bone densitometry technique is the option of vertebral morphometry, which makes it possible to assess previous vertebral fractures with similar precision as conventional X-ray. Such an assessment is of the greatest importance as patients with previous fractures and low BMD have several fold increased risk of further fractures and benefit most from medical therapy. There are errors of accuracy in all bone densitometry techniques and also in the interpretation of the data. Osteoarthritis in the lumbar spine, common in the elderly, creates false increment in BMD as measured by DEXA. For this reason the hip is the site of choice for BMD measurement in the elderly, especially as it predicts best femoral fractures, a major concern in the elderly. Quantitative computed tomography has the advantage of measuring separately cancellous and cortical bone. Ultrasound of bone (at present mostly in calcaneus) may provide new measures of bone fragility. Ultrasound has the advantage of no exposure to radiation and the equipment is portable. Although useful bone ultrasound cannot replace bone densitometry in the diagnosis and monitoring of therapy. Biochemical bone markers are not useful in the diagnosis of osteoporosis, but they can be useful in deciding on intervention and in monitoring the efficacy of treatment. Biochemistry is videly used in the differential diagnosis of secondary osteoporosis. History and physical examination are insufficient in diagnosing osteoporosis, but they are of utmost importance in finding individuals of high risk who might benefit most from undergoing bone densitometry. History and physical examination are also important in targeting other investigations to exclude secondary forms of osteoporosis. Although bone densitometry is usually necessary for the diagnosis of osteoporosis intervention by drugs should be based in addition on general assessment of the patient taking notice of other important independent risk factors for fractures.

English Abstract↗
PubMed1998

Bone atrophy in complex regional pain syndrome patients measured by microdensitometry.

PURPOSE: To determine the usefulness of quantitative measurement of bone atrophy in the diagnosis and the long-term follow-up of patients with complex regional pain syndrome (CRPS). The bone-sparing effect of a 5-hydroxytriptamine (5-HT2) antagonist was also studied. METHODS: Bone mass was measured by computerized micro-densitometry at the middle position of the second metacarpal. The effect of repeated stellate ganglion blocks (SGBs) three times per week with mepivacaine (n = 11), administration of a 5-HT2 antagonist (sarpogrelate hydrochloride, 300 mg a day po) (n = 12), and combined therapy (n = 10) were compared by micro-densitometry and conventional visual analogue scale (VAS) for analgesia after three months of treatment. RESULTS: In CRPS patients, metacarpal index (cortical bone thickness), maximum bone density (cortical bone density), minimum bone density (trabecular bone density), and average bone density were reduced on the affected side (14.1%, 12.1%, 25.0% and 19.3% respectively). The rate of reduction in bone mass correlated with the duration of the disease (P < 0.05). Therapy with the 5-HT2 receptor antagonist (with or without repeated SGBs) decreased pain intensity (from 6.10 to 3.81 with SGB, from 6.30 to 2.91 without SGB, respectively; P < 0.01) and bone atrophy evaluated by micro-densitometry (P < 0.05). In contrast, repeated SGBs alone reduced pain intensity (from 6.30 to 2.91; P < 0.01) but did not ameliorate bone atrophy. CONCLUSION: Bone micro-densitometry is useful in the assessment and follow-up of CRPS and for evaluation of treatment. The 5-HT2 antagonist, sarpogrelate hydrochloride, is a promising treatment for CRPS patients.

Administration, Oral↗
PubMed1997

Assessment of fracture risk by bone density measurements.

