Examining the Feasibility of Quantifying Receptor Availability Using Cross-Modality Paired-Agent Imaging

Area of Science:

• Molecular imaging
• Biophysics
• Radiochemistry

Background:

• Noninvasive quantification of receptor availability (RA) in solid tumors is crucial for molecular imaging.
• Traditional paired-agent imaging (PAI) techniques use spectrally distinct fluorescent agents, limiting applications to superficial tissues and preclinical studies.
• Simultaneous imaging of multiple agents is challenging with conventional clinical modalities.

Purpose of the Study:

• To investigate the feasibility of implementing PAI in a cross-modality paradigm.
• To assess the ability of cross-modality PAI to accurately quantify receptor availability.
• To overcome the limitations of single-modality PAI for human applications.

Main Methods:

• Eighteen mice with orthotopic brain tumors were used.
• Contrast agents included a targeted fluorescent agent (EGFR), an untargeted fluorescent agent, and a gadolinium-based contrast agent (GBCA) for MRI.
• Kinetics were imaged using an MRI-coupled fluorescence tomography system; RA was computed using both conventional all-optical PAI and cross-modality PAI (targeted optical + untargeted MRI-GBCA).

Main Results:

• Cross-modality PAI yielded receptor availability estimates highly correlated with the conventional single-modality approach (r = 0.94; p < 0.00001).
• This demonstrates strong agreement between the two PAI methods.

Conclusions:

• Cross-modality paired-agent imaging is a feasible approach for quantifying receptor availability.
• This technique has the potential to facilitate rapid, noninvasive RA quantification in humans.
• Hybrid clinical imaging modalities could enable widespread application of this cross-modality PAI method.