TY - JOUR
T1 - Cross calibration of QDR-2000 and QDR-1000 dual-energy X-ray densitometers for bone mineral and soft-tissue measurements
AU - Abrahamsen, B.
AU - Gram, J.
AU - Hansen, T. B.
AU - Beck-Nielsen, H.
PY - 1995/3
Y1 - 1995/3
N2 - Replacement of dual energy X-ray densitometry (DXA) equipment may be necessary in many labs with time, or new equipment may be added. In this context we compared patient scans between a Hologic QDR-1000W and a QDR-2000 (n = 29-43, depending on anatomic region) and between QDR-2000 single beam (SB) and fan beam (FB) modes (n = 40-62) as a quality control measure. A total of 83 subjects (79 females and four males) with a wide range of bone mineral densities (BMD) were studied. There was a linear relationship between results with the QDR-1000W and QDR-2000 in SB mode, and between SB and FB mode on the QDR-2000, but the magnitude of the coefficients and constants differed for the different anatomic regions. In SB mode the QDR-2000 underestimated whole body and forearm BMD by 3% relative to the QDR-1000W, even after cross calibration using a spine phantom. Femoral total BMD was slightly, but not significantly, underestimated. Thus, additional postanalysis correction had to be applied to forearm and whole-body scans. In FB with the QDR-2000, spine and whole-body BMD was underestimated by 3%, but femur total and neck BMD was overestimated by 2.2 and 2.8%, respectively, compared with SB scans on the same device. Soft-tissue composition with FB (enhanced analysis protocol) on the QDR-2000 differed greatly from that obtained using SB (standard protocol). Lean tissue mass was 4 kg lower and fat mass 4 kg higher in FB mode. Also, total body BMC was 7% lower using FB. Patients should be followed using the same scanning mode and analysis protocol whenever possible. Cross calibration by means of a single BMD anthropomorphic spine phantom is not sufficient to ensure identical results in all anatomic regions when a QDR-2000 replaces a QDR-1000W or is switched to FB mode. Linear regressions in vivo should be determined for each anatomic region.
AB - Replacement of dual energy X-ray densitometry (DXA) equipment may be necessary in many labs with time, or new equipment may be added. In this context we compared patient scans between a Hologic QDR-1000W and a QDR-2000 (n = 29-43, depending on anatomic region) and between QDR-2000 single beam (SB) and fan beam (FB) modes (n = 40-62) as a quality control measure. A total of 83 subjects (79 females and four males) with a wide range of bone mineral densities (BMD) were studied. There was a linear relationship between results with the QDR-1000W and QDR-2000 in SB mode, and between SB and FB mode on the QDR-2000, but the magnitude of the coefficients and constants differed for the different anatomic regions. In SB mode the QDR-2000 underestimated whole body and forearm BMD by 3% relative to the QDR-1000W, even after cross calibration using a spine phantom. Femoral total BMD was slightly, but not significantly, underestimated. Thus, additional postanalysis correction had to be applied to forearm and whole-body scans. In FB with the QDR-2000, spine and whole-body BMD was underestimated by 3%, but femur total and neck BMD was overestimated by 2.2 and 2.8%, respectively, compared with SB scans on the same device. Soft-tissue composition with FB (enhanced analysis protocol) on the QDR-2000 differed greatly from that obtained using SB (standard protocol). Lean tissue mass was 4 kg lower and fat mass 4 kg higher in FB mode. Also, total body BMC was 7% lower using FB. Patients should be followed using the same scanning mode and analysis protocol whenever possible. Cross calibration by means of a single BMD anthropomorphic spine phantom is not sufficient to ensure identical results in all anatomic regions when a QDR-2000 replaces a QDR-1000W or is switched to FB mode. Linear regressions in vivo should be determined for each anatomic region.
KW - Bone
KW - Bone mineral density
KW - Densitometry
KW - Dual-energy X-ray absorptiometry
KW - Longitudinal studies
KW - Precision
UR - http://www.scopus.com/inward/record.url?scp=0029123724&partnerID=8YFLogxK
U2 - 10.1016/8756-3282(94)00054-9
DO - 10.1016/8756-3282(94)00054-9
M3 - Article
C2 - 7786643
AN - SCOPUS:0029123724
VL - 16
SP - 385
EP - 390
JO - Bone
JF - Bone
SN - 8756-3282
IS - 3
ER -