Glycogen content in rat liver: Importance for CT and MR imaging

Abstract

Purpose: CT and MR imaging are appropriate modalities for imaging of the liver. Contrast media are used to obtain a greater difference in attenuation and signal intensity, respectively, between normal liver tissue and focal lesions. However, no studies have attempted to determine whether physiological nutritional status of the liver during fasting is of importance for the native signal of normal liver tissue. Material and Methods: Using normal and fasting rats, we performed hepatic CT and MR imaging and glycogen analyses from excised tissue. Results: A significantly higher liver attenuation in normal rats compared to fasting rats was found in CT. In MR images, there was a small but significantly lower liver signal-to-noise ratio in normal rats compared to fasting rats in T1-weighted and proton density-weighted images. Glycogen analyses showed depleted glycogen deposits in fasting rats and a mean glycogen content of 50.1 mg glucose equivalent/g liver tissue in normal rats. Conclusion: In CT, a normal nutritional status increases the native attenuation in normal liver tissue. The changes in attenuation in normal liver tissue correlate well with the additional attenuation of glycogen storage in the hepatocyte. The results indicate that the nutritional status is of less importance in MR imaging.