Abstract

Introduction Spectral CT has been an emerging new clinical innovation that enables better discrimination and characterization of tissues. Purpose To assess the accuracy of a new fast kVp-switch spectral CT scanner in estimating the concentration and effective atomic number (Zeff) of iodine (I) in contrast enhanced tissue mimicking vessels. Materials and methods A cardiac CT phantom that simulates the chest of a medium-sized patient with respect to density and attenuation characteristics was coupled with four cylindrical vessels filled with I at 2.5 mg I/ml, 5 mg I/ml, 10 mg I/ml, and 15 mg I/ml. CT acquisitions were performed on a Revolution GSI CT scanner (General Electric, USA). The tube potential was switched from 80 kVp to 140 kVp at 4.8 kHz, while the fast response detector captured the low and high energy data sets. Spectral images in the range of 40–140 keV, iodine density images, as well as Zeff image maps were reconstructed. To investigate the effect of radiation dose on the accuracy of concentration and Zeff estimation, acquisitions were performed at different radiation dose levels. Results Measured iodine concentration and Zeff showed a strong correlation with nominal values (P〈0.001). Measurement error of iodine concentration and Zeff decreased with increasing dose from ±0.489 mg I/ml and ±0.08 at 8.91 mGy to ±0.197 mg I/ml and ±0.02 at 32.01 mGy, respectively. Conclusion Fast kVp-switch spectral CT provides accurate measurements of iodine concentration and Zeff allowing for a reliable estimate of blood volume supply in contrast-enhanced tissue vasculatures.

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