Value of SPECT/CT in suspected prosthetic joint infection evaluated with 111 In-labeled leukocyte/99m Tc-sulfur colloid marrow imaging

Objectives To assess the incremental value of SPECT/CT relative to planar imaging with combined In-111 labeled leukocyte and Tc-99m sulfur colloid bone marrow imaging for diagnosing low-grade joint infections.

Methods 54 patients with painful lower extremity joint prostheses (33 knee,21 hip) who underwent combined In-111 labeled leukocyte and Tc-99m sulfur colloid bone marrow planar and SPECT/CT imaging. 47 patients had three phase bone scan within 1 to 2 days prior to the combined isotops imaging. Blinded retrospective review of the planar images alone and with SPECT/CT was performed. Re-operation was performed on 40 patients and definitive diagnosis of infection was based on history, physical findings, positive intraoperative culture or acute inflammation of the intraoperative frozen section. The diagnostic sensitivity, specificity, and accuracy of planar scintigraphy alone and in conjunction with SPECT/CT were assessed.

Results Prosthetic joint infections were diagnosed clinically in 11 of the 54 patients. The sensitivity of In-111 WBC/99mTc Sulfur colloid planar imaging alone is 81% with a specificity of 79% and an accuracy of 80% . When correlated with SPECT/CT, the sensitivity is 90%, specificity is 93% and accuracy 92%.

Conclusions Relative to planar scintigraphy, SPECT/CT substantially improved the sensitivity to detect occult infection of joint prostheses and improved the specificity of Indium -111 WBC/Tc99m Sulfur colloid planar imaging by differentiating inflammation/infection in adjacent soft tissue from prosthetic infection

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Results

Prevalence of prosthetic infection: 20% (11/54)