The presence of susceptibility shifts gives rise to a phase shift of the excited magnetization which evolves linearly with time. Thus acquisitions at long TE(at ~T₂*) are desirable for SWI and QSM. If TR is kept >TE this leads to lengthy acquisition times. Echo-shift(ES) FLASH^1,2 , which efficiently interleaves 2D slice or slab acquisitions and shifts the echo into the next TR period allows TR<TE and improves efficiency. ES has also been used for other T_2* weighted acquisitions such as fMRI(e.g. PRESTO)³, and later combined with Simultaneous MultiSlice(SMS)⁴ for further acceleration. We previously proposed improving parallel imaging in FLASH using the Wave-CAIPI trajectory⁵ which can provide an order of magnitude acceleration in 3D FLASH acquisition with minimal g-factor and image artifact penalties. Wave-CAIPI uses an innovative controlled aliasing scheme which takes full advantage of the available coil sensitivity information in multi-channel receiver arrays. In this work, we combine the ES and wave-CAIPI method, to provide high quality susceptibility weighted FLASH acquisitions up to 18x faster than unaccelerated, non-echoshifted acquisitions. To achieve better performance, we utilize echo-shift SMS with wave-CAIPI which enables desirable volumetric noise averaging and optimal controlled aliasing performance while avoiding slice profile boundary artifacts in ES multi-slab acquisition². Using ES wave-CAIPI, we demonstrate high quality whole-brain susceptibility weighted gradient echo acquisition at 3T and 7T with 1.5mm isotropic voxel size in 36s. Fig 1 shows the ES-SMS FLASH sequence with echo shift gradients applied on both Gx and Gz gradients, wherein the ES factor is 2 and MB-48 excitation RF pulses with 1.5mm slice thickness are used. In this sequence, the first RF excites the odd slices of the 3D imaging volume with the signal readout echo-shifted to the second TR, while the second RF excites the even slices with the signal readout shifted to the third TR. The use of ES-SMS enables a comb of slices to be acquired simultaneously, which enables desirable volumetric noise averaging while avoids slice edge issues of ES multi-slab acquisitions. Moreover, the combined use of ES-SMS with accelerated Wave-CAIPI acquisition enables controlled aliasing to be performed across the whole imaging FOV rather than a partial FOV in the slice-direction; thereby providing optimal parallel imaging performance to achieve low noise amplification and image artifact penalties. To investigate the performance of the slice profile in ES wave-CAIPI, Bloch simulation was used to calculate the steady-state signal of the acquisition, where the effect of both the interleave MB RF pulses and echo-shift gradients were accounted for (through summing up the signal across multiple sub-voxel positions along x to obtain the slice profile signal at a given z position). A healthy subject was scanned with informed consent at 3T and 7T with 32 channel head array to acquire ES wave-CAIPI FLASH data. Imaging parameters were FOV 220x220x144mm and 1.5mm³ iso resolution, R_yxR_zxES=3x3x2, BW=90Hz/px, RF duration=5ms, TBW=4, FA=10^o, TR_eff/TE_eff=47/35ms, Tacq=36s. After the acquisition, two echo-shifted volumes were reconstructed separately using standard wave-CAIPI reconstruction⁵ and concatenated in an interleaved fashion to generate full volumetric data. The resulting volumetric phase images were then processed with 2D harmonic filtering to the remove the background phase component⁶, and dipole inversion with Total Generalized Variation (TGV) regularization⁷ was applied to estimate the underlying susceptibility distribution.Fig 2 shows the simulated slice profiles for acquisition with and without echo shift demonstrating no cross-talk and minimal slice profile change resulting from the echo-shifting. Fig 3 shows the high quality magnitude, tissue phase and susceptibility images obtained from the ES wave-CAIPI data at 1.5mm isotropic resolution in 36s, with high SNR, low artifact and image distortion. At R_yxR_z=3x3 acceleration, wave-CAIPI has previously been demonstrated to result in very low noise amplification with g-factor of close to one² and ES acceleration does not incur a noise amplification penalty. Furthermore, with adequately large echo shift gradients, no signal leakage and/or image strip artifacts across slices were observed.Echo shift method has been effectively incorporated into the wave-CAIPI sequence to attain rapid, high quality susceptibility mapping at 3T and 7T. This acquisition employed the ES-SMS method to provide high SNR, good slice-profile and optimal controlled aliasing. A relatively high MB factor of 48 is used, where VERSE’ing⁸ was not needed due to the low FA used. Further acquisition acceleration of up to and beyond 30x will be feasible with the use of higher ES factors such as 3-4. This can be achieved through the use of higher BW readout and/or longer TE acquisitions (which are more suitable for e.g. 3T MRI with longer T₂*).