A temporomandibular joint (TMJ) effusion is unusual in asymptomatic patients, and thus should trigger a careful search for underlying pathology. It usually precedes osteoarthritis of the TMJ. Effusions are seen in:
“Small TMJ joint effusion.”
“Mild TMJ effusion”
“large TMJ effusion. ”
On PD / T2 weighted sequences, both synovial proliferation and effusions can be high on signal. If necessary they two can be distinguished by administering gadolinium.