Spine Positioning and Rotation

Case Description:

The artifacts lateral to L2 on the left in the baseline scan can be used to gauge a difference in spine positioning on the followup scan. On the follow-up scan, the clips now project over L2, meaning that L2 should be removed from analysis. For optimal precision, the positioning of the patient should be analogous between baseline and follow-up scans. Differences in axial rotation of the spine have been studied by several authors, with a variety of spine phantoms. Generally, lateral and axial rotation of the spine increases the area, with a corresponding decrease in bone density.

Credit:

Sarah L Morgan, MD, RD, CCD, The University of Alabama at Birmingham

References:

• Cetin, A., et al., Evaluation of the patient positioning during DXA measurements in daily clinical practice. Clin Rheumatol, 2008. 27(6): p. 713-5.
• Cheng, J.C., et al., The effect of vertebral rotation of the lumbar spine on dual energy X-ray absorptiometry measurements: observational study. Hong Kong Med J, 2001. 7(3): p. 241-5.
• Izadyar, S., et al., The Effect of the Lumbar Vertebral Malpositioning on Bone Mineral Density Measurements of the Lumbar Spine by Dual-Energy X-Ray Absorptiometry. J Clin Densitom, 2016. 19(3): p. 277-81.
• Jeon, Y.K., et al., Effect of increased axial rotation angle on bone mineral density measurements of the lumbar spine. Spine J, 2014. 14(9): p. 2150-4.
• Watts, N.B., Fundamentals and pitfalls of bone densitometry using dual-energy X-ray absorptiometry (DXA). Osteoporos Int, 2004. 15(11): p. 847-54.
• Choplin R.H., Lenchik L and S. Wuertzer, A practical approach to interpretation of Dual-Energy X-ray Absorptiometry (DXA) for assessment of bone density. . Curr Radiol Rep 2014. 2(48).
• Dasher, L.G., C.D. Newton, and L. Lenchik, Dual X-ray absorptiometry in today’s clinical practice. Radiol Clin North Am, 2010. 48(3): p. 541-60.
• Theodorou, D.J. and S.J. Theodorou, Dual-energy X-ray absorptiometry in clinical practice: application and interpretation of scans beyond the numbers. Clin Imaging, 2002. 26(1): p. 43-9.
• Mergler, S., et al., Lumbar spine and total-body dual-energy X-ray absorptiometry in children with severe neurological impairment and intellectual disability: a pilot study of artefacts and disrupting factors. Pediatr Radiol, 2012. 42(5): p. 574-83.
• Choi, J.S., The influence of soft tissue recognition erros on BMD value-A case report: Recipient of Young Investigator Award J Clin Densitom, 2012. 15(4): p. 483
• Fuleihan, G.E., et al., Reproducibility of DXA absorptiometry: a model for bone loss estimates. J Bone Miner Res, 1995. 10(7): p. 1004-14.
• Fuerst, T., et al., Quality Assurance in Bone Densitometry in Bone Densitometry and Osteoporosis H.K. Genant, G. Guglielmi, and M. Jergas, Editors. 1998, Springer Berlin.
• Hansen, K., et al., DXA Errors are Common and Likely Adversely Affect Clinical Care: DXA Quality Improvement is Needed. J Bone Miner Res 2016. 31((Suppl 1) Available at http://www.asbmr.org/ItineraryBuilder/Presentation Detail.aspx?pid=83c01c31-237b-4f07-81a5-1eeb2a7968aa&ptag=AuthorDetail&aid=00000000-0000-0000-0000-000000000000. ).
• Promma, S., et al., Errors in Patient Positioning for Bone Mineral Density Assessment by Dual x-ray Absorptiometry: Effect of Technologist Retraining. J Clin Densitom, 2018. 21(2): p. 252-259.
• Cetin, A., et al., Evaluation of the patient positioning during DXA measurements in daily clinical practice. Clin Rheumatol, 2008. 27(6): p. 713-5.
• Staron, R.B., et al., Computerized bone densitometric analysis: operator-dependent errors. Radiology, 1999. 211(2): p. 467-70.
• Baniak, N., S. Grzybowski, and W.P. Olszynski, Dual-energy x-ray absorptiometry scan autoanalysis vs manual analysis. J Clin Densitom, 2014. 17(1): p. 97-103.