Spatial resolution enhancement of spectral results with ultra-high resolution conventional images in dual-source photon-counting CT

Coronary Artery Disease (CAD) is a leading fatal heart disease in the world, but early diagnosis and treatment can effectively prevent fatalities. One diagnostic criterion includes identifying plaques in the coronary arteries via computed tomography (CT) imaging. Spectral CT is especially useful for distinguishing different materials in plaque based on their x-ray absorption, and providing more detailed spectral information compared with conventional (non-spectral) CT. As plaques are small with diameters of 1.5 to 3.5 mm, high resolution is necessary for detection. Photon counting CT (PCCT) enables ultra-high resolution with a 0.2mm minimum slice thickness (ST). PCCT cannot produce both spectral and high-resolution results simultaneously, preventing clinicians from leveraging both in the same scan. Herein, we proposed an image fusion method to combine standard resolution spectral images with high resolution non-spectral images. First, we 3D printed coronary artery mimicking phantoms with inner lumens of 4 to 6 mm diameters using a calcium-doped filament. Within each lumen, plaques of diameters 1.6 mm were mimicked. This design enabled the study of ultra-high-resolution capabilities of the PCCT scanner. A conventional high-resolution image was acquired with 0.4 mm ST. A second iodine density image with 0.8 mm ST was acquired. Utilizing principal component analysis (PCA), we generated ultra-high resolution iodine density image, provided preliminary example of how to amplify spectral results using high-resolution PCCT images for CAD diagnosis.