MR angiography with adiabatic flow excitation

Area of Science:

• Medical Imaging
• Magnetic Resonance Imaging (MRI)
• Angiography

Background:

• Traditional magnetic resonance (MR) angiography methods face challenges in differentiating between flowing and stationary spins.
• Suppression of stationary spins is crucial for clear visualization of vascular structures in MR angiography.
• Inhomogeneity in radio-frequency (RF) and magnetic fields can degrade image quality.

Purpose of the Study:

• To introduce a new MR angiography method utilizing a flow excitation pulse sequence.
• To achieve signal generation from flowing spins while suppressing signals from stationary spins.
• To enhance the robustness of MR angiography against field inhomogeneities.

Main Methods:

• A novel flow excitation pulse sequence employing adiabatic 90-degree and 180-degree radio-frequency (RF) pulses.
• Interleaving RF pulses with flow-dephasing gradient lobes to manipulate spin behavior.
• Utilizing gradient lobes to dephase flowing spins and generate a measurable transverse signal component.

Main Results:

• The proposed method successfully produces signal from flowing spins.
• Stationary spins are effectively suppressed through refocusing along the z-axis.
• The pulse sequence demonstrates high immunity to RF and magnetic field inhomogeneity, applicable with surface coils.

Conclusions:

• The developed MR angiography technique offers improved visualization of blood flow.
• Adiabatic RF pulses provide robustness but may pose challenges for suppressing short T2 stationary spins.
• This method represents a significant advancement in MR angiography for clinical applications.