advanced noise-optimized dual-energy virtual monochromatic imaging vs. conventional 120-kvp ct imaging: image quality assessment

Purpose: this study aimed at evaluating the image quality characteristics of advanced noise-optimized and traditional virtual monochromatic images compared with conventional 120-kvp images from second-generation dual-source ct.materials and methods: for spiral scans six syringes filled with diluted iodine contrast material (1, 2, 5, 10, 15, 20 mg i/ml) were inserted into the test phantom and scanned with a second-generation dual-source ct in both single-energy (120-kvp) and dual-energy modes. images set contain conventional single-energy 120-kvp, and virtual monochromatic were reconstructed with energies ranging from 40 to 190-kev in 1-kev steps. an energy-domain noise reduction algorithm was applied and the mean ct number, image noise, and iodine cnr were calculated. results: the iodine ct number of conventional 120-kvp images compared with monochromatic of 40-, 50-, 60- and 70-kev images showed increase. the improvement ratio of image noise on advanced virtual monochromatic images (avmis) compared with the traditional virtual monochromatic images (tvmis) at energies of 40-, 50-, 60, 70-kev was 52.9%, 35.7%, 8.1%, 2.1%, respectively. at avmis from 75- to 190-kev, the image noise value was less than conventional 120-kvp images. cnr improvement ratio at 20 mg/ml of iodinated contrast material for tvmis and avmis compared to 120-kvp ct images and avmis compared to tvmi was 18.3% and 56.3%, 32.1% respectively. conclusion: both tvmis (in energies ranging from 54 to 71-kev) and avmis (in energies ranging from 40 to 74-kev) represent improvement in the iodine contrast-to-noise ratio than conventional 120-kvp ct images for the same radiation dose. also, avmis compared to tvmis have been obtained considerable noise reduction and cnr improvement for low-energy virtual monochromatic images. in the present study, we show that virtual monochromatic image and its advanced version (avmi) may boost the dual-energy ct advantages by providing higher cnr images in the same exposure value compared to routinely acquired single-energy ct images.