9 March 2018 Calcium decomposition and phantomless bone mineral density measurements using dual-layer-based spectral computed tomography
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Abstract
Dual-layer spectral computed tomography (CT) provides a novel clinically available concept for material decomposition (calcium hydroxyapatite, HA) and thus to estimate the bone mineral density (BMD) based on non-dedicated clinical examinations. In this study, we assessed whether HA specific BMD measurements with dual-layer spectral CT are accurate in phantoms and vertebral specimens.

Dual-layer spectral CT was performed at different tube current settings (500, 250, 125 and 50 mAs) with a tube voltage of 120 kVp. Ex-vivo human vertebrae (n = 13) and a phantom containing different known HA concentrations were placed in a semi-anthropomorphic abdomen phantom. BMD was derived with an in-house developed algorithm from spectral-based virtual monoenergetic images at 50 keV and 200 keV. Values were compared to the HA concentrations of the phantoms and conventional quantitative CT (QCT) measurements using a reference phantom, respectively.

Above 125 mAs, which is the radiation exposure level of clinical examinations, errors for phantom measurements based on spectral information were less than 5%, compared to known concentrations. In vertebral specimens, high correlations were found between BMD values assessed with spectral CT and conventional QCT (correlation coefficients > 0.96; p < 0.001 for all).

These results suggest a high accuracy of quantitate HA-specific BMD measurements based on dual-layer spectral CT examinations without the need for a reference phantom, thus demonstrating their feasibility in clinical routine.
© (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Kai Mei, Benedikt J. Schwaiger, Felix K. Kopp, Sebastian Ehn, Alexandra S. Gersing, Jan S. Kirschke, Daniela Munzel, Alexander A. Fingerle, Ernst J. Rummeny, Franz Pfeiffer, Thomas Baum, Peter B. Noël, "Calcium decomposition and phantomless bone mineral density measurements using dual-layer-based spectral computed tomography", Proc. SPIE 10573, Medical Imaging 2018: Physics of Medical Imaging, 105731H (9 March 2018); doi: 10.1117/12.2292978; https://doi.org/10.1117/12.2292978
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