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PURPOSE To evaluate the impact of advanced monoenergetic dual-energy computed tomography(DECT)datasets on detection rate and contrast-to-noise ratio(CNR)of early gastric cancer(EGC)on the third generation DECT.METHOD AND MATERIALS 20 patients suspected of EGC were prospectively enrolled in this study.Arterial phase(AP)and portal phase(PP)imaging were acquired in dual-energy mode(80/Sn150KV)using third-generation DECT(SOMATOM Force,Siemens Healthcare,Germany).Monoenergetic images(MEIs)(range 40-100keV)were calculated from the 80 and Sn150KV image data using monoenergetic software(Dual energy Mono+,syngo via,Siemens).Differences in detection rates of EGC and CNR numbers were compared between different MEIs from 40 to 100 keV and conventionally reconstructed polyenergetic images(PEIs)at 120 kVp.Histopathologic analysis of resected gastric specimens was used as reference standard.Radiation metrics were compared with those obtained in the second-general DECT(Definition Flash,Siemens Healthcare,Germany)from published reports.RESULTS MEIs at 40keV and 50keV showed the highest detection rates(60.0%and 60.0%respectively)for EGC,which showed no significant difference with PEIs(35%)(P=0.205).For EGC lesions of less than2cm,an increase in the detection rates was observed from MEIs at 40keV and 50keV(53.8%,7/13 and 53.8%,7/13)as compared to PEIs(23.1%,3/13),though no statistical significance was found(P=0.226).MEIs at 40keV and 50keV revealed statistical higher CNR-AP and CNR-PP compared to PEIs(all P<0.05).The CTDIvol of the AP and PP were 4.28 ± 0.92 mGy and 4.67 ± 0.95 mGy respectively,which was about 35%of the radiation dose when using routine second-generation DECT(100/Sn140KV)from literatures.CONCLUSION Virtual 40keV and 50keV monoenergetic images calculated using the Mono+algorithm significantly increase the CNR of EGC,which was helpful to enhance the EGC detection rate.Third-generation DECT could potentially allow for radiation dose reduction in EGC detection as compared to the second-general DECT.