A new approach to study angiogenesis in rheumatoid arthritis by power Doppler sonography and serum vascular endothelial growth factor level measurement

Background

Joint destruction in rheumatoid arthritis (RA) is caused by hypervascularized pannus which invades cartilage and bone. Angiogenesis is recognized as a key event in the formation and maintenance of the pannus, which is regulated by a delicate balance of angiogenesis inducers, including vascular endothelial growth factor (VEGF), and different angiostatic agents. Technological improvements such as high-resolution ultrasound and power Doppler mode make the discrimination between periarticular and intra-articular blood flow possible.

Objective

We used power Doppler sonography to visualize intra-articular new blood vessel formation as a result of angiogenesis to evaluate a possible correlation with serum VEGF levels.

Methods

Vascularity near and inside the wrist of 23 RA patients and 12 healthy controls was visualized by power Doppler sonography. Microvascular doppler flow was localized to either inside or outside the joint capsule, and estimated according to a grading from 1 to 4. Serum levels of VEGF were measured using a standard quantitative sandwich ELISA.

Results

Power Doppler mode identified increased synovial microvascular blood flow inside the joint capsule in 20 RA patients (87%), in comparison with in none of the healthy controls (P < 0.0001). Although the median serum VEGF level in RA patients (853 pg/ml) was higher than in healthy controls (638 pg/ml), qualitative Doppler sonographic estimation of the intensity of intra-articular synovial blood flow did not correlate with the actual serum VEGF level of the same patient.

Conclusion

Power Doppler sonography is a reliable imaging modality to detect increased intra-articular synovial microvascular blood flow as a result of vasodilatation and new blood vessel formation (angiogenesis) in acute arthritis of RA patients. A correlation with elevated serum VEGF levels indicates this method as a helpful tool to study the role of blood vessels in the rheumatoid inflammatory process.