Diffusion-relaxation correlation spectroscopic imaging: A multidimensional approach for probing microstructure.

Area of Science:

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

Background:

• Multiexponential modeling of MRI diffusion or relaxation data is used to infer microscopic tissue compartments within voxels.
• Estimating these compartments is challenging due to the ill-posed nature of multiexponential modeling.
• Higher dimensional analysis can theoretically reduce the ill-posedness of compartment estimation.

Purpose of the Study:

• To propose and evaluate Diffusion-Relaxation Correlation Spectroscopic Imaging (DRCSI), a novel multidimensional approach for imaging subvoxel tissue compartments.
• To enhance the resolution of microscopic tissue structures within macroscopic MRI voxels.
• To overcome limitations of conventional diffusion and relaxation imaging methods.

Main Methods:

• DRCSI employs a novel multidimensional imaging experiment that simultaneously encodes diffusion and relaxation information.
• A constrained reconstruction technique is utilized to generate a multidimensional diffusion-relaxation correlation spectrum for each voxel.
• This spectrum's peaks are hypothesized to represent distinct tissue microenvironments.

Main Results:

• Numerical simulations and phantom experiments demonstrated DRCSI's superior multicompartment resolving power.
• Data from a mouse model of traumatic spinal cord injury validated the technique's effectiveness.
• DRCSI significantly outperformed conventional diffusion- and relaxation-based methods in resolving tissue compartments.

Conclusions:

• DRCSI offers powerful new capabilities for resolving components within multicompartment tissue models.
• This approach can significantly expand insights gained from MRI studies of tissue microstructure.
• DRCSI represents a significant advancement in MRI for characterizing complex biological tissues.