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Ignac Fogelman

Publications and source records attributed to Ignac Fogelman.

36 records · Page 2Linked to original sources
PubMed2004

Pitfalls and artifacts in 18FDG PET and PET/CT oncologic imaging.

It is estimated that in excess of one million positron emission tomography (PET) scans are performed each year and PET can now truly be regarded as a routine imaging procedure in clinical management. Many potential pitfalls and artifacts have previously been described with (18)F-fluorodeoxyglucose PET imaging, but more continue to become apparent as worldwide experience increases. In addition, the advent of combined PET/CT scanners in clinical imaging practice has brought their own specific pitfalls and artifacts. It is essential that we learn these potential pitfalls so that patients can be optimally prepared for their scans and that accurate interpretation can be made.

Artifacts↗
PubMed2004

Thyroid hormone and parathyroid hormone competing to maintain calcium levels in the presence of vitamin D deficiency.

Weight loss and bone disease in the elderly are very often attributed to malignancy. Rarely, benign treatable conditions may be overlooked. Thyrotoxicosis, a benign treatable condition, needs to be excluded in such patients. The diagnosis may be delayed, since the symptoms are often subtle, and secondary complications including bone disease (osteoporosis) are therefore more frequent at the time of presentation. The case presented here illustrates this well, and also highlights the value of measuring vitamin D levels in such patients. The most interesting aspect of this case was the reciprocal relationship between thyroxine and parathyroid hormone observed in maintaining calcium homeostasis in this thyrotoxic patient with low vitamin D levels.

Calcium↗
PubMed2004

Polymorphisms in the P450 c17 (17-hydroxylase/17,20-Lyase) and P450 c19 (aromatase) genes: association with serum sex steroid concentrations and bone mineral density in postmenopausal women.

The CYP 17 and CYP 19 genes encode 17alpha-hydroxylase/17,20-lyase and aromatase, respectively, both involved in sex hormone synthesis. We investigated the association between 2 common polymorphisms in 1) the promoter region (T-->C substitution) of CYP 17, and 2) exon 3 (G-->A) of CYP 19, bone mineral density (BMD) and serum androgen/estradiol, in a case-control study of 252 postmenopausal women aged 64.5 +/- 9.2 yr (mean +/- SD). There was no significant difference in serum estradiol concentrations between cases (n = 136) and controls (n = 116). The CYP 19 genotype was significantly associated with serum estradiol (P = 0.002). Women with the AA genotype had higher serum estradiol concentrations compared with those with the GG genotype (P = 0.03). In older women, those with the CYP 19 GA and GG genotypes had an increased prevalence of osteoporosis (P = 0.04) and fractures (P = 0.003). We found no significant association between CYP 17 genotype and serum androgens and estradiol concentrations. However, a significant association was seen between BMD values at the femoral neck with CYP 17 genotype in cases (P = 0.04) and in the whole study population (P = 0.012). Subjects with the CC genotype had significantly lower BMD (mean +/- SD: TT, 0.7 +/- 0.16; CC, 0.6 +/- 0.08 g/cm(2); P = 0.006). In conclusion, both CYP 17 and CYP 19 are candidate genes for osteoporosis in postmenopausal women.

Aged↗
PubMed2003

Effects of dietary improvement on bone metabolism in elderly underweight women with osteoporosis: a randomised controlled trial.