Bone densitometry in its various applications has become an established tool for the diagnosis of osteoporosis. Bone density has been shown to be significantly associated with the risk of future fracture in many prospective studies. From long-term prospective studies, it can be concluded that peak bone density and bone loss are important predictors of subsequent fracture, and that fracture can be predicted over a longer period. Bone density predicts fracture even in elderly persons aged 80 years and older. However, in this population some fractures, such as the cervical hip fracture, may be more strongly influenced by other risk factors. The differences between the various densitometric techniques in predicting future osteoporotic fracture of any type is marginal. However, it seems that bone density measurements at the site of fracture do perform better than measurements at other sites. There is no evidence that measuring a second site improves the diagnostic capability of bone densitometry. The association between bone density and future fracture is partly independent of age and other significant predictors of fracture such as falls, cognizance, and mobility. Quantitative ultrasonic measures of bone quality have been shown to have a predictive capability that is comparable to that of bone density. From the perspective that bone densitometry and quantitative ultrasound independently predict fractures, these measures actually seem complementary rather than competitive. Simple geometric measures of the bones such as hip axis length and vertebral depth may be derived from images of bone densitometry scans and are also predictive of hip fracture or vertebral fracture independently of bone density. Using the current knowledge of the association between bone density, quantitative ultrasound, geometric properties, and fractures as well as clinical risk factors, new models for fracture prediction can be developed for future application in clinical practice for the benefit of the individual patient.

Adult↗
PubMed1999

Effect of body build on the validity of predicted body fat from body mass index and bioelectrical impedance.

The objective of this study was to test whether differences between body fat percent (BF%) measured by densitometry and BF% predicted from body mass index (BMI) or bioimpedance (BIA) can be explained by differences in body build. Weight, height, sitting height (leg length), arm length, skeletal widths, BIA, bone mineral content from dual-energy X-ray absorptiometry, and BF% from densitometry were measured in 90 apparently healthy, young adult subjects (age range 18-31 years). The BMI was calculated and BF% predicted from BMI, age, and sex. BF% was also predicted from BIA. BF% measured by densitometry was 29.3 +/- 5.0% for women and 14.6 +/- 5.1% for men. BF% predicted from BIA (27.1 +/- 6.7% in women, 19.0 +/- 6.0% in men) was significantly different from measured values in both sexes. BF% predicted from BMI (25.9 +/- 2.2% for women, 15.6 +/- 2.4% for men) was only significantly different from BF% from densitometry in women, not in men. In both sexes skeletal widths, especially elbow width, were related to the prediction error of BF% from BMI, confirming the hypothesis that BF% predicted from BMI underestimates BF% in persons with a relatively slender body build or frame. The prediction error of BF% from BIA was found to be related to the length of the arms and legs, confirming the hypothesis that BIA overestimates BF% in persons with relatively long limbs.

Adipose Tissue↗
PubMed2001

Quantification of coronary artery lumen volume by digital angiography: in vivo validation.

BACKGROUND: Coronary artery lumen volume may potentially have several advantages over the commonly used variables, such as percent stenosis or minimal lumen diameter, in the assessment of coronary artery disease. The goal of this study is to validate a quantitative assessment of lumen volume using a video densitometry technique. METHODS AND RESULTS: Coronary arteriography was performed in 9 swine (body weight 20 to 55 kg) after power injection of contrast material (2 mL/s for 3 seconds) into the left main coronary artery. Phase-matched subtracted images were used to quantify regional lumen volume by a video densitometry technique. The in vivo volume measurements were validated by a polymer cast of the coronary arterial tree made at physiological pressure. The measured cast volume (V(C)) and video densitometric regional lumen volume (V(VD)) were related by V(VD)=1.06 V(C)-0.01 mL (r=0.99). The root mean square and systematic errors for these measurements were 17% and -3%, respectively. CONCLUSIONS: A video densitometry technique for quantification of coronary lumen volume was validated both in vitro and in vivo in a swine animal model. The present results demonstrated the feasibility and potential utility of the video densitometry technique for accurate measurement of regional lumen volume in vivo. This study contributes to the understanding of the angiographic methods used for the assessment of coronary artery disease and indicates that this technique can potentially be used for quantification of diffuse coronary artery disease during routine coronary arteriography.

Angiography, Digital Subtraction↗
PubMed2004

Standards and guidelines for performing central dual-energy x-ray absorptiometry in premenopausal women, men, and children.

