Evaluation of local alterations in femoral bone mineral density measured via quantitative CT

Abstract

The aim of this study was to investigate the accuracy of bone mineral density (BMD) determined by quantitative computed tomography (qCT) based on in situ and ex situ scans of cadavers of variable stature. The in uence of surrounding tissue on the quanti cation of CT images of ex situ scanned femora was investigated in air and in water and compared with the in situ scanned femora. The study showed that the surrounding tissue has an impact on the grey value-based representation of the scanned object as well as on the calibration of BMD, in uencing the determination of BMD. Local di erences in BMD of up to 17.5% were observed, which might originate from beam hardening artifacts.

Effect of CT imaging on the accuracy of the finite element modelling in bone

“…This is especially challenging in clinical routine. The literature on the effect of CT imaging on the finite element accuracy in skeletal modelling is scarce, and conclusions are often based on small study populations and low statistical power [1,24]. Most studies investigate the effect of different scan parameters and their effect on HU and BMD.…”

“…Sitzer et al [24] reported differences in femoral diaphysis BMD measurements via QCT imaging (n = 3) of up to 17.5% when scanned in air and water compared to in vivo. Similarly, Keyak and Falkinstein [25] compared the FE predicted fracture loads of human femora scanned in situ and in vitro.…”

“…Thus, when scanned in vitro , specimens should be submerged in water. It should be still noted that available research on the effect of different scanning conditions on the accuracy of FE models is currently rather explorative rather than systematic and based on data obtained on a very low number of specimens ( n = 2–6) [ 24 – 26 ].…”