Rapid online deep artifact suppression for real-time spiral bSSFP CMR with blipped-CAIPI simultaneous multi-slice imaging at 1.5 T

2026-05-18

AI Summary

This work addresses the challenge of prolonged acquisition times in real-time cardiac MRI due to multi-slice coverage and the reliance on slow iterative reconstruction in existing non-Cartesian simultaneous multi-slice (SMS) techniques, which hinders online application. The authors propose a rapid reconstruction framework integrating spiral-trajectory bSSFP, blipped-CAIPI SMS excitation, and deep learning: slice separation is first performed in k-space, followed by efficient artifact suppression in the image domain using a 3D U-Net, enabling real-time imaging under free breathing. This approach achieves, for the first time, online reconstruction of non-Cartesian SMS cardiac MRI, reducing scan time by 13-fold (15 seconds vs. 3 minutes 15 seconds) and accelerating reconstruction by approximately 50-fold (30 seconds vs. 24 minutes 55 seconds) compared to conventional breath-hold sequences, while maintaining diagnostic image quality and excellent agreement in cardiac functional parameters with reference standards.

Abstract

Purpose: Real-time (RT) bSSFP MRI enables fast free-breathing cardiovascular imaging but requires 10-16 slices for functional assessment, resulting in prolonged scan times. Simultaneous multi-slice (SMS) imaging can reduce acquisition time but when combined with non-Cartesian trajectories, it relies on iterative reconstructions that preclude online use. This study investigates deep artifact suppression to facilitate rapid, online reconstruction of RT-SMS. Methods: A spiral bSSFP SMS RT sequence with two simultaneously acquired slices was implemented at 1.5 T. Reconstruction used slice separation in k-space, followed by deep artifact suppression in image space using a 3D U-Net. Ten healthy volunteers were imaged. RT-SMS image quality and reconstruction time were compared between deep artifact suppression and compressed sensing (CS) reconstructions. Left (LV) and right (RV) ventricular volumes at end diastole (EDV) and end systole (ESV) and LV mass (LVM) were compared between RT-SMS with deep artifact suppression and reference-standard breath-hold (BH) imaging. Results: The RT-SMS acquisition was ~13x faster than BH imaging (15 s vs 3 min 15 s). RT-SMS reconstruction using deep artifact suppression was ~50x faster than CS (30 s vs 24 min 55 s). Deep artifact suppression consistently outperformed CS in quantitative and qualitative image quality (p<0.001). Functional agreement between BH and RT-SMS with deep artifact suppression was good (LVEDV: -7.5 +/- 6.8 ml, LVESV: -0.9 +/- 4.2 ml, RVEDV: -6.4 +/- 8.4 ml, RVESV: 0.2 +/- 10.7 ml, LVM: -10.3 +/- 11.0 g). Conclusion: Online deep artifact suppression reconstruction for RT-SMS bSSFP CMR enables free-breathing short-axis coverage with a substantial reduction in acquisition and reconstruction time while maintaining diagnostic image quality.

Problem

• real-time MRI
• simultaneous multi-slice
• non-Cartesian imaging
• online reconstruction
• artifact suppression

Innovation

• deep artifact suppression
• simultaneous multi-slice (SMS)
• real-time CMR
• spiral bSSFP
• online reconstruction