Malnutrition in elderly people contributes to osteoporosis and fracture. The aim of the study was to investigate the effects of nutritional improvement on bone metabolism in elderly community-dwelling women. A 12-month randomized controlled trial of 71 ambulant women aged > or =70 years with BMI < or =21 kg/m(2 )and osteoporosis at the hip was undertaken. They received either calcium (1 g) and vitamin D (800 units of cholecalciferol) only (group 1: n=35) or calcium/vitamin D and one or two cartons of a nutritional supplement drink which provided 300 Kcal, 12 g protein, 11.6 g fat and 36.8 g carbohydrate per carton (group 2: n=36). Body composition and bone mineral density (BMD) were assessed at baseline and 12 months. Biochemical markers of bone turnover were measured at baseline and at 1, 3, 6, 9 and 12 months. Group 2 gained significantly more weight [mean (SD) group 1: 0.15 (2.45), group 2:2.66 (2.8) kg P<0.001] and fat mass [group 1: -0.26 (1.8), group 2:1.9 (1.7) kg P<0.001]. BMD at the spine, femoral neck and total hip did not change significantly, although there was a positive trend at the total hip in group 2 [group 1: -0.5 (5.2), group 2:1.25 (3.3)%, P=0.13]. In a subgroup analysis, irrespective of their treatment group, there was a significant difference in changes in BMD at the lumbar spine and total hip in those who lost body weight (A) compared to those who had maintained or increased their weight (B), [mean (SD) % change in BMD lumbar spine; A: -1.64 (3.75), B: 0.96 (2.75) P=0.013, total hip A: -2.09 (6.0), B: 1.04 (3.3), P=0.05)] A significant reduction in serum CTX, a marker of bone resorption, was seen in group 2 [% decrease at 3 months, group 1: 1 (8.7), Group 2: 32 (5.8), P<0.01]. Serum osteoprotegerin (OPG) increased significantly in group 2 with a maximal increase (27%) observed at 6 ( P<0.01) and 9 months ( P<0.05). A small increase in bone-specific alkaline phosphatase was seen at 12 months in group 2 [% increase group 1:5 (5), group 2: 17 (6), P=0.05]. Serum osteocalcin increased at 12 months in group 2 ( P=0.01). Dietary improvement in elderly women with low BMI is associated with a reduction in bone resorption with a small but "net" positive effect on bone formation.

Aged↗
PubMed2003

Solid-phase synthesis of peptide radiopharmaceuticals using Fmoc-N-epsilon-(hynic-Boc)-lysine, a technetium-binding amino acid: application to Tc-99m-labeled salmon calcitonin.

Labeling of proteins with metallic radionuclides for use in radiopharmaceuticals involves covalently attaching a bifunctional chelator. In principle, use of smaller peptides allows this chelator to be incorporated during solid-phase peptide synthesis (SPPS) with total site specificity. To realize the advantages of this approach, a lysine-hynic conjugate Fmoc-N-epsilon-(Hynic-Boc)-Lys was synthesized for incorporating the well-known technetium-99m-binding hydrazinonicotinamide ligand into peptides during SPPS. It was used to synthesize a technetium-99m-labeled salmon calcitonin with the hynic-linked amino acid in place of lysine-18. A trifluoroacetate group protected the hynic during alkaline oxidation to the cyclic disulfide and was readily removed by mild acid treatment. The peptide was efficiently labeled (91-98% radiochemical yield) with Tc-99m in the presence of tricine and SnCl(2) with high specific activity (>100 MBq/microg). The product showed good serum stability and specific affinity for human calcitonin receptors. Fmoc-N-epsilon-(Hynic-Boc)-Lys is a highly versatile technetium-binding amino acid for incorporation into peptides during SPPS. This allows total flexibility and control in the site of attachment and is suitable for a combinatorial approach to peptide radiopharmaceuticals.

Calcitonin↗
PubMed2003

F-18 FDG positron emission tomography and benign fractures.

PURPOSE: F-18 2-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) has been used extensively in the imaging of cancer, including metastatic skeletal disease. Although uptake into benign osseous disease has been reported, there is very limited information regarding uptake into benign fractures. This report provides additional information regarding the appearance of benign fractures on FDG-PET images. MATERIALS AND METHODS: Four case reports of FDG-PET scanning are presented in patients with proved benign fractures. RESULTS: In three of these cases, FDG uptake was noted in fractures when images were obtained 17 days to 8 weeks after injury, with the most avid uptake observed when FDG-PET imaging was performed 17 days after fracture. In the patient in whom imaging was performed 8 weeks after fracture, no uptake of FDG was seen in a benign fracture. CONCLUSIONS: Fractures may accumulate FDG to varying degrees, and false-positive findings may occur when FDG-PET imaging is performed to assess for metastases, although the different pattern of uptake and clinical correlation usually allows accurate differentiation of fracture from skeletal metastases.

Aged↗
PubMed2003

DXA scanning and its interpretation in osteoporosis.

