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Infectious diseases represent one of the most common causes of hospital admission worldwide. The diagnostic work-up requires a complex clinical approach, including laboratory data, CT and MRI, other imaging tools, and microbiologic cultures. PET/CT with 18F-FDG can support the clinical diagnosis, allowing visualization of increased glucose metabolism in activated macrophages and monocytes; this tracer presents limits in differentiating between aseptic inflammation and infection. Novel PET radiopharmaceuticals have been developed to overcome these limits; 11C/18F-labeled bacterial agents, several 68Ga-labeled molecules, and white blood cells labeled with 18F-FDG are emerging PET tracers under study, showing interesting preliminary results. The best choice among these tracers can be unclear. This overview aims to discuss the most common diagnostic applications of 18F-FDG PET/CT in infectious diseases and, as a counterpoint, to describe and debate the advantages and peculiarities of the latest PET radiopharmaceuticals in the field of infectious diseases, which will probably improve the diagnosis and prognostic stratification of patients with active infectious diseases. [ABSTRACT FROM AUTHOR]

Background. As artificial intelligence is expanding its applications in medicine, metabolic imaging is gaining the ability to retrieve data otherwise missed by even an experienced naked eye. Also, new radiopharmaceuticals and peptides aim to increase the specificity of positron emission tomography (PET) scans. Herein, a preliminary experience is reported regarding searching for a texture signature in routinely performed [F18]Fluciclovine imaging in prostate cancer. Materials and methods. Twenty-nine patients who underwent a PET/computed tomography (CT) scan with [18F]Fluciclovine because of biochemical prostate cancer relapse were retrospectively enrolled. First- and second-order radiomic features were manually extracted in lesions visually considered pathologic from the Local Image Features Extraction (LIFEx) platform. Statistical analysis was performed on a database of 29 lesions, one1 per patient. The dataset was split to have 20 lesions for the model training set and 9 lesions for the validation set. The Wilcoxon–Mann–Whitney test was used on the training set to select the most significant features (p-value < 0.05) predicting the dichotomous outcome in a univariate analysis. Results. The best model for predicting the outcome was found to be a multiple logistic linear regression model with two features as variables: an intensity histogram type and a gray-level size zone-based type. Conclusions. Texture analysis of [F18]Fluciclovine PET scans helps in defining prostate cancer relapse in a daily clinical setting. [ABSTRACT FROM AUTHOR]

Objective: Numerous studies have shown that gallium-68-labeled fibroblast activation protein inhibitor ( 68 Ga-FAPI) positron emission tomography/computed tomography (PET/CT) scans would yield high intra-tumoral tracer uptake and low uptake in normal tissues as background, thus allowing for excellent visualization of lesions in the cancer microenvironment. This study set out to compare the suitability of novel 68 Ga-FAPI-46 PET versus routine fluorine-18-fluorodeoxyglucose ( 18 F-FDG) PET and other few cases of 68 Ga-DOTATATE/ 68 Ga-Pentixafor PET/CT for the assessment of different types of cancer., Subjects and Methods: A retrospective analysis of 11 patients (6 males, 5 females; average age: 53 years, range: 10-58 years) with histopathologically confirmed, well-differentiated adenocarcinoma, medullar thyroid cancer (MTC), papillary thyroid carcinoma (PTC), cervical, gastric, glioblastoma multiform (GBM), colon, Ewing's sarcoma, and breast cancer was performed. These patients underwent PET/CT scans using four different radiotracers (9 18 F-FDG, 11 68 Ga- FAPI, 3 68 Ga-DOTATATE, and 1 68 Ga-Pentixafor). The patients' PET/CT images were visually evaluated for cancer detection, and analyzed semi-quantitatively through image- derived metrics, such as target-to-background ratio (TBR) and maximum standardized uptake value (SUVmax), for recurrence and metastasis., Results: The study of 11 patients revealed that 68 Ga-FAPI-46 was more effective than other tracers for detecting metastases, with 55 vs. 49 metastases in the lymph nodes, 4 vs. 3 in the liver, and 4 vs. 3 in the bones detected in comparison to 18 F-FDG. No significant differences were observed in 68 Ga-DOTATATE and 68 Ga-Pentixafor PET images. In addition, in five patients, the SUVmax and TBR values in 68 Ga-FAPI-46 PET images were significantly higher than those in 18 F-FDG PET images for lymph nodes and bone metastases. Although the SUVmax in 68 Ga-FAPI-46 and 18 F-FDG PET images for liver metastases was comparable, 68 Ga-FAPI- 46 had a significantly higher TBR than 18 F-FDG., Conclusion: Our findings suggest that FAPI PET/CT is not suitable for evaluating GBM and Ewing sarcoma but generally outperforms 18 F-FDG PET/CT in various types of breast cancer, gastrointestinal, gynecological, PTC and MTC. However, larger trials are needed to validate these preliminary findings.