64 year old male with history of atypical mycobacterial infection within the right wrist. Abnormal signal intensity and enhancement within the distal ulna is compatible with the stated history of osteomyelitis. On large field-of-view images, this signal abnormality and enhancement appears to extend from the distal end of the ulna into the diaphysis over a length of at least 8 cm. Signal abnormality and enhancement is most prominent within the distal aspect of the ulna, where it is associated with several cortical defects / sinus tracts.There is a heterogeneously enhancing soft tissue mass surrounding the distal ulna, perhaps containing tiny pockets of fluid, but with no large drainable collection is identified. Overall, the circumferential mass measures approximately 4 cm in greatest diameter and presumably represents extension of infection into the soft tissues. There is also enhancement of the distal radioulnar joint indicating inflammation/infection, with a small cortically-based erosion along the medial aspect of the distal radius.Enhancement appears to extend through a defect in the triangular fibrocartilage into the radiocarpal joint, and there is abnormal signal and enhancement within the medial aspect of the triquetrum that may represent early osteomyelitis. This inflammation extends further distally along the dorsal aspect of the wrist and into the dorsal soft tissues of the hand, although the remaining carpal bones are of normal signal. Inflammation within the dorsal soft tissues of the hand is incompletely evaluated on today's MRI, but signal abnormality and enhancement along the length of the third metacarpal and within the distal half of the second metacarpal are also suspicious for osteomyelitis. Additional enhancement is seen in the soft tissues between the second and third metacarpals as well as third and fourth metacarpals. The signal intensity of the first, fourth, and fifth metacarpals appears normal.Diffuse subcutaneous edema involves the wrist and dorsum of the hand. Small foci of signal void in the soft tissues medial to the distal ulna likely represent metallic susceptibility artifact from prior surgery.There is medial subluxation of the extensor carpi ulnaris tendon as it courses through the aforementioned inflammatory mass. Mild generalized tenosynovial enhancement of the extensor tendons of the wrist indicates mild inflammation. There is perhaps minimal tenosynovial enhancement of the flexor tendons but this is of uncertain clinical significance.
1.Extensive soft tissue inflammation as described above, extending from the distal ulna into the wrist and dorsal soft tissues of the hand. This presumably represents infection with possible tiny foci of fluid along the ulna, although no large drainable fluid collection is seen.2.Signal abnormality within the distal ulna represents osteomyelitis that has likely progressed when compared to radiographs from May 2015. Additional foci of signal abnormality within the triquetrum and second and third metacarpals is also concerning for osteomyelitis.3.Enhancement of the radiocarpal joint and distal radioulnar joint, suggestive of septic arthritis.