To compare in dual-energy CT ( DECT ) conventionally reconstructed polyenergetic images ( PEI ) at @ kVp to virtual monoenergetic images ( MEI ) at different kiloelectron volt ( keV ) levels for evaluation of liver and gastrointestinal stromal tumor ( GIST ) hepatic metastases with regard to objective ( IQob ) and subjective image quality ( IQsub ) assessed by two readers of varying experience .