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Biomedical subjects

I Fogelman

Publications and source records attributed to I Fogelman.

At least 73 records · Page 4Linked to original sources
PubMed2000

Differences in skeletal kinetics between vertebral and humeral bone measured by 18F-fluoride positron emission tomography in postmenopausal women.

We have sought to investigate regional differences in skeletal kinetics between lumbar vertebrae and the humerus of postmenopausal women with 18F-fluoride positron emission tomography (PET). Twenty-six women, mean age 62 years, had dynamic PET scans of the lumbar spine and lower humerus after the injection of 180 MBq 18F-fluoride ion. Plasma arterial input functions (IFs) were calculated from a mean IF measured arterially from 10 women and scaled according to late individual venous activity. Vertebral and humeral time activity curves were measured by placing regions of interest (ROI) over lumbar vertebrae and the humeral shaft. Using a three-compartmental model and nonlinear regression analysis the macroconstant Ki, representing plasma clearance of fluoride to bone mineral, and the individual rate constants K1 (related to regional skeletal blood flow) and k2 to k4 describing transport between plasma, an extracellular fluid compartment and a bone mineral compartment, were measured. Mean vertebral Ki (3.47x10(-2) ml x min(-1) x ml(-1)) and K1 (1.08x10(-1) ml x min(-1) x ml(-1)) were found to be significantly greater than humeral Ki (1.64x10(-2) ml min(-1) ml(-1); P<0.0001) and K1 (3.90x10(-2) ml x min(-1) x ml(-1); P<0.0001) but no significant differences were found in k2, k3, and k4. These findings confirm differences in regional skeletal kinetics between lumbar vertebrae and the lower humerus. These observations may help increase our understanding of the regional differences in pathophysiology and response to treatment that have been observed in sites consisting predominantly of either trabecular or cortical bone. 18F-fluoride PET may prove to be a valuable technique in the noninvasive measurement of regional skeletal metabolism.

Adult↗
PubMed2000

Monitoring skeletal response to treatment which site to measure in the femur?

In the past it was usual to interpret bone mineral density (BMD) scans of the femur using the femoral neck, trochanter, or Ward's triangle sites. Recently, a study by the International Committee for Standards in Bone Measurement recommended that the total hip should be the preferred site for the interpretation of femur BMD, and another study described a new central hip site that may offer improved precision. This article compares the longitudinal sensitivities of the different femur BMD sites for monitoring patient response to treatment. The study population was 152 postmenopausal women enrolled in a trial of a bisphosphonate therapy. Spine and hip BMD scans were performed at 0, 1, and 2 yr. The mean percentage change at 2 yr was calculated for six sites in the hip, and the spine was also included for comparison. Treatment effect was defined as the difference in the BMD change between the treated and placebo groups. Although the data analysis incorporated a term for a calibration change caused by a repair of the dual X-ray absorptiometry scanner, the effect of this event on the estimation of treatment effect was negligible. Longitudinal sensitivity was derived by dividing the treatment effect by the root mean square error (RMSE) of the statistical model. Results (and standard errors) normalized to the ratio of treatment effect: RMSE for femoral neck BMD were as follows: femoral neck: 1.00; trochanter: 1.33 (0.38); intertrochanteric: 0.84 (0.41); total hip: 1.20 (0.38); Ward's triangle: 1.03 (0.27); central hip: 1.09 (0.30); spine: 2.08 (0. 45). At none of the femur sites was the change in BMD large enough to allow monitoring of response to treatment in individual patients. However, for studies involving the follow-up of a group of subjects, the longitudinal sensitivities of the different femur sites were equal within the statistical errors of the study. In particular, total hip BMD appears to be as effective as femoral neck BMD for detecting response to treatment in the femur in the setting of a clinical trial or similar research study.

Absorptiometry, Photon↗
PubMed2000

Different approaches to bone densitometry.

From 1990 to 2000, several effective new treatments were introduced for the prevention of osteoporotic fractures; these treatments were proven effective in large, international, clinical trials. At the same time, there was rapid technologic innovation, with the introduction of new radiologic methods for the noninvasive assessment of patients' bone density status. These developments led to the publication of guidelines for the clinical use of bone densitometry that include criteria for the referral of patients for investigation as well as recommendations for intervention thresholds for the initiation of preventive treatment of osteoporosis. Dual-energy x-ray absorptiometry scanning of the spine and hip remains the technique of choice for bone densitometry studies, although there is now a wider appreciation of the need for smaller, cheaper devices for scanning the peripheral skeleton if the millions of women most at risk of a fragility fracture are to be identified and treated. This article reviews these developments, concentrating in particular on the advantages and disadvantages of the different types of equipment available for performing bone densitometry investigations, the guidelines for the referral of patients, and the principles for the interpretation of the scan findings.

