Quantitative contrast-enhanced MRI with superparamagnetic nanoparticles using ultrashort time-to-echo pulse...

Area of Science:

• Biomedical Imaging
• Magnetic Resonance Imaging
• Nanotechnology

Background:

• Conventional MRI contrast agents are semiquantitative due to artifacts like susceptibility, field inhomogeneity, and motion.
• Accurate measurement of contrast agent concentration is crucial for quantitative analysis in various medical applications.

Purpose of the Study:

• To develop and validate a quantitative contrast-enhanced MRI technique for precise ferumoxytol concentration measurement.
• To overcome limitations of conventional MRI by employing ultrashort time-to-echo (UTE) pulse sequences.

Main Methods:

• Utilized rapid signal acquisition with UTE sequences for positive contrast and minimal T2* decay.
• Employed spoiled gradient echo equations to convert UTE intensities into concentration values.
• Optimized acquisition parameters for high-fidelity measurements and validated results with elemental iron analysis.

Main Results:

• Achieved high sensitivity and precision (∼7.1% error) in longitudinal ferumoxytol concentration measurements in mice.
• Demonstrated robust and reproducible quantitative measurements.
• Generated high-quality 3D images for perfusion visualization through automated segmentation.

Conclusions:

• Quantitative UTE contrast-enhanced (QUTE-CE) MRI enables longitudinal quantification of blood pool contrast agent concentration.
• QUTE-CE MRI is a powerful, non-invasive imaging modality competitive with nuclear imaging for perfusion assessment.