A New Trabecular Region of Interest for Femoral Dual X‐Ray Absorptiometry: Short‐Term Precision, Age‐Related Bone Loss, and Fracture Discrimination Compared with Current Femoral Regions of Interest

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Abstract
We defined a new region of interest (ROI) for femoral Ward's triangle, centered on the femoral neck axis including comparatively trabecular-rich bone. Forty-seven premenopausal, 39 healthy postmenopausal, and 35 osteoporotic postmenopausal women with vertebral fractures were evaluated comparing the new with the standard femoral ROIs, using a Hologic QDR-2000. Additionally, spinal dual X-ray absorptiometry (DXA) was performed. The short-term precision error of the new ROI expressed as the root mean square of the coefficient of variations was 1.34% for premenopausal women, 1.69% for healthy postmenopausal women, and 2.46% for osteoporotic postmenopausal women. Bone mineral density (BMD) values of the new ROI correlated highly with those of the standard femoral ROIs (r = 0.91 - 0.96) and the spinal BMD (r = 0.74). Age-related bone loss of the new ROI was 0.75% per year (r = 0.66) in healthy women, which was approximately 1.5 times higher than the bone loss of the standard femoral ROIs, except for Ward's triangle. Regarding the intergroup discrimination, the t-value of the new ROI was similar to the t-value of Ward's triangle, and the intergroup percent decrements in BMD of the new ROI approximated those of Ward's triangle. For discriminating women with vertebral fractures, the new ROI demonstrated odds ratios of 1.6 similar to most ROIs but lower than that of the trochanteric region. The new, substantially trabecular ROI appears to be an alternative to the Ward's ROI traditionally used in femoral DXA having improved short-term precision and comparable sensitivity.