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P Ruegsegger

Publications and source records attributed to P Ruegsegger.

11 recordsLinked to original sources
PubMed1999

Bone density reduction in various measurement sites in men and women with osteoporotic fractures of spine and hip: the European quantitation of osteoporosis study.

We have measured bone mineral density (BMD) using dual X-ray absorptiometry (DXA) of the spine and hip, spinal quantitative computed tomography (QCTspi), and peripheral radial quantitative computed tomography (pQCTrad) in 334 spine and 51 hip fracture patients. The standardized hip and spine BMD for each patient was calculated and compared with the combined reference ranges published previously, each densitometer having been cross-calibrated with the prototype European Spine Phantom (ESPp) or the European Forearm Phantom (EFP). Male and female fracture cases had similar BMD values after adjusting for body size, where appropriate. This suggests that the relationship between bone density (mass per unit volume) and fracture risk is similar between men and women. However, compared with age-matched controls, mean decreases in BMD ranged from 0.78 SD units (women with hip fracture, DXAspi) to 2.57 SD units (men with spine fractures, QCTspi). The proportion of spine and hip fracture patients falling below the cutoff for osteoporosis (T-score <-2.5 SD) proposed by the World Health Organization (WHO) study group varied according to different BMD measurement procedures (range 18-94%). This finding suggests that the WHO definition requires different thresholds when used with non-DXA BMD measurement techniques. Receiver operator characteristic (ROC) analysis was used to compare measurement techniques for their ability to discriminate between cases and controls. Among DXA sites, the proximal femur was preferred when evaluating generalized bone loss, particularly in elderly people. An additional spinal BMD measurement may add clinical value if spine fracture risk assessment has a high priority. Both axial and peripheral QCT techniques performed comparably to DXA in spinal osteoporosis, so investigators and clinicians may use any of the three technologies with similar degrees of confidence for the diagnosis of generalized or site-specific bone loss providing straightforward clinical guidelines are followed.

Absorptiometry, Photon↗
PubMed1996

Radial cortical and trabecular bone densities of men and women standardized with the European Forearm Phantom.

We previously showed that it is possible to cross-calibrate peripheral bone densitometers using the European Spine Phantom (ESP). We have now performed a multinational study of cross-calibrated radius bone density based on normal subjects of both sexes in eight European centers. Six centers were equipped with machines made by Scanco or Stratec for determining distal radial trabecular bone density by quantitative computed tomography (QCT) and two were equipped with Lunar SP2 single photon absorptiometry (SPA) equipment for measuring midshaft cortical bone density. Subjects recruited ranged from 20 to over 80 years of age. Over one hundred and fifteen men were studied by QCT and a different cohort of 104 men were studied with SPA; the equivalent figures for women were 235 and 123. Reference ranges were derived for bone density against age for each of the four groups, and their applicability is discussed in relation to between-center differences in the results obtained. There were insignificant differences (P > 0.05 with Bonferroni correction) between centers in the values obtained by QCT in the different populations. However, there were considerably larger and highly statistically significant differences between midshaft cortical bone density values of about 10% of overall means between subjects from eastern Finland and central Belgium (P < 0.001), with higher Finnish values. Women had considerably lower radial trabecular bone density values than men at all ages, a result that differentiates the radius from the spine. This sex difference widened after menopause. These results have important implications for understanding the contribution of bone density to the differential risk of Colles' fracture in the two sexes and suggest that further work is needed to establish young normal reference ranges for radial bone density in Europe.

Absorptiometry, Photon↗
PubMed1995

Dual X-ray absorptiometry--cross-calibration and normative reference ranges for the spine: results of a European Community Concerted Action.

Bone density measurements by dual X-ray absorptiometry (DXA) of the spine can now be made precisely, but there is no uniformity in reporting results and in presenting reference data. A European Union Concerted Action therefore devised a uniform procedure for cross-calibrating and standardizing instruments, using the European spine phantom (ESP) prototype. This phantom differs in a number of respects from the final version of the ESP. Eighteen centers in nine countries obtained 1619 records (1035 women) from Caucasian subjects, aged 20-80 years, drawn from normal populations. The DXA machines used were made by the Hologic, Lunar, and Norland companies. Highly statistically significant differences were evident between populations, both in apparent rates of bone loss with age and in the spread of values about the age-adjusted means. There were small residual differences in the results obtained with the three machine brands which could have been due to the relatively large between-center population differences we observed. The alternative or additional explanation that they were attributable, in part, to the design differences between the ESP prototype and the definitive ESP, which became available after this study was completed, was shown to be a valid possibility. Results from postmenopausal women reported in relation to the years that have elapsed since menopause showed reduced population variance when compared with conventional reporting in relation to age. After cross-calibration, the center with the highest age-adjusted normal density value averaged 23% more than the center with the lowest. It is therefore crucially important to select appropriate reference data in clinical and epidemiological studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1994

European semi-anthropomorphic phantom for the cross-calibration of peripheral bone densitometers: assessment of precision accuracy and stability.

