In vivo cardiac diffusion tensor imaging on an MR system featuring ultrahigh performance gradients with 200 mT/m...

Area of Science:

• Cardiovascular Magnetic Resonance Imaging
• Diffusion Tensor Imaging
• Biomedical Engineering

Background:

• Cardiac Diffusion Tensor Imaging (DTI) faces challenges with low signal-to-noise ratio (SNR) and sensitivity to cardiac motion.
• Advancements in MRI hardware are needed to overcome these limitations for better myocardial tissue characterization.

Purpose of the Study:

• To evaluate the efficacy of ultrahigh performance gradients (200 mT/m) in cardiac DTI.
• To assess the impact of gradient strength on SNR and motion sensitivity in cardiac DTI.
• To determine the optimal motion compensation strategy for high-performance gradient cardiac DTI.

Main Methods:

• Cardiac DTI was performed on healthy volunteers, patients, and swine using varying gradient strengths (40, 80, 200 mT/m).
• Spin echo sequences with second-order motion compensation were employed.
• Acquisitions at 200 mT/m were analyzed with zeroth-, first-, and second-order motion compensation to assess motion robustness.

Main Results:

• Increasing gradient strength to 200 mT/m significantly increased SNR (150% and 40%) by reducing echo time (TE).
• Improvements were observed in DTI metrics, including reduced variance in mean diffusivity and helix angle transmurality.
• Second-order motion compensation demonstrated robustness against motion-induced signal dropout, unlike lower orders.

Conclusions:

• Ultrahigh performance gradients (200 mT/m) enable high-SNR cardiac diffusion-weighted imaging (DWI).
• These gradients lead to improved diffusion tensor metrics, enhancing myocardial tissue characterization.
• Second-order motion compensation is essential for overcoming cardiac motion sensitivity in high-performance gradient DTI.