Could Photon-Counting CT Have an Impact as a Platform for Molecular Imaging?

For decades, computed tomography (CT) contrast agents have primarily been designed to increase X-ray attenuation, but photon-counting CT (PCCT) is opening an entirely new perspective.

What if we could design contrast agents with specific spectral signatures, potentially targeting specific biological processes?

A new study by Ibrahim and colleagues published in the International Journal of Nanomedicine takes an experimental step in this direction.¹

The researchers developed multifunctional nanoparticles combining gold, terbium, albumin, and folic acid for spectral PCCT and MRI imaging. The results from their study are encouraging.

• Gold and terbium provide distinct K-edge signatures (approximately 81 and 52 keV).
• Spectral CT demonstrated concentration-dependent attenuation and promising material quantification (R² = 0.98).
• MRI demonstrated predominantly T2-related contrast properties.
• Folic acid functionalization increased nanoparticle uptake in triple-negative breast cancer cells.

Could This Be a New Direction for Photon-Counting CT?

This is much more interesting than simply developing another contrast agent. It suggests that PCCT is beginning to become experimentally viable as a molecular imaging platform.

Instead of merely visualizing anatomy and measuring attenuation, we may eventually identify and quantify specifically engineered materials associated with biological targets.

Of course, this is still early preclinical research. Experiments were limited to cells and phantoms, receptor-specific targeting remains unproven, and clinical applicability is still distant.

However, the conceptual shift is substantial.

For decades, we have improved CT by making scanners faster, sharper, and more sophisticated. Now we are beginning to engineer materials that exploit the unique spectral capabilities of those scanners.

The next revolution in PCCT may not be about seeing more anatomy, it may be about seeing biology.

Dr. Cademartiri is the director of advanced cardiovascular imaging and photon-counting CT at the Scientific Institute for Research, Hospitalization, and Healthcare Synlab Diagnostic Network in Naples, Italy. He is also a consultant in advanced cardiovascular imaging at CDI/Centro Diagnostico Italiano in Milan, Italy.

Reference

1. Ibrahim YO, Maalej N, Raja AY, et al. Folic acid-conjugated albumin-stabilized gold-terbium nanoparticles for SPCCT/MRI imaging: an in vitro cellular and phantom study. Int J Nanomed. 2026. doi: 10.2147/IJN.S584189 .

(Editor’s note: This blog is adapted with permission from Dr. Cademartiri’s original LinkedIn post available at https://www.linkedin.com/feed/update/urn:li:activity:7518588929709907968/ :.)