Search

International audience; The HR-pQCT (XtremeCT Scanco®) with a voxel size at 82 (µm3) is carried out routinely in clinical research protocols. Micro-computed tomography (micro-CT) has become a standard tool for examination of trabecular and cortical bone in 3 dimensions (3D).The purpose of this study is to evaluate the accuracy and precision of cortical measurements derived from HR-pQCT images using a local comparison with morphological measurements from synchrotron radiation (SR) micro-CT.Thirty tibias specimens (mean age 82.2±9.7) were scanned at 3.5 cm from the tibial pilon. The acquisition and analysis protocols provided by the manufacturer were used. Fourteen samples were scanned twice to calculate the Root Mean Square Coefficient of Variation (RMSCV,%). The usual outcomes include: volumetric bone density (gHA/cm3) for entire (Dtot) and cortical (Dcomp) regions, cortical thickness (Ct.Th,mm). New features as cortical porosity (Ct.Po) and mean pore diameter (mPo.Dm) were measured with manual correction of the endosteal contour. In a site matched region of HR-pQCT images, bone samples were taken at the posterior part of the tibia and imaged on beamline ID19 (ESRF,Grenoble). The acquisition parameters used were 30 keV, 3500 views over 360°, the exposure time for each view was 0.3s. The voxel size is 7.5 (µm3). Ct.Th_SR was manually measured. A unique threshold was used for the whole dataset. Using the CTAn Skyscan® software, the following parameters were obtained: Pore volume/Bone volume (PoV/TV_SR %), pore diameter (Po.Dm_SR,mm), pore spacing (Po.Sp_SR,mm), pore number (Po.N_SR,mm-1) and the degree of anisotropy (DA,no unit). Maps of linear attenuation coefficient were converted into degrees of mineralization of bone (DMB) with data expressed in g/cm3.Pearson correlation coef. (r) between Ct.Th vs Ct.Th_SR was r=0.58**. Correlation coef. were not significant for Dcomp vs DMB and for m.Po.Dm vs Po.Dm_SR and PoV/TV_SR. Significant correlation coef. between PoV/TV_SR and cortical parameters from HR-pQCT are shown in Table 1.To explain Dcomp in multivariate analysis, the determination coef (r2) was 0.80 with a combination of PoV/TV_SR, Po.N_SR and Po.Sp_SR instead of 0.77 with PoV/TV_SR alone.In conclusion, Dcomp from HR-pQCT images is the most pertinent parameter reflecting with a good precision cortical porosity measured from SR micro-CT images. Dcomp was not better explained by a combination of morphological parameters from SR micro-CT images.

Background: The randomized, double-blind Multiple Outcomes of Raloxifene Evaluation (MORE) trial found that 4 years of raloxifene therapy decreased the incidence of invasive breast cancer among postmenopausal women with osteoporosis by 72% compared with placebo. We conducted the Continuing Outcomes Relevant to Evista (CORE) trial to examine the effect of 4 additional years of raloxifene therapy on the incidence of invasive breast cancer in women in MORE who agreed to continue in CORE. Methods: Women who had been randomly assigned to receive raloxifene (either 60 or 120 mg/day) in MORE were assigned to receive raloxifene (60 mg/day) in CORE (n = 3510), and women who had been assigned to receive placebo in MORE continued on placebo in CORE (n = 1703). Breast cancer incidence was analyzed by a log-rank test, and a Cox proportional hazards model was used to compute hazard ratios (HRs) and 95% confidence intervals (CIs). All statistical tests were two-sided. Results: During the CORE trial, the 4-year incidences of invasive breast cancer and estrogen receptor (ER)-positive invasive breast cancer were reduced by 59% (HR = 0.41; 95% CI = 0.24 to 0.71) and 66% (HR = 0.34; 95% CI = 0.18 to 0.66), respectively, in the raloxifene group compared with the placebo group. There was no difference between the two groups in incidence of ER-negative invasive breast cancer during CORE (P = .86). Over the 8 years of both trials, the incidences of invasive breast cancer and ER-positive invasive breast cancer were reduced by 66% (HR = 0.34; 95 % CI = 0.22 to 0.50) and 76% (HR = 0.24; 95% CI = 0.15 to 0.40), respectively, in the raloxifene group compared with the placebo group. During the CORE trial, the relative risk of thromboembolism in the raloxifene group compared with that in the placebo group was 2.17 (95% CI = 0.83 to 5.70). This increased risk, also observed in the MORE trial, persisted over the 8 years of both trials. Conclusions: The reduction in invasive breast cancer incidence continues beyond 4 years of raloxifene treatment in postmenopausal women with osteoporosis. No new safety concerns related to raloxifene therapy were identified during CORE. © Oxford University Press 2004, all rights reserved.