Diagnostic Performances of PET/CT Using Fibroblast Activation Protein Inhibitors in Patients with Primary and Metastatic Liver Tumors: A Comprehensive Literature Review.

PET/CT using radiolabeled fibroblast activation protein inhibitors (FAPIs) is a promising diagnostic tool in oncology, especially when non-increased and/or physiologically high [18F]FDG uptake (as in liver parenchyma) is observed. We aimed to review the role of PET/CT using radiolabeled FAPIs in primary and/or metastatic liver lesions, and to compare their performances with more "conventional" radiopharmaceuticals. A search algorithm based on the terms "FAPI" AND ("hepatic" OR "liver") was applied, with the last update on 1st January 2024. Out of 177 articles retrieved, 76 studies reporting on the diagnostic application of radiolabeled FAPI PET/CT in at least one patient harboring primary or metastatic liver lesion(s) were fully analyzed. Although there was some heterogeneity in clinical conditions and/or study methodology, PET/CT with radiolabeled FAPIs showed an excellent performance in common primary liver malignancies (hepatocarcinoma, intrahepatic cholangiocarcinoma) and liver metastases (mostly from the gastrointestinal tract and lungs). A higher tumor-to-background ratio for FAPIs than for [18F]FDG was found in primary and metastatic liver lesions, due to lower background activity. Despite limited clinical evidence, radiolabeled FAPIs may be used to assess the suitability and effectiveness of FAPI-derived therapeutic agents such as [177Lu]Lu-FAPI. However, future prospective research on a wider population is needed to confirm the excellent performance.

The Role of PET Imaging in Patients with Prion Disease: A Literature Review.

Prion diseases are rare, rapidly progressive, and fatal incurable degenerative brain disorders caused by the misfolding of a normal protein called PrPC into an abnormal protein called PrPSc. Their highly variable clinical presentation mimics various degenerative and non-degenerative brain disorders, making diagnosis a significant challenge for neurologists. Currently, definitive diagnosis relies on post-mortem examination of nervous tissue to detect the pathogenic prion protein. The current diagnostic criteria are limited. While structural magnetic resonance imaging (MRI) remains the gold standard imaging modality for Creutzfeldt-Jakob disease (CJD) diagnosis, positron emission tomography (PET) using 18fluorine-fluorodeoxyglucose (18F-FDG) and other radiotracers have demonstrated promising potential in the diagnostic assessment of prion disease. In this context, a comprehensive and updated review exclusively focused on PET imaging in prion diseases is still lacking. We review the current value of PET imaging with 18F-FDG and non-FDG tracers in the diagnostic management of prion diseases. From the collected data, 18F-FDG PET mainly reveals cortical and subcortical hypometabolic areas in prion disease, although fails to identify typical pattern or laterality abnormalities to differentiate between genetic and sporadic prion diseases. Although the rarity of prion diseases limits the establishment of a definitive hypometabolism pattern, this review reveals some more prevalent 18F-FDG patterns associated with each disease subtype. Interestingly, in both sporadic and genetic prion diseases, the hippocampus does not show significant glucose metabolism alterations, appearing as a useful sign in the differential diagnosis with other neurodegenerative disease. In genetic prion disease forms, PET abnormality precedes clinical manifestation. Discordant diagnostic value for amyloid tracers among different prion disease subtypes was observed, needing further investigation. PET has emerged as a potential valuable tool in the diagnostic armamentarium for CJD. Its ability to visualize functional and metabolic brain changes provides complementary information to structural MRI, aiding in the early detection and confirmation of CJD.

3-Methoxy-Phencyclidine Induced Psychotic Disorder: A Literature Review and an 18F-FDG PET/CT Case Report.

New Psychoactive Substances (NPS) are modifying the drug scenario worldwide and have become a public health concern because of their toxicological profiles and their harmful physical/psychological effects. 3-Methoxy-Phencyclidine (3-MeO-PCP), a non-competitive antagonist of glutamate N-methyl-D-aspartate (NMDA) receptors, belongs to the phencyclidine-like subfamily of arylcyclohexylamines and has gained attention for its toxic, sometimes fatal, effects. Despite several cases of intoxication and death reported in the literature, little is known about substance-induced psychotic disorders (SIP) and potential cognitive impairment following 3-MeO-PCP intake. This literature review aimed to summarize available evidence about 3-MeO-PCP mechanisms of action and physical and psychotropic effects and to spread preliminary findings about persistent psychotic symptoms and impaired cognitive functioning. Additionally, the case of an SIP is reported in a 29-year-old man with small oral intakes of 3-MeO-PCP over two weeks until a high dose ingestion. Psychometric and neuropsychological assessment and brain [18F]-fluorodeoxyglucose positron emission tomography integrated with computed tomography were used to support clinical description. Identifying and addressing the characteristic clinical features and neural substrates of NPS-induced psychoses might help clinicians with a more precise differentiation from other psychotic disorders. Although further studies are required, phenotyping the cognitive profile of NPS users might provide targets for tailored therapeutic approaches.