Is Phase-Contrast Computed Tomography More Sensitive Than Magnetic Resonance Imaging in Quantifying Cartilage Damage in Osteoarthritis?

Purpose: Articular cartilage, damaged in Osteoarthritis, remains a challenging tissue to accurately characterize using clinical imaging techniques. This project quantitatively compares the use of magnetic resonance imaging (MRI) and synchrotron based phase-contrast-imaging computed tomography (PCI-CT) in making clinically relevant, three-dimensional assessments of articular cartilage. Methods: The medial tibial plateau of disarticulated human knee joints from four healthy and four osteoarthritic donors was imaged using PCI-CT at 45 keV and MRI technique, 3D FLASH. The respective pixel resolutions were 28 and 313 micron. Using commercial software, computed tomography data was manually segmented to generate three-dimensional surface reconstructions of the plateau cartilage, thus permitting quantitation of its total volume and average thickness. Results: PCI-CT effectively visualizes articular cartilage, differentiating it from other tissues and surrounding synovial fluid (simulated by a phosphate buffered saline solution). The ten-fold resolution advantage of PCI-CT over MRI, allowed for very accurate characterization of articular cartilage. PCI-CT yielded statistically significant lower “average thickness” measures of articular cartilage compared to MRI. Conclusions: PCI-CT may be more sensitive than MRI in quantifying early deterioration of articular cartilage. The knowledge obtained from this project supports efforts to, eventually, increase the diagnostic and preventative capabilities in Osteoarthritis. Improved imaging would enhance the ability to characterize tissue changes that occur in Osteoarthritis in vivo, and better relate these changes to patient symptoms.