Quantification of multiple mixed contrast and tissue compositions using photon-counting spectral computed tomography

Area of Science:

• Medical Imaging
• Biomedical Engineering
• Radiology

Background:

• Current molecular imaging modalities have limitations in differentiating multiple, spatially coincident materials.
• Accurate quantification of both contrast agents (gadolinium, iodine) and tissue compositions (calcium, water) is crucial for advanced diagnostics.

Purpose of the Study:

• To demonstrate quantitative material decomposition of multiple mixed compositions using photon-counting spectral CT.
• To evaluate the accuracy and efficacy of this technique for differentiating and quantifying gadolinium, iodine, calcium, and water.

Main Methods:

• Photon-counting spectral computed tomography (CT) was employed for material decomposition.
• Constrained maximum likelihood estimation (MLE) in the image domain, calibrated by multiple linear regression of pure material compositions, was utilized.
• Color material concentration maps were generated for visualizing decomposed materials.

Main Results:

• A strong correlation was observed between measured x-ray attenuation and known concentrations in a calibration phantom.
• Material decomposition successfully differentiated and mapped multiple mixed compositions.
• High accuracy in material identification (AUC = $$) and quantitative estimation (RMSE $$) was achieved.

Conclusions:

• Photon-counting spectral CT enables accurate quantitative molecular imaging of multiple, spatially coincident contrast agents and tissue compositions.
• This technique surpasses the capabilities of current clinical molecular imaging methods.
• The findings pave the way for advanced diagnostic applications requiring precise material quantification.