Purpose:The K-edge of gold (81 keV) is located
within the energy range of diagnostic CT. This might be advantageous
for material differentiation in dual-energy CT (DECT). The aim of this in vitro study was to compare the differentiation
between iodine or gold and body tissues using DECT at different kV spectra.Methods and Materials:A water filled tank phantom containing specimens with iodine
(iopamidol), gold (sodium aurothiomalate), compact bone (compact porcine bone)
and porcine muscle was scanned using a dual source CT (Definition, Siemens
Healthcare). Consecutive scans were performed at 80 kVp, 100 kVp, 120 kVp and
140 kVp with constant mAs settings. The mean attenuation values of the
specimens were measured, and differences in calculated dual-energy ratios (DEratio)
between body tissues and iodine or gold were determined for different DE
spectra. Results:The attenuation of gold increased compared
to 80 kVp at higher kVp-settings, while the attenuation of all other specimens
decreased. The calculated DEratios at 80/100 kVp, 80/120 kVp and
80/140 kVp were 1.31, 1.62 and 1.91 for iodine, 0.89, 0.88 and 0.92 for gold,
1.20, 1.39 and 1.45 for compact bone, 1.01, 1.03 and 1.08 for muscle. The
differences between the DEratios 80/100 kVp, 80/120 kVp and 80/140
kVp were 0.11, 0.23 and 0.46 for iodine and bone, 0.31, 0.51 and 0.53 for gold
and bone, 0.29, 0.59 and 0.83 for iodine and muscle, 0.12, 0.15 and 0.16 for
gold and muscle.Conclusion:DEratio of gold remains relatively
stable along the energy spectrum of diagnostic CT and allows a reliable
material differentiation between gold and bone already at contiguous low tube
voltage settings (80 kV and 100 kV). Thus, gold might have a potential as a contrast
agent for DECT.
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