Magnetic resonance separation imaging using a divided inversion recovery technique (DIRT)

Area of Science:

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

Background:

• The divided inversion recovery technique is an MRI method leveraging T(1) relaxation differences for tissue separation.
• Incomplete longitudinal magnetization recovery in segmented inversion recovery sequences can lead to phase changes and spatial displacement in balanced steady-state free-precession imaging.

Purpose of the Study:

• To demonstrate the utility of magnetization phase changes for image separation using the divided inversion recovery technique.
• To show how adjusting the time between inversion pulses (T180) enables water-fat and fluid separation.

Main Methods:

• Utilizing the divided inversion recovery pulse sequence with adjustable time between inversion pulses (T180).
• Applying the technique to generate water-fat and fluid separation images of the head, heart, and abdomen.
• Evaluating water-fat separation by analyzing signal intensity in cardiac images and assessing fat, blood, and fluid suppression.

Main Results:

• Successful separation of water and fat, as well as fluid, was achieved using the adjusted T180 parameter.
• Images of the head, heart, and abdomen demonstrated effective water-fat and fluid separation.
• Fat, blood, and fluid signals were suppressed to background noise levels in the separated images.
• The separation performance remained consistent despite main magnetic field inhomogeneities.

Conclusions:

• The divided inversion recovery technique effectively utilizes magnetization phase changes for robust water-fat and fluid separation in MRI.
• Adjusting the time between inversion pulses (T180) is a key parameter for achieving specific tissue separations.
• The method shows promise for improved diagnostic imaging across various anatomical regions, unaffected by magnetic field variations.