These subjects spanned a wide range of ages (20 to 78 years) and anthropometrics (BMI range 17 to 39). For this study, DXA screening was not performed prior to enrollment; therefore, no BMD inclusion/exclusion criteria was used. Nivolumab mouse For both cohorts, history of or

evidence for metabolic bone disease other than postmenopausal bone loss was an exclusion criterion, as was treatment within the previous year with any compound known to influence bone turnover. Both study protocols were approved by the UCSF Committee of Human Research, and all subjects gave written informed consent prior to participation. HR-pQCT All subjects described below were imaged in a clinical HR-pQCT system (XtremeCT, Scanco Medical AG, Brüttisellen, Switzerland)

using the manufacturer’s standard selleck compound library in vivo protocol described in previous patient studies [11, 12, 14]. This system consists of a microfocus X-ray source with a 70-µm focal spot size. The tube voltage was fixed at 60kVp while the current was 900 μA. Filters of 0.3 mm Cu and 1 mm Al are positioned at the aperture to filter soft X-rays in order to reduce patient dose and limit beam-hardening effects. The cone beam X-ray field is incident upon a structured CsI (40 mg/cm2) scintillator coupled by a fiber optic taper to a 2D 3,072 × 256 element CCD detector with a 41-µm pitch. The subject’s forearm was immobilized in a carbon fiber cast that was fixed within the gantry of the scanner. A single dorsal–palmar projection image of the distal radius was acquired to define the tomographic scan region.

This region spans 9.02 mm in length (110 slices) and was fixed starting at 9.5 mm proximal from the mid-jointline and extending proximally (Fig. 1a). For tomography, 750 projections were acquired over 180° with a 100-ms integration time at each angular position. The 12.6-cm field of view was reconstructed across a 1,536 × 1,536 matrix using a modified Feldkamp algorithm, yielding 82 µm voxels [21]. Total scan time was 2.8 min with an equivalent Celecoxib dose of approximately 4.2 µSv. Fig. 1 Images indicating the standard ultra-distal ROI for each device; HR-pQCT scout scan (a), Hologic DXA (b), Lunar DXA (c) The reconstructed linear attenuation values were converted to hydroxyapatite (HA) mineral densities using a beam-hardening correction and phantom calibration procedure previously described for an ex vivo microtomography system [22]. The calibration phantom (Scanco Medical AG, Brüttisellen, Switzerland) was composed of five cylinders of HA–resin mixtures with a range of mineral concentrations (0, 100, 200, 400, and 800 mg HA/cm3) where 0 mg HA/cm3 represents a soft tissue equivalent background devoid of mineral. The reconstructed images were segmented using semi-automatically drawn contours at the periosteal surface of the radius. The total vBMD of the radius was calculated as the mean calibrated mineral density within this volume of interest (VOI).