Absorptiometry, Photon↗
PubMed1999

An unexpected change in DXA calibration not detected by routine quality control checks.

Since its commercial introduction a decade ago, the technique of dual-energy X-ray absorptiometry (DXA) has been widely recognized as a useful and sensitive method of measuring changes in bone mineral density (BMD) at selected sites in the skeleton such as the spine and proximal femur. Because of their high precision and stable calibration, DXA scanners are frequently used in clinical trials to evaluate new treatments for osteoporosis. Quality assurance procedures based on regular scanning of phantoms are widely adopted in such trials, and continuity of the phantom BMD measurements is generally believed to ensure continuity in the in-vivo calibration. We report a change in calibration of a DXA scanner that occurred during a clinical trial where the calibration shift was different for the spine and femur sites and was not predicted or explained by the standard quality control procedures using phantoms. However, we show that provided patients enrolled in studies are thoroughly randomized and the statistical analysis is confined to the differences between the treated and control groups, then the effects of such calibration shifts on conclusions regarding the efficacy of treatment are considerably smaller than the random statistical errors.

Absorptiometry, Photon↗
PubMed1999

Morphometric X-ray absorptiometry and morphometric radiography of the spine: a comparison of analysis precision in normal and osteoporotic subjects.

Morphometric techniques, which use conventional lateral spine radiographs to quantify vertebral body shape (morphometric radiography, MRX), have proved a useful tool in the identification and evaluation of osteoporotic vertebral deformities. Recently a new method of acquiring the images required for vertebral morphometry using dual-energy X-ray absorptiometry scanners (morphometric X-ray absorptiometry, MXA) has been developed. In this study we compare repeat analysis precision of vertebral height measurement using MXA and MRX. Twenty-four postmenopausal women were recruited (mean age 67 +/- 5.8 years): 12 normal subjects and 12 with osteoporosis and vertebral deformities. Each subject had a MXA scan and lateral thoracic and lumbar radiographs at a single appointment, which were each analyzed quantitatively in a masked fashion, using a standard 6-point method, twice by one observer and once by a second observer. Anterior (Ha), mid (Hm) and posterior (Hp) vertebral heights were measured and wedge (Ha/Hp) and mid-wedge (Hm/Hp) ratios calculated for each vertebral body. Intra- and interobserver precision were consistently poorer in MXA compared with MRX in both normal subjects and those with vertebral deformities, with MXA CV% generally at least 50% higher than corresponding values for MRX. For both MXA and MRX interobserver precision was clearly poorer than intraobserver precision, a problem associated with any morphometric technique. MXA intra- and interobserver precision were significantly poorer for subjects with vertebral deformities compared with those without, with a CV% for deformity subjects up to twice that of normal subjects. Conversely, MRX showed little or no obvious worsening of intra- or interobserver precision for deformity subjects. Comparison of MXA precision in the normal and deformed vertebrae of the deformity subjects demonstrated that the poorer precision in these subjects compared with normal subjects was the result of increased variability in point placement on the deformed vertebrae themselves. However, the precision for normal vertebrae in these subjects was also somewhat poorer than the precision in normal subjects. We conclude that MXA precision is generally poorer than that of MRX and that the presence of vertebral deformities has a more pronounced effect on MXA precision than on MRX precision.

Absorptiometry, Photon↗
PubMed1999

Contact quantitative ultrasound: an evaluation of precision, fracture discrimination, age-related bone loss and applicability of the WHO criteria.

The aim of this study was to assess a dry calcaneal quantitative ultrasound (QUS) device by examining: (i) short- and long-term precision; (ii) the ability of the ultrasound parameters to identify women with vertebral fractures; (iii) age- and menopause-related bone loss; (iv) applicability of the WHO criteria in scan interpretation. The study group consisted of 422 healthy women with no risk factors associated with osteoporosis (227 premenopausal and 195 postmenopausal) and 93 women with one or more vertebral fractures. All women had calcaneal QUS and bone mineral density (BMD) measurements of the lumbar spine and hip performed. Broadband ultrasound attenuation (BUA) and speed of sound (SOS) measurements in the heel were combined and expressed as estimated heel BMD. Short-term precision studies yielded coefficient of variations of 0. 3% for SOS, 4% for BUA and 3.3% for estimated heel BMD. Standardized short-term precision values were approximately 0.2 SD. Long-term standardized precision errors ranged from 0.17 to 0.38 SD. All the QUS and BMD measurement parameters showed significant negative relationships with age in the postmenopausal group. Annual losses were 0.35 dB/MHz per year for BUA, 0.56 m/s per year for SOS and 0. 002 g/cm(2) per year for estimated heel BMD. All the QUS and BMD parameters were able to discriminate between healthy postmenopausal women and women with vertebral fracture. Age-adjusted odds ratios for each SD decline in QUS measurements were 3.63, 5.25 and 4.79 for BUA, SOS and estimated heel BMD respectively. Corresponding odds ratios for BMD at the lumbar spine, femoral neck and total hip were 2.39, 2.51 and 2.95 respectively. When the QUS and BMD parameters were expressed as T-scores, estimated heel BMD showed the least age-related decline, while femoral neck BMD displayed the greatest decrease with age. The mean T-score and prevalence of osteoporosis (T<-2.5) for a Caucasian woman aged 60-65 years were -1.35 and 21% respectively for the lumbar spine compared with -0.59 and 2% for estimated heel BMD. In conclusion, this study revealed that contact ultrasound can detect age- and menopause-related influences on bone status and was able to discriminate between healthy individuals and women with vertebral fracture. However, the widely accepted threshold of a T-score of less than -2.5 for the definition of osteoporosis may need modifying for the interpretation of QUS scans.

Absorptiometry, Photon↗
PubMed1999

Non-invasive assessment of skeletal kinetics using fluorine-18 fluoride positron emission tomography: evaluation of image and population-derived arterial input functions.

To measure regional skeletal kinetics using fluorine-18 fluoride positron emission tomography (PET) it is necessary to know the concentration of radioactive tracer being delivered to bone by arterial plasma with relation to time, the arterial input function (IFa). Methods by which IFa can be derived without arterial sampling are attractive because of their relative technical simplicity and the reduction in possible morbidity to the subject. We have compared the use of a scaled population input function (IFp) and a corrected image-derived input function from the aorta (IFi) with an IFa directly measured from a radial artery line in ten normal postmenopausal women. Both of the aforementioned methods rely only on a small number of discrete venous samples. Each subject had a dynamic PET acquisition of the lumbar spine performed after the intravenous injection of 180 MBq (18)F-fluoride. Both the IFp and the IFi were compared with the IFa in terms of the accuracy of determination of six parameters. These were: plasma clearance of fluoride to bone mineral (K(i)), unidirectional plasma clearance to total bone tissue (K(1)) and individual rate constants k(2), k(3) and k(4), calculated using non-linear regression with a three-compartment model, and the plasma clearance to bone mineral calculated using the Patlak method (K(pat)). For both the IFp and the IFi method the root mean square errors for K(pat) and K(i) were similar and small (<8.2%). The errors in determining K(1) and the rate constants k(2) to k(4) are larger by either method, but with a small advantage using the IFp method. It is concluded that the use of either non-invasive method for determining the arterial plasma input function is suitable for the measurement of the most important parameters, K(i) and K(pat), in these subjects.

Female↗
PubMed1999

Normal variants, artefacts and interpretative pitfalls in PET imaging with 18-fluoro-2-deoxyglucose and carbon-11 methionine.

Interpretation of studies from all imaging modalities requires a knowledge of the possible pitfalls that may occur due to normal variation, artefacts and processes which may mimic pathology. The applications and use of not only 18-fluoro-2-deoxyglucose but also l-[methyl-(11)C] methionine positron emission tomography (PET) are widening and it is timely that the currently recognised interpretative pitfalls are reviewed as the number of dedicated PET scanners and coincidence gamma cameras increases.

Animals↗
PubMed1999

Skeletal metastases from breast cancer: imaging with nuclear medicine.

