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At least 1,063 records · Page 59Linked to original sources
PubMed1994

Densitometry of the radius using single and dual energy absorptiometry.

Though spinal and femoral measurements are typically preferred for evaluating skeletal density, an abundance of forearm data exists, primarily from single photon absorptiometry (SPA) devices. Most dual X-ray absorptiometry (DXA) scanners are capable of scanning the forearm and provide analysis tools to duplicate conventional SPA measurements. In this study, we have compared the radius density measurements from three commonly available densitometers: a Norland 278 SPA, a Lunar DPX-L, and a Hologic 1000/W. Radius bone mineral density (BMD) on the nondominant forearm was measured in 28 volunteers (21 women and 7 men) aged 24-78, with an average age of 51 +/- 17 years. Values were compared and regression relationships derived at corresponding measurement sites. SPA and DXA BMD values were found to be highly correlated (r = 0.99) with small standard errors (0.014 g/cm2-0.021 g/cm2), though significant absolute differences were observed at most measurement regions. Correlation slopes ranged from 0.85 to 1.04, with intercepts from 0.01 to 0.08 g/cm2. Using the resultant regression equations, SPA BMD values can be converted to DXA values with an expected error of roughly 3%. DXA BMD can also be interconverted between Lunar and Hologic with a similar expected error. In situations where this level of imprecision is acceptable, patient forearm measurements obtained on different systems can be interconverted.

Absorptiometry, Photon↗
PubMed1994

Influence of weight and seasonal changes on radiogrammetry and bone densitometry.

We studied the behavior of radiogrammetric and densitometric measurements in relation to season and body weight in a group of 30 healthy premenopausal women. Measurements were made at 6-month intervals, in summer/fall when bone density increases and in winter/spring when bone density declines. Total body bone mineral content (TBBMC) and regional bone mineral content (RBMC) were measured using dual-energy X-ray absorptiometry (DXA). Metacarpal radiogrammetry was carried out with computed radiography. Weight and body mass index increased significantly in winter (P < 0.05) and total body and RBMC decreased (P < 0.001). The opposite occurred in summer: weight and body mass index decreased significantly (P < 0.05) and total body and regional bone mineral content increased (P < 0.001). Differences in TBBMC persisted when the measurement was corrected for weight (TBBMC/W) (P < 0.001), but not for metacarpal cortical thickness corrected for weight. In the first measurement made there were significant relations between weight and both TBBMC (P < 0.001) and metacarpal cortical thickness (P < 0.005). The relation between weight and TBBMC remained significant in later measurements, but the relation between weight and metacarpal cortical thickness ceased to be significant in the second and fourth measurements. Our results show that there is an important seasonal variation in bone mass and that DXA is more sensitive than radiogrammetry in registering these changes.

Absorptiometry, Photon↗
PubMed1993

Spine and femur densitometry at the menopause: are both sites necessary in the assessment of the risk of osteoporosis?

The aim of our study was to compare the results provided by the measurement of vertebral and femoral bone mineral density (BMD) for assessing the individual risk of osteoporosis as defined by either low BMD and/or rapid bone loss. Vertebral and femoral BMD were measured twice at a mean interval of 21 months in 85 normal, early postmenopausal women who had passed a natural menopause 6 months to 3 years previously. According to the measurement site, 36% (spine), 29% (femoral neck), 35% (Ward's triangle), and 25% (trochanter) fall in the "at risk" category, defined by a BMD value of 1 SD or more below the normal values for premenopausal women. Based on vertebral BMD, 39-48% of the women at risk had a normal femoral BMD. On the other hand, 24-37% of the women classified at risk based on femoral BMD maintained a low risk at the vertebral level. The annual rate of bone loss was significantly greater for the Ward's triangle (-2.7 +/- 3.8%) and femoral neck (-2.1 +/- 2.5%) than for the spine (-1.5 +/- 2.1%) and trochanter (-1.5 +/- 3.4%). There was a significant relationship between the rate of loss measured at the spine and femoral levels (r = 0.34-0.58). Among the 21 women with a rapid vertebral bone loss, 48-67% had a low bone loss at the femoral level and vice versa. The ratio between mean rate of loss and the precision of the measurement sites was greater for the spine (1.6) compared with the femur (1.1-0.71).(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1993

Predicting various fragility fractures in women by forearm bone densitometry: a follow-up study.

