Frequency resolved single‐shot MR imaging using stochastic k‐space trajectories

A new single‐shot stochastic imaging technique with a random k‐space path that provides very selective filtering with respect to chemical shift or off‐resonance signals of the investigated tissue is proposed. It is demonstrated that in stochastic imaging only on‐resonance compartments are visible whereas frequency shifted compartments cancel to noise that is distributed over the whole image. This method can be used as a single‐shot chemical shift selective imaging technique and allows to calculate frequency resolved spectra for each spatial position of the image based on a single signal aquisition. The single‐shot stochastic imaging sequence makes high demands on the gradient system and the theoretical k‐space trajectory is distorted by imperfect gradient performance. Therefore an additional k‐space guided imaging technique that uses the true, measured k‐space trajectory to correct artifacts generated by eddy currents and delay times of the rapid switched gradients is presented. In vitro and in vivo measurements demonstrate the successful implementation of single‐shot stochastic imaging on a conventional MR scanner with unshielded gradient systems.