Breast cancer is a disease that commonly metastasizes to bone, increasing morbidity, mortality, and health service costs. The 99m technetium (99mTc) diphosphonate bone scan historically has played a significant part in the evaluation of skeletal disease and continues to be one of the most clinically utilized investigations in the staging and follow up of breast cancer patients. More tumor-specific radiopharmaceuticals are now being evaluated and, in particular, 18-fluoro-2-deoxyglucose positron emission tomography (18FDG PET) may have a greater role in this disease in the future.

Bone Neoplasms↗
PubMed1999

Radiation dose to the patient and operator from a peripheral dual X-ray absorptiometry system.

Although peripheral dual X-ray absorptiometry (pDXA) scanners for measuring bone mineral density (BMD) in the forearm are known to produce an exceptionally low radiation dose to the patient, quantitative assessment of patient dose from pDXA procedures is important for reassuring patients about their safety. We have estimated the effective dose of radiation (ICRP-60) to the patient and also the scattered dose to the operator from a forearm BMD examination performed on a DTX-200 pDXA system (Osteometer Meditech, Hoersholm, Denmark). Measurements were performed using thermoluminescent dosimeters (TLD's) attached to the forearm phantom supplied by the manufacturer. The effective dose to a patient was estimated to be 0.1 microSv. At a distance of 1 m from the center of the forearm, the time-averaged scattered dose to the operator assuming scanning five patients per hour was measured to be <0.1 microSv/h. The dose rate over the outside surface of the DTX-200 in line with the primary X-ray beam was measured to be 1.4 microSv/h. These figures compare with a natural background radiation in the United Kingdom of 7 microSv/d. In conclusion the radiation doses from forearm pDXA to both patients and operator were found to be truly trivial.

Absorptiometry, Photon↗
PubMed1998

Vitamin D and bone mineral density.

Bone mineral density (BMD) at the lumbar spine and the neck of femur and serum concentrations of 25-hydroxyvitamin D (25OHD), intact parathyroid hormone (PTH), alkaline phosphatase, calcium, albumin, creatinine and phosphate were measured in a group of 166 postmenopausal women (30-79 years) attending a bone clinic for bone density measurements. Four subjects with suspected primary hyperparathyroidism were excluded from analysis. BMD at the lumbar spine was correlated with body mass index (BMI) (r = 0.278, p = 0.0003), age (r = -0.194, p = 0.0134) and serum 25OHD (r = 0.188, p = 0.0167). BMD at the neck of femur correlated with BMI (r = 0.391, p < 0.0001), age (r = -0.356, p < 0.0001), PTH (r = -0.156, p = 0.047) and serum 25OHD (r = 0.231, p = 0.0031). Stepwise multiple regression analysis showed that age, BMI and serum 25OHD contributed to the variation in BMD at lumbar spine. At the neck of femur, PTH was an additional contributor. We conclude that serum 25OHD makes a contribution to BMD a lumbar spine and neck of femur.

Adult↗
PubMed1998

Optimizing data acquisition and analysis of morphometric X-ray absorptiometry.

Morphometric X-ray absorptiometry (MXA) uses dual-energy X-ray absorptiometry (DXA) scanners to perform vertebral morphometric measurements of the vertebrae. In this study we evaluated the four available MXA scan modes--single-energy (SE) and dual-energy fast (F), array (A) and high definition (HD)--on a commercial bone densitometer (Hologic QDR-4500A). Sixty postmenopausal women (mean age 59 years, range 40-73 years) were recruited and split into two groups matched for body mass index (BMI, kg/m2). Three MXA scans, covering 13 vertebrae from T4 to L4, were acquired on each subject; all subjects were scanned in SE and A modes, while the third scan was performed in F mode in group 1 and in HD mode in group 2. Subjects were invited to return 6 months after the commencement of the study to repeat their scans. The HD mode produced the most reliable image, with 97% of all scans analyzable to T7 and the fewest vertebrae being lost to analysis (1.5/13 vertebrae lost per scan). A SE + HD combination (using whichever image allows the analysis of more vertebrae) further decreased the number of vertebrae lost to 0.8 of 13 vertebrae, i.e. a typical scan was analyzable up to and including T5. BMI had a noticeable and scan-mode-dependent effect on MXA image quality, an increase in the number of vertebrae lost to analysis occurring once BMI exceeded 30. BMD had a far smaller effect on image quality and no effect at all using the SE + HD combination. Precision (CV%) was similar for all three dual-energy modes at around 3.5% without the scan 'compare' facility and 2.6% with it. The best precision was obtained with SE scan (2.7%/2.2%). BMI and BMD had little or no effect on precision. We conclude that optimal results are obtained by the acquisition of both SE and HD scans. However, for rapid assessment by trained operators SE scans alone offer almost equal utility.

