is supported by the China Scholarship Council for a 2-year study at Massachusetts General Hospital Purpose: To rapidly obtain high isotropic-resolution T 2 maps with whole-brain coverage and high geometric fidelity. Methods: A T 2 blip-up/down EPI acquisition with generalized slice-dithered enhanced resolution (T 2 -BUDA-gSlider) is proposed. A RF-encoded multi-slab spinecho (SE) EPI acquisition with multiple TEs was developed to obtain high SNR efficiency with reduced TR. This was combined with an interleaved 2-shot EPI acquisition using blip-up/down phase encoding. An estimated field map was incorporated into the joint multi-shot EPI reconstruction with a structured low rank constraint to achieve distortion-free and robust reconstruction for each slab without navigation. A Bloch simulated subspace model was integrated into gSlider reconstruction and used for T 2 quantification. Results: In vivo results demonstrated that the T 2 values estimated by the proposed method were consistent with gold standard spin-echo acquisition. Compared to the reference 3D fast spin echo (FSE) images, distortion caused by off-resonance and eddy current effects were effectively mitigated.How to cite this article: Cao X, Wang K, Liao C, et al. Efficient T 2 mapping with blip-up/down EPI and gSlider-SMS (T 2 -BUDA-gSlider).