LONG-TERM PRECISION OF DUAL PHOTON-ABSORPTIOMETRY IN THE LUMBAR SPINE IN CLINICAL SETTINGS

  • 1 March 1988
    • journal article
    • research article
    • Vol. 3  (4) , 305-315
Abstract
We have investigated the long-term in vivo precision of a dual photon spine scanner using three different Gd sources and compared it with that of the single photon scanner. Standard values were significantly different with the three Gd sources. With the second there was also a systematic increase of 2% per 60 000 cps in the 44 KeV channel as the source decayed, whereas no such shift was found with other two sources. This resulted in a significant in vivo intrasource (P < 0.05) and intersource (P < 0.01) variation and a six-month reproducibility ranging from 3.7 to 8.1%. After correction of these systematic errors the clinically important 2-year reproducibility in 26 premenopausal women was 3.4 .+-. 1.3% for spinal BMC and 3.7 .+-. 1.7% for spinal BMD. In comparison, the forearm single photon scanner had a longterm precision of 1.0 .+-. 0.3%. With the presented techniques spinal measurements may therefore require 11.6 times (3.42:1.02) as many participants as the forearm measurements to detect the same changes in bone mass.