Method and apparatus for imaging instruments during interventional MRI using asymmetric spin echo sequences

摘要

An asymmetric spin-echo (ASE) sequence having a variable asymmetry (&Dgr;TE) with respect to the RF pulse is used for imaging paramagnetic, diamagnetic or ferromagnetic instruments within tissues during interventional MRI procedures. The degree of asymmetry introduced determines an apparent size of the imaged instrument. In one embodiment of the invention, the amount of asymmetry is varied as a function of the phase encoding gradient steps. In this manner, the sequence is made sensitive to local gradients in the magnetic field but left insensitive to large scale variations such as those introduced by main magnetic field inhomogeneities.