Authors:
R. Ochiai, H. Sugimura, T. Kodama, T. Jinnouchi, E. Furukouji, T. Sakae, S. Tamura; Kiyotake/JP
DOI:
10.1594/ecr2009/C-833
Conclusion
The results of quantitative and qualitative analyses suggested that the spin labeling portography with SPIO was more effective than that without SPIO in depicting the portal vein. After SPIO administration, the background signal was considerably suppressed because of the decrease in the signal of the liver parenchyma. The increase in the vessel-to-liver contrast was also influenced by the T1 shortening effect. Therefore, the depiction of intrahepatic vessels, including the portal vein, was improved after SPIO administration. We speculate that the suppression of the background signal mainly influenced the depiction of the intrahepatic vessels.
The effects of SPIO were different between the LC and the non-LC groups. The depiction of the portal vein was better in the latter after SPIO administration. The difference in both the portal vein blood flow and iron uptake ability of the liver parenchyma might have contributed to this difference.
This study however had some limitations. The intrahepatic vessels were not selectively depicted, although the hepatic veins were remarkably depicted. The signal intensity of the hepatic veins was increased after SPIO administration. Thus, signal suppression of the spin labeling pulse was not sufficient. The depiction of the vessels by the spin labeling technique was mainly influenced by both the location of the pulse and BBTI. When the BBTI was short, the clarity of portal vein depiction was decreased because the high-signal blood flowing to the portal vein did not reach the tip. When the BBTI was long, the portal vein contrast decreased in order to recover the background signal. Hence, it is necessary to investigate the dose of the contrast agent and the timing of scan that would effectively suppress the background signal and not overemphasize the depiction of the hepatic vein.
In conclusion, spin labeling portography with SPIO was more effective than that without SPIO in depicting the portal vein. This technique is easy to be used with MR portography and serves as a useful tool for screening procedures.