Photon-counting cine-cardiac CT in the mouse.

Area of Science:

• Medical Imaging
• Biomedical Engineering
• Radiology

Background:

• Photon-counting detector (PCD) technology offers advanced spectral information for CT imaging.
• Atherosclerosis, particularly calcified plaque, poses significant challenges in cardiovascular disease diagnosis.
• 4D imaging captures dynamic processes, crucial for cardiac and vascular studies.

Purpose of the Study:

• To demonstrate the utility of 4D cardiac photon-counting detector CT (PCD-CT) in a mouse model of atherosclerosis.
• To evaluate advanced iterative reconstruction techniques for high-fidelity spectral and spatio-temporal data.
• To assess the capability of PCD-CT for visualizing calcified plaques and assessing cardiac function in vivo.

Main Methods:

• In vivo cardiac micro-CT scans were performed on ApoE knockout mice with calcified plaques using a prototype PCD with 4 energy thresholds.
• Data acquisition involved projections sampled every 10 ms with 10 ms exposure, enabling reconstruction of 10 cardiac phases at 4 energies.
• Iterative reconstruction using the split Bregman method with spectral rank and spatio-temporal gradient sparsity constraints was employed.

Main Results:

• The study presents the first in vivo 4D PCD-CT data in a mouse atherosclerosis model.
• Robust regularization reduced noise by 8-fold while maintaining spectral bias below 13 HU.
• Material decomposition clearly separated iodinated contrast, soft tissue, and calcified plaque; spatial resolution was preserved (10% MTF: 2.8-3.0 lp/mm).
• Cardiac functional metrics showed ~1% error, and small calcifications (615 μm) were detectable.

Conclusions:

• 4D cardiac PCD-CT, combined with advanced reconstruction, provides high-fidelity spectral and material information in vivo.
• This technology holds significant promise for enhancing dynamic CT imaging in cardiovascular research and clinical applications.
• PCD-CT enables detailed characterization of atherosclerotic plaques and accurate assessment of cardiac function.