Spatially tracked three-dimensional ultrasound imaging for monitoring the synovial membrane in knee arthritis

Abstract

Osteoarthritis (OA) is the most common chronic health condition and a leading cause of disability and pain in the United States and Canada. Current methods for monitoring the development of knee OA (KOA) involve x-ray radiography and magnetic resonance imaging (MRI) to assess femoral articular cartilage (FAC) degradation and synovial membrane inflammation. However, x-ray radiography cannot be used to quantify FAC loss or synovial membrane inflammation due to a lack of soft tissue contrast, and MRI is associated with high costs, long waitlists, long scan times, and is inaccessible to many patients. We have developed a counterbalanced point-of-care (POC) system to track multiple three-dimensional (3D) ultrasound (US) acquisitions and register them for visualizing the entire suprapatellar synovium. This work aims to validate the tracking accuracy of the POC system against an external optical tracking system. Validation was conducted using optical tracking as a reference by mounting a custom optical tracking stylus in place of the 3D US scanner on the POC system. The stylus was manipulated in 3D space and Euclidean distances were calculated using the initial and final positions of the stylus and were compared between systems to quantify POC tracking system error. Results indicated that the overall mean absolute tracking error of the POC system was 3.08 ± 2.01 mm with no statistically significant difference between the POC and optical systems (p = 0.965). The POC system has the potential to enable clinicians and researchers to obtain additional information without added complexity or discomfort to patients.