Cationic Contrast Agents for Cartilage Imaging for Early Diagnosis of Arthritis
A team led by Ambika Bajpayee, associate professor, bioengineering, published a paper, “Cationic Carrier Mediated Delivery of Anionic Contrast Agents in Low Doses Enable Enhanced Computed Tomography Imaging of Cartilage for Early Osteoarthritis Diagnosis,” in the journal ACS Nano. The paper details the creation of positively charged contrast agents that can target cartilage tissue in joints affected by osteoarthritis, enabling computed tomography (CT) imaging at very low doses. The paper’s first author is Chenzhen Zhang, a PhD candidate in Bajpayee’s lab graduating in 2023.
Early detection is key to effective treatment of osteoarthritis, a debilitating disease that causes loss of joint function and affects millions of people. Currently, x-ray imaging is used for diagnosis, but this method can only examine the narrowing of joint spaces and is an indirect, less effective measurement of cartilage health. While CT scans have been considered for cartilage imaging, they rely on introducing radio-opaque contrast agents like ioxaglate (IOX) into the joint. IOX is repelled by the negative electrical charge in cartilage, which leads to poor CT attenuation. Furthermore, it remains in joint tissue for only short periods, necessitating higher doses and risking toxicity.
Bajpayee’s team engineered optimally charged cationic contrast agents that can penetrate through the full thickness of cartilage using electrostatic interactions and elicit similar CT signals with a dose about 40 times lower compared to IOX. Their research demonstrates that CT scanning can be a viable imaging modality for early detection of osteoarthritis and staging of its severity.