Learning objectives
To review Dual X-ray absorptiometry (DXA) procedure in terms of proper positioning and analysis, in order to achieve correct interpretation. To describe potential artifacts and disorders that can affect bone mineral density (BMD) measurements.
Background
DXA is the technique of choice in the assessment of bone mineral density (BMD). The scanner consists of a low dose X-ray tube employing two different energies to separate mineral and soft tissue components and a high-resolution multi-detector array. Devices may use two different systems: either a fan-beam emitting alternating high (140 kVp) and low (70-100 kVp) X- rays, which sweeps across a scan area, or a constant X-ray beam with a rare earth filter with energy-specific absorption, which separates photons of higher (70 KeV)...
Imaging findings OR Procedure details
1. TECHNICAL ASPECTS a. REGIONS OF INTEREST Central DXA measurements should be performed on lumbar spine and proximal femur in all adult patients. Two regions should be analysed, so if one of those is not eligible the forearm is scanned. The image obtained should include the area of interest, exceeding the superior and inferior limits, in order to be sure that the complete anatomical region is scanned. i. LUMBAR SPINE The AP lumbar spine includes vertebral bodies L1 through L4. Altered vertebrae should be excluded...
Conclusion
TAKE HOME POINTS. - Inappropriate patient positioning is the most important source of false BMD measurements. - Correct ROI placement is also important. - Artifacts should be detected in order to avoid pitfalls in BMD analysis, and lesions sometimes previously not diagnosed may also be found.
Personal Information
-Rosa Lorente Ramos. Radiology Department. Infanta Leonor Hospital (Vallecas). Unidad Central de Radiodiagnóstico (UCR). Madrid. Spain - Yolanda del Valle Sanz. Radiology Department. Infanta Cristina Hospital (Parla). Unidad Central de Radiodiagnóstico (UCR). Madrid. Spain -Javier Azpeitia Armán. Radiology Department. Infanta Leonor Hospital (Vallecas). Unidad Central de Radiodiagnóstico (UCR). Madrid. Spain - José Acosta Battle. Radiology Department. Infanta Sofía Hospital (San Sebastian de los Reyes). Unidad Central de Radiodiagnóstico (UCR). Madrid. Spain
References
1. Baim S, Leonard MB, Bianchi ML, Hans DB, kalkwarf HJ, Langman CB, Rauch F. Official positions of the International Society for Clinical Densitometry and executive summary of the 2007 ISCD pediatric position development conference. J Clin Densitom 2008;11:6-21. 2. Rauch F, Plotkin H, DiMeglio L, Engelbert RH, Henderson RC, Munns C, Wenkert D, Zeitler P. Fracture prediction and the definition of osteoporosis in children and adolescents: the ISCD 2007 pediatric official positions. J Clin densitom 2008;11:22-28 3. Gordon CM, Bachrach LK, Carpenter TO, Crabtree...