The diagnostic accuracy of 18F-FDG PET/CT in diagnosing fracture-related infections

Abstract

Purpose 18 F-Fluorodeoxyglucose positron emission tomography ( 18 F-FDG PET/CT) is frequently used to diagnose fracture-related infections (FRIs), but its diagnostic performance in this field is still unknown. The aims of this study were: (1) to assess the diagnostic performance of qualitative assessment of 18 F-FDG PET/CT scans in diagnosing FRI, (2) to establish the diagnostic performance of standardized uptake values (SUVs) extracted from 18 F-FDG PET/CT scans and to determine their associated optimal cut-off values, and (3) to identify variables that predict a false-positive (FP) or false-negative (FN) 18 F-FDG PET/CT result. Methods This retrospective cohort study included all patients with suspected FRI undergoing 18 F-FDG PET/CT between 2011 and 2017 in two level-1 trauma centres. Two nuclear medicine physicians independently reassessed all 18 F-FDG PET/CT scans. The reference standard consisted of the result of at least two deep, representative microbiological cultures or the presence/absence of clinical confirmatory signs of FRI (AO/EBJIS consensus definition) during a follow-up of at least 6 months. Diagnostic performance in terms of sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) was calculated. Additionally, SUVs were measured on 18 F-FDG PET/CT scans. Volumes of interest were drawn around the suspected and corresponding contralateral areas to obtain absolute values and ratios between suspected and contralateral areas. A multivariable logistic regression analysis was also performed to identify the most important predictor(s) of FP or FN 18 F-FDG PET/CT results. Results The study included 156 18 F-FDG PET/CT scans in 135 patients. Qualitative assessment of 18 F-FDG PET/CT scans showed a sensitivity of 0.89, specificity of 0.80, PPV of 0.74, NPV of 0.91 and diagnostic accuracy of 0.83. SUVs on their own resulted in lower diagnostic performance, but combining them with qualitative assessments yielded an AUC of 0.89 compared to an AUC of 0.84 when considering only the qualitative assessment results ( p = 0.007). 18 F-FDG PET/CT performed <1 month after surgery was found to be the independent variable with the highest predictive value for a false test result, with an absolute risk of 46% (95% CI 27–66%), compared with 7% (95% CI 4–12%) in patients with 18 F-FDG PET/CT performed 1–6 months after surgery. Conclusion Qualitative assessment of 18 F-FDG PET/CT scans had a diagnostic accuracy of 0.83 and an excellent NPV of 0.91 in diagnosing FRI. Adding SUV measurements to qual...

Diagnosing fracture-related infections: can we optimize our nuclear imaging techniques?

“…Infection was correctly detected on visual analysis of FDG PET/CT scans in 23 patients, whereas two patients showed no increased FDG uptake and the scans were considered false-negative (diagnostic accuracy 81%). These results are consistent with those of the previous study (diagnostic accuracy 83%) by Lemans et al [13]. The authors concluded that FDG PET/CT is a promising tool for the specific evaluation of infected nonunion [16].…”

“…WBC scintigraphy and FDG PET provide higher accuracy for diagnosing FRI. Recently, two studies in a large homogeneous patient group with suspected FRI have been published [12,13]. In the first study [12], WBC scintigraphy was performed (using the correct dual time point imaging with decay correction, and the correct interpretation criteria according to EANM protocols [14,15]) in 192 consecutive patients.…”

“…In the second retrospective cohort study, 156 FDG PET/CT scans were performed in 135 patients with suspected FRI [13]. Besides the visual analysis (uptake location, uptake pattern, and grade of uptake), semiquantitative evaluation was also performed by measuring standardized uptake values (SUVs) on EARL reconstruction scans.…”

The accuracy of diagnostic Imaging techniques in patients with a suspected Fracture-related Infection (IFI) trial: study protocol for a prospective multicenter cohort study.

“…Another recent publication from our group has shown that the sensitivity and specificity of WBC scintigraphy to diagnose FRI in a large retrospectively analysed patient cohort is 0.86 and 0.98, respectively 31. In two other recent retrospective studies on the accuracy of FDG-PET/CT sensitivities and specificities between 0.65 and 0.89 and 0.77 and 0.80 are reported, respectively 32 33. Based on these results we expect a difference of at least 15% in sensitivity and specificity between the WBC scintigraphy and the FDG-PET/CT.…”

Regional SUV quantification in hybrid PET/MR, a comparison of two atlas-based automatic brain segmentation methods

“…Because physiologic images are relatively low in spatial resolution, 3 computed tomography (CT) has been combined with PET for both anatomical location and attenuation correction. PET/CT scanning is widely applied in the evaluating of tumors, cardiac disease, CNS disorders, and infection/inflammation [1,2].…”