What is the Accuracy of Nuclear Imaging in the Assessment of Periprosthetic Knee Infection? A Meta-analysis

Abstract

BackgroundIn the assessment of possible periprosthetic knee infection, various imaging modalities are used without consensus regarding the most accurate technique.Questions/PurposesTo perform a meta-analysis to compare the accuracy of various applied imaging modalities in the assessment of periprosthetic knee infection.MethodsA systematic review and meta-analysis was conducted with a comprehensive search of MEDLINE and Embase® in accordance with the PRISMA and Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) recommendations to identify clinical studies in which periprosthetic knee infection was investigated with different imaging modalities. The sensitivity and specificity of each imaging technique were determined and compared with the results of microbiologic and histologic analyses, intraoperative findings, and clinical followup of more than 6 months. A total of 23 studies, published between 1990 and 2015, were included for meta-analysis, representing 1027 diagnostic images of symptomatic knee prostheses. Quality of the included studies showed low concerns regarding external validity, whereas internal validity indicated more concerns regarding the risk of bias. The most important concerns were found in the lack of uniform criteria for the diagnosis of a periprosthetic infection and the flow and timing of the included studies. Differences among techniques were tested at a probability less than 0.05 level. Where there was slight overlap of confidence intervals for two means, it is possible for the point estimates to be statistically different from one another at a probability less than 0.05. The z-test was used to statistically analyze differences in these situations.ResultsBone scintigraphy was less specific than all other modalities tested (56%; 95% CI, 0.47–0.64; p < 0.001), and leukocyte scintigraphy (77%; 95% CI, 0.69–0.85) was less specific than antigranulocyte scintigraphy (95%; 95% CI, 0.88–0.98; p < 0.001) or combined leukocyte and bone marrow scintigraphy (93%; 95% CI, 0.86–0.97; p < 0.001). Fluorodeoxyglucose positron emission tomography (FDG-PET) (84%; 95% CI, 0.76–0.90) was more specific than bone scintigraphy (56%; 95% CI, 0.47–0.64; p < 0.001), and less specific than antigranulocyte scintigraphy (95%; 95% CI, 0.88–0.98; p = 0.02) and combined leukocyte and bone marrow scintigraphy (93%; 95% CI, 0.86–0.97; p < 0.001). Leukocyte scintigraphy (88%; 95% CI, 0.81–0.93; p = 0.01) and antigranulocyte scintigraphy (90%; 95% CI, 0.78–0.96; p = 0.02) were more sensitive than FGD-PET (70%; 95% CI, 0.56–0.81). However, because of broad overlapping of confidence intervals, no differences in sensitivity were observed among the other modalities, including combined bone scintigraphy (93%; 95% CI, 0.85–0.98) or combined leukocyte and bone marrow scintigraphy (80%; 95% CI, 0.66–0.91; p > 0.05 for all paired comparisons).ConclusionsBased on current evidence, antigranulocyte scintigraphy and combined leukocyte and bone marrow scintigraphy appear to be highly specific imaging modalities in confirming peripr...

18F-FDG PET for Diagnosing Infections in Prosthetic Joints

“…Bone scintigraphy with technetium Tc 99m ( 99m Tc)labeled diphosphonates or, alternatively, sodium fluoride F 18 PET 20 can be used to assess osteoblastic activity around the prosthesis. Because sensitivity is high, 21,22 normal findings can be considered strong evidence against the presence of PJI. 23 Specificity, however, generally is low 21,22 ; positive findings can indicate either PJI or aseptic loosening.…”

“…Because sensitivity is high, 21,22 normal findings can be considered strong evidence against the presence of PJI. 23 Specificity, however, generally is low 21,22 ; positive findings can indicate either PJI or aseptic loosening. Moreover, a bone scan may be positive for at least 2 years after hip replacement and at least 5 years after knee replacement due to physiologic bone remodeling.…”

“…Labeled leukocyte imaging has shown superior accuracy for diagnosing PJI compared with bone scintigraphy. 21,22 A caveat, however, is the normal physiologic accumulation of white blood cells in the bone marrow, which may be variable from 1 person to another. 23 Furthermore, hematopoietically active marrow usually develops around joint prostheses, producing an alteration of the normal bone marrow distribution.…”

“…The diagnostic performance of 18 F-FDG PET in detecting PJI in hip and knee replacements seems sufficiently high for routine clinical application and has not proved inferior to labeled leukocyte scintigraphy. 21,22,25,27 A meta-analysis reported a pooled sensitivity of 86% (95% CI, 80% to 90%) and a pooled specificity of 93% (95% CI, 90% to 95%) for hip prostheses. 22 Another meta-analysis reported a pooled sensitivity of 70% (95% CI, 56% to 81%) and a pooled specificity of 84% (95% CI, 76% to 90%) for knee prostheses.…”

“…22 Another meta-analysis reported a pooled sensitivity of 70% (95% CI, 56% to 81%) and a pooled specificity of 84% (95% CI, 76% to 90%) for knee prostheses. 21 In addition, 18 F-FDG PET has shown useful in patients with nonspecific clinical presentation (ie, without apparent clinical signs and symptoms, such as absence of a sinus tract). 32,33 Furthermore, it has additional value to conventional tests (including radiography, erythrocyte sedimentation rate [ESR]/C-reactive protein [CRP] testing, and joint aspiration culture and white blood cell count) in diagnosing PJI (ie, it increases accuracy).…”