Ex-vivo atherosclerotic plaque characterization using spectral photon-counting CT: Comparing material quantification...

Area of Science:

• Medical Imaging
• Cardiovascular Research
• Materials Science

Background:

• Atherosclerotic plaques possess features like lipid-rich necrotic cores, spotty calcification, and ulceration, indicating vulnerability to rupture.
• Current imaging methods struggle to differentiate plaque materials and structural details effectively.

Purpose of the Study:

• To evaluate the capability of X-ray spectral photon-counting computer tomography (SPCCT) in distinguishing key features of vulnerable atherosclerotic plaques.
• To compare SPCCT imaging findings with histological analysis of surgically excised carotid artery specimens.

Main Methods:

• An excised carotid plaque was scanned using a small-bore SPCCT scanner (30-120 keV) with a Medipix3RX detector.
• Material identification and quantification (MIQ) images were generated using specialized software at 0.09 mm voxel resolution.
• The plaque was subsequently sectioned, stained, and photographed for high-resolution histological comparison.

Main Results:

• MIQ images successfully identified a lipid-rich core with spotty calcification, consistent with histological findings.
• Lipid core regions showed a mean concentration of 260 mg lipid/ml (-22 HU), and calcified regions averaged 41 mg Ca/ml (123 HU).
• Ulceration at the carotid bifurcation was identified as lipid-lined, with adjacent calcification near the arterial wall breach.

Conclusions:

• SPCCT-derived MIQ images effectively visualized hallmarks of vulnerable plaque, including lipid-rich necrotic cores, spotty calcifications, and ulcerations.
• This demonstrates SPCCT's potential for detailed plaque characterization and assessment of rupture risk.