A DXA Primer for the Practicing Clinician

Introduction * What prompted the authors to write this text * A brief comment on the Bone & Joint Decade * A brief word on the epidemiology of osteoporosis * Primary disease * Secondary disease * That seen in chronic disease, due to Rx, men, bariatric surgery pts. * Introduction to Densitometry * The gold standard for non-invasive skeletal assessment * Ultimate goal: prevent fractures * Limitations: only a 'snap-shot'; can not reveal what has gone on with the bones up to that point * The many challenges of DXA * Obtaining the images * Interpreting the data * Even radiologists are prone to errors * Specific training is essential * Clinical application to the individual patient * Looking into the future * New technologies * Vision of an 'optimal' noninvasive, accurate, measure of bone quality * Chief Medical Officer aboard the USS Enterprise: Lt Commander Leonard "Bones" McCoy * Hand-held 'tricorder' *3D-QCT * Finite element analysis (FEA) SECTION I: Fundamental Concepts 1. The History of Non-Invasive Skeletal Assessment * Imaging Techniques * Radiographic absorptiometry * SPA * DPA * QCT * DXA * QUS * PIXI 2. Common Terms and Abbreviations Defined * Accuracy * Apparent bone mineral density * BMD = areal density in g/cm2 in this text * Areal vs. volumetric * Bone accretion * Bone markers * Bone Mineral Density * Coefficient of variation * Database * Distal 3rd Radius * DPA * DXA, Central * DXA, Peripheral * Femoral Neck * Femoral Shaft * FRAX - incl application limited to untreated pts. - should not be completed by Techs; emphasize importance of clinical judgment * Hip, Total * LSC * Lumbar spine (L1 - L4)