What is the effect of reducing the echo time (TE) on image contrast?

Reducing the echo time (TE) in MRI affects image contrast by emphasizing T1-weighted information and diminishing T2-weighted information. As TE decreases, there is less time for T2 relaxation to occur before the echo is collected, which means that T2-weighted signals, which are sensitive to the decay of transverse magnetization, will have less time to decay. This results in a reduction of T2 contrast in the image.

On the other hand, a shorter TE can facilitate greater T1 effects, producing images that showcase T1 properties more prominently due to the minimal time allowed for T2 decay. This shift in emphasis results in increased visibility of tissues with shorter T1 relaxation times at the expense of T2-weighted contrast. Enhanced signal intensity might be seen with shorter TE, but that is more related to the timing of the signal acquisition rather than a direct influence on contrast.