Usefulness of Dynamic FDG PET/CT in Detecting Lymph Node Metastasis of Esophageal Squamous Cell Carcinoma Using a Silicon Photomultiplier PET Scanner

Purpose: In patients with esophageal squamous cell carcinoma (ESCC), it can be challenging to distinguish whether mediastinal lymph nodes (LNs) with an increased 18 F-fluorodeoxyglucose (FDG) uptake are metastatic LNs or inflammatory ones. The aim of this study was to verify the superiority of dynamic 18 F-fluorodeoxyglucose-positron emission tomography (FDG-PET) over conventional static positron emission tomography (PET) for detecting LN metastases in patients with ESCC using a silicon photomultiplier (SiPM) PET scanner. Patients and Methods: This prospective single-center study included 18 patients with ESCC who underwent dynamic PET/CT using SiPM PET and subsequently underwent radical esophagectomy and lymphadenectomy. FDG kinetics in the LNs were analyzed through spectral analysis and Patlak plots to calculate influx rate constant (Ki) values, followed by a conventional static PET scan and maximum standardized uptake value (SUVmax) measurement. Pathological analysis was used to define LN metastasis, and a receiver operating characteristic curve analysis was used to determine the diagnostic cutoffs for Ki and SUVmax. Results: Among 47 LNs (11 metastatic and 36 nonmetastatic) analyzed, metastatic LNs exhibited significantly higher Ki and SUVmax values than those of nonmetastatic LNs. The sensitivity for LN metastasis was comparable between SUVmax and Ki (both 72.7%). Meanwhile, the specificity in LN metastasis of Ki was higher than that of SUVmax (94.4% vs. 80.1%), as was the overall diagnostic accuracy of Ki (89.4% vs. 78.8%). Conclusions: Dynamic FDG PET/CT using SiPM PET may enhance the diagnostic accuracy for LN metastases in ESCC, enabling appropriate treatment intervention and improved outcomes for patients with ESCC.