Frequency modulated (FM) pulses have certain benefits over amplitude modulated (AM) pulses, including broadband excitation with low peak power and uniform rotation of magnetization in the presence of extreme B₁ inhomogeneity¹. A two-dimensional (2D) adiabatic pulse was previously demonstrated in which k-space was sampled using amplitude modulation in one orthogonal direction and frequency modulation in the other². It was further shown that the quadratic phase of FM pulses such as the chirp and hyperbolic secant (HS1) can be extended to two dimensions by exploiting radial symmetry when sampling k-space. Exploiting the spatiotemporal nature of phase coherence, B₁⁺ compensation was demonstrated³. However, due to being based on the small-tip-angle approximation⁴, the linear relation between peak B₁ and flip angle was limited to within 20°. In this work, we introduce a new method of designing adiabatic pulses in both two- and three-dimensions.The design approach utilizes a parent adiabatic pulse that is divided into sub-pulse elements, each of which is a 2D spatially selective pulse. Specifically, an adiabatic pulse, such as an HS1, is discretized and sufficiently oversampled. These sampled elements are then binned into sub-pulse elements. The B₁ amplitudes of consecutive pulse elements are modulated by the HS1 amplitude function, whereas the phase of these elements are given by the sum of the 2D pulse and HS1 pulse phases. Between sub-pulses, a blip is inserted to nullify the area accrued under the gradients to re-center k-space for the subsequent sub-pulse element. In the case of using a 2D pulse weighted by a jinc function along a 2D spiral k-trajectory⁵, the resulting pulse is shown in FIG 1. By selectively exciting using the 2D pulse while driving it adiabatically through the parent adiabatic HS1 pulse, an infinitely long cylinder can be excited to any flip angle until inversion, where it becomes adiabatic. This 2D adiabatic pulse can be extended to three-dimensions by applying blips in the remaining direction between sub-pulses, as will be shown below.A 2D HS1 pulse (T_p = 33.28 ms and R = 20) was designed using the method described above. Spiral gradients were time warped to meet slew rate constraints. Bloch simulations were performed to confirm selective excitation and adiabatic inversion. Phantom experiments were carried out on a 90 cm 4T scanner (Varian). Gradients were measured⁶ and calibrated, followed by modification of the RF pulse based on these measurements for high fidelity. The signals obtained from two gradient echo (GRE) acquisitions, one with the 2D inversion pulse used as a preparation pulse and one without, were subtracted to extract the inversion profile. Finally, in-vivo experiments were carried out on human brain.The cylindrical excitation profile of the 2D HS1 pulse at adiabatic inversion, along with the linear projection of M_z along the middle of the cylinder as a function of resonance offset (Ω) and RF amplitude ω₁ (=γB₁/2π), both obtained from Bloch simulations, are shown in FIG 2. Similar to the 1D case, the 2D HS1 exhibits both a linear regime and an adiabatic regime. Comparing the phantom images acquired from GRE (FIG 3A) with the inversion profile obtained as described above (FIG 3B), it is apparent uniform selective cylindrical inversion is achieved. The inversion profile obtained by sweeping RF amplitude ω₁ and taking a linear projection through the center of the cylindrical inversion (FIG 3C), shows adiabatic property. FIG 4 is a human brain image with 2D HS1 applied prior to slice select in the GRE sequence. As indicated by the black ring, which is the location where M_z is 0 along the wall of the inversion profile, inversion is accomplished. Last, excitation profile of a 3D HS1 pulse along the x-y plane (FIG 5A), x-z plane (FIG 5B), and y-z plane (FIG 5C) obtained using simulations, demonstrates excitation of a finite height cylinder while maintaining adiabatic inversion. To address the long pulse duration inherent to multi-dimensional pulses, we have confirmed through simulations that this can be shortened by segmenting the pulse and using multi-shot excitation.A new method of designing two- and three-dimensional adiabatic pulses has been introduced. Through simulations, it was shown that using a 2D HS1 pulse, cylindrical selective excitation is achieved with adiabatic inversion. This was further verified through phantom and in-vivo experiments. A 3D HS1 pulse was also demonstrated through simulations in which a cylinder of finite height was inverted with adiabaticity. These pulses have potential applications for use in inner-volume selection, navigation techniques, and for inverting magnetization with inhomogeneous B₁.