The recent growth in the clinical use of bone densitometry began with the introduction of the first dual X-ray absorptiometry (DXA) scanning systems in the late 1980s. Today, scans to measure bone mineral density are seen as having an essential role in the evaluation of patients at risk of osteoporosis.

Absorptiometry, Photon↗
PubMed2003

Does the combination of two BMD measurements improve fracture discrimination?

UNLABELLED: Combining information from different types of BMD measurement should improve the evaluation of patients' risk of fracture. This study used a bivariate gaussian model to examine the effect of combining two different BMD measurements. The results show that, in practice, there is little benefit unless the measurements are completely unrelated. INTRODUCTION: Intuitively, the combination of information from two or more different types of bone densitometry investigation should improve our ability to identify patients at high risk of fracture. However, the best way to combine measurements and the resulting gain in fracture discrimination are not known. MATERIALS AND METHODS: In this study, we used a bivariate gaussian model to investigate the effect of combining two different types of bone densitometry measurements. The measurements had individual relative risk values RR1 and RR2 and a correlation coefficient r between their Z-scores. Different approaches to the combination of the two measurements were compared by calculating the area under the curve (AUC) for the receiver operating characteristic (ROC) curve, which was obtained by plotting the percentage of fracture patients against the percentage of the whole population with a Z-score below some chosen threshold. ROC curves were calculated for three cases: (1) one type of measurement only; (2) two different types of measurements combined using their mean Z-score weighted according to the theoretical optimum weighting factors predicted by the bivariate gaussian model; and (3) two different types of measurements combined using the conventional World Health Organization (WHO) approach, where one or other measurement is below a set threshold. The theoretical model was tested using measurements of speed of sound (SOS) in the radius, phalanx, and metatarsal in patients with vertebral and Colles' fractures. RESULTS: Results were calculated for RR values of 1.5, 2.0, and 2.5 and r = 0, 0.5, and 0.7. Although a significant improvement in fracture discrimination was obtained when r = 0 and RR1 = RR2, the improvements obtained when r > or = 0.5 or RR1 double dagger RR2 were relatively modest. Slightly better fracture discrimination was obtained using the weighted mean Z-score approach compared with the WHO approach, although the differences were small. The results of the in vivo study in Colles' and vertebral fracture patients showed close agreement with the predictions of the bivariate gaussian model. CONCLUSION: In practice, from a theoretical point of view, there is unlikely to be any benefit from combining information from different types of bone densitometry measurements unless they are completely unrelated.

Bone Density↗
PubMed2003

A prospective study of risedronate on regional bone metabolism and blood flow at the lumbar spine measured by 18F-fluoride positron emission tomography.

UNLABELLED: The effect of risedronate on bone metabolism at the lumbar spine was assessed in 18 women who had a 18F-fluoride PET scan at baseline and after 6 months of therapy. The net plasma clearance of fluoride to bone mineral reflecting osteoblastic activity decreased significantly after therapy. INTRODUCTION: Quantitative radionuclide studies of bone reflect bone blood flow and regional osteoblastic activity, and the latter should change after treatment with a bisphosphonate, although this has not been previously demonstrated. The aim of this study was to examine regional 18F-fluoride kinetics in the lumbar spine measured by 18F-fluoride positron emission tomography (PET) before and after treatment with risedronate. MATERIALS AND METHODS: Eighteen women, with a mean age of 67.0 years and a T-score of less than -2 at the spine or hip, had a dynamic PET scan of the lumbar spine after the injection of 90 MBq 18F-fluoride ion at baseline and 6 months after commencing risedronate therapy. The arterial plasma input function was derived using aorta arterial activity from the PET image. Time-activity curves were measured by placing regions of interest over the lumbar vertebrae. A three-compartmental model was used to calculate bone blood flow (K(1)) and the net plasma clearance of tracer to bone mineral (K(i)). Rate constants k(2), k(3), and k(4), which describe transport between plasma, the extracellular fluid (ECF) compartment, and the bone mineral compartment, respectively, were also measured. RESULTS: Mean vertebral K(i) decreased significantly by 18.4% from baseline (3.32 x 10(-2) ml/min/ml) to 6 months post-treatment (2.71 x 10(-2) ml/min/ml; p = 0.04). This decrease was similar in magnitude to the decrease observed for bone-specific alkaline phosphatase, a marker of bone formation. There was no significant difference in K(1) from baseline (1.49 x 10(-1) ml/min/ml) to 6 months after treatment (1.38 x 10(-1) ml/min/ml; p > 0.05). There was a significant increase in k(2), reflecting the reverse transport of fluoride from the extravascular tissue compartment to plasma, after 6 months of treatment (2.90 x 10(-1)/min versus 4.43 x 10(-1)/min; p = 0.01). No significant changes were seen for k(3) or k(4). There was a significant decrease from baseline in the fraction of tracer in the extravascular tissue space that underwent specific binding to the bone matrix (k(3)/[k(2) + k(3)]), decreasing by 18.1% (p = 0.02). CONCLUSION: K(i), the net plasma clearance to bone mineral reflecting regional osteoblastic activity, displayed a significant decrease after 6 months of antiresorptive therapy. This is the first study to show a direct metabolic effect of antiresorptive therapy on skeletal kinetics at the clinically important site of the lumbar spine. The use of 18F-fluoride PET may provide a useful noninvasive tool to assess novel treatments currently being developed for osteoporosis.

