$T_{2}$ -Selective Magnetization Preparation Pulses

The purpose of this work was to present and evaluate a new method for directly designing T₂-selective preparation pulses. Using a modified Shinnar-Le-Roux (SLR) transform, the design of T₂-selective pulses becomes equivalent to designing a pair of polynomials one of which represents the longitudinal magnetization and the other the transverse magnetization. The polynomials enable one to directly analyze the various tradeoffs involved in the design. To evaluate the new method, a short-T₂-selective magnetization preparation pulse was designed. Following the preparation pulse, a 2D Fourier transform (2DFT) multislice gradient echo sequence was used for imaging. For verification Bloch equation simulations were performed along with both in vivo and phantom scans. Phantom scans showed good signal suppression of long-T₂ species. This is supported by good long-T₂ signal suppression seen on the in vivo images. Simulations indicate that the pulse is robust to plusmn150 Hz B₀ inhomogeneities and plusmn10% B₁ inhomogeneities.