Analysis of multi-slice CT imaging features of portal vein cancer embolus and portal vein thrombosis

Objective To evaluate the difference of multi-slice spiral CT (MSCT) imaging features and the anatomical positions of portal vein cancer embolus and portal vein thrombosis involving in patients with cirrhosis. Methods Clinical data of 18 cases of liver cirrhosis complicated with hepatocellular carcinoma and portal vein cancer embolus and 12 cases of portal vein thrombosis confirmed by clinically from May 2011 to May 2016 in Peking University Shenzhen Hospital and from August 2013 to August 2014 in Haifeng Pengpai Memorial Hospital of Guangdong Province were retrospectively analyzed. The pre-contrast enhancement scanning, hepatic artery phase, portal venous phase and delay phase of MSCT were performed in all two group patients, all patients suffered from cirrhosis which were confirmed by clinical or laboratory. The three-dimensional(3D) imaging reconstruction technologies for portal vein included multiplanar reconstruction(MPR) and 5 mm maximum intensity projection(MIP). The imaging manifestations and distribution of the portal vein cancer embolus and thrombosis were observed, the collateral vessels accompanied by the portal vein cancer embolus and thrombosis were analyzed too. The statistics analyses were made for the attenuation between the cancer embolus and thrombosis on pre- and post-contrast multi-phase enhancement scanning. Results The portal vein cancer embolus was presented as hypodensity on pre-contrast enhancement scanning accompanied by the portal vein diameter dilated in 12 of 18 cases, it showed as isodensity in the other 6 cases. The cancer embolus was enhanced as hyperdensity on arterial phase in all 18 cases, and its supply arteries were also detected in 15 cases, the cancer embolus appeared as hyperdensity, isodensity and hypodensity on portal venous phase in 4, 5 and 9 cases respectively, it all showed as hypodensity in delay phase. The cancer embolus involved in portal right and/or left branch in all 18 cases, it extended to main branch of portal in only 6 cases. The thrombosis was appeared as isodensity, hypodensity and slightly hyperdensity on pre-contrast enhancement scanning in 3, 3 and 6 cases respectively, there were no attenuation changed on post-contrast enhancement scanning, and all showed as hypodensity filling defect on portal vein phase and delay phase. The thrombosis involved in the main branch of portal vein in 11 cases, it spread to left or/and right branch of portal vein in 6 cases. There were no statistical significance for the attenuation between the cancer embolus and thrombosis on pre-contrast enhancement scanning and delay phase (all P values>0.05); the attenuations of cancer embolus were significant high than those of thrombosis in both artery phase and portal vein phase(all P values<0.05). The ratio of cancer embolus involved in portal right and(or) lift was significantly higher than that of thrombosis, the ratio of thrombosis involved in main branch of portal vein was significantly higher than that of cancer embolus(all P values<0.05). Conclusions The imaging features and the correlative lesion of portal vein cancer embolus and portal vein thrombosis can be displayed well by combining MSCT axial imaging and its 3D reconstruction imaging in the patients who suffer from liver cirrhosis, it can provide the clear evidence for the diagnosis of portal vein cancer embolus and thrombosis, and guide appropriate treatment options. Key words: Portal vein; Portal vein cancer embolus; Portal vein thrombosis; Diagnosis; Cirrhosis; Hepatocellular carcinoma; Tomography, X-ray computer