Evaluation Of 64-slice Spiral CT Multiple-phase Scanning In Hepatic Metastases: A Preliminary Study

Objective:Detail the phases of the contrast-enhanced computed tomography and investigate the multi-phase contrast-enhanced imaging feature of the hepatic metastases prospectively by the 64 multi-slice spiral computed tomography (MSCT), so as to find the point at which the best equilibrium phase image could be acquire and thus to elevate the detection rate of hepatic metastases.Materials and Methods:All imaging data of 40 patients confirmed by surgery and pathology or clinical follow-up were analyzed. Unenhanced and dynamic sextuple-phase contrast-enhanced CT were performed in all patients.The scanning which is detailed by the technique of Smart Prep started at 22-24s (early arterial phase, EAP),29-31s (mid-arterial phase, MAP), 37-39s (late arterial phase, LAP),60-65s (early portal venous phase, EPVP),80-85s (late portal venous phase, LPVP) and 150s (liver equilibrium phase) after initial injection of contrast medium. Analyzed the imaging feature of the HMs, especially the contrast-enhanced characteristic of the lesions.Compared the detection rate of the every detailed phase.And then several programs were worked out such as EAP plus MAP, MAP plus LAP, EAP plus LAP, etc.The joint detection rates were compared in order to find the best scanning program. According to the density measurements, each of the T-D curve was drawn. Density contrast and CNR of the lesions and peripheral liver parenchyma were analyzed. Results:The great majority of HMs were hypovascular, more than 50%(22/38)presented TDC type of gradual going-up. While the hypervacular(2/40)showed a TDC type of rapid rise-rapid fall, reach the peak value at LAP. At LPVP, liver parenchyma reach the peak value, the CNR between the HMs and liver parenchyma was maximal.LAP+LPVP can detect the largest number of lesions and the lesions which diameter were lower than 1.5cm.LAP can distinguish the hypervascular and hypovascular lesions.Conclusion:LAP+LPVP can elevated the detection rate of HMs utmost, especially the lesions which diameter were lower than 1.5cm. LAP could manifested the blood supply feature, which was in favor of diagnosis and deferential diagnosis.