Krypton-enhanced ventilation CT with dual energy technique: Experimental study for optimal krypton concentration

ABSTRACT

Purpose/Aim of the study. To assess the feasibility of krypton-enhanced ventilation CT using dual energy (DE) technique for various krypton concentrations and to determine the appropriate krypton concentration for DE ventilation CT through an animal study. Materials and Methods. Baseline DECT was first performed on seven New Zealand white rabbits. The animals were then ventilated using 20%, 30%, 40%, 50%, 60%, to 70% krypton concentration, and DECT was performed for each concentration. Krypton extraction was performed through a workstation, and results were displayed on a color map. Overlay Hounsfield unit (HU) values were obtained by two observers in consensus readings. A linear mixed model was used to correlate overlay HU values and krypton concentrations. Visual assessments of the homogeneity of krypton maps were also performed. Results. Mean overlay HU values according to krypton concentration were as follows; 20% krypton, 1.68 ± 5.15; 30% krypton, 3.73 ± 5.93; 40% krypton, 6.92 ± 5.51; 50% krypton, 10.88 ± 5.17; 60% krypton, 14.54 ± 4.23; and 70% krypton, 18.79 ± 3.63. We observed a significant correlation between overlay HU values on krypton maps and krypton concentrations (P < .001). For the krypton color maps, all observers determined universal enhancement on the 70% krypton map for all animals. Conclusion. It is feasible to evaluate lung ventilation function using DECT with a krypton concentration of at least 70%.

KEYWORDS :

• dual energy CT
• krypton
• lung function
• material decomposition
• ventilation