Abstract：Objective: To assess whether hepatic diffusion measurements are influenced by hepatic perfusion changes due to different b values in both posterior and anterior segments of right lobe. Materials and Methods: DWI was performed on a 1.5T MRI unit among 26 healthy volunteers after an 8h fast and 1h after a standard meal(which is regarded as an effective method to increase hepatic perfusion including portal venous flow and hepatic sinusoidal perfusion), we used a breath-hold technique for 20.5s at b-values of 750, 500 and 250 and 0s/mm2. The hepatic apparent diffusion coefficient(ADC) values were measured and compared due to different prandial states in both posterior and anterior segments of right lobe. Results: Compared the two sets of ADCs before and after meal, the ADC measurements using b=750s/mm2 in both posterior and anterior right lobe were unaffected by the perfusion changes(t=1.419, P=0.178; t=1.943, P=0.072) whereas the ADC values from b=250s/mm2 increased significantly after meal in both posterior and anterior segments of right lobe(t=3.839, P=0.002; t=5.178, P<0.001). As for b=500s/mm2, only the ADCs in the posterior right lobe was unchanged significantly after meal(t=1.519, P=0.151) when compared to the significantly changed ADCs in the anterior right lobe(t=2.449, P=0.028). Conclusion: With regard to the measurements of ADC, the effect of perfusion can be minimized at the higher b values(b≥500s/mm2) and in the posterior right lobe at the fasted state, which may offer the most consistent ADC values and optimized measuring conditions for further studies of hepatic DWI.
2007, Vol. 18 
