Triple-phase computed tomography during arterial portography with bolus tracking for hepatic tumors

Optimal delay for triple-phase hepatic computed tomography using a bolus-tracking technique in cats

The objective of this study was to provide the characteristics of hepatic computed tomography images and optimize their transition delay with a bolus-tracking technique for triple-phase hepatic computed tomography in cats. Dynamic triple-phase computed tomography was performed in nine healthy cats. The upper third of the liver was dynamically scanned every 0.5 s for 40 s. The time density curves of the aorta and hepatic parenchyma mean enhancement were analyzed. Triple-phase hepatic computed tomography was performed three times with a bolus trigger of 200 Hounsfield units of aortic enhancement. The transition delays of the arterial, portal, and hepatic parenchymal phases were respectively 0, 5 and 60 s in the first scan; 2, 7 and 62 s in the second scan; and 4, 9 and 64 s in the third scan. All computed tomography images were evaluated by a certificated radiologist. The arterial vessels and their main branches were well enhanced at a 2 s transition delay. The contrast of the portal vein to the liver parenchyma was most obvious at a 7 s transition delay. The mean enhancement of the hepatic parenchyma peaked at a 62 s transition delay, whereas the degree of enhancement of the hepatic vasculature decreased. In this study, the recommended transition delays for the arterial, portal, and hepatic parenchymal phases were 2 s, 7 s and 62 s, respectively, after triggering at 200 Hounsfield units of aortic enhancement. This information may be helpful in diagnosing feline liver diseases and provides a key reference for the clinical implementation of CT.

Change in portal vein hemodynamics after chemoembolization for hepatocellular carcinoma: evaluation through multilevel dynamic multidetector computed tomography during arterial portography

OBJECTIVE

This study aimed to clarify the effect of embolization with lipiodol on portal vein hemodynamics.

METHODS

Time-density curves of the main portal vein on multilevel dynamic multidetector computed tomography during arterial portography were used to analyze peak computed tomography value (PV), time to PV (TPV), arrival time of contrast medium at the main portal vein (ATMPV), slope [(PV - 150) / (TPV - ATMPV)], and slope ratio (slope after embolization / slope before embolization).

RESULTS

In 20 patients with hepatoma, ATMPV and TPV were significantly prolonged and the time-density curve slope was significantly less after embolization. The difference in TPV increased (P = 0.02) and the slope ratio decreased with increasing embolized volume rate (P < 0.001). Strong correlation (R = -0.86) was found between the slope ratio and the embolized volume rate.

CONCLUSIONS

Time-density curves revealed significant portal vein flow delay after embolization; the degree of which was correlated with the extent of the embolized volume.