ABSTRACT
Nuclear Medicine multimodality imaging, such as positron emission tomography/computed tomography PET/CT, refers to metabolic tissue characteristics integrated with anatomical details. Fluorine-18-fluorodeoxyglucose (18F-FDG) is the most diffuse radiopharmaceutical and its application is spreading beyond the area of oncology. The causes of high 18F-FDG uptake that were once considered false positives have been identified and the new knowledge about them led to non-cancerous pathologies that can be studied by 18F-FDG PET/CT. This technique, due to the inflammatory cells high avidity of 18F-FDG, can be useful in studying a variety of inflammatory and infectious systemic conditions. Studies performed in patients with fever of unknown origin (FUO) indicate that 18F-FDG PET/CT offer a great advantage of detecting malignancy, inflammation and infection at the same time both in adults and children. Furthermore, the 18F-FDG PET/CT has proved useful in the study of specific organs such as the heart and brain that represent separate topics also for the development of new specific radiopharmaceuticals. In all the non-oncologic conditions 18F-FDG PET/CT imaging may offer an "all-in-one" procedure, thanks also to its panoramic whole-body acquisition, as an alternative to other diagnostic procedures, reducing the number of unnecessary investigations. The 18F-FDG PET/CT finding of the simultaneous presence of radiopharmaceutical uptake for multiple disease interconnect to different medical disciplines. It is important to describe unexpected occasional typical or atypical PET/CT findings to the growth of scientific and medical community; it can be the starting point to the enlargement of PET/CT indications for a better and wider comprehension of the human system. To recognize unexpected occasional findings is very important a well knowledge of many aspects: physiological biodistribution, diagnostic imaging instrumentations and techniques, pathological aspects of the different neoplastic diseases, patient story, such as previous therapy, and its comorbidity. An unexpected occasional finding can lead to suggest further tests or investigations in order to have a wider comprehension of patients' clinical situation and they are easily explainable when we have a physician's approach towards patient.
Subject(s)
Disease , Positron Emission Tomography Computed Tomography , HumansABSTRACT
Background: Infection of Cardiac Implantable Electronic Devices (CIEDI) is a real public health problem. The main aim of this study was to determine the diagnostic performance of 18F-FDG PET/CT in the diagnosis of CIEDI. Methods: A total of 48 patients, who performed 18F-FDG PET/CT for the clinical suspicion of CIEDI were retrospectively analyzed; all patients were provided with a model with procedural recommendations before the exam. Sensitivity (Se), specificity (Sp), positive predictive value (PPV), negative predictive value (NPV) and diagnostic accuracy (DA) of 18F-FDG PET/CT were calculated; the reproducibility of qualitative analysis was assessed with Cohen's κ test. The semi-quantitative parameters (SUVmax, SQR and TBR) were evaluated in CIEDI+ and CIEDI- patients using the Student' t-test; ROC curves were elaborated to detect cut-off values. The trend of image quality with regards to procedural recommendation adherence was evaluated. Results: Se, Sp, PPV, NPV and DA were respectively 96.2%, 81.8%, 86.2%, 94.7% and 89.6%. The reproducibility of qualitative analysis was excellent (K = 0.89). Semiquantitative parameters resulted statistically different in CIEDI+ and CIEDI- patients. Cut-off values were SUVmax = 2.625, SQR = 3.766 and TBR = 1.29. Trend curves showed increasing image quality due to adherence to procedural recommendations. Conclusions:18F-FDG-PET/CT is a valid tool in the management of patients suspected of CIEDI and adherence to procedural recommendations improves its image quality.
ABSTRACT
Differentiated thyroid cancer (DTC) represents the most common thyroid cancer histotype. Generally, it exhibits a good prognosis after conventional treatments; nevertheless, about 20% of patients can develop a local recurrence and/or distant metastasis. In one-third of advanced DTC, the metastatic lesions lose the ability to take up iodine and become radioactive iodine-refractory (RAI-R) DTC. In this set of patients, the possibility to perform localized treatments should always be taken into consideration before the initiation of systemic therapy. In the last decade, some multi-tyrosine kinase inhibitor (MKI) drugs were approved for advanced DTC, impacting on patient's survival rate, but at the same time, these therapies have been associated with several adverse events. In this clinical context, the role of 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography/computed tomography ([18F]FDG PET/CT) in the early treatment response to these innovative therapies was investigated, in order to assess the potentiality of this diagnostic tool in the early recognition of non-responders, avoiding unnecessary therapy. Herein, we aimed to present a critical overview about the reliability of [18F]FDG PET/CT in the early predictive response to MKIs in advanced differentiated thyroid cancer.
ABSTRACT
The presence of a cardiovascular implantable electronic device (CIED) can be burdened by complications such as late infections that are associated with significant morbidity and mortality and require immediate and effective treatment. The aim of this study was to evaluate the role of 18F-fluorodeoxyglucose positron-emission tomography/computed tomography (18F-FDG PET/CT) in patients with suspected CIED infection. Fifteen patients who performed a 18F-FDG PET/CT for suspicion of CIED infection were retrospectively analyzed; 15 patients, with CIED, that underwent 18F-FDG PET/CT for oncological reasons, were also evaluated. Visual qualitative analysis and semi-quantitative analysis were performed. All patients underwent standard clinical management regardless 18F-FDG PET/CT results. Sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) resulted as 90.91%, 75%, 86.67%, 90.91% and 75% respectively. Maximum standardized uptake values (SUVmax) and semi-quantitative ratio (SQR) were collected and showed differences statistically significant between CIED infected patients and those who were not. Exploratory cut-off values were derived from receiver operating characteristic (ROC) curves for SUVmax (2.56) and SQR (4.15). This study suggests the clinical usefulness of 18F-FDG PET/CT in patients with CIED infection due to its high sensitivity, repeatability and non-invasiveness. It can help the clinicians in decision making, especially in patients with doubtful clinical presentation. Future large-scale and multicentric studies should be conducted to establish precise protocols about 18F-FDG PET/CT performance.