MR Imaging Fat Signal Suppression via Inversion Timing

The patent applies parameter changes by utilizing the different spin-lattice relaxation times (T1) of fat and water protons. By selecting a specific inversion time (TI) that corresponds to the zero-crossing point of the fat signal recovery curve, the method achieves complete fat signal suppression. This parameter-based approach (timing the excitation pulse at the optimal TI) is less sensitive to magnetic field inhomogeneities compared to frequency-based methods like Dixon or SSGR, as it relies on the inherent temporal relaxation characteristics rather than frequency shifts that vary with field inhomogeneity.

The patent employs parameter changes by optimizing the inversion time (TI) to match the zero-crossing point of the fat signal recovery, which typically occurs around 200-300ms for conventional fat suppression. By using this optimized TI parameter, the method achieves complete fat suppression in a single inversion-recovery cycle, eliminating the need for multiple sequential pulses or complex multi-step sequences required by alternative methods, thus reducing overall preparation time.

The patent applies parameter changes by utilizing the different T1 relaxation times of the two spin species to achieve selective suppression through timing alone. The inversion pulse is applied with a flip angle optimized for the first spin species (e.g., 90°), and the excitation pulse is timed to occur at the zero-crossing point of the second spin species' recovery curve. This approach achieves complete suppression of the second species without requiring complex pulse sequences with varying flip angles for different species, as the temporal separation at the zero-crossing point provides the selectivity.