Background The detection of intraarticular Power Doppler (PD) signal in metacarpophalangeal (MCP) joints may play a key role in the assessment of patients with early arthritis. Currently used quantification methods for PD however do not provide information related to the intraarticular topographic distribution of the signal. The evaluation of PD signal in the MCP joint is further hindered by the fact that new, highly sensitive PD systems allow the detection of normal PD signal in the MCP joints of healthy subjects, likely corresponding to physiological feeding vessels.
Objectives Our aim within this pilot investigation was to identify different patterns of intraarticular PD signal in the MCP joint based on its topographic location and to demonstrate the presence of physiological feeding vessels in cadaver preparations obtained with corrosion and also in histological sections.
Methods We evaluated a panel of one hundred images obtained at MCP joint level in both healthy subjects and patients with early arthritis using dorsal longitudinal and transverse views. The presence of physiological vessels in the metacarpal head was evaluated in cadaver specimens subjected to corrosion, while those in the dorsal fat pad were demonstrated in histological sections obtained from cadavers of patients, with negative case histories for diseases involving the small joints of the hand.
Results We identified at least two distinct patterns of intraarticular PD signal: pattern 1 (extrasynovial) was characterized by intraarticular, but not intrasynovial PD signal while pattern 2 (intrasynovial) was characterized by intraarticular and intrasynovial PD signal in structures possessing a synovial lining. Both patterns could be demonstrated in healthy individuals and also in patients with early arthritis. We also confirmed the presence of physiological vessels in the metacarpal head as well as in the dorsal fat pad of cadavers.
Conclusions Extrasynovial PD signal may be due to the vasodilation of pre-existing feeding vessels in intraarticular areas that do not possess a synovial lining, e.g. the dorsal fat pad as often seen in patients with early arthritis. Intrasynovial PD signal may correspond to the presence of physiological feeding vessels at the metacarpal head seen in healthy individuals, similar signals however may also be detected in patients with erosive disease. The evaluation of intraarticular PD signal in the MCP joint therefore remains problematic, especially in cases where grey-scale changes characteristic to synovitis are lacking.
Disclosure of Interest None Declared