Objectives Material suppressed iodine images(MSI)is a new technique provide by CT spectral imaging,which remove iodine contribution on 70keV monochromatic image.This study aims to evaluate theiodine suppressing efficiency for different abdomen organs of material suppressed iodine images(MSI).Methods Totally 40 patients(mean age 49.6±12.2 years)received abdominal CT,including non-enhanced and contrastenhanced images during the artery phase(AP)and portal phase(PVP)(Discovery CT750HD,GE healthcare)on a single-source dualenergy CT(Discovery CT 750HD,GE healthcare)with CTspectral imaging mode.MSI wasgeneratedby suppressing iodine on 70keV monochromatic image with a dedicated software(GSI Volume Viewer,Advantage Workstation 4.6).The mean CT number(CT)of abdominal organs including liver,kidney,pancreatic and abdominal aorta were measured in 70keV monochromatic images,MSI and true non-enhanced images(TNI).The iodine-suppressed radio(ISR)was calculated from formula as follow: ISR=(CT70keV-CT MSI)/(CT70keV-CTTNI).Results There were significant difference in the ISR of liver and kidney between AP and PVP(AP: liver,0.49±0.23vs kidney,0.88±0.050;PVP: liver,0.80±0.09 vs kidney,0.91±0.04;both p<0.05).There were no significant difference in the ISR of pancreatic and abdominal aorta between AP and PVP(AP: pancreatic,0.75±0.12vsabdominal aorta,0.90±0.04;PVP: pancreatic,0.79±0.13vsabdominal aorta,0.88±0.07;both p>0.05).ISR of kidney in PVP was superior over other organs.Conclusions The iodine suppressing efficiency of MSI varies for different abdomen organs and scan phases.Hypervascular organs seem to get more ISR.Although the MSI is supposed to be a potential replacement for TNI.To some extent,the efficiency of MSI is influenced by the characteristic of organ and scan phase.