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Biomedical subjects

R B Mazess

Publications and source records attributed to R B Mazess.

At least 91 records · Page 5Linked to original sources
PubMed1988

The relationship of peripheral to axial bone density.

Bone measurements were made in young normal women (n = 125) using single-photon absorptiometry (SPA with 125I) of the radius shaft and ultradistal radius, dual-photon absorptiometry (DPA with 153Gd) of the lumbar spine and the proximal femur, and 125I-based quantitative computed tomography (QCT) of the distal radius. Measurements of the appendicular and axial sites also were made in 21 women with spinal osteoporosis. The standard error of estimate in predicting axial densities from peripheral measurements was about 0.11 g/cm2 (10-13%) with all methods. The osteoporotic-normal difference was 21% for SPA of the radius shaft and 125I-QCT of the distal radius, 30% for the lumbar spine and 34% for the femoral neck. Prediction of spine and femur density, and diagnostic sensitivity, with 125I-QCT were equivalent to that obtained with conventional SPA, but the precision of 125I-QCT (0.8%) was 2-3 times better than both SPA and DPA.

Adult↗
PubMed1987

Spine and femur density using dual-photon absorptiometry in US white women.

Bone mineral density (BMD) of the spine (n = 892) and femur (n = 634) was measured using dual-photon absorptiometry in normal white women from seven diverse locations. The same model commercial scanner with a 153Gd source was used in all locations (SD = 1.3% among locations). There was not an age-associated decrease of spinal BMD during young adulthood (20-40 years); the correlation of age and femoral BMD in this period was low but significant (r = -0.21). There was a narrow range of intra-population variation at all ages (10-12%). The cross-sectional data showed an average diminution of about 20% in the spine and 25% in the femur between 40 and 70 years of age, followed by a continued but slower, decrease of density in older women. Adjustment of values for height and weight was called for mainly at extremes of body size.

Aging↗
PubMed1986

Influence of vertebral fat content on quantitative CT density.

Single- and dual-energy (85 and 130 kVp) computed tomographic (CT) measurements of bone density were made in 74 lumbar (L-3) vertebral specimens. Single-energy CT densities at 130 kVp consistently underestimated actual ash density by about 25 mg/cm3 in men and 40 mg/cm3 in women. CT densities overestimated age changes by 73% in women and 26% in men. These errors of the single-energy CT approach seemed due to increased marrow fat caused by age. At 130 kVp, there was a large decrease in apparent bone density (13 mg/cm3) for each increase of 100 mg/cm3 in fat content, but the decrease was lower at 85 kVp (11 mg/cm3), suggesting the use of lower energies for quantitative CT. In the vertebrae from the younger subjects (up to age 69), the relative error was 20%-31%, but in the oldest group it amounted to 31%-45%. The 95% confidence interval for an individual determination was +/- 38 mg/cm3. Dual-energy CT greatly reduced the above errors. Ash density was predicted with only a small accuracy error (7 mg/cm3) using a postprocessing dual-energy calculation, but the prediction error was 19 mg/cm3 for determinations at 130 kVp. The large uncertainty in the fat content of marrow (+/- 110 mg/cm3) and the variability in distribution of fat make dual-energy approaches necessary for accurate determinations of vertebral mineral density.

Absorptiometry, Photon↗
PubMed1985

Bone mineral and vitamin D in Aleutian Islanders.

Serum concentrations of vitamin D metabolites (chromatography) and bone mineral status (125I absorptiometry) were examined in a group of Aleutian Islanders age 40-75 from St Paul Island, Alaska. Based on 25-(OH)D (16.6 ng/ml) vitamin D status appeared adequate. However, high concentrations of 1,25-(OH)2D (44.3 pg/ml) and very low concentrations of 24,25-(OH)2D3 (0.6 ng/ml) were found. Among females, low bone mineral levels were associated with high concentrations of 1,25-(OH)2D. A low calcium intake in these Aleutians may be responsible for high concentrations of 1,25-(OH)2D and resorption of calcium from bone.

Adult↗
PubMed1985

Dual-photon Gd-153 absorptiometry of bone.

Dual-photon absorptiometry with gadolinium 153 was used to measure the mineral content of lumbar vertebrae in cadavers, excised vertebrae with marrow, and dry, marrow-free vertebrae. The error introduced by the surrounding soft tissue of cadavers was 3%, and the error in determining mineral mass or density in excised vertebrae was about 5%. The correlation coefficient between the results of Gd-153 and corrected iodine 125 (single-photon) absorptiometry on 24 femoral necks was 0.99, and the predictive error was 3.7%. Dual-photon absorptiometry accurately indicates bone mass and bone density and is only slightly affected by either surrounding tissue or fat changes in bone marrow.

Bone Marrow↗
PubMed1985

Bone mass in normal children and young adults.

The growth of bone mass in the radius of children from age 6 on was studied in Indiana and Wisconsin. Growth curves describing change in bone mass, bone width, body height and weight were fitted separately to the data of males and females in the two states. Statistically significant differences between states were found in almost all growth measurements in both sexes. Refined growth curves with standard deviations were generated separately for the two states. When adjusted for age and bone width, Wisconsin subjects always had higher mean bone mass than Indiana subjects. Thus researchers should exercise caution when using published normative values established elsewhere.

Adolescent↗