Fig 2. Graph showing variations in the adjusted R² values of the mono-exponential, bi-exponential, stretched-exponential and kurtosis models with an increase in b-value.

The mean value of the adjusted R² of the mono-exponential model decreased with the increase of b-value, while the mean value of the adjusted R² of the bi-exponential, stretched-exponential and kurtosis models were stable and excellent with the increase of b-value (It should be noted that, because the adjusted R² values of the bi-exponential and stretched-exponential models were close, their curves have been superimposed).