Runners showed elevated T1ρ and T2 values after a marathon, suggesting biochemical changes in articular cartilage, T1ρ values remain elevated after 3 months of reduced activity. The patellofemoral joint and medial compartment of the knee show the highest signal changes, suggesting they are at higher risk for degeneration.
Micro-computed tomography (µCT) has become an important tool for morphological characterization of cortical and trabecular bone. Quantitative assessment of bone tissue mineral density (TMD) from µCT images may be possible; however, the methods for calibration and accuracy have not been thoroughly evaluated. This study investigated hydroxyapatite (HA) phantom sampling limitations, short-term reproducibility of phantom measurements, and accuracy of TMD measurements by correlation to ash density. Additionally, the performance of a global and a local threshold for determining TMD was tested. The full length of a commercial density phantom was imaged by µCT, and mean calibration parameters were determined for a volume of interest (VOI) at 10 random positions along the longitudinal axis. Ten different VOI lengths were used (0.9-13 mm). The root mean square error (RMSE) was calculated for each scan length. Short-term reproducibility was assessed by five repeat phantom measurements for three source voltage settings. Accuracy was evaluated by imaging rat cortical bone (n = 16) and bovine trabecular bone (n = 15), followed by ash gravimetry. Phantom heterogeneity was associated with<0.5% RMSE. The coefficient of variation for five repeat measurements was generally<0.25% across all energies and phantom densities. Bone mineral content was strongly correlated to ash weight (R 2 = 1.00 for both specimen groups and both threshold methods). Ash density was well correlated for the trabecular bone specimens (R 2 > 0.80). In cortical bone specimens, the correlation was somewhat weaker when a global threshold was applied (R 2 = 0.67) compared to the local threshold method (R 2 = 0.78). © Springer Science+Business Media, LLC 2008Correspondence to: Andrew J. Burghardt, andrew.burghardt@radiology.ucsf.edu. NIH Public Access Author ManuscriptCalcif Tissue Int. Author manuscript; available in PMC 2010 January 4. Micro-computed tomography (µCT) has become an important tool for addressing a wide range of research questions related to the biology of bone and other calcified tissues. Quantitative measures derived from µCT have generally been limited to geometric and topological parameters describing the size and shape of trabecular and cortical bone [1][2][3][4]. These microstructural features have been shown to improve the prediction of bone strength independently of traditional measures of bone density [5,6] and, therefore, represent a target for therapeutic manipulation. In addition to geometry, bone material composition is a determinant of bone strength [7] and can be positively modified pharmacologically [8].Quantification of the mineral and organic properties of bone tissue has primarily been limited to two-dimensional (2D), destructive methods, including microradiography [9], infrared spectroscopic imaging [10], and backscatter electron imaging [11]. The ability to characterize tissue-level mineralization through 3D, nondestructive means would be an attractive complement to microstructural and biomechanical analyses already e...
