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Calcif Tissue Int (2005) 76:348354DOI: 10.1007/s00223-004-0050-zTowards Standardization of Dual X-ray Absorptiometry (DXA) at the
ForearmA Common Region of Interest (ROI) Improves the Comparability among DXA DevicesS. Prevrhal, Y. Lu, H. K. Genant, J. O. Toschke, J. A. ShepherdDepartment of Radiology, University of California, San Francisco, California, USAReceived: 19 March 2004 / Accepted: 22 October 2004 / Online publication: 4 May 2005Abstract. Manufacturer-implemented regions of interest
(ROIs) to determine the bone mineral density (BMD) at
the forearm are currently not standardized across dual X-
ray absorptiometry (DXA) devices. We hypothesized that
their dierences introduce considerable variation in
measurement results for forearm BMD when taken on
dierent devices, and that a ROIs common to all devices
with standardized placement and size signicantly improve device comparability. The common ROI was de-
ned to have a xed length of 2 cm and to extend
proximally from the location where the ulna and radius
bones superimpose on the DXA image. The eects of
universal standardization of forearm BMD were combined with and compared to those of the common ROI.
They were drawn on 91 female study participants (ages
2080 years, 10 per decade) who were scanned on Hologic
QDR-4500, Aloka DCS-600EX, GE Lunar PIXI and
Norland pDEXA DXA scanners. For all device combinations, manufacturer-implemented ROI root meansquare errors were signicantly higher than for the common ROI, suggesting that implementing an ROI with
common design on all scanners is a good way to reduce
interdevice variability. When manufacturer-implemented
ROIs were universally standardized root mean-square
error (RMSE) values were less dierent from that of the
nonstandardized Common ROI, suggesting that universal standardization can further improve interdevice
comparability even when a common ROI such as the one
implemented here is used. ROI standardization dramatically improves interdevice comparability.Key words: Bone densitometry Forearm Standardization Regions of interestBone mineral density (BMD), currently most commonly
assessed by dual X-ray absorptiometry (DXA), is the
single most important predictor of osteoporotic fractures. The distal forearm has been shown to be a good
predictor of osteoporotic fractures, both at the spine
and the hip [13]. BMD is calculated within a usually
automatically placed region of interest (ROI). It is clear
that conformance of results obtained with dierent
DXA devices will depend not only on scanner hardware
characteristics and calibration standards,...