Whole‐heart, ungated, free‐breathing, cardiac‐phase‐resolved myocardial perfusion MRI by using Continuous Radial Interleaved simultaneous Multi‐slice acquisitions at sPoiled steady‐state (CRIMP).

Purpose: To develop a whole‐heart, free‐breathing, non‐electrocardiograph (ECG)‐gated, cardiac‐phase‐resolved myocardial perfusion MRI framework (CRIMP; Continuous Radial Interleaved simultaneous Multi‐slice acquisitions at sPoiled steady‐state) and test its quantification feasibility. Methods: CRIMP used interleaved radial simultaneous multi‐slice (SMS) slice groups to cover the whole heart in 9 or 12 short‐axis slices. The sequence continuously acquired data without magnetization preparation, ECG gating or breath‐holding, and captured multiple cardiac phases. Images were reconstructed by a motion‐compensated patch‐based locally low‐rank reconstruction. Bloch simulations were performed to study the signal‐to‐noise ratio/contrast‐to‐noise ratio (SNR/CNR) for CRIMP and to study the steady‐state signal under motion. Seven patients were scanned with CRIMP at stress and rest to develop the sequence. One human and two dogs were scanned at rest with a dual‐bolus method to test the quantification feasibility of CRIMP. The dual‐bolus scans were performed using both CRIMP and an ungated radial SMS saturation recovery (SMS‐SR) sequence with injection dose = 0.075 mmol/kg to compare the sequences in terms of SNR, cardiac phase resolution and quantitative myocardial blood flow (MBF). Results: Perfusion images with multiple cardiac phases in all image slices with a temporal resolution of 72 ms/frame were obtained. Simulations and in‐vivo acquisitions showed CRIMP kept the inner slices in steady‐state regardless of motion. CRIMP outperformed SMS‐SR in slice coverage (9 over 6), SNR (mean 20% improvement), and provided cardiac phase resolution. CRIMP and SMS‐SR sequences provided comparable MBF values (rest systolic CRIMP = 0.58 ± 0.07, SMS‐SR = 0.61 ± 0.16). Conclusion: CRIMP allows for whole‐heart, cardiac‐phase‐resolved myocardial perfusion images without ECG‐gating or breath‐holding. The sequence can provide MBF if an accurate arterial input function is obtained separately. [ABSTRACT FROM AUTHOR]