Abstract Objectives To evaluate the distribution patterns of sarcoidosis involvement on FDG-PET/CT in patients with known or suspected cardiac sarcoidosis (CS), with a particular focus on upper abdominal lymph nodes (LN) (periportal LN PLN, anterior pancreaticoduodenal LN APDLN, and posterior pancreaticoduodenal LN PPDLN) and the association of them with other lesions and myocardium. Methods We identified 861 FDG-PET/CT scans performed between July 2016 and August 2024 in patients with known or suspected CS, and included 178 cases for analysis of FDG uptake patterns suggestive of sarcoid involvement. FDG-positive LNs or regions were classified as sarcoidosis-related based on treatment response, characteristic uptake patterns, or histological confirmation. The occurrence ratio of FDG-positive lymph nodes or regions was also assessed in relation to myocardial FDG uptake patterns. Results FDG uptake was observed most frequently in hilar and mediastinal LNs (79% and 76%, respectively). Upper abdominal LN uptake was observed in 49.4% of patients, most commonly in the PLN (31.5%), APDLN (38.2%), and PPDLN (37.1%). Heatmap analyses revealed strong co-occurrence between thoracic and upper abdominal LNs, suggesting a lymphatic dissemination pattern. Peripheral LNs such as axillary, subclavian, and inguinal/pelvic stations demonstrated low uptake and minimal co-occurrence. Conclusions FDG-PET/CT provides valuable insight into the structured lymphatic dissemination of sarcoidosis. Frequent FDG uptake in upper abdominal lymph nodes, particularly when accompanied by thoracic involvement, represents a characteristic finding in sarcoidosis. Recognition of this pattern can improve diagnostic accuracy and help differentiate sarcoidosis from other systemic diseases. Secondary abstract This study assessed lymph node involvement on FDG-PET/CT in patients with suspected or known cardiac sarcoidosis, revealing distinct dissemination patterns into the upper abdomen. These findings enhance understanding of disease pathophysiology and may improve diagnostic evaluation.
Minamimoto et al. (Thu,) studied this question.