Simultaneous quantification of SPIO and gadolinium contrast agents using MR fingerprinting

Area of Science:

• Biomedical Imaging
• Quantitative MRI
• Molecular Imaging

Background:

• Magnetic Resonance Fingerprinting (MRF) is a powerful technique for quantitative MRI.
• Simultaneous mapping of multiple contrast agents is crucial for advanced molecular imaging applications.

Purpose of the Study:

• To develop an MRF methodology capable of R2* quantification.
• To enable simultaneous contrast agent concentration mapping, specifically for gadolinium (Gd) and iron-labeled CD8+ T cells.

Main Methods:

• Variable-density spiral SSFP MRF was modified for variable TE and dictionary modulation.
• In vitro phantoms with SPIO-labeled cells and Gd were used for validation.
• In vivo imaging in mice demonstrated feasibility at 8x undersampling for a 25-min scan.

Main Results:

• High agreement between conventional and MRF-derived R1, R2, and R2* values.
• Successful quantification of iron-loaded CD8+ T cells using expanded MRF.
• Robustness to 8x undersampling, enabling simultaneous relaxation profile recreation for Gd and iron-labeled cells.

Conclusions:

• Expanded MRF allows R1, R2, and R2* mapping for simultaneous Gd and SPIO quantification.
• This methodology supports future in vivo studies using dual MR contrast agents.
• Potential for molecular imaging of labeled cells with enhanced dual contrast agent tracking.