Feasibility of single scan for simultaneous evaluation of regional krypton and iodine concentrations with dual-energy CT: An experimental study

Purpose: To evaluate the feasibility of a simultaneous single scan of regional krypton and iodine concentrations by using dualenergy computed tomography (CT). Materials and Methods: The study was approved by the institutional animal experimental committee. An airway obstruction model was first made in 10 beagle dogs, and a pulmonary arterial occlusion was induced in each animal after 1 week. For each model, three sessions of dual-energy CT (80% krypton ventilation [krypton CT], 80% krypton ventilation with iodine enhancement [mixed-contrast agent CT], and iodine enhancement [iodine CT]) were performed. Krypton maps were made from krypton and mixed-contrast agent CT, and iodine maps were made from iodine and mixed- contrast agent CT. Observers measured overlay Hounsfield units of the diseased and contralateral segments on each map. Values were compared by using the Wilcoxon signed-rank test. Results: In krypton maps of airway obstruction, overlay Hounsfield units of diseased segments were significantly decreased compared with those of contralateral segments in both krypton and mixed-contrast agent CT (P = .005 for both). However, the values of mixed-contrast agent CT were significantly higher than those of krypton CT for both segments (P = .005 and .007, respectively). In iodine maps of pulmonary arterial occlusion, values were significantly lower in diseased segments than in contralateral segments for both iodine and mixed-contrast agent CT (P = .005 for both), without significant difference between iodine and mixed-contrast agent CT for both segments (P = .126 and .307, respectively). Conclusion: Although some limitations may exist, it might be feasible to analyze regional krypton and iodine concentrations simultaneously by using dual-energy CT.