Email from Jon Hickle on February 7, 2020:

Not everything that’s green is gout. 

1.       Nailbed.  Commonly labeled as gout. 

 2.       Skin calluses and skin apposition.  On the transverse images sent to PACS this looks like gout in the toe, but on coronal reformats it’s the skin.  Removing the gout overlay shows no mineralization in the soft tissues.

 3.       Tendons.  When the x-ray beam is shot down the length of a tendon, the algorithm will produce “green dot artifacts” or GDAs.  Urate can also deposit in tendons, so checking in syngo or on the routine non contrast images is important to correlate for focal areas of mineralization. Usually these are chunkier than these little dots. 

 If something is labeled green and is mineralized on the CT, you can be confident that what you’re looking at is truly urate. 

Jon

Another decent article on the topic: