Complementary bioimaging of Gadofluorine P in myocardial infarction in mic

Significance of the Topic

The precise visualization of targeted contrast agents in biological tissues is critical for understanding disease mechanisms and improving diagnostic imaging. Combining elemental and molecular imaging techniques addresses limitations of standalone methods by providing both quantitative elemental distribution and molecular specificity.

Objectives and Study Overview

This study evaluates the complementary use of laser ablation–inductively coupled plasma mass spectrometry (LA-ICP-MS) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) to map the distribution of the collagen-affine contrast agent Gadofluorine P in mouse hearts following experimental myocardial infarction (MI). The aim is to quantify gadolinium accumulation and validate its localization on a molecular level.

Methodology and Instrumentation

Animal Study and Sample Preparation:

• MI was induced in mice; six weeks later, Gadofluorine P was administered intravenously prior to MRI.
• Hearts were harvested, snap-frozen, and sectioned at 10 µm thickness.
• Parallel sections underwent hematoxylin–eosin staining to delineate infarct regions.

LA-ICP-MS Analysis:

• Instrument: Teledyne CETAC LSX-213 G2+ laser ablation coupled to Shimadzu ICPMS-2030.
• Laser wavelength 213 nm, spot size 15 µm, scan speed 30 µm/s, 20 Hz repetition.
• Cell gas (He) flow 0.8 L/min; ICP plasma power 1.2 kW; gas flows: plasma 9.0 L/min, auxiliary 1.10 L/min, carrier 0.45 L/min, collision gas 6.0 mL/min.
• Matrix-matched gelatin standards (0–5000 µg/g Gd) prepared for external calibration.

MALDI-MS Imaging:

• Instrument: Shimadzu iMScope TRIO with ion trap–TOF analyzer.
• Matrix: α-cyano-4-hydroxycinnamic acid deposited via sublimation using iMLayer™ (20 min); recrystallization with water/methanol.
• Positive mode, mass range m/z 700–1200; spot size 40 µm; 500 laser shots at 1000 Hz; sample voltage 3.5 kV, detector 1.9 kV.

Main Results and Discussion

LA-ICP-MS Findings:

• Linear calibration up to 5000 µg/g Gd with R2 = 0.997.
• Limit of detection 43 ng/g and LOQ 140 ng/g Gd (158Gd isotope).
• Healthy myocardium exhibited ~50 µg/g Gd; infarct zones showed ~110 µg/g, peaking at 370 µg/g.

MALDI-MS Validation:

• Detected the protonated Gadofluorine P ligand (m/z 1168.39) rather than intact complex.
• Intensity map closely matched elemental Gd distribution, confirming accumulation in MI and ventricular regions.

Correlation with Histology:

• H&E staining delineated infarct areas, aligning with elevated Gd signals in both imaging modalities.

Benefits and Practical Applications

The dual-imaging approach offers:

• Quantitative, high-resolution elemental maps of contrast agents.
• Molecular confirmation of probe localization and integrity.
• Enhanced understanding of probe–tissue interactions in preclinical cardiac research.

This methodology is applicable to targeted agent development, pharmacokinetic studies, and translational imaging research.

Future Trends and Potential Applications

Advancements may include:

• Integration with three-dimensional imaging and tomography.
• Multiplexed isotope labeling for simultaneous multi-element mapping.
• Automated matrix deposition and AI-driven data analysis.
• Translation to clinical imaging workflows for personalized diagnostics.

Conclusion

The combination of LA-ICP-MS and MALDI-MS provides a powerful platform for quantitative elemental imaging coupled with molecular specificity. This synergy enables detailed mapping of targeted gadolinium probes in myocardial infarction models, offering valuable insights for contrast agent evaluation and cardiac research.

References

1. P.W.J.M. Boumans, Spectrochimica Acta Part B, 1991, 46B, 641–665.