This is a follow-up of a previous study on the predictive power of bone mineral measurements; two more observation years have been added. A group of women (n = 1076) had their forearm bone mineral content (BMC) measured from 1970-1976. All fractures that occurred in 1975-1987 (13 years) were recorded. Four hundred sixty-nine fragility fractures occurred during the collection period. Again, it was found that BMC at the distal end of the forearm is a good predictor of future fracture before the age of 70. The measurement at the proximal site (forearm shafts), however, in contrast to our previous study, has a capacity of predicting fracture also in the age group 70-80. BMC measurements were good predictors of vertebral crush fractures and trochanteric hip fracture but lesser predictors of fractures of the distal end of the forearm. In age groups 40-70, BMC was a stronger predictor of fracture than age, and the risk associated with a 1 SD decrease of BMC 6 was 3.2 for a hip fracture as compared with those without any fragility fracture, even when adjusted for age. In addition to BMC, low body weight was a fracture predictor. Body weight 5 kg below age-adjusted mean increased the risk of a trochanteric hip fracture by 30%. The data are used in hypothetical calculations of the effects of screening.

Absorptiometry, Photon↗
PubMed1995

Ultrasound and dual X-ray absorptiometry densitometry in women with hip fracture.

To assess the usefulness of the measurement of the os calcis by ultrasound, a method that probably reflects bone quality as well as density, we have studied 54 women with hip fracture of the proximal femur and a control group. Ultrasound evaluation of the os calcis [broadband ultrasound attenuation (BUA), speed of the sound (SOS), and a combined index ("stiffness")], and bone mineral density (BMD) determination over the proximal femur by dual X-ray absorptiometry (DXA) were performed. Weight, BMD, and ultrasound values in the hip fracture patients were significantly lower than controls (P < 0.001). The Z-scores for BUA and stiffness were not different than that for femoral neck, Ward's triangle or trochanteric BMD (between -1.7 and -1.5). The odds ratios determined by receiver-operating characteristics (ROC) analysis were greater at the femoral neck (25.1) and BUA (24.4). Intermediate values were found at stiffness (16.9), Ward's triangle (12.8), and trochanter (11.1), and lower values were obtained at SOS (4.2). In turn, patients with trochanteric hip fractures had a significantly lower femoral neck and Ward's triangle BMD, stiffness, and BUA than patients with cervical hip fractures. Comparing a subgroup of 30 women with hip fractures without vertebral fractures with an age-matched group of 87 women with osteoporotic vertebral fractures, both groups were of similar weight and BMD but all ultrasound values were significantly lower in the hip fractures compared with vertebral fracture patients (P < 0.05 - P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1997

Localized osteoarticular change due to joint immobilization; biomechanical test and bone densitometry in rat's hind limb model.

Bone change induced by knee immobilization was assessed on dissected femurs and tibias to clarify the influences upon the mechanical properties and their demands. Fifty-eight Wistar-Imamichi male rats (11-12 weeks old, body weight 350-450 g) were subjected to knee joint immobilization (150 degrees flexed position) on one side while the opposite side served as a control. Animals were killed in seven groups at time intervals of 1, 2, 3, 4, 5, 7, and 10 weeks. The hind leg was extirpated and prepared for (1) biomechanical analysis by the indentation method at the articular surfaces of the femoral condyle and head and at the subchondral bone of the proximal tibia, and for (2) dual-energy X-ray absorptiometry of the distal metaphysis of the femur. The biomechanical parameters measured induced dynamic stiffness and phase lag derived from forced oscillation (preload 3 N, cyclic load 2 N and 11 Hz, 35 Hz), and bone mineral density was analyzed. These were compared between the immobilized side and control side, and among the seven time groups. The biomechanical results showed an early change of osteocartilaginous properties at the femoral condyle, a late response at the tibial subchondral bone, and no change at the femoral head. The measurement of bone mineral density revealed that a very sensitive reaction started within 1-2 weeks. This study provides objective data demonstrating that disuse or lack of mechanical stress greatly affects the remodeling activity for homeostasis of joints, and dramatically impairs normal bone mineral density next to the immobilized joint in young animals.

