Effect of tissues T1 content on the ADC values obtained with breast DWI using STIR fat-suppression

Motivation: Fat signal suppression is essential for breast DWI as the very low diffusion coefficient of fat tends to decrease ADC values. STIR is a popular method, but signal suppression/attenuation is not specific to fat. Goal(s): To show how ADC values obtained with STIR DWI may be biased toward tissue components with long T1s. Approach: Results were obtained from simulations and data acquired in a dedicated breast DWI phantom made of vials with water and various concentration of PVP. Results: ADC values obtained with STIR fat suppression may be over/under estimated depending on the T1 and ADC profile within tissues. Impact: Fat suppression is essential for DWI. Among techniques STIR leads to low SNR and ADC misestimation depending on the tissues T1/ADC content, as STIR signal attenuation is not specific to fat. Other methods should be preferred, such as SPAIR.