MRgFUS treatments require rapid imaging to visualize the temperature and accurately determine thermal dose. We propose accelerated gradient echo keyhole trajectories for MR-thermometry, which acquire the middle of k-space densely (keyhole) while interleaving the outer k-space data. The trajectory acquisitions were synchronized to the ultrasound pulse to increase temperature accuracy. Different combinations of the keyhole size and number of interleaves were created and their accuracy was tested in a MATLAB simulation that uses the Bioheat Transfer Equation as a gold standard for temperature. The trajectories were implemented in RTHawk and results validated in a phantom experiment during focused ultrasound.