Combined simultaneous multislice bSSFP and compressed sensing for first‐pass myocardial perfusion at 1.5 T with high spatial resolution and coverage

Abstract

Purpose To implement and evaluate a pseudorandom undersampling scheme for combined simultaneous multislice (SMS) balanced SSFP (bSSFP) and compressed‐sensing (CS) reconstruction to enable myocardial perfusion imaging with high spatial resolution and coverage at 1.5 T. Methods A prospective pseudorandom undersampling scheme that is compatible with SMS‐bSSFP phase‐cycling requirements and CS was developed. The SMS‐bSSFP CS with pseudorandom and linear undersampling schemes were compared in a phantom. A high‐resolution (1.4 × 1.4 mm2) six‐slice SMS‐bSSFP CS perfusion sequence was compared with a conventional (1.9 × 1.9 mm2) three‐slice sequence in 10 patients. Qualitative assessment of image quality, perceived SNR, and number of diagnostic segments and quantitative measurements of sharpness, upslope index, and contrast ratio were performed. Results In phantom experiments, pseudorandom undersampling resulted in residual artifact (RMS error) reduction by a factor of 7 compared with linear undersampling. In vivo, the proposed sequence demonstrated higher perceived SNR (2.9 ± 0.3 vs. 2.2 ± 0.6, P = .04), improved sharpness (0.35 ± 0.03 vs. 0.32 ± 0.05, P = .01), and a higher number of diagnostic segments (100% vs. 94%, P = .03) compared with the conventional sequence. There were no significant differences between the sequences in terms of image quality (2.5 ± 0.4 vs. 2.8 ± 0.2, P = .08), upslope index (0.11 ± 0.02 vs. 0.10 ± 0.01, P = .3), or contrast ratio (3.28 ± 0.35 vs. 3.36 ± 0.43, P = .7). Conclusion A pseudorandom k‐space undersampling compatible with SMS‐bSSFP and CS reconstruction has been developed and enables cardiac MR perfusion imaging with increased spatial resolution and myocardial coverage, increased number of diagnostic segments and perceived SNR, and no difference in image quality, upslope index, and contrast ratio.

Improved simultaneous multislice cardiac MRI using readout concatenated k‐space SPIRiT (ROCK‐SPIRiT)

“…The FLASH imaging has been used in this study due to its resilience against off‐resonance and susceptibility artifacts at higher field strength, although SSFP cine MRI has inherent advantages in terms of contrast‐to‐noise ratio and acquisition speed 49 . However, SMS acceleration rates with SSFP sequences are limited for wider coverage in cardiac MRI applications 18,19,59 and were not considered in this study. We also note that in a 7T cine imaging study with retrospective gating, it was noted that to maintain steady state, phase‐encode lines per segment were chosen as a multiple of the SMS/multiband factor 12 .…”

“…8 Multiple studies have explored the use of SMS imaging in CMR for faster coverage. [9][10][11][12][13][14][15][16][17][18][19][20][21][22] In particular, SMS acceleration has been used for myocardial T 1 mapping, 13,18 for cine imaging, 16,21 and for perfusion imaging 11,14,15,17,22 using both Cartesian and non-Cartesian acquisitions at different acceleration rates. However, due to coil geometry limitations, SMS acceleration remains limited for CMR, especially in conjunction with in-plane parallel imaging, in which leakage artifacts and noise amplification are observed at high acceleration rates, 23 necessitating improvements in reconstruction.…”

“…Simultaneous multislice imaging is typically coupled with controlled aliasing, to further increase dissimilarities among the coil profiles across the slices and to reduce g‐factor noise amplification 8 . Multiple studies have explored the use of SMS imaging in CMR for faster coverage 9‐22 . In particular, SMS acceleration has been used for myocardial T 1 mapping, 13,18 for cine imaging, 16,21 and for perfusion imaging 11,14,15,17,22 using both Cartesian and non‐Cartesian acquisitions at different acceleration rates.…”

Compressed sensing acceleration of cardiac cine imaging allows reliable and reproducible assessment of volumetric and functional parameters of the left and right atrium

“…These artifacts are successfully reduced utilizing wavelet regularization during the non-linear iterative reconstruction [22]. CS acceleration has been implemented and found feasible in multiple other CMR techniques, such as 4D flow, perfusion imaging, and T1 mapping [40][41][42]. Other strategies have been described to accelerate cine imaging using k-t acceleration in combination with parallel imaging such as k-t SENSE or k-t GRAPPA [43,44].…”

High spatial resolution spiral first‐pass myocardial perfusion imaging with whole‐heart coverage at 3 T

“…[24][25][26][27] Recent advance in high-resolution SMS Cartesian perfusion imaging using balanced steady-state free precession (bSSFP) provides another possibility for high-resolution perfusion imaging. 28 However, bSSFP could have significant banding artifacts at 3T without using frequency scouts, and requires a special phase cycling compatible with both bSSFP and SMS.…”