The Effect of T1-Relaxation on Tensor-Derived ADC-Maps

Finn Lennartsson^1,2, Bo Nordell¹, Olof Flodmark²

The T1-relaxation process is a well-known issue in diffusion-weighted magnetic resonance imaging (DWI). A typical diffusion-tensor imaging (DTI) scheme collects first the S0:s followed by gradient directions: S01,..., S0m S(r1),..., S(rn). The T1-weighting among the initial S0:s is not homogenous, giving an erroneously high baseline (mean of S0:s), which results in an overestimation of the tensor elements. T1-relaxation effects in the initial volumes of a DTI experiment have an impact on the estimation of a tensor-derived ADC-map, and the same effect is expected for non-tensor models. The effect is especially prominent in tissues with long T1 like CSF, where a overestimation of ADC is expected.