Phantomless bone mineral density assessment in patients using dual-energy CT

Abstract

OBJECTIVES – To evaluate the accuracy of bone mineral density (BMD) measurement using various three-material decomposition approaches. METHODS – Six three-material decomposition methods were developed to quantify BMD in the first lumbar vertebra of 15 patients. Virtual monoenergetic images at 50 and 200 keV were employed for the analyses. Spectral data were decomposed into calcium hydroxyapatite (HA), red bone marrow or water, and marrow adipose tissue. HA-based BMD measurements were compared to corresponding quantitative CT (QCT) results. RESULTS – Strong linear correlations, but lack of agreement was found between the results obtained with the three-material decomposition methods and QCT. Spectral-based BMD values were substantially overestimated compared to QCT measurements. Average Hounsfield unit values at 50 and 200 keV inside the regions of interest suggested the presence of tissue that was not evaluated in the decomposition analyses. Furthermore, the three-material decomposition methods detected physiologically questionable volume fractions in some patients. CONCLUSIONS – The three-material decomposition methods developed in this study show promising correlations with QCT, but further research is required to improve accuracy.