Absorptiometry, Photon↗
PubMed1983

A quantitative determination of anticonvulsant-induced bone demineralization by an improved X-ray densitometry technique.

Quantitative studies of the influence of anticonvulsant drugs on bone mineral content of 88 epileptics were performed by a microcomputer-aided densitometer system. The results showed that the mineral content decreases significantly with the duration of the therapy. This decrease was found to be approximately 1.2% per year for a Diphenylhydantoin (DPH) monotherapy and 1.8% per year and 2.0% per year for a DPH plus Phenobarbital and DPH plus Carbamazepin combination therapy.

Absorptiometry, Photon↗
PubMed1992

The effect of overlying calcification on lumbar bone densitometry.

We studied bone mineral density (BMD) of the spine using dual photon absorptiometry, as well as standard anterior-posterior and lateral lumbar spine X-ray film in 113 ambulatory elderly male volunteers with a mean age of 72 years (range 66-91 years). Each subject had three measurements taken for lumbar vertebrae 1 through 4: BMD, length of aortic calcification (AC), and degenerative facet sclerosis graded 0-3. A separate statistical model was fit to BMD for each vertebra using analysis of covariance. AC did not contribute significantly to BMD. BMD was increased by 0.28-0.03 g/cm2 (L1-L4) with a sclerosis score of 2, and by 0.47-0.25 g/cm2 with a sclerosis score of 3, P less than 0.001. The association between increased BMD and overlying facet sclerosis may be related to the bone density within the sclerosis itself or to an association between degenerative joint disease and a generalized increase in subchondral bone.

Absorptiometry, Photon↗
PubMed1993

Screening for osteoporosis by bone densitometry: a stratified intervention approach.

We have performed computer modelling of the relationship between bone mass, age and hip fracture in a conditional probability model using a national population of 100,000 postmenopausal women aged 50 who have their bone density measured once. The computer model very closely reproduced the actual number of fractures in a Western Australian population. Intervention to bone loss completely in subjects with the lowest bone density (below 1 SD below the mean) would prevent 0.42 of a hip fracture per patient treated if the whole population were treated. Halving the rate of bone loss in the whole population would reduce hip fracture by two-thirds. These data suggest that hormone replacement therapy, which is the most effective therapy for preventing bone loss but which has the most side effects, should be focused on subjects with bone mass below 1 SD below the mean. The remainder of the population could be targeted with a public health campaign based on the lifestyle factors of increased dietary calcium and exercise which have been shown to slow but not stop bone loss.

Bone Density↗
PubMed1994

Ultrasound bone densitometry of the os calcis in Japanese women.

The velocity (SOS), attenuation slope (BUA) and stiffness index in the os calcis were measured using the 'Achilles' ultrasound bone densitometer (Lunar, Madison, WI). We evaluated the basic attributes of this ultrasound bone densitometer, and showed the age-related changes in ultrasound values in normal Japanese women. The precision was measured in vivo on ten occasions over a 2-week period in 5 subjects. The short-term precision errors (CVs) in vivo were 0.6% for stiffness index, 0.3% for SOS and 1.0% for BUA. Spine, femur neck and total body BMD using dual X-ray absorptiometry (DXA) were highly correlated with stiffness index (r = 0.80, 0.77 and 0.78, respectively) in 194 subjects. Ultrasound values for patients with osteoporosis were significantly lower than those for the normal controls. The Z-score compared with young normals was significantly higher for spine bone mineral density (-4.4) than for stiffness index (-3.5); BUA and SOS gave significantly lower Z-scores -2.9 and -3.0, respectively). Ultrasound values were also lower compared with age-matched normal controls. The Z-score for stiffness index (-2.1) was significantly superior to that for either SOS or BUA (-1.5). Age-related change in ultrasound values was evaluated in 842 normal women. There was a decline in stiffness index of about 24% from the values in young adulthood to those of women in their seventies, about 75% of which occurred from age 44-49 years onward. These findings seem to indicate that the menopause affected the change in ultrasound values.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1993

Interpretation of lumbar spine densitometry in women with fractures.