Absorptiometry, Photon↗
PubMed2003

An investigation of unique and shared gene effects on speed of sound and bone density using axial transmission quantitative ultrasound and DXA in twins.

UNLABELLED: The genetic influences of speed of sound (SOS) and BMD were evaluated using 215 pairs of healthy female twins. Genetic influences were found for all SOS and BMD measurements. A combination of shared and unique genetic influences was found to control BMD and SOS at the radius. INTRODUCTION: The aim of this study was to investigate to what extent axial transmission speed of sound (SOS) measurements in cortical bone at multiple, peripheral skeletal sites will be influenced by genetic factors and to estimate the proportion of shared and unique genetic influences controlling bone mineral density (BMD) and SOS at a single site, the radius. MATERIALS AND METHODS: The study population consisted of 215 pairs of healthy female twins. Of these, 85 pairs were monozygotic (MZ) and 130 pairs were dizygotic (DZ). The twins had measurements of the nondominant third proximal phalanx, one-third radius, midshaft tibia, and fifth metatarsal using the Sunlight Omnisense and DXA measurements of the lumbar spine, nondominant proximal femur, nondominant radius, and whole body using Hologic QDR-4500W densitometers. Calcaneal quantitative ultrasound (QUS) measurements were performed using the McCue CUBA clinical. Intraclass correlations were calculated, and heritability was estimated using multiple regression analysis. Bivariate analysis of site-matched SOS and BMD measurements at the radius was performed using a variance components analysis program. RESULTS: Age- and body mass index-adjusted heritability estimates ranged from 0.51 (95% CI, 0.32-0.70) to 0.56 (0.37-0.76) for SOS measurements, 0.58 (0.41-0.75) for broadband ultrasound attenuation (BUA), 0.72 (0.58-0.86) to 0.77 (0.63-0.91) for axial BMD, and 0.53 (0.16-0.90) to 0.63 (0.26-1.00) for radius and whole body BMD. The correlation between SOS and DXA at the radius was r = 0.34 (0.29-0.47). Thirty-eight percent (16-57%) of the genetic variance explained by SOS at the radius was also explained by BMD (one-third radius region of interest), with 62% being unique. CONCLUSION: In conclusion, genetic influences were demonstrated for SOS measurements in cortical bone at multiple sites, axial BMD, calcaneal BUA, radius, and whole body BMD. At the radius, up to 38% of the genetic influence is shared by genes controlling BMD and SOS. Clarifying the site specificity and pleiotropic effects of bone genes should help our understanding of these complex pathways.

Adult↗
PubMed2003

Validation of ultrafiltration as a method of measuring free 99mTc-MDP.

