Original Article
An Overlying Fat Panniculus Affects Femur Bone Mass Measurement

https://doi.org/10.1385/JCD:6:3:199Get rights and content

Abstract

Dual-energy X-ray absorptiometry (DXA) is currently the gold standard technique for osteoporosis diagnosis. However, DXA has limitations, including artifacts, such as degenerative disease or metallic foreign bodies, that may confound bone mineral density (BMD) results. Because fat folds overlying the proximal femur may alter soft-tissue density in a nonuniform manner, this may be a currently unappreciated confounder of proximal femur BMD measurement. This possibility was evaluated in 127 patients (52 women/75 men) referred for routine BMD measurement who were identified as having a fat panniculus overlying their proximal femur scan area. Presence of a fat panniculus within the scan field was confirmed by visual assessment of images obtained utilizing a GE Lunar Expert-XL. Subsequently, these individuals were rescanned while retracting their fat panniculus away from the femur scan area without other repositioning between scans. In 49% of the men, and 56% of the women, either the femoral neck, trochanter, or total femur BMD differed by more than the least significant change at our facility. No pattern was observed to predict whether BMD would increase or decrease upon fat retraction. Subsequently, 30 patients were scanned using the standard and retracted technique twice, with repositioning between scans to establish precision. Retracted and standard precision was similar. In conclusion, an overlying fat panniculus may alter proximal femur BMD measurement, which would be expected to impair the ability to accurately diagnose low bone mass and monitor osteoporosis therapy. When a fat panniculus overlays the proximal femur scan area, its retraction should be part of routine densitometric practice.

References (17)

There are more references available in the full text version of this article.

Cited by (69)

  • Operator-Related Errors and Pitfalls in Dual Energy X-Ray Absorptiometry: How to Recognize and Avoid Them

    2021, Academic Radiology
    Citation Excerpt :

    Finally, the operator should try to place as much as possible the lateral aspect of the greater trochanter at half-height in the scan; this can be done by keeping the same amount of space under the ischium (lower part of the scan) and over the greater trochanter (upper part). In case of obese patients, abdominal fat folds may overlay the proximal femur area, leading to a fictitious and non-uniform variation of BMD values (usually an increase, but also a decrease of BMD has also been observed) (24). A variation over the LSC was observed in almost 50% of the cases, both in males and females; therefore, when a fat panniculus is observed over the proximal hip region, manual retraction should be routinely done (24).

View all citing articles on Scopus
View full text