Multimodality imaging using SPECT/CT and MRI and ligand functionalized 99mTc-labeled magnetic microbubbles.

Area of Science:

• Biomedical Engineering
• Radiochemistry
• Nanotechnology

Background:

• Investigating novel drug delivery systems is crucial for targeted therapies.
• Polymer-shelled microbubbles (MBs) offer a versatile platform for drug delivery and imaging.
• Functionalization of MBs with various ligands can modulate their biodistribution and targeting capabilities.

Purpose of the Study:

• To evaluate the biodistribution of novel 99mTc-labeled polymer-shelled microbubbles (MBs) functionalized with different ligands.
• To assess the impact of incorporating super paramagnetic iron oxide nanoparticles (SPIONs) into MBs on their imaging characteristics.
• To explore the utility of multimodal imaging (SPECT/CT and MRI) for visualizing MB biodistribution.

Main Methods:

• Intravenous administration of 99mTc-labeled MBs in rats.
• Utilizing planar dynamic scintigraphy and hybrid SPECT/CT imaging for biodistribution analysis.
• Employing magnetic resonance imaging (MRI) for co-registration and enhanced visualization of SPION-containing MBs.
• Ex vivo organ radioactivity measurements to quantify biodistribution.

Main Results:

• Biodistribution of 99mTc-labeled MBs varied significantly based on ligand type and SPION incorporation.
• Highest uptake for DTPA and chitosan MBs was observed in the lungs at 1 hour post-injection.
• SPION-functionalized MBs (NOTA-SPION and DTPA-SPION) showed accumulation in the lungs, liver, and kidneys.
• SPECT/CT and MRI results were consistent with ex vivo organ measurements, confirming biodistribution patterns.

Conclusions:

• Radiotracer-labeled MBs are suitable for SPECT/CT imaging, while SPION incorporation enables MRI visualization.
• Ligand modification is an effective strategy to control MB biodistribution.
• Fusion SPECT/CT/MR multimodal imaging provides comprehensive functional and anatomical information, enhancing diagnostic value.