Evaluation of hypointense liver lesions during hepatobiliary phase MR imaging in normal and cirrhotic livers: is increasing flip angle reliable?

Gd-EOB-DTPA is a newly developed liver specific magnetic resonance contrast agent, which is widely used for focal liver lesion (FLL) detection and liver function evaluation. However, it has been demonstrated that hepatocytes uptake of Gd-EOB-DTPA obviously decreased in cirrhotic liver, and cirrhotic liver parenchyma may show reduced enhancement in hepatobiliary phase, which would result in decreased liver-to-lesion contrast (LLC) and liver to lesion signal intensity ratio (LLSIR). Therefore, it is important to improve the image quality in cirrhotic liver, as it may alter therapeutic strategy. In this paper, we have shown adjustments of the flip angle (FA) provides a simple step to achieve better image quality for evaluation of FLLs, especially to those patients with severe liver cirrhosis. On the basis of our quantitative analysis, both of the LLC and the LLSIR with high FA protocol were always higher than those of low FA protocol. Additionally, on high FA images, more FLLs were detected, peritumoral invasion was found, boundary of the tumor was more remarkably, and better visualization of bile duct was observed. In conclusion, for the patient with severe liver cirrhosis, increasing FA can obviously improve the image quality, which is helpful for FLLs depiction.