Women of reproductive age with endometriosis are not osteopenic.

OBJECTIVE: To determine whether women of reproductive age with endometriosis are osteopenic and whether bone density decreases with higher stages of endometriosis. DESIGN: A multicenter cross-sectional study was performed. SETTING: Thirty-nine gynecological clinics in the United States, Canada, and Puerto Rico. PATIENT(S): Two hundred forty-one women of reproductive age with laparoscopically proved endometriosis. INTERVENTION(S): Diagnostic laparoscopy, bone densitometry. MAIN OUTCOME MEASURE(S): Endometriosis stages according to the criteria of the American Society for Reproductive Medicine, lumbar spine bone mineral density (L2-L4) as measured by dual-energy x-ray absorptiometry. RESULT(S): The mean lumbar spine bone mineral density, as well as the distribution of bone mineral density, of the women with endometriosis was similar to that of a normal population. There were no significant differences between endometriosis stage groups I-IV regarding bone mineral density as well as body weight, body mass index, and height. CONCLUSION(S): Women of reproductive age with endometriosis are not osteopenic. More advanced stages of endometriosis are not associated with a decrease in lumbar spine bone mineral density.

A comparison of two dual-energy X-ray absorptiometry systems for spinal bone mineral measurement.

Two dual-energy X-ray absorptiometry (DEXA) systems--the Hologic QDR-1000 and the Norland XR-26 bone densitometers--were evaluated in terms of precision, accuracy, linearity of response, X-ray exposure, and correlation of in vivo spinal measurements. In vitro precision and accuracy studies were performed using the Hologic anthropomorphic spine phantom; linearity of response was determined with increasing thicknesses of aluminum slabs and concentrations of Tums E-X in a constant-level water bath. Both systems were comparable in precision, achieving coefficients of variation (CVs) of less than 1% in bone mineral content (BMC, g), bone area (cm2), and bone mineral density (BMD, g/cm2). Both were accurate in their determination of BMC, bone area, and BMD with reference to the Hologic spine phantom. Both systems also showed good BMC and BMD linearity of response. Measured X-ray skin surface exposures for the Hologic and the Norland systems were 3.11 and 3.02 mR, respectively. In vivo spinal measurements (n = 65) on the systems were highly correlated (BMC: r = 0.993, SEE = 1.770 g; area: r = 0.984, SEE = 1.713 cm2; BMD: r = 0.990, SEE = 0.028 g/cm2). In conclusion, both systems are comparable in terms of precision, accuracy, linearity of response, and exposure efficiency.

In vitro comparability of dual energy X-ray absorptiometry (DEXA) bone densitometers.

Six Hologic QDR-1000 DEXA bone densitometers at different centers across the USA were compared to determine the intermachine variability. Nine scans in succession were acquired on each machine using a single anthropomorphic lumbar spine phantom (manufactured by Hologic). Values for BMC, area, and BMD were recorded for each measurement. Means, standard deviations (SD), and coefficients of variation (CV) were calculated for each machine. All the CVs (BMC, area, BMD) were less than 1% (range 0.3%-0.6%). The CV of the means at the six sites were 0.4%, 0.6%, and 0.5% for BMC, area, and BMD, respectively. Although several significant differences for BMC, area, and BMD were noted by ANOVA between machines at different sites, the difference between the highest and lowest means of the individual machines was only 1.1%, 1.31%, and 1.07% for BMC, area, and BMD. The small variations between the DEXA systems are encouraging for researchers involved in multicenter trials in which data are pooled.

A DPA technique for simultaneously measuring bone, soft tissue, and fat content.

Although conventional dual photon absorptiometry (DPA) techniques can be used to estimate fat and soft tissue content, such estimates are not possible where bone is present. We propose a method that can make these estimates in the presence of bone in the extremities of the body. The combination of this method with the conventional method should yield fat and soft tissue composition from most points within the body. The proposed technique simultaneously measures thicknesses of bone, soft tissue, and fat. These thicknesses are determined of bone, soft tissue, and fat. These thicknesses are determined from a combination of gamma-ray transmission data at two energies and a measurement of total tissue thickness. To test the technique, a feasibility study was performed with known thicknesses of aluminum (simulating bone), lucite (simulating tissue), and polyethylene (simulating fat). A variety of thicknesses of each material were employed (Al: 0-1.3 cm, lucite: 0-5 cm, polyethylene: 0-5 cm). The accuracies (standard errors of the estimates) of the calculated versus true thicknesses of aluminum, lucite, and polyethylene were 0.6%, 2.6%, and 2.5%, respectively. The estimates of "bone" thickness were insensitive to the presence of varying thicknesses of "fat." (In contrast, application of the conventional DPA method to the same gamma-ray transmission data yielded underestimates in "bone" thickness due to "fat" by as much as 11%.) For a 60 minute (whole body) scan time, the reproducibility of the measurements of the thicknesses of aluminum, lucite, and polyethylene were 0.4%, 1.0%, and 1.3%, respectively. All of these values are in a clinically useful range.(ABSTRACT TRUNCATED AT 250 WORDS)

Total body calcium by neutron activation analysis in normals and osteoporotic populations: a discriminator of significant bone mass loss.

