Comparison between 3-phase bone scan and MRI in diagnosis of osteomyelitis

Objectives To evaluate the diagnostic value of 3-phase bone scan and MRI for diagnosis of osteomyelitis.

Methods We retrospectively reviewed the clinical records of patients with both 3-phase bone scan and MRI from June 1, 2007 to January 1, 2010, performed under clinical suspicion of cellulitis or osteomyelitis. The final diagnosis was confirmed by excisional biopsy or culture, or clinical response to antibiotics.

Results 35 patients (21 men 14 women; age, 48±17 y) were included in this study. The mean interval of 3-phase bone scan and MRI was 3±5 days. Suspected lesions were lower legs in 28 cases, thighs in 5 cases and back in 2 cases. Cellulitis was concluded in 25 patients, osteomyelitis in 6 patients and one case each of Charcot joint, bursitis, post-traumatic arthritis and rhabdomyosarcoma. 3-phase bone scan showed sensitivity of 83% (5/6), specificity of 93% (27/29), positive predictive value of 71% (5/7) and negative predictive value of 96% (18/27) in diagnosis of osteomyelitis. MR imaging showed sensitivity of 83% (5/6), specificity of 93% (27/29), positive predictive value of 71% (5/7) and negative predictive value of 89% (24/27) in diagnosis of osteomyelitis. Of the 6 patients confirmed as osteomyelitis, 4 had true positive findings in both 3-phase bone scan and MI, and 1 case had false negative finding in MIR, and another case had false negative finding in3-phase bone scan.

Conclusions 3-phase bone scan and MR imaging showed similar sensitivity and complementary roles in diagnosis of osteomyelitis