Abstract
The association between 18F-fluorodeoxyglucose (18F-FDG) myocardial uptake and clinical presentations in cardiac sarcoidosis (CS) has not yet been clarified. The Patlak slope, Ki, which represents the rate of 18F-FDG uptake is a quantitative index of 18F-FDG metabolism. This study aims to investigate the usefulness of standardized uptake value (SUV) and Patlak Ki images (Ki images) extracted from dynamic 18F-FDG-PET/CT for evaluating the risk of clinical events (CEs) in CS. The SUV and Ki myocardial images were generated from 30 dynamic 18F-FDG-PET/CT scans of 21 CS patients. The SUV and Ki images both were rated as positive in 19 scans and negative in 11 scans with the same incidence of CEs which were significantly higher in positive than negative scans [cardiac dysfunction: 78.9% (15/19) vs. 27.2% (3/11); arrhythmic events: 65.5% (10/19) vs. 0% (0/11)]. In 19 positive scans, the three Ki parameters (Ki max, Ki mean and Ki volume) were significantly higher in scans for patients with arrhythmic events than in those without. Logistic regression analysis showed that the Ki volume alone was significantly associated with the risk of arrhythmic events. Our study suggests that Ki images may add value to SUV images for evaluating the risk of CEs in CS patients.
Highlights
Sarcoidosis is a systemic granulomatous disease of unknown etiology
To our knowledge, only one report has investigated dynamic 18F-FDG-positron emission tomography (PET)/computed tomography (CT) images for diagnosis of CS19, and it is unknown if Patlak Ki images (Ki images) extracted from dynamic 18F-FDG-PET/CT are useful for evaluating the disease activity or clinical events in cardiac sarcoidosis (CS) patients
Arrhythmic events were observed for 10 18F-FDG PET/CT scans, and seven and three scans were performed before treatment and under treatment, respectively
Summary
Sarcoidosis is a systemic granulomatous disease of unknown etiology. Clinical manifestations of cardiac involvement are estimated to occur in 5% of patients with sarcoidosis, but the prevalence at autopsy has ranged from 25 to 58%1,2. Patlak analysis is more demanding than calculation of SUV and inconvenient for patients. The SUV measures the total activity in the lesion, and includes both metabolized 18F-FDG and unmetabolized 18F-FDG (unphosphorylated 18F-FDG) in the blood, intercellular spaces, and/or cells. Patlak analysis separates these two components, and the Patlak slope is determined only by metabolized 18F-FDG13. To our knowledge, only one report has investigated dynamic 18F-FDG-PET/CT images for diagnosis of CS19, and it is unknown if Patlak Ki images (Ki images) extracted from dynamic 18F-FDG-PET/CT are useful for evaluating the disease activity or clinical events in CS patients
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