[Measurement of vertebral bone density. Quantitative tomodensitometry or dual-photon absorptiometry?].
We have compared vertebral bone density measurements (QCT and DXA) in women in the postmenopausal period who underwent both examinations. Our aim was to study the results and to define the respective indications of QCT and DXA in various clinical pictures of osteoporosis. The subjects of the study were distributed into various groups according to the presence or absence of vertebral collapse and/or peripheral fractures. The results of the measurements were expressed as Z-scores (deviation from age-normal average) to suppress the age effect and to make comparison between both methods possible. The values of both measurements are significantly lower in case of vertebral involvement. QCT is more sensitive than DXA to discriminate vertebral collapse. A vertebral fragility threshold was defined at a Z-score of -1 with DXA and -1.25 with QCT, corresponding to the best sensitivity for an acceptable specificity. The results of densitometry suggest that there is a peripheral osteoporosis, different from vertebral osteoporosis, as early as the postmenopausal period. Since DXA is easy to implement, it can be used to screen osteoporosis. When the vertebral measurement with DXA is normal although osteoporosis is obvious (previous collapse or fracture), QCT must be used as it is more sensitive.
Bergot
C
C
Laboratoire de Radiologie Expérimentale, UFR Lariboisière-Saint-Louis, Université Paris VII.
Laval-Jeantet
A M
AM
Laval-Jeantet
M H
MH
Kuntz
D
D
D015502:Absorptiometry, Photon; D015519:Bone Density; D005069:Evaluation Studies as Topic; D005260:Female; D005598:Fractures, Spontaneous / Q000000981:diagnostic imaging; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000000981:diagnostic imaging*; D011877:Radionuclide Imaging; D012016:Reference Values; D012680:Sensitivity and Specificity; D016103:Spinal Fractures / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed
Mesure de la densité osseuse vertébrale. Tomodensitométrie quantitative ou absorptiométrie biphotonique?