Proliferation imaging with 11C-4DST PET/CT for the evaluation of cardiac sarcoidosis, compared with FDG-PET/CT given a long fasting preparation protocol

Various Aspects of Fasting on the Biodistribution of Radiopharmaceuticals

It is demonstrated that fasting can alter the biodistribution of radiopharmaceuticals in nuclear medicine. Various studies have highlighted that fasting is interpreted to be easy for physicians during PET study, fasting is one of the most important factors determining the usefulness of this protocol. It is well documented that fasting can suppress normal ¹⁸F-FDG PET uptake during nuclear cardiology. However, there is no consensus about the usefulness of fasting on radiopharmaceuticals, especially on ¹⁸F-FDG in PET imaging, but special attention should be paid to the setting of the fasting duration. Nevertheless, it does seem we still need extensive clinical studies in the future. The present study aims to review the various aspects of fasting, especially metabolic alteration on radiopharmaceutical biodistribution. In this study, we focused more on the effect of fasting on ¹⁸F-FDG biodistribution, which alters its imaging contrast in cardiology and cancer imaging. Therefore, shifting substrate metabolism from glucose to free fatty acids during fasting can be an alternative approach to suppress physiological myocardial uptake.

PET Imaging in Cardiac Sarcoidosis: A Narrative Review with Focus on Novel PET Tracers

Sarcoidosis is a multi-system inflammatory disease characterized by the development of inflammation and noncaseating granulomas that can involve nearly every organ system, with a predilection for the pulmonary system. Cardiac involvement of sarcoidosis (CS) occurs in up to 70% of cases, and accounts for a significant share of sarcoid-related mortality. The clinical presentation of CS can range from absence of symptoms to conduction abnormalities, heart failure, arrhythmias, valvular disease, and sudden cardiac death. Given the significant morbidity and mortality associated with CS, timely diagnosis is important. Traditional imaging modalities and histologic evaluation by endomyocardial biopsy often provide a low diagnostic yield. Cardiac positron emission tomography (PET) has emerged as a leading advanced imaging modality for the diagnosis and management of CS. This review article will summarize several aspects of the current use of PET in CS, including indications for use, patient preparation, image acquisition and interpretation, diagnostic and prognostic performance, and evaluation of treatment response. Additionally, this review will discuss novel PET radiotracers currently under study or of potential interest in CS.

Proliferation PET/CT Imaging of Salivary Gland Tumor

Salivary gland tumors are rare neoplasms which vary in terms of origin and malignant potential. 2-[18F]-fluoro-2-deoxy-d-glucose (FDG)-positron emission tomography (PET) has limited ability to differentiate between different types of salivary gland tumors because both Warthin’s tumors and pleomorphic adenomas usually show increased FDG uptake, with no statistically significant difference in standardized uptake value (SUV) compared with malignant salivary gland tumors. Here, we discuss 4′-[methyl-11C]-thiothymidine (4DST) PET, which provides cell proliferation imaging capable of demonstrating intense uptake in parotid carcinoma and Warthin’s tumor, but no uptake in parotid pleomorphic adenoma. This is the first report of the potential of proliferation PET/ computed tomography (CT) imaging for characterizing salivary gland tumors based on the molecular pathogenesis of the tumor.