Measurements of bone mineral density of the proximal femur by two commercially available dual energy X-ray absorptiometric systems.

Two dual energy X-ray absorptiometric (DXA) instruments have recently become commercially available for local bone densitometry: the QDR-1000 (Hologic Inc.) and the DPX (Lunar Radiation Corp.). We report the precision, influence of femoral rotation, correlation and agreement of bone mineral measurements of the proximal femur by these two instruments. In vitro (femur phantom) short-term precision was 1.1%-3.5%, and the long-term precision was 1.2%-3.8%. In vivo (groups of 10 premenopausal and 10 post-menopausal women) short-term precision of duplicate measurements was 1.6%-4.7%, and long-term precision was 1.9%-5.5%. Overall, the precision for Ward's triangle was over 3% and that for the femoral neck and trochanter, 2%-3%. Rotation of a femur phantom produced a statistically significant change in the bone mineral density (BMD) of the femoral neck. Within a clinically relevant range of femoral rotation (20 degrees inward rotation +/- 5 degrees) the coefficient of variation (CV%) increased by a mean factor of 1.1-1.4. Although the correlation (r less than 0.9) between BMD measurements of the proximal femur by the DPX and QDR-1000 in 30 postmenopausal women was high, there was lack of agreement between the two instruments. We found no statistically significant differences between the right and left femur in 30 postmenopausal women. A bilateral femur scan took a mean total time of about 22 min. We conclude that with the introduction of DXA instruments, the precision of bone mineral measurements of the proximal femur has improved. However, for comparability between commercially available DXA instruments, it might be advantageous if units were standardized.     

Changes in calcanean bone mineral occurring spontaneously and during hormone replacement therapy in early post-menopausal women.

The spontaneous calcanean bone loss occurring in healthy early post-menopausal women and the effect of two hormone replacement therapies (HRT's) were investigated in a longitudinal study. There was no difference between the right and left calcanean BMC or BMD (p > 0.15). The spontaneous bone loss was similar at all the skeletal sites measured, with a mean spontaneous loss in calcanean BMD of 1.6% over one year. Both HRT's significantly (p < 0.01) prevented the bone loss from all skeletal sites irrespective of the weight-bearing or content of trabecular bone, and (for the weight-bearing bones) there was even a gain in calcanean BMC and BMD and spinal BMD (p < 0.01). Bone mineral of the calcaneus and the spine correlated equally to body weight (r approximately 0.4, p < 0.001), whereas bone mineral in the forearm was not correlated to body weight. The correlations between the changes in bone mineral at the sites measured were all significant (r approximately 0.2-0.4).     

Impact of surgical aortic valve replacement on global and regional longitudinal strain across four flow gradient patterns of severe aortic stenosis

The International Journal of Cardiovascular Imaging - To evaluate the impact of surgical aortic valve replacement (SAVR) on global (GLS) and regional longitudinal strain (RLS) across four...     

Tissue Doppler imaging as a guide to resynchronization therapy in patients with congestive heart failure

PURPOSE OF REVIEW: Cardiac resynchronization therapy is a nonpharmacological treatment option in patients with heart failure and left bundle branch block but response rates are still disappointing. RECENT FINDINGS: Extent of mechanical left ventricular asynchrony as detected by tissue Doppler imaging has emerged as an independent predictor of outcome to CRT. In addition, long-term therapy delivery may be further improved through optimized lead positioning and pacemaker programming. SUMMARY: Tissue Doppler imaging should be included in the evaluation of potential CRT candidates but standardized evaluation criteria have not yet been provided.     

The effect of a gonadotropin-releasing hormone agonist analog (nafarelin) on bone metabolism

The effect on bone metabolism of an agonist analog of GnRH, nafarelin, was studied in 16 premenopausal women, who received 200 micrograms nafarelin/day for 6 months, and 9 premenopausal women, who received 400 micrograms nafarelin/day for 6 months, followed by a 6-month follow-up period. Bone mineral content in the forearm (measured by single photon absorptiometry) and in the spine (measured by dual photon absorptiometry) significantly decreased after 6 months of treatment with 400 micrograms nafarelin, but 6 months after termination of treatment all bone mineral measurements had returned to pretreatment levels. The bone mineral measurements in the 200 micrograms group did not change throughout the study. In both treatment groups the biochemical estimates of bone turnover increased significantly to postmenopausal levels. Withdrawal of treatment resulted in an abrupt decrease in the bone resorption parameters (fasting urinary hydroxyproline to creatinine and calcium to creatinine excretion ratios and serum phosphate), whereas there was a protracted fall in the bone formation parameters (plasma bone Gla protein and serum alkaline phosphatase) 6 months after termination of treatment. Our findings demonstrate that nafarelin in both doses increased biochemical indices of bone turnover, that 400 micrograms/day nafarelin resulted in a significant decrease in bone mineral content, and that these effects were reversible.