Quantification of cartilage and subchondral bone cysts on knee specimens based on a spectral photon-counting computed tomography

Abstract

Abstract Spectral Photon-Counting Computed Tomography (SPCCT) is a new technique with the capability to provide mono-energetic (monoE) images with high signal to noise ratio. We demonstrate the feasibility of SPCCT to characterize at the same time cartilage and subchondral bone cysts (SBCs) without contrast agent in osteoarthritis (OA). To achieve this goal, 5 human knee specimens (3 normal and 2 with OA) were imaged with a clinical prototype SPCCT. The monoE images at 60 keV with isotropic voxels of 250x250x250 µm3 were compared with monoE synchrotron radiation CT (SR CT) images at 55 keV with isotropic voxels of 45x45x45 µm3 used as benchmark for cartilage segmentation. The volume and density of SBCs were evaluated in the two OA knees in SPCCT images. In 25 compartments (tibial lateral, tibial medial, femoral lateral, femoral medial and patella), the mean bias between SPCCT and SR CT analyses were 106 ± 196mm3 for cartilage volume and − 0.006mm ± 0.06 for mean cartilage thickness. The 2 OA knees displayed different SBCs profiles in terms of volume, density, and distribution according to size and location. SPCCT with fast acquisitions is able to characterize cartilage morphology and SBCs. SPCCT can be used potentially as a new tool in clinical studies in OA.