Short echo-time 3D radial gradient-echo MRI using concurrent dephasing and excitation.

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Biomedical Engineering
• Radiological Physics

Background:

• Ultrashort echo-time (UTE) and sweep imaging with Fourier transformation (SWIFT) are advanced MRI techniques for imaging ultrashort T2 species.
• Implementing UTE and SWIFT on standard clinical MRI systems is challenging due to hardware limitations.

Purpose of the Study:

• Investigate the limits of minimum echo-time (TE) and repetition time (TR) using 3D radial gradient-echo sequences on clinical scanners.
• Introduce and evaluate a novel 3D radial gradient-echo sequence, COncurrent Dephasing and Excitation (CODE), for ultrashort TE imaging.

Main Methods:

• Analytical description and comparison of minimum TE for CODE versus standard 3D radial gradient-echo sequences.
• Implementation of the CODE sequence on a clinical 3 T MRI scanner (Siemens 3 T MAGNETOM Trio).
• Acquisition and demonstration of phantom and in vivo human knee images using the CODE sequence.

Main Results:

• The CODE sequence achieves ultrashort echo-times on the order of approximately 0.2 ms in a clinical setting.
• CODE enables ultrashort TE imaging on standard clinical MRI hardware, overcoming previous limitations.
• Demonstrated feasibility of CODE for imaging ultrashort T2 species with phantom and in vivo knee data.

Conclusions:

• The CODE sequence offers a practical solution for achieving ultrashort echo-times on standard clinical MRI systems.
• CODE expands the applicability of ultrashort T2 imaging in clinical research and diagnostics.
• This technique holds promise for imaging tissues and materials with very short T2 relaxation times.