Absorptiometry, Photon↗
PubMed1998

The relationship between the female menopause and serum sialic acid, a known cardiovascular risk factor.

Serum total sialic acid (SA) has recently been reported as a cardiovascular risk factor. The risk of cardiovascular disease increases after the menopause in females. However, there are little data looking at the relationship between serum SA and the menopause. Overall 92 females were studied. The women were divided into five groups: the first three groups were age-matched pre-menopausal (n = 20), peri-menopausal (n = 10) and post-menopausal women (n = 20). In order to study serum SA changes with adult female age we also studied 14 young pre-menopausal women and 28 elderly women. There was no significance difference between the serum SA concentration in the age-matched pre-, peri- or post-menopausal women (62.7 +/- 10.4 mg/dl, 61.7 +/- 4.5 mg/dl, 62.9 +/- 7.0 mg/dl respectively). Furthermore, there was no significant difference between the serum SA in the "young" women (64.7 +/- 9.8 mg/dl) and that of the peri-, pre- or post-menopausal women. However, in the elderly women the serum SA was elevated (75.6 +/- 16.6 mg/dl) with P < 0.05 for each comparison group. In conclusion, serum SA does not seem to change at the time of the female menopause although in elderly women (average age 75.6 +/- 16.6 years) it increases. The reason for this increase is not known and may merit further research.

Adolescent↗
PubMed1998

Applications of bone densitometry for osteoporosis.

Over the past decade, growing awareness of the impact of osteoporosis on the elderly population and the availability of new treatments to prevent fractures have stimulated the rapid development of new radiologic techniques to assist in diagnosis. With the ability to perform high precision measurements of bone mineral density (BMD) in the spine and hip, dual X-ray absorptiometry (DXA) is well suited to meet this latter need. However, there is continuing interest in smaller, cheaper systems for assessing the peripheral skeleton that include DXA scanning of the distal forearm and a variety of devices for performing quantitative ultrasound (QUS) measurements on bone. Alongside the new equipment, new guidelines have been developed to assist in the interpretation of bone densitometry studies and, following a report by a World Health Organization working group, osteoporosis is increasingly diagnosed on the basis of the patient's T-score value (difference of BMD from young adult mean normalized to the population SD). For the future, wider provision of bone densitometry services is required to properly target the new treatments now becoming available. Since it is unlikely that conventional DXA can meet these needs, QUS is an attractive alternative, especially because this technique is now proven in its ability to predict fracture risk in the elderly and FDA approval is imminent.

Absorptiometry, Photon↗
PubMed1998

Insulin-like growth factor-I and bone mineral density.

To assess the relationship between insulin-like growth factor-I (IGF-I) and bone mineral density (BMD) 201 healthy postmenopausal women (age 41-68 years) within 10 years of menopause were studied. In all subjects, BMD at the lumbar spine and left hip were measured using dual-energy X-ray absorptiometry and blood samples were obtained. In all subjects, serum IGF-I and parathyroid hormone (PTH) were measured. In a subgroup of these subjects serum concentrations of IGF-binding protein-3 (IGFBP-3), osteocalcin (OC), bone-specific alkaline phosphatase (BALP), tartrate-resistant acid phosphatase (TRAP), and carboxyterminal propeptide of type I procollagen (PICP) were also measured. Serum IGF-I correlated significantly with age (r = -0.159, p = 0.0241), serum OC (r = 0.226, p = 0.0131), BALP (r = 0.259, p < 0.0001), and TRAP (r = 0.261, p < 0.0015), but not with PICP, PTH, or BMD at any site. Although there was a strong correlation between IGF-I and IGFBP-3 (r = 0.559, p < 0.0001), there was no correlation between IGFBP-3 and any of the markers of bone turnover (OC, BALP, TRAP, or PICP) nor with PTH or BMD at any site. We conclude that IGF-I and markers of bone turnover are related, but there is no relationship between IGF-I and BMD.

Absorptiometry, Photon↗