Combined use of bone and bone marrow scintigraphies for the diagnosis of active sacroiliitis: A new approach

Diagnosis of sacroiliitis (SI) with hone scintigraphy may involve difficult ies even with a quantitative approach. The aim of this study was to evaluat e the combined use of bent: and bone marrow scintigraphies for the diagnosi s of active sacroiliitis. Thirty-one patients who were clinically suspected to have SI were included in the study. Bone and bone marrow scintigraphies were done after injection s of 740 MBq of Tc-99m-MDP (MDP) and 370 MBq of Tc-99m-sulfur colloid (SC) respectively with a 2-day interval. Both visual and quantitative assessment of MDP uptake and visual assessment of SC uptake in sacroiliac joints were performed. Also sacroiliac joint radiographic findings for each patient we re evaluated and graded from 0 to 4 according to the New York grading syste m. Patients were divided into 2 groups according to their x-ray findings (G roup A: grade 0-2, Group B: grade 3-4). A total of 14 patients(10 bilateral, 4 unilateral) had increased MDP uptake with decreased/normal SC uptake. Twelve of 14 patients hail grade 0-2 radi ographic changes while only 2 patients had grade 3-4 radiographic changes. Increased MDP uptake with decreased/normal SC uptake is the most common sci ntigraphic pattern seen in acute phase SI in which radiographic findings ar e generally found to be normal or slightly changed. In at least in 8 patien ts the decreased bone marrow uptake of SC was demonstrated, supporting the diagnosis. Although our results did not reveal any significant superiority of bone mar row scintigraphy to bone scan for the detection of active sacroiliitis, com bined use of hone and bone marrow scintigraphies was presented as an altern ative method to characterize patients with active sacroiliitis.