The unique noninvasive MRI technique was used to assess trabecular microarchitecture at multiple skeletal sites in 91 postmenopausal osteoporotic women receiving nasal spray salmon calcitonin (CT-NS) or placebo over 2 years. In the distal radius and lower trochanter of the hip, individuals treated with CT-NS exhibited significant preservation of trabecular bone microarchitecture compared with placebo, where significant deterioration was shown. MRI analyses of os calcis or µCT/histomorphometric analyses of bone biopsies did not reveal consistent differences in architecture between CT-NS and placebo.Introduction: It is postulated that the reduction in osteoporotic fracture risk in response to certain antiresorptive osteoporosis therapies is caused less by effects on bone quantity than on bone quality (specifically trabecular microarchitecture). To test this hypothesis, the QUEST study was conducted to assess the effects of nasal spray salmon calcitonin (CT-NS) or placebo on parameters of trabecular microarchitecture at multiple skeletal sites using noninvasive MRI technology and iliac crest bone biopsies by CT/histomorphometry. Materials and Methods: Ninety-one postmenopausal osteoporotic women were followed for 2 years (n ס 46 for CT-NS, n ס 45 for placebo); all women received 500 mg calcium daily. MRI measurements at distal radius, hip (T2 relaxation time [T2*]), and os calcis (obtained yearly), iliac crest bone biopsies with 2D histomorphometry and 3D CT (obtained at study onset and conclusion), DXA-BMD at spine/hip/wrist/os calcis (obtained yearly), and markers of bone turnover (obtained at 2-week to 12-month intervals) were analyzed, with an analysis of covariance model used to assess treatment effect for parameters of interest. Results and Conclusions: MRI assessment of trabecular microarchitecture at individual regions of the distal radius revealed significant improvement, or preservation (no significant loss), in the CT-NS-treated group compared with significant deterioration in the placebo control group, as reflected in apparent BV/TV (p < 0.03), apparent trabecular number (p < 0.01), and apparent trabecular spacing (p < 0.01). Also, at the hip, the CT-NS group exhibited preservation of trabecular microarchitecture at the lower trochanter (p < 0.05) as determined by T2* MRI technology. Significant deterioration of trabecular bone architecture was noted in the placebo group at the femoral neck, Ward's triangle, and lower trochanteric sites. Apart from a significant increase in apparent trabecular number in the CT-NS group, significant changes within or between groups were not noted at the os calcis. Combined CT/histomorphometric analysis of iliac crest bone biopsies did not reveal significant differences between treated and placebo groups. In the CT-NS group, regardless of the change in BMD (gain or loss) at the spine, hip, or distal radius, preservation of parameters of trabecular microarchitecture was noted, whereas in the placebo group, regardless of the change in BMD (gain or loss) at the...
This study evaluated the effect of Cenestin, a synthetic conjugated estrogens product, on the maintenance of trabecular bone microarchitecture, bone strength, and of bone turnover in the ovariectomized (ovx) rat model. Two doses of Cenestin were chosen in an attempt to approximate the equivalent human oral doses of 0.3 mg and 0.625 mg. Forty-nine 6-month-old retired female breeder Sprague-Dawley rats were randomly assigned to one of four groups: (1) sham-operated + vehicle; (2) ovx + vehicle; (3) ovx + day 1 post-ovariectomy Cenestin (8.12 mg/kg); (4) ovx + day 1 post-ovariectomy Cenestin (16.24 mg/kg) for 8 weeks. Trabecular structure of the right proximal tibia of each rat was imaged noninvasively by microCT. A compression test to induce a tibial plateau fracture was performed to determine the mechanical properties of the proximal tibia. Urine was collected on days 0, 14, 28, 42 and 56 and serum on days 0, 28 and 56 to assess biochemical markers of bone turnover including deoxypyridinoline crosslinks and osteocalcin. Both biochemical markers of bone turnover were analyzed by ELISA. Trabecular bone mass, structure, and connectivity density in the Cenestin-treated groups did not differ statistically ( p>0.05) from those of the sham-operated + vehicle-treated rats, but all were significantly higher ( p<0.05) than in the ovx + vehicle-treated rats. Structure Model Index, a measure of trabecular plate morphometry, in Cenestin-treated rats maintained a more equal mix of plate- and rod-like structures similar to the sham group, whereas the ovx group had predominantly rod-like trabeculae. Fracture load in the Cenestin (16.24 mg/kg) treated group was 31% ( p<0.01) higher than in the sham + vehicle-treated group and 61% ( p<0.05) higher than in the ovx + vehicle-treated group. Both the sham-operated + vehicle-treated and Cenestin-treated groups showed significantly lower urinary deoxypyridinoline crosslink excretion at all timepoints and serum osteocalcin at day 56 compared with the ovx + vehicle-treated group. In summary, Cenestin maintained trabecular bone microarchitecture and strength in an ovariectomized rat model of estrogen deficiency.
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