1. A method for phase-calibrating an MRI pulse sequence comprising the steps of: before conducting a diagnostic scan, including generating a phase encoding gradient, to obtain a diagnostic MRI data, conducting a pre-scan corresponding to said diagnostic scan but without generating said phase encoding gradient, in which a plurality of echoes are obtained; selecting one of said echoes obtained in said pre-scan as a reference echo; using said reference echo, automatically electronically calculating a linear phase and a constant phase; and calibrating said diagnostic scan using said linear phase and said constant phase to produce a calibrated diagnostic scan, and executing said calibrated diagnostic scan to obtain diagnostic MRI data.