Fig. 4.

Tenosynovitis of the flexor digitorum profundus tendon on the right hand and extensor carpi ulnaris tendon on the right wrist of a rheumatoid arthritis patient. a The blood pool image showed the curvilinear activity (left, arrows) which was not clearly visualized on the bone phase image (middle left) and the plain radiograph image (middle right). The curvilinear activity was matched with the flexor digitorum profundus tendon (right, arrows) on the illustration of the hand [28]. b The linearly increased blood pool phase activity (left, arrows) with negative bone phase scan (middle left), and the ill-defined soft tissue swelling on the plain radiography (middle right, arrows) was shown on the ulnar side of the right wrist, which was matched with the extensor carpi ulnaris tendon (right, arrows) on the illustration of the wrist [28]. The second metacarpophalangeal joint of the left hand had arthritis on both of the blood pool (left, arrowhead) and bone phase image (middle left, arrowhead)