Small field of view imaging using wavelet encoding with 2 dimensional RF pulses and gradient echo: phantom results.

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Signal Processing
• Medical Imaging Technology

Background:

• Folding artifacts, also known as aliasing, are a common problem in MRI, particularly in dynamic studies with a small field of view (FOV).
• Traditional Fourier encoding methods struggle to mitigate these artifacts in reduced FOV imaging.
• Developing novel imaging sequences is essential for improving image quality in specialized MRI applications.

Purpose of the Study:

• To propose and evaluate a novel MRI imaging sequence utilizing wavelet encoding.
• To achieve MRI images free from folding artifacts in the small FOV regime.
• To enhance the utility of dynamic MRI studies through improved image quality.

Main Methods:

• A 2D spatially selective radiofrequency (RF) excitation pulse was integrated into a gradient-echo pulse sequence.
• Wavelet encoding was implemented in one direction for spatially localized excitation, restricting the FOV.
• Slice selection was performed in the second direction, with variations in RF pulse profile width and position to meet wavelet encoding conditions.
• The sequence was implemented on a 3 Tesla Siemens whole-body scanner.

Main Results:

• The proposed wavelet encoding technique successfully generated gradient-echo reduced FOV images.
• The technique effectively eliminated aliased signals, demonstrating superiority over Fourier encoding.
• Testing on phantoms with diverse shapes and structures confirmed the artifact-free nature of the generated images.

Conclusions:

• Wavelet encoding is a suitable and effective method for small FOV imaging in dynamic MRI.
• This approach significantly reduces folding artifacts, enhancing image quality for dynamic studies.
• The proposed sequence offers a valuable advancement for specific MRI applications requiring high-fidelity small FOV imaging.