Simultaneous Multi-Slice Cardiac MR Multitasking for Motion-Resolved, Non-ECG, Free-Breathing T1-T2 Mapping

Area of Science:

• Cardiovascular Magnetic Resonance (CMR) Imaging
• Quantitative Myocardial Tissue Characterization
• Medical Imaging Physics

Background:

• Traditional cardiovascular magnetic resonance (CMR) T1/T2 mapping requires breath-holding and electrocardiogram (ECG) monitoring, prolonging scan times.
• Accurate quantification of myocardial T1 and T2 relaxation times is crucial for diagnosing and monitoring various cardiac conditions.
• There is a need for faster, more patient-friendly CMR techniques for comprehensive myocardial assessment.

Purpose of the Study:

• To develop and validate a novel Multitasking-Simultaneous Multi-Slice (SMS) cardiovascular magnetic resonance (CMR) technique.
• To achieve simultaneous T1/T2 quantification across three left-ventricular myocardial slices within a 3-minute scan.
• To eliminate the need for breath-holds and ECG monitoring during quantitative CMR.

Main Methods:

• Incorporation of radial simultaneous multi-slice (SMS) encoding, self-gating, and image reconstruction into the CMR Multitasking framework.
• Design and implementation of a T2prep-Inversion Recovery (IR) FLASH sequence with two flip angles for B1+-robust T1 and T2 mapping.
• Validation in a standardized phantom and 10 healthy volunteers, comparing Multitasking-SMS T1/T2 measurements and repeatability against reference methods (MOLLI, T2-prep FLASH).

Main Results:

• Multitasking-SMS demonstrated excellent correlation (R² > 0.996) and agreement (ICC ≥ 0.999) with reference measurements in phantom studies.
• In vivo, Multitasking-SMS T1/T2 values in healthy volunteers were comparable to reference methods (T1: 1215 ± 91.0 ms vs. 1239 ± 67.5 ms; T2: 41.5 ± 6.3 ms vs. 42.7 ± 4.1 ms).
• Good in vivo repeatability was observed for Multitasking-SMS T1 (4.7% CV) and T2 (8.9% CV), comparable to reference techniques.

Conclusions:

• Multitasking-SMS is a feasible technique for free-breathing, non-ECG myocardial T1/T2 quantification across three short-axis slices in 3 minutes.
• This method allows for the assessment of 16 American Heart Association (AHA) myocardial segments efficiently.
• The Multitasking-SMS approach holds significant potential for reducing examination time in quantitative CMR without compromising diagnostic accuracy.