Comparison between the QCT and the DEXA Scanners in the Evaluation of BMD in the Lumbar Spine

Objectives: To evaluate BMD in lumbar spine of the same subjects under similar conditions both by QCT and DEXA scanners on the same day and to compare their findings in evaluating these subjects as osteoporotic, osteopenic or normal. Materials and Methods: In this cross sectional study a population of 165 subjects both male and female which included 37 young healthy volunteers, 46 post menopausal females, 32 elderly patients above 65 years of age, 15 patients between 4065 years of age and 35 patients on steroid therapy for more than 6 months period underwent bone densitometry both by QCT and DEXA scanners. Light Speed Plus CT scanner of GE and DEXA scanner Norland XR 46 were used for measurement of BMD and accordingly, these subjects were diagnosed as osteoporotic, osteopenic and normal on the basis of WHO defined criteria of T score. Results: In the present study QCT has diagnosed more cases of osteoporosis (both osteopenic and osteoporotic) as compared to DEXA lateral and DEXA AP in the total population as well as in females and males separately. In the total population, 67.3% (111) cases were diagnosed for osteoporosis by QCT as compared to 46.7% (77) and 49.7% (82) cases by DEXA lateral and DEXA AP respectively. In females, 75.8% (97) cases were diagnosed for osteoporosis by QCT as compared to 52.3% (67) each by DEXA lateral & DEXA AP. Similarly in males 37.8% (14) cases were diagnosed for osteoporosis by QCT as compared to 27% (10 ) cases by DEXA lateral and 40.6% (15 ) cases by DEXA AP.