Results: According to the results of the qualitative evaluation of image quality, 59.6%, 17.8%, and 22.6% of triphasic CT scans had good, acceptable, and poor quality, respectively. There was a significant relationship between image quality and Hounsfield units of all ROIs in the arterial phase (P<0.005). Also, a significant relationship was observed between the Hounsfield units of the portal vein right on the anterior and posterior segments of the liver (P<0.03) in the venous phase.
Conclusion: In a high quality triphasic CT scan, the Hounsfield unit of different parts in the arterial phase should be as follows: aorta 310±78, portal vein 150±40, hepatic vein 44±7, right posterior and anterior and left lateral segments of liver 77±11, 77±7 and 78±12. Hounsfield units of the portal vein, hepatic vein, and right posterior and anterior segments of the liver in the venous phase should be 155±27, 167±30, 111±19, and 112±16, respectively.
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