Skip to main content

Rapid cardiac cine imaging using MACH

Introduction

Previously, we developed a sparsely distribute k-space-time sampling approach termed BRISK, Block Regional Interpolation Scheme for K-space [1]. This approach allowed a nominal acceleration factor of 4 with good quality and low artifact. Others have developed alternative k-space-time sampling schemes, such as KT-BLAST and SLAM [2, 3]. We note that even at high acceleration factors, KT-BLAST/SLAM allowed a smooth transition from frame to frame, while BRISK experienced ringing artifacts. From these considerations we isolated key features that contribute to a successful k-space-time sparse sampling scheme:

1) Update of k-space should be rapid near the center and lower near the periphery (as in BRISK) to capture highly dynamic features.

2) Update of k-space should smoothly vary over time (as in KT-BLAST/SLAM) avoiding sudden transitions between k-space regions to result in smoother transition between frames.

From these design principles we developed a new sparse k-space-time sampling scheme, MACH, Multiple Acceleration Cycle Hierarchy. MACH incorporates a gradually changing rate over time, starting with the highest rate near the center of k-space and becoming progressively sparser towards the periphery, Figure 1 shows the k-space-time sampling scheme. In MACH, the progressively decreasing sampling rates are not confined to integer steps, thereby providing greater opportunity for a smooth transition over the k-space-time domain. Data that are not directly sampled in MACH are interpolated prior to applying conventional Fourier transformation to generate the series of images. Since each frame incorporates a full set of k-space data, the SNR is similar to the conventional scan.

Figure 1
figure1

Figure 1

Methods

Simulations were performed using fully acquired stead-state-free-precession (SSFP) cine image data to allow direct comparison of MACH and KT-BLAST/SLAM when using the same acceleration factors. Further, MACH was implemented on a 1.5 T scanner (GE, Milwaukee, WI). Using the SSFP cine acquisition, long and short axis acquisitions were acquired using the conventional examination and MACH applied with a net sparse factors ranging from 2 to 5, with matrices ranging from 224 to 336. Comparable cine acquisitions were acquired of the heart in 10 volunteers. The end-diastolic and end-systolic phases were identified and areas were planimetered and compared between the conventional and the MACH accelerated scans.

Results

Simulations showed that for a moderate acceleration factor of 5, KT-BLAST/SLAM represented myocardial motion well, but lost detail of the relatively fast moving valvular features, while MACH still represented these features. In the in vivo acquisitions, the average MACH acceleration factor applied was 3.5 ± 1.1, end-diastolic and end-systolic ventricular chamber areas were not significantly different between the conventional and the accelerated MACH scans (p = 0.7, 0.6, respectively) and correlations were excellent at 0.99 for each. Compared to the conventional scan, there is no additional overhead with MACH. See Figures 2 and 3.

Figure 2
figure2

Figure 2

Figure 3
figure3

Figure 3

Conclusion

In sparse k-space-time acquisition strategies, rapidly updating the central region of k-space is known to be important. We note that MACH achieves this condition very efficiently while also achieving a smooth transition of update rate between each region of k-space since MACH does not use a uniform or even a regular update rate. MACH was successfully implemented and shown to accurately represent cardiac regions with good fidelity.

References

  1. 1.

    Doyle M, Walsh EG, Blackwell GG, Pohost GM: Block Regional Interpolation Scheme for K-space (BRISK): A Rapid Cardiac Imaging Technique. Magn Reson Med. 1995, 33: 163-170. 10.1002/mrm.1910330204.

    CAS  Article  PubMed  Google Scholar 

  2. 2.

    Kozerke S, Tsao J, Razavi R, Boesiger P: Accelerating cardiac cine 3D imaging using k-t BLAST. Magn Reson Med. 2004, 52 (1): 19-26. 10.1002/mrm.20145.

    Article  PubMed  Google Scholar 

  3. 3.

    Rehwald WG, Kim RJ, Simonetti OP, Laub G, Judd RM: Theory of high-speed MR imaging of the human heart with the selective line acquisition mode. Radiology. 2001, 220 (2): 540-7.

    CAS  Article  PubMed  Google Scholar 

Download references

Author information

Affiliations

Authors

Corresponding author

Correspondence to Mark Doyle.

Rights and permissions

Open Access This article is published under license to BioMed Central Ltd. This is an Open Access article is distributed under the terms of the Creative Commons Attribution 2.0 International License (https://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Reprints and Permissions

About this article

Cite this article

Doyle, M., Rayarao, G., Vido, D.A. et al. Rapid cardiac cine imaging using MACH. J Cardiovasc Magn Reson 11, P250 (2009). https://doi.org/10.1186/1532-429X-11-S1-P250

Download citation

Keywords

  • Acceleration Factor
  • Ringing Artifact
  • SSFP Cine
  • Sparse Factor
  • Axis Acquisition