Diagnostic value of 99mTc-ubiquicidin scintigraphy in differentiation between osteomyelitis and bone tumors

The differentiation of osteomyelitis from bone tumors is of great importance in clinical decision-making; however, the features of both osteomyelitis and bone tumors are noncontributory. Tc-ubiquicidin scintigraphy is a new promising method with the ability to specifically localize the infection site by bacterial cell membrane binding. This study aimed to evaluate the ability of this radiopeptide for the differentiation of these two entities.

Thirty consecutive patients (mean age=20.9 years) suspected of having either osteomyelitis or bone tumor were included in this prospective study. A Tc-UBI scan was performed in both dynamic and static phases and the images were assessed qualitatively and semiquantitatively. The final diagnosis was established for 29 patients on the basis of surgical findings and microbiological and pathology assessments as well as any other clinical, laboratory, or imaging findings during patient follow-up.

The final diagnosis was infectious and noninfectious processes in 19 and 10 patients, respectively. Visual assessment could not distinguish between osteomyelitis and bone tumors. However, the time-activity pattern of the images proved to be promising. The sensitivity, specificity, negative and positive predictive value, and accuracy of the time-activity curve for osteomyelitis were 73.6 (54-93), 100, 66.6 (43-91), 100, and 82%, respectively. The mean±SD tumor/nontumor (T/NT) ratios for 30 min images were 2.22±0.45 and 2.02±0.51 for infectious and noninfectious processes, respectively (P=0.29). Using a cutoff value of 0.97 for the T/NT ratio, the sensitivity and specificity were calculated to be 78.9 and 50%, respectively.

Although Tc-UBI scintigraphy in the dynamic imaging format was very useful with high accuracy in differentiating between infectious and tumoral lesions, it was not useful to distinguish these two entities on the basis of visual assessment or T/NT ratio measurement on static images. The study also showed the high accuracy of this noninvasive modality in acute osteomyelitis with low diagnostic value in chronic infectious processes.