The impacts of time of echo and time of repetition on slow diffusion coefficient (SDC) measure and the potential age- and gender-related variations in liver and spleen SDC values: studies of healthy volunteers

Background: The time of echo (TE) and time of repetition (TR) impact the apparent diffusion coefficient (ADC) value. This study investigates the impact of TE and TR on slow diffusion coefficient (SDC) values of the liver and spleen. An age-related decline of liver ADC has been described for both men and women. However, a lower perfusion level, a higher fat level and a higher iron level can all lead to a decrease in liver ADC value in older populations. This study also investigates whether there is an age-related decrease in the liver slow diffusion as measured by SDC. Methods: . Dataset 2 had 68 men (mean age: 50.2 years, range: 25-70 years) and 43 women (mean age: 45.6 years, range: 20-71 years). Results: ratio remained unchanged across TR values. Dataset 2 showed, there was no age-related change in SDC value for men's liver, for men's spleen, and for the livers of women aged 54 years' > 'men'. The spleen median SDC values were also 'women aged 54 years' > 'men'. For all comparisons, spleen SDC values were higher than liver SDC values. Conclusions: The TE and TR have very notable impacts on SDC values. There may be no true tissue diffusion change following aging for men and women. The difference in liver SDC between pre-menopausal women value and post-menopausal women value suggest that iron-related T2* shortening lead to a lower SDC measure. SDC may be insensitive to tissue perfusion and liver fat signal.