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Positron emission tomography (PET) using O-(2-[18F]fluoroethyl)-L-tyrosine (18F-FET) PET has been shown to be a useful tool for differentiating radiation therapy outcomes, such as brain metastasis recurrence or radiation necrosis. We present the case of a female patient with brain metastases from pulmonary mucinous adenocarcinoma with suspicion of tumor recurrence on follow-up magnetic resonance imaging (MRI) after radiosurgery. 18F-FET PET/computed tomography (CT) was indicative of radiation necrosis. Due to the patient's medical history and the discrepancy between the brain MRI and PET/CT results, surgical biopsies were decided, which were positive for brain metastasis recurrence. The diagnosis of metastasis recurrence may also be challenging on 18F-FET PET/CT. In case of discrepancies between MRI and PET/CT results, false-negative 18F-FET PET/CT remains a possibility and requires careful follow-up or biopsy.

Objectives To assess the interobserver reliability (IOR) of the Tile classification system, and its potential influence on outcomes, for the interpretation of CT images of pelvic fractures by radiologists and surgeons. Methods Retrospective data (1/2008–12/2016) from 238 patients with pelvic fractures were analyzed. Mean patient age was 44 years (SD 20); 66% were male. There were 54 Tile A, 82 Tile B, and 102 Tile C type injuries. The 30-day mortality rate was 15% (36/238). Six observers, three radiologists, and three surgeons with different levels of experience (attending/resident/intern) classified each fracture into one of the 26 second-order subcategories of the Tile classification. Weighted kappa coefficients were used to assess the IORs for the three main categories and nine first-order subcategories. Results The overall IORs of the Tile system for the main categories and first-order subcategories were moderate (kappa = 0.44) and fair (kappa = 0.31), respectively. IOR was fair to moderate among radiologists, but only fair among surgeons. By level of training, IOR was moderate between attendings and between residents, whereas it was only fair between interns. IOR was moderate to substantial (kappa = 0.56–0.70) between the radiology attending and resident. Association of the Tile fracture type with 30-day mortality was present based on two out of six observer ratings. Conclusions The overall IOR of the Tile classification system is only fair to moderate, increases with the level of rater experience and is better among radiologists than surgeons. In the light of these findings, results from studies using this classification system must be interpreted cautiously. Key Points • The overall interobserver reliability of the Tile pelvic fracture classification is only fair to moderate. • Interobserver reliability increases with observer experience and radiologists have higher kappa coefficients than surgeons. • Interobserver reliability has an impact on the association of the Tile classification system with mortality in two out of six cases.

Background: Diagnostic performance of positron emission tomography using white blood cells labeled with fluorine-18-fluorodeoxyglucose (18F-FDG-WBC PET or PET/CT) in patients with suspicious infectious diseases has been evaluated in several studies; however, there is no consensus about the diagnostic accuracy of this method. Therefore, a systematic review and meta-analysis was carried out on this topic. Methods: A comprehensive computer literature search screening PubMed/MEDLINE, Embase and Cochrane library databases through March 2019 was performed. Pooled sensitivity, specificity, positive and negative likelihood ratios (LR+ and LR−), and diagnostic odds ratio (DOR) of 18F-FDG-WBC PET or PET/CT in patients with infectious diseases were calculated. Results: Eight studies on the use of 18F-FDG-WBC PET or PET/CT in suspicious infectious diseases were discussed in the systematic review. The meta-analysis of seven studies (236 patients) provided these pooled results on a per patient-based analysis: sensitivity was 86.3% [95% confidence interval (95%CI) 75−92.9%], specificity 92% (95%CI 79.8−97.1%), LR+ 6.6 (95%CI: 3.1−14.1), LR− 0.2 (95%CI: 0.12−0.33), DOR 43.5 (95%CI: 12.2−155). A statistically significant heterogeneity was not detected. Conclusions: Despite limited literature data, 18F-FDG-WBC PET or PET/CT demonstrated a good diagnostic accuracy for the diagnosis of infectious diseases; nevertheless, larger studies are needed.