UNLABELLED: Quantitative studies of the kinetics of (99m)Tc-methylene diphosphonate ((99m)Tc-MDP) in metastatic and metabolic bone disease require the measurement of free tracer in plasma to derive the input function. Several methods of measuring free (99m)Tc-MDP have been described including ultrafiltration, precipitation using trichloroacetic acid, and a direct in vivo measurement based on the assumption that free MDP is cleared through the kidneys by glomerular filtration. The aim of this study was to validate ultrafiltration as a convenient and accurate method of measuring the free fraction of (99m)Tc-MDP by comparing it with the glomerular filtration rate (GFR) method. A second aim was to measure the percentage of free (99m)Tc-MDP in a cross-section of patients using ultrafiltration to determine the interpatient variability and, therefore, whether individual measurements are required for bone kinetic studies. METHODS: In study 1, 10 volunteers (7 women, 3 men; mean age, 37 y; range, 26-55 y) were injected with 3 MBq (99m)Tc-MDP and 3 MBq (51)Cr-ethylenediaminetetraacetic acid, and multiple blood and urine samples were taken between 0 and 4 h. Plasma samples were spun in 5-, 10-, and 30-kDa filters and counted in a gamma-counter. In study 2, 51 randomly selected patients (26 women, 25 men; mean age, 66 y; range, 31-87 y) attending our department for a routine bone scan were injected with 600 MBq (99m)Tc-MDP, and 4 blood samples were taken between 0 and 4 h and spun in 10-kDa filters. RESULTS: In study 1, the mean percentages (+/-SD) of free (99m)Tc-MDP at 5 min and 4 h after injection measured using the 10-kDa filters were 83.1% +/- 3.4% and 44.0% +/- 10.0%. The mean ratios (+/-SEM) of the free (99m)Tc-MDP in ultrafiltrate compared with the GFR method for the 5-, 10-, and 30-kDa filters were 0.894 +/- 0.010, 0.943 +/- 0.009, and 0.987 +/- 0.010. In study 2, the mean percentages (+/-SD) of free (99m)Tc-MDP at 15 min and 4 h were 75.3% +/- 8.0% and 48.8% +/- 9.5%, with a precision error of 2.3%. The percentages of free MDP at 150 min and 4 h were significantly correlated with GFR but not with serum albumin. CONCLUSION: Ultrafiltration provides an accurate method of evaluating free (99m)Tc-MDP in plasma for bone kinetic studies. The results from both the healthy volunteers in study 1 and the patients in study 2 show that protein binding varied with time and showed significant differences between individuals that were partly dependent on GFR. It is thus necessary to measure individual protein binding values for bone kinetic studies.

Adult↗
PubMed2002

Conventional measurements of GFR using 51Cr-EDTA overestimate true renal clearance by 10 percent.

It is widely believed that measurement of the area under the plasma clearance curve (AUC) following a single intravenous injection of chromium-51 labelled ethylene diamine tetra-acetic acid ((51)Cr-EDTA) is a gold standard method for determining glomerular filtration rate (GFR). However, there are reports that (51)Cr-EDTA may have a significant extrarenal clearance. The aim of this study was to identify the non-renal component of (51)Cr-EDTA plasma clearance contributing to the AUC measurement of GFR. Seventy healthy postmenopausal women (mean age 60 years, range 45-79 years) were injected with 3 MBq (51)Cr-EDTA and 0.25 MBq iodine-125 labelled human serum albumin and 11 blood samples taken between 0 and 4 h through an indwelling venous cannula. For the first 21 subjects, two complete urine collections were made 0-2 h and 2-4 h after injection, and for the final 49 patients, four 1-h urine collections were made. The mean (51)Cr-EDTA total plasma clearance was 84 ml/min (range 50-132 ml/min). The mean ratio (SEM) of urine to total clearance determined from the cumulative 1-, 2-, 3- and 4-h data was 0.903 (0.018), 0.891 (0.013), 0.898 (0.011) and 0.899 (0.010) respectively and remained constant despite the mean urine concentration decreasing from 122% to 15%/litre during this period. A least squares fit to data from the 238 individual urine collections was used to determine the fraction of the total plasma clearance attributable to renal clearance, alpha(0), and the residual urine volume, delta V. The results were alpha(0)=0.910 (95% CI: 0.889-0.932) and delta V=14 ml (95% CI: -4 to +34 ml). The overestimation of the true renal clearance of (51)Cr-EDTA by the AUC method is believed to be due to the failure of the plasma clearance curve to reach the true terminal exponential by 2 h after injection as usually assumed. As a result, conventional measurements of GFR using (51)Cr-EDTA overestimate the true renal clearance of tracer by approximately 10%.

