Abstract
BACKGROUND: Age-related liver diffusion metrics changes have been described. We aim to further clarify these questions: 1) whether an age-related reduction of liver perfusion can be observed by DDVD (diffusion derived vessel density) in older males; 2) whether there is a male female difference in liver perfusion; 3) whether liver ADC values and spleen ADC values are correlated. It is known that, physiologically, males' liver has a higher iron level (thus a shorter T2) than females' liver; pre-menopausal females have a lower liver iron level (thus a longer T2) than post-menopausal females. The observations of this study will be interpreted with the recently gained knowledge of the T2 contribution to diffusion metrics. METHODS: Included in this healthy volunteer's study were 68 males (mean age:50.22 years, range: 25-70 years) and 43 females (mean age 45.56 years, range:20-71 years). DWI images with b-values of 0, 2, 10, 20, 60, and 600 s/mm(2) were acquired at 1.5T. DDVD were calculated with b = 0, b = 2, b = 10, and b = 20 s/mm(2) images. ADC were calculated with b = 0, b = 2, b = 60 and b = 600 s/mm(2) images. RESULTS: There was a statistically significant age-related decline of liver DDVD values for females (p = 0.024). A similar trend was observed for males, though statistical significance was not achieved (p = 0.113). Liver DDVD values were all higher in females than in males (p < 0.001). There was a statistically significant age-related decline of liver ADC values both for males (ADC((b0b600)), p = 0.009) and for females (ADC((b0b600)), p = 0.016). Liver ADC values and spleen ADC values were positively correlated (ADC((b0b600)), r = 0.33 for males and 0.31 for females, p < 0.05). When the spleen ADC was used to normalize the liver ADC, then the age-related trend was largely removed, both for males and for females (p > 0.05). CONCLUSION: Females have a larger liver perfusion volume than males. There is an age-related decrease of DDVD and ADC, both for males and females. Liver ADC values and spleen ADC values are positively correlated. These gender and age-related changes are unlikely mainly caused by the liver T2 relaxation time variations. CLINICAL TRIAL NUMBER: Not applicable.