SNR and Echo Time
Let's think about this. What would decreasing the echo time do? There would be less time for dephasing to occur, and that means a higher signal when we read out the signal echo. So less dephasing produces SNR increase (but not if the TE is reduced by decreasing the sampling time (Tline, for a whole line of k-space): this is a bandwidth increase which includes more noise).
Tradeoffs: less T2 weighting, more T1 or proton density weighting.