A semi-anthropomorphic 'distal radius like' phantom, developed by Kalender and Ruegsegger for use in peripheral bone densitometry using single photon (DPA) dual X-ray (DXA) and quantitative computed tomography (QCT) machines, has been studied with a view to cross-calibrating different types and brands of densitometers in current use. In the context of an EU 'Concerted Action' (second Framework Programme) the phantom was repeatedly measured on six SPA machines, three DXA machines and nine QCT machines (545 measurements). Linear regression equations were derived, individual to each machine, which allowed the derivation of 'standardized densities'. In this way we converted measurements made by machines of the same modality to a common scale of measurements. Two machines (one DXA, one SPA) showed statistically significant instability over time emphasising the need for rigorous quality control in the application of densitometry. In other respects these results provide an encouraging basis for the derivation of standardized normative ranges and the more effective use of peripheral densitometry in future clinical and epidemiological studies.

Absorptiometry, Photon↗
PubMed1986

Long-term fluoride therapy of postmenopausal osteoporosis.

The benefit of sodium fluoride (NaF) in the therapy of osteoporosis is still controversial. For 3 years we monitored patients with postmenopausal osteoporosis subjected to a continuous treatment with 80 mg NaF/day and patients without fluoride treatment. Every 3 months peripheral total and trabecular bone densities were evaluated with high-precision low-dose quantitative computed tomography, every 6 months biochemical parameters were measured, and every year new crush fractures were determined. The untreated osteoporotics as a group lost bone at a rate of 2.5%/year. In the fluoride-treated group trabecular bone density of the distal tibia remained unchanged in 5 of 15 treated patients; 2 patients experienced a bone loss, 8 patients showed at least a temporary bone gain. After 3 years trabecular bone density of the treated patients was 8% higher than that of the untreated patients. Total bone density was not increased. The fracture rates in a group of untreated and a group of NaF-treated patients matched with regard to age, height, weight, initial fracture rate, and initial trabecular bone density were significantly different in the first year, with 0.3 new fractures in the untreated group and 2.9 new fractures in the treated group. During the second and third year the mean number of new fractures was approximately equal in both groups. In 47% of the treated patients, osteoarticular side effects were observed. In 27%, scintigraphy of the ankle was positive, alkaline phosphatase was increased, and radiologic signs of healing stress fractures were present.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1984

Bone loss in premenopausal and postmenopausal women. A cross-sectional and longitudinal study using quantitative computed tomography.

Trabecular and total bone densities were determined by quantitative computed tomography in patients with untreated postmenopausal osteoporosis and in normal premenopausal and postmenopausal women. A special procedure was used for precise low-dose examinations of the distal end of the radius and the distal end of the tibia. The results indicate that the trabecular bone density of the peripheral skeleton is a reliable index of postmenopausal osteoporosis. In general, osteoporotic patients could be distinguished from patients with age-related bone loss based on differences in the magnitude of the decrease in trabecular bone density. Serial determinations of trabecular bone density in individual patients indicated that trabecular bone loss in postmenopausal osteoporotic patients shows a step-wise pattern in which phases of relative stability are followed by brief phases of bone loss. Quantitative computed-tomography measurements of bone density should provide a better understanding of the pathogenesis of postmenopausal osteoporosis and be useful in the assessment of different methods of treatment.

Adult↗
PubMedDate not supplied

Noninvasive numerical vivisection of anatomic structure and function of the intact circulatory system using high temporal resolution cylindrical scanning computerized tomography.

A high temporal resolution cylindrical scanning computerized tomographic system (DSR) is being built for study of anatomic structural/functional relationships of heart, lungs, vascular anatomy, and circulatory dynamics in any region of the body. Unlike current commercial CT scanners which scan only one or, at most, a few cross sections at a time, cylindrical scanners such as the current Mayo SSDSR and upcoming DSR scan nearly 250 cross sections simultaneously. Twenty-eight or more multiplanar images over a range of 160 or more degrees of an entire rapidly moving structure such as the heart or a segment of the circulation will be recorded in periods as short as 10 msec by the DSR at 60/sec rates and stored in computer memory. The scanned volumes can then be sectioned mathematically in any direction at will, including zooming in on regions of interest to problems at hand (e.g., clinical diagnoses). Progression from biomedical investigation to practical clinical and health care uses requires development of special-purpose, readily replicable, economical (but very high speed and volume) data handling and computational devices. The ultimates overall objective is to quantitatively characterize the performance of the human cardiopulmonary and circulatory systems utilizing pertubations associated with various types of physiologic stress and congenital or acquired disease processes including neoplasia.

Animals↗