FeCl₃ and GdCl₃ solutions as superfast relaxation modifiers for agarose gel: a quantitative analysis

Area of Science:

• Magnetic Resonance Imaging (MRI) Contrast Agents
• Biomedical Engineering
• Materials Science

Background:

• MRI contrast agents are crucial for enhancing image quality and diagnostic accuracy.
• Relaxation modifiers alter the T1 and T2 relaxation times of water protons, influencing MRI signal intensity.
• Agarose gel phantoms serve as standardized phantoms for evaluating MRI properties.

Purpose of the Study:

• To evaluate the relaxivity and signal uniformity of agarose gel phantoms containing gadolinium chloride (GdCl₃) and iron(III) chloride (FeCl₃) as relaxation modifiers.
• To investigate the impact of these modifiers on T1 and T2 relaxation times and signal-to-noise ratio (SNR).

Main Methods:

• Preparation of 20 agarose gel phantoms with varying GdCl₃ and FeCl₃ volume fractions.
• Acquisition of T1 and T2-weighted images using a 3-Tesla scanner and turbo spin echo sequence.
• Computation of SNR from multiple regions-of-interest (ROIs) to generate T1 and T2 curves.

Main Results:

• T1 SNR increased with higher concentrations of relaxation modifiers, reaching saturation at short repetition times (TR).
• GdCl₃-containing phantoms exhibited higher T1 saturation values compared to FeCl₃-containing phantoms.
• Signal uniformity was maintained across different ROIs for both relaxation modifier groups.

Conclusions:

• GdCl₃ and FeCl₃ are effective relaxation modifiers for reducing T1 relaxation times in agarose gel phantoms.
• These modifiers primarily influence T1 relaxation and do not significantly alter T2 relaxation.
• The findings support the potential use of these agents for manipulating MRI contrast.