Peripheral quantitative CT of the forearm: scanner cross-calibration using patient data

Bone density measurements by peripheral quantitative CT (pQCT) of the distal radius in 87 women (age 38.4+/-12.3 years) were obtained on a both a Stratec XCT 900 and an updated version XCT 1400. Axial area, and total and trabecular bone mineral density (BMD) results from both scanners were compared for all patients using linear regression analysis. To achieve scanner calibration we used the intercept and slope of the patients' correlations. The correlations of the patients' values were good for area (r=0.83) as well as total BMD (r=0.90) and excellent for trabecular BMD (r=0.97). The cross-calibration approach in our study provided compatibility of pQCT for trabecular and total ROIs, the clinically mostly utilized volumes of measurement.