Imaging the fetal brain in utero is challenging due to sporadic head movements, maternal breathing, and surrounding maternal tissue, which requires large field of view (FOV) encoding. Typically, single shot Turbo Spin-Echo (ss-TSE) sequences are employed [1-2]. However, due to the large FOVs required, and imposed limits on SAR, PNS and acoustic noise, TSE shot lengths can be relatively long, and may limit realisable resolution. The time per slice may be 100s of msec, making the acquisition rate quite slow. Multiband accelerated TSE imaging has previously been demonstrated in the adult brain [3-4]. Here we present initial experiences of using multiband accelerated ss-TSE imaging in the fetus, and test using zoom TSE to allow reduced PE encoding for shorter shot length. Combining this with multiband not only offers scan time reduction, but should also provide data with improved slice-to-volume (SVR) reconstructions [5], compared to conventional single-band multislice acquisitions.Scanner code was modified to enable multiband modulation of RF pulses in standard TSE sequences. Additional caipi gradient blips were added around the refocusing pulses to allow FOV/2 shifting of adjacent simultaneous slices, in order to reduce g-factor and improve unfolding. In addition MB zoom TSE was implemented with single band orthogonal excitation and multiband refocusing pulses (Figure 1). The excitation pulse was modified to maximise its bandwidth to ensure precise FOV definition and minimise slab direction water-fat shifts, which will appear in plane in the final images. Data was processed and reconstructed offline using ReconFrame (GyroTools, Zurich, CH.) Parameters common to all sequences tested were: TE=180ms (suitable for the long T2s of fetal brain), in-plane resolution 1.5 x 1.5 mm, slice thickness 2.5 mm, refocusing pulse angle of 130°. The max RF b1 was adjusted to balance SAR vs minimum echo spacing (9-13 uT). Echo train length and halfscan (partial Fourier) factor were adjusted according to reduced (PE) FOV, SENSE factor and MB pulse duration requirements, in order to maintain fixed TE. TR was fixed at 2 seconds for zoom TSE, while minimised for non-zoom (multislice) TSE (SB: TR=26.6s, MB2: TR=19.4s) All sequences operated in low SAR (<2W/Kg) and low PNS mode, while reduced gradient slew was used to ensure acoustic noise did not exceed 110 dBA maximum (measured in the bore), although average sound levels was considerably lower. All data was acquired on a 3T Philips Achieva system. Initial tests were performed on adult volunteers using a 32-channel head coil, and subsequently three pregnant participants (GA range 31-34 weeks) were scanned using a 32-channel cardiac coil. Written informed consent was obtained prior to scanning.Data collected on an adult brain with the fetal protocol (TE=180ms) reveals good image quality in the conventional full FOV sequence and MB2 accelerated acquisition, both also employed SENSE=2 in-plane (Figure 2 a-b). In the zoom ss-TSE images (2c-d) good localised excitation allowed for reduced PE FOV. In addition, in combination with MB2 acceleration, image quality remains. In the fetal example (Figure 3 a-b) full FOV TSE with SENSE2 and MB2 shows good contrast and image quality within the fetal brain. In the zoom implementation (3c-d) some contrast is lost due to the significant TR reduction, but image quality is again comparable. Maternal fat is a significant issue and needs careful consideration especially for multiband acceleration and zoom TSE. The high bandwidth excitation pulse used in zoom MB2 (Fig. 3d) reduces shift in fat excited compared to water. This avoids FOV aliasing (3c arrow), as produced by standard pulses which are often stretched relative to the refocusing pulse to match bandwidth. This problem would be exaggerated with the multiband factor.Multiband accelerated TSE imaging in combination with reduced FOV zoom excitation has been demonstrated in the fetal brain. Further work is required to assess the extent of acceleration factor supported by the coils and geometry involved in fetal scanning. Although here anterior-posterior FOV reduction and fold-over was used, turning this right-left in some cases could offer advantages in reducing fat fold-over and respiratory artefacts. Optimisation of TE and refocusing angle control with the new reduction in TR used in the zoom TSE may improve contrast. The use of multiband TSE to excite simultaneous slices in the fetal brain should lead to improved SVR reconstructions in the face of fetal motion, because multiple slices locked in fixed relative geometry can stabilise image registration.