The Canadian Panel of the International Society for Clinical Densitometry has developed standards in order to establish the minimum level of acceptable performance for the practice of bone densitometry in Canada. Previously, this group addressed the performance of densitometry in postmenopausal women. This report addresses the use of densitometry in men, premenopausal women, and children with a focus on dual-energy X-ray absorptiometry.

Absorptiometry, Photon↗
PubMed1994

Comparative evaluation of body composition methods and predictions, and calculation of density and hydration fraction of fat-free mass, in obese women.

The objective of this study was to apply a three-component model of body composition to a group of obese women in order to (a) establish the relative value of a number of readily available prediction equations by comparison of the extent of agreement between these predictions and body composition estimated by the model and other reference methods and (b) evaluate density and hydration of fat-free mass. Estimation of body composition was carried out by reference methods and prediction equations and the usefulness of these prediction equations for application specifically to obese women was evaluated. The subjects were 15 obese, otherwise healthy, Caucasian women (body mass index > 30kg/m2 and body fat > 40% of body weight, as originally determined using densitometry). Body composition was estimated using three established reference methods (deuterium dilution which primarily measures total body water, densitometry for body fat and fat-free mass and total body potassium) and the three component model constructed from deuterium dilution and densitometry. Density and hydration fraction of the fat-free mass were calculated from appropriate values obtained as integral parts of the three-component model. In addition, body composition was predicted from various prediction equations incorporating weight and height (some of which include a factor for age), from a number of prediction equations utilizing different terms involving the same whole-body bio-electrical impedance measurement and from measurements of skinfold thickness and near infrared interactance. The extent of agreement between methods was assessed using bias and 95% limits of agreement. Mean density of fat-free mass was found to be 1.104 kg/l (s.d. 0.006kg/l) with a range of 1.093 to 1.117 kg/l, and mean hydration fraction was 0.712 (s.d. 0.016) with a range of hydration from 68.2% to 75.1% (all values were calculated from the three-component model). In general, the reference methods (densitometry, deuterium dilution, the three-component model and total body potassium) demonstrated better agreement with each other than with the prediction methods or equations. In these obese women, skinfold thickness measurements are apparently less reliable (large bias and 95% limits of agreement) than in the lean subjects of a variety of other studies. A majority of interpretations of weight and height measurements and predictions incorporating impedance/resistance measurements are apparently not applicable to this group of obese women, due to large values for both bias and 95% limits of agreement.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed2000

Quantitative reverse transcription-polymerase chain reaction to study mRNA decay: comparison of endpoint and real-time methods.

Four quantitative reverse transcription-PCR (RT-PCR) methods were compared to evaluate the time course of mRNA formation and decay. Mouse fibroblasts (NIH 3T3) transfected with the human beta-globin open reading frame/c-myc 3'-untranslated region chimeric gene under control of the c-fos promoter (fos-glo-myc) were used for serum-inducible transcription. The amount of fos-glo-myc mRNA, relative to beta-actin, was measured by quantitative, RT-PCR at various times following the addition of serum to serum-starved fibroblasts transfected with the chimeric gene. Both endpoint (band densitometry and probe hybridization) and real-time (SYBR green and TaqMan) PCR methods were used to assay the identical cDNA. The real-time methods produced a 4- to 5-log dynamic range of amplification, while the dynamic range of the endpoint assays was 1-log. The real-time and probe hybridization assays produced a comparable level of sensitivity that was considerably greater than band densitometry. The coefficient of variation from 22 replicate PCR reactions was 14.2 and 24.0% for the SYBR green and TaqMan detection, respectively, and 44.9 and 45.1% for the band densitometry and probe hybridization assays, respectively. The rank order for the values of r(2) obtained from the linear regression of the first-order mRNA decay plots was SYBR green > TaqMan > probe hybridization > band densitometry. Real-time PCR is more precise and displays a greater dynamic range than endpoint PCR. Among the real-time methods, SYBR green and TaqMan assays produced comparable dynamic range and sensitivity while SYBR green detection was more precise and produced a more linear decay plot than TaqMan detection.

3T3 Cells↗