Identification of postmenopausal women at risk of developing osteoporotic fractures is a major clinical problem. In this study the use of projected planar lumbar bone density values for individual fracture risk assessment was questioned. Osteodensitometry (DXA) results from 415 normal women, 62 women with previous vertebral compressions, and 76 women with previous low-energy fractures were analyzed, together with their body size and lumbar vertebral body size variables. The following were found: (1) Lumbar vertebral projected bone mineral areal density (BMD) and bone mineral content (BMC) of normal women correlated with body size variables (p < 0.001). (2) Lumbar vertebral body size variables also correlated with body size variables (p < 0.001). Logistic regression analysis of measured and derived physical variables from women without and with vertebral compression fractures (n = 477) showed: (3) The best compression fracture discriminator, significantly better than BMD, was BMC divided by (Hmax/165 cm)1.5 x (D/4.35 cm)1.5, where Hmax is the body height (cm) at the menopause, and D the mean lumbar vertebral diameter of the three mid-lumbar vertebral bodies (cm). This parameter was termed BMCcorr.. ROC analysis showed: (4) At a BMCcorr. true positive ratio of 80% the corresponding uncorrected BMC or BMD true positive ratio was only 60%. The corresponding false positive ratio was 6%. Lumbar osteodensitometry could not be used to identify women with a history of peripheral low-energy fractures. (5) BMCcorr. did not, unlike BMC and BMD, correlate with body size and vertebral size variables. (6) Likewise, an observed correlation between BMC and lean body mass in a subpopulation of 116 normal women was abolished when BMCcorr. replaced BMC.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1995

Diagnostic value of ultrasound analysis and bone densitometry as predictors of vertebral deformity in postmenopausal women.

Bone fractures depend not only on bone density, but also on bone quality. Ultrasound (US) has been proposed as a technique for evaluating skeletal status. Speed of sound (SOS) and broadband ultrasound attenuation (BUA) are the US properties currently used to assess bone strength and fragility. In 304 postmenopausal women (age 58.8 +/- 5.5 years) we measured: bone mineral density (BMD) of the lumbar spine (by dual-energy X-ray absorptiometry), SOS, BUA and Stiffness in the os calcis (using an Achilles machine). In all subjects we performed lateral lumbar and thoracic radiographs. Morphometric parameters were derived by measuring the anterior, middle and posterior height of each vertebral body, to obtain a semiquantitative grading of vertebral fractures as follows: 0, no vertebral deformity; 1, any vertebral height reduced between 20% and 25%; 2, any vertebral height reduced between 25% and 40%; 3, any vertebral height reduced more than 40%. On the basis of the number and severity of vertebral deformities the women were divided into: group 1 (n = 79), normal; group 2 (n = 80), mild; group 3 (n = 85), moderate; and group 4 (n = 60), severe. Mean values of SOS, BUA, Stiffness and BMD were significantly lower (p < 0.001) in women with vertebral deformity than in normals. In the whole population SOS, BUA and Stiffness values were significantly correlated with BMD. SOS, BUA and Stiffness values were significantly decreased (p < 0.001) with vertebral deformity, as was BMD. Receiver operating characteristic (ROC) curve analysis showed BMD to be slightly better than Stiffness in discriminating among groups. Logistic regression analysis showed that BMD, BUA, SOS and Stiffness were independent predictors of vertebral fracture risk. Ultrasound parameters were still significant independent predictors of vertebral fracture even after adjusting for BMD.

Absorptiometry, Photon↗