Comparative Analysis of Tc-99m-MDP Three-phase Bone Scan with SPECT/CT and Tc-99m-HMPAO-Labeled WBC SPECT/CT in the Differential Diagnosis of Clinical Post-traumatic Osteomyelitis

Abstract

Purpose

To identify differences between three-phase bone scan and SPECT/CT (TBS) and WBC SPECT/CT (WS) and compare diagnostic accuracies of each modality in patients with clinical post-traumatic osteomyelitis (OM).

Materials and Method

Twenty-one patients with suspicious post-traumatic OM were enrolled. All patients performed TBS and WS within one week. Foci of MDP and WBC accumulation were divided into three categories: bone (OM), soft tissue (soft tissue inflammation; STI), negative for inflammation (NI). Confirmative diagnosis was made upon operative pathology or long-term clinical follow-up. Results

Of 21 patients, 4 OM, 8 STI, 9 NI were finally diagnosed. TBS diagnosis was correct in 3 of 4 positive cases and 9 of 17 negative cases. Sensitivity, specificity, accuracy, positive predictive value (PPV), negative predictive value (NPV) of TBS were 75%, 52.9%, 57.1%, 27.3%, 90%. WS diagnosis was correct in 2 of 4 positive cases and 17 of 17 negative cases. Sensitivity, specificity, accuracy, PPV, NPV were 50%, 100%, 81.0%, 100%, 89.5%. Twelve of 21 cases showed agreement between TBS and WS. TBS misdiagnosed 9 cases (6 STI and 2 NI as 8 OM; 1 OM as 1 STI), while WS misdiagnosed 4 cases (2 OM as 2 STI; 2 STI as 2 NI). Combining results from TBS and WS led to better diagnostic accuracy (91.7%) than either TBS or WS alone.

Conclusion

TBS and WS showed moderate agreement in assessment of clinically suspected post-traumatic OM. WS better evaluated bone inflammation than TBS. WS tended to underestimate inflammation whereas TBS tended to overestimate inflammation. Combining TBS and WS enhanced diagnostic accuracy.