This paper reports total body calcium by neutron activation (TBC) measurements in 94 normal individuals and 86 osteoporotic patients. The ability of TBC to discriminate normal from osteoporotic females was evaluated with decision analysis. Bone mineral content (BMC) by single-photon absorptiometry was also measured. TBC was higher in males (range 826 to 1363 gm vs 537 to 1054 in females) and correlated with height in all normals (r = 0.55 in males, 0.58 in females; p less than 0.001). In females over age 55 there was a negative correlation with age (r = -0.51, p less than 0.01). Thus, for normals an algorithm was derived to allow comparison between measured TBC and that predicted by sex, age, and height (TBCp). In the 28 normal females over age 55, the TBC was 764 +/- 115 gm vs. 616 +/- 90 in the osteoporotics (p less than 0.001). In 63 of the osteoporotic females an estimated height, from tibial length, was used to predict TBC. In normals the TBC/TBCp ratio was 1.00 +/- 0.12, whereas in osteoporotic females it was 0.80 +/- 0.12 (p less than 0.001). A receiver operating characteristic curve showed better discrimination of osteoporosis with TBC/TBCp than with wrist BMC. By using Bayes' theorem, with a 25% prevalence of osteoporosis (estimate for postmenopausal women), the posttest probability of disease was 90% when the TBC/TBCp ratio was less than 0.84. We conclude that a low TBC/TBCp ratio is very helpful in determining osteoporosis.

[Biological and surgical aspects of the use of polymers in experimental surgery. 1: implants on the oculo-extrinsic musculature]. / Aspetti biologici e chirurgici dell'impiego di un polimero nella chirurgia sperimentale. Nota 1:protesi della muscolatura oculo-estrinseca.

Composite sheets obtained reinforcing PHEMA with a tricot PET net have been implanted in rabbits to test their potential applications for cross-eye surgical correction. The mechanical characterization of the composites has been carried out both in static tension and fatigue. The clinical evaluation was performed on twelve adult New Zealand white Rabbits implanting the sheets on the rectus dorsalis muscle of the eye. The material seems to be highly compatible with the surrounding tissue, mechanical satisfying and clinically helpful in correcting many of the pathological conditions connected with strabismus. The long term behaviour of the implanted prosthesis in still under investigation.

A comparison of count rate parameters in gamma cameras.

Pulse pile-up is a fundamental problem that limits the ability of a gamma camera to produce high quality images at high count rates. Pulse pile-up results in loss of events and spatial distortions in the image. The question asked in this study is how well do some of the test procedures for measuring count rate performance in gamma cameras compare. In four gamma cameras we compared measurements of spectral fraction, count-rate curve, pulse-pair resolution, deadtime, maximum count rate, full width at half maximum of the line spread function, and misplaced event count rate. The results indicated that no one technique provides a complete description of the count-rate effects in gamma cameras. The misplaced-event measurements provided the most information.

A system for measuring total body calcium in man using the 40Ca(n, alpha)37 Ar reaction.

A technique to measure total body calcium using the 40Ca(n, alpha)37 Ar reaction has been developed. The technique is based on collecting 37Ar exhaled in the breath following a 10 mrad uniform total body irradiation by 14 MeV neutrons. The 37Ar in the exhaled breath is extracted by selective absorption and its radioactivity is measured inside a low-background proportional detector. The facilities developed include an activation facility providing a +/-2.7% activation uniformity, a closed circuit rebreathing and gas collection system, and a gas purification and counting system. The technique provides a precision of +/-2.4% as determined by repetitive measurements of human volunteers and has an accuracy for determination of total body calcium in grams of +/-5%.

A field procedure for the quantitative assessment of nuclear imaging cameras.

Techniques developed for the quantitative assessment of gamma cameras are described. The performance parameters discussed include energy resolution, intransic line spread function, uniformity, and extrinsic line spread function. In addition to describing the equipment used and indicating methods used in analyzing data, some of the potential problems in interfacing multichannel analyzers to gamma cameras are discussed.

Absolute measurement of total-body calcium by the Ar-37 method-preliminary results: concise communication.

Measurements of exhaled Ar-37 produced by total-body neutron irradiation of Ca-40, were used to determine total-body calcium in ten human subjects. There was a good correlation between the Ar-37 yield and total-body calcium determined by measurement of Ca-49.

Preliminary observations on excretion of 37Ar from man following whole-body neutron activation--an indicator of total-body calcium.

Measurements of exhaled 37-Ar produced by total-body neutron irradiation of 40-Ca were used to determine total-body calcium in 16 human subjects. There was a good correlation between body calcium using the 30-min postirradiation breath sample of 37-Ar and body calcium determined by measurement of 49-Ca.