- Discussion:
- is the newest and the most precise technique for evaluating
osteoporosis, and has emerged as the successor to
DPA;
- anatomic sites for DXA measurement include:
- lumbar spine, proximal femur, forearm and calcaneus;
- advantages of an x-ray system over a DPA radionuclide system include:
- shortened examination time (2 min);
- greater accuracy and precision due to higher resolution
- lowest radiation of the available techniques and lack of radionuclide decay (1/10th radiation dose of a CXR);
- can distinguish between regions w/ distinct compositions of trabecular and cortical bone (eg the femoral neck and Ward's triangle);
- disadvantages: gives an area measurement study versus a volumetric study;
- T-scores:
- bone-mineral-density values are expressed in terms of "T-scores"
- these indicate the number of standard deviations by which the patient's bone-mineral density differs from a normal mean value;
- osteopenia is defined as a T-score of between -1 and -2.5
- osteoporosis is defined as a T-score of below -2.5;
Musculoskeletal Radiology: Review Article: Noninvasive Measurements of Bone Mass, Structure, and Strength: Current Methods and Experimental Techniques.
Faulkner-Kenneth-G. et al.
American Journal of Roentgenology. 1991 Dec. 157(6). pp 1229-1237.
Bone density at various sites for prediction of hip fractures.
SR Cummings et al.
Lancet. Vol 341. 1993. p 72-75.
Special Articles: Review: Current Methods and Recent Advances in the Diagnosis of Osteoporosis.
Jergas, Michael.
Genant, Harry K.
Arthritis & Rheumatism.
1993 Dec.
36(12).
pp 1649-1662.
