Joint Space/Bursal/Synovial Uptake of FDG

Uptake of FDG within a joint space or bursa is a frequent finding, most commonly affecting the hip and glenohumeral joints.

This uptake is nearly always inflammatory in nature, reflecting synovitis. It may or may not be associated with osseous evidence of a degenerative or inflammatory arthropathy.

Metastatic disease to the joint space or bursae is exceedingly rare.

Joint space or bursal uptake can be diffuse or very focal.

In the absence of an associated soft tissue abnormality, such uptake is considered inflammatory and is only mentioned in a report if unusually prominent or very focal:

“Marked and intense uptake is noted within the left hip joint space, without an associated abnormality on the co-registered CT images. This typically reflects synovitis. 

OR

“A 7.0 mm focus of intense FDG uptake projects within the right hip joint space. An associated soft tissue density is not visualized on the co-registered CT images. This typically represents focal synovitis.”

If an associated soft tissue density is present, MRI characterization is a reasonable recommendation, even though nearly all of these cases will still be inflammatory in nature, typically representing focal (nodular) synovitis.