First-pass contrast-enhanced myocardial perfusion CMR has proven to be a powerful noninvasive technique for evaluating coronary artery disease¹. Current techniques image a limited number of 2D slices, and small, but clinically relevant perfusion defects may be missed. 3D perfusion imaging is potentially advantageous for quantifying ischemic burden by covering the whole ventricle at the same cardiac phase, but current techniques have limited spatiotemporal resolution. Considering the heart only occupies a small portion of the chest, reduced field-of-view (rFOV) perfusion imaging with 2D outer volume suppression² (OVS) significantly improves sampling efficiency and has enabled single-shot 2D spiral perfusion imaging³. We hypothesized that the application of OVS to 3D stack-of-spiral (SoS) perfusion imaging could significantly reduce the temporal footprint while increasing the in-plane and through-plane spatial resolution as compared to previous 3D approaches.2D OVS preparation was incorporated into a 3D centrically ordered SoS perfusion sequence (Fig 1a). The OVS consists of a non-selective adiabatic BIR-4 tip-down pulse, a 2D spiral spatially selective tip-back pulse and a spoiler to suppress signal outside the heart (Fig 1b). The 3D sequence parameters included: FOV 170×170 mm², TE 1.0 ms, TR 9.0 ms, saturation recovery time 150 ms, flip angle 35^o, 2×2 mm in-plane resolution, 20 partitions with 4 mm thickness, 180ms temporal footprint. For each partition, single 8 ms spiral with a dual density design with a broad Fermi shape transition⁴ was implemented and the spiral trajectory was rotated by golden angle through time to generate an incoherent k-t sampling pattern. The proposed sequence was performed in 10 healthy subjects with a 0.075 mmol/kg Gd-DTPA bolus on a 1.5T Avanto Siemens scanner. The data was reconstructed with two approaches: 1) (thin-slice) 2×2×4 mm with 180 ms temporal footprint and 2) (high-temporal resolution) 2×2×8 mm with 90 ms temporal footprint using only the central 10 partitions. Block LOw-rank Sparsity with Motion guidance (BLOSM)⁵ combined with SENSE was used for image reconstruction. Images were graded on a 5 point scale (5 excellent, 1 poor) by a single cardiologist. 2×2×4 mm data-sets were also interpolated to an isotropic 2x2x2 mm resolution for display in arbitrary image orientations.Fig 1c shows the spatial profile of the 2D OVS with the 100 mm rFOV design. The 1D spatial profile across the center (Fig 1d), illustrates the stopband at approximately ±400 mm, which was large enough to suppress the signals outside heart to prevent spatial aliasing. Fig 2 shows perfusion images at a single time frame during first-pass of contrast from one healthy volunteer using the 2 different strategies: a) 10 slices with 2×2×8 mm and 90 ms temporal footprint presented high SNR and good quality perfusion images; b) 20 slices with 2×2×4 mm and 180 ms temporal footprint showed high through-plane resolution images with similar image quality (3.6±0.6 vs 3.4±0.6 p=NS). By 2x sinc-interpolation of the 2x2x4 mm dataset, 40 slices with isotropic 2 mm resolution can be displayed (Fig 3) enabling isotropic visualization of perfusion in short and long axis image orientations (Fig 4).OVS enabled high resolution thin-slice (4 mm) 3D perfusion data to be acquired in only 180 ms, while high temporal-resolution 3D data with 8mm slices can be acquired in only 90 ms. 3D centrically ordered allows for a flexible reconstruction strategy to produce either relative higher SNR but lower through-plane resolution (8 mm) perfusion images or lower SNR but higher through-plane (4 mm) resolution. The higher through-plane resolution could reduce partial volume effects and provide better depiction of the apical slices. The isotropic reconstruction provides the ability to reformat the data in arbitrary slice orientations. The short temporal footprint 3D spiral acquisition should have reduced sensitivity to cardiac motion as compared to techniques with a longer temporal footprint resulting in sharper depiction of trabeculae and papillary muscles.We demonstrated the successful application of rFOV 3D SoS perfusion techniques. The high sampling efficiency using OVS enables 3D imaging with an excellent combination of high in-plane and through-plane spatial resolution and a short temporal footprint of 180 ms. The technique can also achieve 3D perfusion coverage with an 8mm slice thickness in 90 ms, a temporal footprint shorter than most clinically available 2D perfusion pulse sequences. Further validation will be required in patients undergoing adenosine stress CMR.