What are normal relaxation times of tissues at 3 T?

The T₁ and T₂ relaxation times are the basic parameters behind magnetic resonance imaging. The accurate knowledge of the T₁ and T₂ values of tissues allows to perform quantitative imaging and to develop and optimize magnetic resonance sequences. A vast extent of methods and sequences has been developed to calculate the T₁ and T₂ relaxation times of different tissues in diverse centers. Surprisingly, a wide range of values has been reported for similar tissues (e.g. T₁ of white matter from 699 to 1735ms and T₂ of fat from 41 to 371ms), and the true values that represent each specific tissue are still unclear, which have deterred their common use in clinical diagnostic imaging. This article presents a comprehensive review of the reported relaxation times in the literature in vivo at 3T for a large span of tissues. It gives a detailed analysis of the different methods and sequences used to calculate the relaxation times, and it explains the reasons of the spread of reported relaxation times values in the literature.