PubMed · 15255418
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Gary M Kiebzak. 2004. Peripheral bone densitometry.. https://doi.org/10.1097/00007611-200406000-00005
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Dual energy X-ray absorptiometry (DXA) is a rarely used technology in forensic anthropology. These densitometers quantify bone mineral density (BMD) and bone mineral content (BMC) and thus introduce new variables which are important for the application of forensic anthropology. This study investigates the importance of these variables and of this technology using bone scans of the proximal femur in sex and body weight determination. Two data sets from studies conducted at the University of Alabama at Birmingham were examined. The first study had 41 White patients, of which there were 17 males and 24 females, ranging in age from 61 to 79 years and in weight from 99 to 242 lb. The following variables were utilized from the DXA scans: BMD in the femoral neck, greater trochanter and in Ward's triangle. A manual ruler in the software facilitated measurements on the minimum neck diameter and shaft diameter just below the lesser trochanter from each scan. The second study had 128 female patients, 71 of which were Black and 57 were White. They ranged in age from 23 to 47 1/2 years and they weighed between 31 1/2 and 98 1/4 kg. The same variables were examined on these DXA scans as in the first study, with the addition of BMC of the femoral neck and the deletion of the minimum shaft diameter below the lesser trochanter. The first study showed statistically significant sex determination relationships (p < 0.02, t-tests for equality of means) at the supero-inferior femoral neck and lesser trochanter diameters, and from BMD at the femoral neck, trochanter, and Ward's triangle. Discriminant function analysis correctly classified sex over 92% of the original grouped cases using these variables. Multiple regression analysis using body weight as the dependent variable and various measures of the proximal femur as independent variables shows that while they are statistically significant and they have reasonably high R2 values up to 0.49; nevertheless, their standard errors of the estimates are too wide to be of much forensic use. The second study examined ethnic differences, Blacks and Whites, and body weight relationships in a larger, all female data set. Statistically significant differences between Blacks and Whites of BMD were found at Ward's triangle. Multiple regression analyses were again run on body weight and various measures of the proximal femur. The results were also broken down by ethnicity. Some body weight relationships were again statistically significant such as between the BMC of the femoral neck and the BMD of the greater trochanter and the BMC of the neck and the minimum neck diameter, but again, the standard error of the estimate is too wide to be of much use. In addition, the square of the correlation coefficient (R2) is very low, for example, below 0.1 in all cases. Thus, there is very little variability in weight that can be accounted for with these variables. DXA technology offers the potential of a living skeletal data bank and of variables that are useful in cause-effect relationships between bone mineralization and skeletal loads.
BACKGROUND: Androgen deprivation therapy (ADT) is a strong risk factor for osteoporosis. The current study identified physician practices in preventing or treating osteoporosis during ADT. The practices of interest are the uses of dual-energy X-ray absorptiometry (DXA) scans, bisphosphonates, calcium or vitamin D supplement, calcitonin, or estrogen. METHODS: A retrospective medical record review was conducted. Patients were included if they had received ADT with goserelin injection for >/= 1 year. Multivariable logistic regression analysis was performed to identify independent predictors of receiving at least one intervention. RESULTS: Analyses included 184 patients. Most were the elderly with multiple risk factors for osteoporosis. Only 8.7% (95% confidence interval [CI], 4.6-13.0%) of patients received a DXA scan at least once during the past 3 years. Oral and intravenous bisphosphonates were prescribed in 4.9% (95%CI, 1.8-8.0%) and 0.5% (95%CI, 0-2.0%) of patients, respectively, during the past year. Overall, 14.7% of patients (95%CI, 9.5-20.0%) received at least one intervention. Concurrent risk factors for osteoporosis, including smoking, alcoholism, advanced age, low body mass index, long duration of ADT, multiple comorbidities, history of fractures, and steroid use, were not independent predictors of having received interventions. However, bone metastasis was, with a hazard ratio of 5.6 (95%CI, 1.99-15.6%). Primary care physicians provided the greatest number of interventions and cancer-related specialists provided the fewest. CONCLUSIONS: The majority of patients with prostate carcinoma undergoing ADT did not receive interventions to prevent or treat osteoporosis. Having other concurrent risk factors for osteoporosis was not predictive of receiving these few interventions.
The effect that growth has on dual-energy x-ray absorptiometry (DXA) bone measurements is yet to be fully defined. The purpose of this study was to determine the best method for optimizing pediatric bone measurements using DXA. Height, weight, body mass index, skeletal age, and Tanner stage of sexual development were determined for 64 healthy boys and 60 healthy girls ages 6-17 yr. DXA of the lumbar vertebrae was performed to measure bone mineral content (BMC, grams) and areal bone mineral density (aBMD, grams per square centimeter), and geometric corrections were used to calculate volumetric bone mineral densities (vBMD): vBMD1 = aBMD/ radical(DXA-area) and vBMD2 = aBMD/bone height. Computed tomography (CT) imaging was performed to measure volumetric bone density (vBD) and vertebral volume (Vol) and to calculate CT-BMC = vBD * Vol. Linear regression was used to compare DXA-BMC vs. CT-BMC and CT vBD vs. DXA aBMD, vBMD1, and vBMD2. Multiple regression including the anthropometric and developmental parameters was also performed. DXA and CT BMC were highly correlated (r2= 0.94). However, DXA aBMD correlated more strongly with CT Vol (r2= 0.68) than with CT density (r2= 0.39), and calculation of DXA volumetric densities only slightly improved the density correlations (r2= 0.49 for vBMD1; r2= 0.55 for BMD2). The correlations for density were particularly poor for subjects in Tanner stages 1-3 (r2= 0.02 for aBMD; r2= 0.13 for vBMD1; r2= 0.27 for vBMD2). In contrast, multiple regression accounting for the anthropometric and developmental parameters greatly improved the agreement between the DXA and CT densities (r2= 0.91). These results suggest that DXA BMC is a more accurate and reliable measure than DXA BMD for assessing bone acquisition, particularly for prepubertal children and those in the early stages of sexual development. Use of DXA BMD would be reasonable if adjustments for body size, pubertal status, and skeletal maturity are made, but these additional assessments add significant complexity to the studies.