The value of SPECT/CT in carpal boss.

PURPOSE

To assess the value of SPECT/CT in patients with carpal boss (CB).

METHODS

In 24 wrists with CB (18 right-sided, 6 left-sided) in 21 patients, planar images and SPECT/CT images were obtained. Three patients had bilateral CB. The grade of uptake (0 absent, 1 low, 2 moderate, 3 high) on planar imaging and SPECT/CT was assessed and compared with CT findings, clinical symptoms and follow-up findings.

RESULTS

CB affected carpometacarpal joint II in 4 wrists, carpometacarpal joint III in 17 wrists and both carpometacarpal joints II and III in 3 wrists. Of the 24 CB, 12 (50 %) were active (i.e. increased radionuclide uptake) on planar images and 18 (75 %) on SPECT/CT images. Of the 17 symptomatic CB, 10 (59 %) were active on planar images and 14 (82 %) were active (mean grade 1.9, range 1 - 3) on SPECT/CT images. Of the 7 asymptomatic CB, 2 were active on planar images and 4 were active (mean grade 1.25, range 1 - 2) on SPECT/CT images. CT alone showed CB in all patients and an accessory ossicle (os styloideum) in 8 wrists. MR imaging was available in 7 patients and positive for CB in 5 (sensitivity 71 %). Plain radiographs were available in 17 patients and positive in 10 (59 %). Therapeutic infiltration of the CB was performed in 9 patients, and resection of the CB in 7 patients.

CONCLUSION

SPECT/CT provides important morphological and metabolic information for the clinical assessment of CB, but because SPECT/CT tends to overestimate the clinical importance of CB, we recommend that planar images should still be obtained.