Aged↗
PubMed2002

Dual energy x-ray absorptiometry and its clinical applications.

Bone density scans using the technique of dual energy X-ray absorptiometry (DXA) are widely seen as having an essential role in the evaluation of patients at risk of osteoporosis. DXA scans of the spine and hip are the most useful because fractures at these sites result in the greatest impairment of quality of life. A hip DXA scan is the most reliable way of evaluating hip fracture risk, and the spine is the most sensitive site for monitoring response to treatment. Fundamental to the clinical role of DXA scanning are the findings of epidemiological studies that relate fracture risk to bone mineral density. The results of spine and hip DXA scans are interpreted using the World Health Organisation (WHO) definition of osteoporosis as a T-score less than -2.5. DXA scans are also used in longitudinal studies, both for research studies and for follow-up scans of individual patients. Although the former have an important role in the development of new treatments for osteoporosis, the latter are more controversial and are likely to be less important in the future. There is also interest in the use of smaller, less expensive DXA systems for scanning sites in the peripheral skeleton. However, in general, the results from these devices cannot be interpreted using the WHO definition of osteoporosis, and until there is a consensus over establishing an equivalent threshold, their use is premature.

Absorptiometry, Photon↗
PubMed2002

Nuclear medicine studies in metabolic bone disease.

The principal application of nuclear medicine in metabolic bone disease is the isotope bone scan. Often, it is not a diagnostic tool but can be useful in clarifying the nature of a clinical problem. The best-established role for the bone scan in metabolic bone disease is in Paget's disease, in which it is diagnostic, provides definition of the extent of disease, and probably reflects disease activity. The isotope bone scan is also important in osteoporosis, for which it is not diagnostic but may often provide useful information to confirm that fracture has occurred, determine the age of the fracture, identify unsuspected fractures, and identify other causes for pain, for example, facet joint disease. The bone scan is less useful in other metabolic bone diseases, for example, renal osteodystrophy and osteomalacia, but will often have a characteristic appearance, with several metabolic features. The degree of positivity of the scan generally relates to the severity of the hyperparathyroidism. In patients with metabolic bone disease, other specific clinical problems may arise, such as osteomyelitis or avascular necrosis, and the bone scan may be diagnostic in these conditions. Nuclear medicine techniques are also of value in hyperparathyroidism and to localize the site of the adenoma where surgical treatment is being considered; the use of technetium Tc 99m sestamibi is now routine. More recently, positron emission tomography (PET) scanning has been found to be helpful in the more difficult cases.

Bone Diseases, Metabolic↗
PubMed2002

Bone densitometry, steroids and osteoporosis.

PURPOSE OF REVIEW: Scans to measure bone mineral density at the spine and hip have an important role in the evaluation of patients at risk of osteoporosis. Oral corticosteroid use is an important risk factor for a fragility fracture and the relative risk is particularly high for vertebral and hip fractures. In Europe and the USA, guidelines have been published for the investigation of patients at risk of corticosteroid-induced osteoporosis, with recommendations on the diagnostic use of bone mineral density scans and the initiation of treatment based on the findings. RECENT FINDINGS: Large trials of bisphosphonates, selective oestrogen receptor modulators and parathyroid hormone have addressed the issue of fracture prevention in women with postmenopausal osteoporosis and there is a growing consensus that the World Health Organization definition of osteoporosis of a -score=-2.5 is an appropriate threshold for preventive treatment in these patients. For most agents separate studies have been conducted of their use for the prevention and treatment of corticosteroid-induced osteoporosis. SUMMARY: There is increased awareness of the importance of preventive treatment for osteoporosis in patients taking high doses of oral corticosteroids (daily dose of 7.5 mg prednisolone or greater). In view of evidence that corticosteroid use is an independent risk factor for fracture over and above bone mineral density, guidelines for intervention set a higher threshold than the World Health Organization figure ( -score=-1.5 rather than -2.5) for intervention with bone sparing treatment in these patients.

Aged↗
PubMed2002

Absolute fracture risk varies with bone densitometry technique used. A theoretical and in vivo study of fracture cases.

