The aim of this retrospective study was to investigate the ability of 18 fluorine-fluorodeoxyglucose positron emission tomography/CT (¹⁸F-FDG-PET/CT) metrics and radiomics features (RFs) in predicting the final diagnosis of solitary pulmonary nodules (SPN). We retrospectively recruited 202 patients who underwent a ¹⁸F-FDG-PET/CT before any treatment in two PET scanners. After volumetric segmentation of each lung nodule, 8 PET metrics and 42 RFs were extracted. All the features were tested for significant differences between the two PET scanners. The performances of all features in predicting the nature of SPN were analyzed by testing three classes of final logistic regression predictive models: two were built/trained through exploiting the separate data from the two scanners, and the other joined the data together. One hundred and twenty-seven patients had a final diagnosis of malignancy, while 64 were of a benign nature. Comparing the two PET scanners, we found that all metabolic features and most of RFs were significantly different, despite the cross correlation being quite similar. For scanner 1, a combination between grey level co-occurrence matrix (GLCM), histogram, and grey-level zone length matrix (GLZLM) related features presented the best performances to predict the diagnosis; for scanner 2, it was GLCM and histogram-related features and metabolic tumour volume (MTV); and for scanner 1 + 2, it was histogram features, standardized uptake value (SUV) metrics, and MTV. RFs had a significant role in predicting the diagnosis of SPN, but their accuracies were directly related to the scanner.

The clinical and prognostic role of 2-deoxy-2-[¹⁸F]fluoro-D-glucose positron emission tomography/computed tomography (2-[¹⁸F]FDG PET/CT) in the study of patients affected by differentiated thyroid carcinoma (DTC) with positive serum thyroglobulin (Tg) level and negative [¹³¹I] whole-body scan ([¹³¹I]WBS) has already been demonstrated. However, the potential prognostic role of semi-quantitative PET metabolic volume features, such as metabolic tumor volume (MTV) and total lesion glycolysis (TLG), has not yet been clearly investigated. The aim of this retrospective study was to investigate whether the main metabolic PET/CT parameters may predict the prognosis. We retrospectively included 122 patients with a positive 2-[¹⁸F]FDG PET/CT for DTC disease after a negative [¹³¹I]WBS with Tg > 10 ng/mL. The maximum and mean standardized uptake value (SUVmax and SUVmean), MTV and TLG of the hypermetabolic lesion, total MTV (tMTV) and total TLG (tTLG) were measured for each scan. Progression-free survival (PFS) and overall survival (OS) curves were plotted according to the Kaplan–Meier analysis. After a median follow up of 53 months, relapse/progression of disease occurred in 87 patients and death in 42. The median PFS and OS were 19 months (range 1–132 months) and 46 months (range 1–145 months). tMTV and tTLG were the only independent prognostic factors for OS. No variables were significantly correlated with PFS. The best thresholds derived in our sample were 6.6 cm³ for MTV and 119.4 for TLG. In patients with negative WBS and Tg > 10 ng/mL, 2-[¹⁸F]FDG PET/CT metabolic volume parameters (tMTV and tTLG) may help to predict OS.

Background/Objectives: Extranodal NK-/T-cell lymphoma (ENKTCL) is a rare and highly aggressive lymphoma with a bad prognosis. The aim of our analysis is to evaluate existing research on the potential usefulness of fluorine-18-fluorodeoxyglucose positron emission tomography or positron/computed tomography (2-[18F]FDG PET or PET/CT) in the management of patients with ENKTCL. Methods: A complete search of the literature was conducted across Scopus, PubMed/MEDLINE, and Embase databases, focusing on articles published up to March 2025. Results: A total of 21 studies that investigated the role of 2-[18F]FDG PET or PET/CT in ENKTCL were included in our analysis. The main findings from the literature analysis were (1) 2-[18F]FDG PET/CT seems to be helpful in staging settings, showing a better diagnostic performance than conventional imaging and a positive impact on clinical stage; (2) 2-[18F]FDG PET/CT had excellent negative predictive value for detecting bone marrow involvement, especially in early-stage disease; and (3) qualitative and semiquantitative PET parameters might predict prognosis. Conclusions: Despite several limitations affecting this analysis, especially related to the heterogeneity of the studies included, 2-[18F]FDG PET/CT seems to be a useful tool for the evaluation of ENKTCL.

Differentiated thyroid carcinoma (DTC) is the most common malignant endocrine tumor, with a generally favorable prognosis. Imaging, including iodine radioactive isotope scintigraphy (IRIS), is crucial for diagnosis and follow-up. While ¹³¹I has long been used for both therapeutic and diagnostic purposes, ¹²³I is reserved for diagnostic imaging due to its shorter half-life and γ emissions. This review highlights the utility of ¹²³I scintigraphy, especially in pre-treatment assessment and dosimetry for DTC. It is particularly valuable before radioiodine (RAI) ablation, providing accurate imaging in patients with iodine-refractory (IR) or biochemically incomplete response (BIR) DTC. When compared to post-therapeutic ¹³¹I scans, ¹²³I scintigraphy appears to have a lower sensitivity for detecting metastatic lesions, particularly in lymph nodes and lungs. However, its diagnostic performance compared to low-dose diagnostic ¹³¹I is more variable, with some studies suggesting superiority due to the absence of stunning. Further research is needed to standardize its use and optimize its role in guiding DTC management.

Early diagnosis of endocarditis has an important prognostic value because a delay in antibiotic therapy and cardiac surgery may adversely affect clinical outcome. However, its diagnosis remains a challenging one.

The use of PET/CT hybrid imaging in ischemic heart disease, integrating information from PET and CT, has grown in the last decade, particularly because of its capacity of quantifying myocardial perfusion, allowing the assessment of myocardial blood flow (MBF) and myocardial flow reserve (MFR). This feature makes PET/CT the technique best suited to detect multivessel coronary artery disease which might not be identified with SPECT due to its inherent limitation in cases of balanced ischemia. Additionally, the CT component of these hybrid imaging systems allows calculation of coronary artery calcium score (ChACS) and the visualization of the epicardial coronary arteries with coronary CT angiography (CCTA). PET/CT has therefore a great potential in the diagnosis and management of CAD. This chapter will cover several clinical cases, illustrating many different clinical applications in ischemic heart disease.