PT - JOURNAL ARTICLE AU - Charito Love AU - Scott E. Marwin AU - Maria B. Tomas AU - Eugene S. Krauss AU - Gene G. Tronco AU - Kuldeep K. Bhargava AU - Kenneth J. Nichols AU - Christopher J. Palestro TI - Diagnosing Infection in the Failed Joint Replacement: A Comparison of Coincidence Detection <sup>18</sup>F-FDG and <sup>111</sup>In-Labeled Leukocyte/<sup>99m</sup>Tc-Sulfur Colloid Marrow Imaging DP - 2004 Nov 01 TA - Journal of Nuclear Medicine PG - 1864--1871 VI - 45 IP - 11 4099 - http://jnm.snmjournals.org/content/45/11/1864.short 4100 - http://jnm.snmjournals.org/content/45/11/1864.full SO - J Nucl Med2004 Nov 01; 45 AB - The objectives of this study were to investigate 18F-FDG imaging, using a coincidence detection system, for diagnosing prosthetic joint infection and to compare it with combined 111In-labeled leukocyte/99mTc-sulfur colloid marrow imaging in patients with failed lower extremity joint replacements. Methods: Fifty-nine patients—with painful, failed, lower extremity joint prostheses, 40 hip and 19 knee—who underwent 18F-FDG, labeled leukocyte, and bone marrow imaging, and had histopathologic and microbiologic confirmation of the final diagnosis, formed the basis of this investigation. 18F-FDG images were interpreted as positive for infection using 4 different criteria: criterion 1: any periprosthetic activity, regardless of location or intensity; criterion 2: periprosthetic activity on the 18F-FDG image, without corresponding activity on the marrow image; criterion 3: only bone–prosthesis interface activity, regardless of intensity; criterion 4: semiquantitative analysis—a lesion-to-background ratio was generated, and the cutoff value yielding the highest accuracy for determining the presence of infection was determined. Labeled leukocyte/marrow images were interpreted as positive for infection when periprosthetic activity was present on the labeled leukocyte image without corresponding activity on the marrow image. Results: Twenty-five (42%) prostheses, 14 hip and 11 knee, were infected. The sensitivity, specificity, and accuracy of 18F-FDG, by criterion, were as follows: criterion 1: 100%, 9%, 47%; criterion 2: 96%, 35%, 61%; criterion 3: 52%, 44%, 47%; criterion 4: 36%, 97%, 71%. The sensitivity, specificity, and accuracy of labeled leukocyte/marrow imaging were 100%, 91%, and 95%, respectively. WBC/marrow imaging, which was more accurate than any of the 18F-FDG criteria for all prostheses, as well as for hips and knees separately, was significantly more sensitive than criterion 3 (P &lt; 0.001) and criterion 4 (P &lt; 0.001) and was significantly more specific than criterion 1 (P &lt; 0.001), criterion 2 (P &lt; 0.001), and criterion 3 (P &lt; 0.001). Conclusion: Regardless of how the images are interpreted, coincidence detection–based 18F-FDG imaging is less accurate than, and cannot replace, labeled leukocyte/marrow imaging for diagnosing infection of the failed prosthetic joint.