Abstract In this first clinical trial liposome-encapsulated iodixanol, CT particles (CTP) were studied. The aims of the present trial were to assess the efficacy of CTP in CT and to determine the safety of different doses of CTP. A total of 47 healthy volunteers were enrolled in the present study. The CTP was administered at doses 10, 30, 70 and 100 mg encapsulated I/kg bw. Efficacy was assessed using single-slice CT of the abdomen and evaluated by dose-response attenuation curves over time in liver, spleen, and abdominal vessels. Safety was assessed by blood tests, clinical examinations and recording of subjective adverse events (AE). The attenuations in liver tissue increased with the dose and maximal values above baseline were 20, 39 and 45 HU at the doses 30, 70 and 100 mg encapsulated I/kg bw, respectively. Maximal increases were seen 12.5 min after contrast administration. As for liver, the attenuations in spleen increased with the dose, but higher attenuations were obtained. In early images clinically significant enhancement was seen in abdominal vessels. Mild and moderate subjective AE were encountered at the doses 70 and 100 mg encapsulated I/kg bw. The CTP is efficacious in enhancing hepatic and splenic tissues and in early imaging of abdominal vessels. Adverse event precludes a clinical use of CTP in the current formulation.