The lack of consensus of how the results of peripheral bone mineral density (BMD) measurements should be interpreted is proving a barrier to the wider use of these devices. One approach is to interpret peripheral measurements using thresholds (so-called equivalent T-scores) defined to have the same absolute fracture risk as a femoral neck T-score of -2.5. For this concept to be valid, the estimates of fracture risk for a population should be the same irrespective of the measurement technique used. We tested this prediction both theoretically and in vivo using data for 63 postmenopausal women with Colles fracture and 191 control subjects. The theoretical analysis showed that if the normal population has a Gaussian BMD distribution and fracture risk varies exponentially with Z-score as exp(-beta Z) then patients who experience a low-trauma fracture have a fracture risk that is larger by a factor exp(beta(2)) compared with the fracture risk of the whole population. Using data from the in vivo study, fracture risk predictions were compared for seven different types of measurement (lumbar spine; femoral neck; total hip BMD; and speed of sound [SOS] at the radius, tibia, phalanx, and metatarsal). When quantitative estimates of fracture risk were made for individual subjects, the average risk of fracture for the Colles group varied between 1.03 times larger (for tibial SOS) and 2.77 times larger (for total hip BMD) than the average fracture risk for the whole population. As predicted by the theoretical study, fracture risk varied according to the odds ratio determined by logistic regression analysis. Therefore, estimates of fracture risk derived for the same group of patients varied almost threefold according to the type of measurement. It was concluded that equating estimates of absolute fracture risk for different types of scan should not be used as the basis of deriving equivalent T-scores for interpreting peripheral measurements.

Aged↗
PubMed2002

Quantitative studies of bone in postmenopausal women using (18)F-fluoride and (99m)Tc-methylene diphosphonate.

UNLABELLED: Quantitative radionuclide studies of bone using the short-lived tracers (18)F-fluoride and (99m)Tc-methylene diphosphonate (MDP) are an alternative method to biochemical markers of bone turnover for investigating the dynamic state of the skeleton. In this study we evaluated their use to quantify bone turnover in women receiving antiresorptive therapy compared with that of untreated control subjects. METHODS: The patients were 69 healthy postmenopausal women. Twenty-six women were receiving hormone replacement therapy (HRT) and 43 were untreated age-matched control subjects. After bolus injection of (18)F-fluoride (1 MBq), (99m)Tc-MDP (1 MBq), (51)Cr-ethylenediaminetetraacetic acid (3 MBq), and (125)I-labeled human serum albumin (0.25 MBq), multiple blood samples and urine collections were taken between 0 and 4 h. The clearance to bone mineral K(bone) was first evaluated using the area under the plasma concentration curve (AUC) on the assumption that the rate constant k(4) for the outflow of tracer from bone was negligibly small. AUC values of K(bone) were then compared with those found using a compartmental model method that allowed k(4) to be fitted as a free parameter. RESULTS: Using the AUC method the mean plus minus SD for K(bone) for the 2 tracers were: (18)F-fluoride, 61.8 plus minus 12.0 mL center dot min(-1) (HRT group) versus 67.2 plus minus 12.6 mL center dot min(-1) (control group) (P = 0.045); and (99m)Tc-MDP, 40.3 plus minus 8.2 mL center dot min(-1) (HRT group) versus 44.2 plus minus 7.6 mL center dot min(-1) (control group) (P = 0.024). Values for the 2 tracers in individual patients were moderately well correlated (r = 0.76; P < 0.001). Using the compartmental model method, k(4) for (18)F-fluoride was shown to lie in the range 0--0.0025 min(-1) with a best-fit value of 0.0018 min(-1). Values of K(bone) determined using k(4) = 0.0018 min(-1) were highly correlated with the AUC values (r = 0.989; SEE = 2.05 mL center dot min(-1)) with numeric values that were larger by a factor of 1.53. Analysis of the (99m)Tc-MDP data was more difficult because of uncertainties in protein binding in the extracellular fluid compartment space. The best fit for k(4) was in the range 0.0010--0.0014 min(-1) with values of K(bone) similar to those found using the AUC method. CONCLUSION: Values of K(bone) determined using the AUC method were able to differentiate between HRT-treated women and postmenopausal women who were not treated and were highly correlated with those determined using a compartmental model method with nonzero values of k(4).

Aged↗