Iodine quantification and detectability thresholds among major dual-energy CT platforms

Objectives: To estimate the minimum detectable iodine concentration on multiple dual-energy CT (DECT) platforms. Methods and materials: A phantom containing iodine concentrations ranging from 0 to 10 mg ml^-1 was scanned with five dual-energy platforms (two rapid kilo volt switching (r-kVs), one dual source (DS), one sequential acquisition and one split-filter). Serial dilutions of 300 mg ml^-1 iodinated contrast material were used to generate concentrations below 2 mg ml^-1. Iodine density and virtual monoenergetic images were reviewed by three radiologists to determine the minimum visually detectable iodine concentration. Contrast-to-noise ratios (CNRs) were calculated. Results: 1 mg mL^-1 (0.8 mg mL^-1 corrected) was the minimum visually detectable concentration among the platforms and could be seen by all readers on the third-generation r-kVs and DS platforms. Conclusions: At low concentrations, CNR for monoenergetic images was highest on the DS platform and lowest in the sequential acquisition and split-filter platforms. Advances in knowledge: The results of this study corroborate previous in vivo estimates of iodine detection limits at DECT and provide a comparison for the performance of different DECT platforms at low iodine concentrations in vitro.