Measurement of Vascular Diameter in Computed Tomography Angiography With Reduced Iodine Load: Comparison of Virtual Monochromatic Imaging in Dual-Energy Computed Tomography and Conventional Polychromatic Scan In Vitro

The aim of this study was to compare accuracy of measurement between virtual monochromatic imaging (VMI) in dual-energy computed tomography and conventional polychromatic 120-kVp computed tomographic scan in vascular models containing various densities of contrast material. We evaluated measured diameters of 12 models of vessels of 4 inner diameters containing high, intermediate, and low densities of contrast material using software automation. Measurement errors with 70-keV VMI were significantly larger than or comparable to errors with 120-kVp scan for all models, and those with 50-keV VMI were significantly smaller than errors with 120-kVp scan for low-density models and larger for high-density models. Acquisition of images by VMI at low energy facilitates accurate measurement of diameters of poorly enhanced vessels with reduced iodine load but can increase measurement errors in other situations by decreasing spatial resolution, so VMI should be applied carefully to evaluate vessel diameter.