The value of FDG-PET/CT in node-negative endometrial cancer on MRI

Abstract

Objectives: To evaluate the diagnostic performance of preoperative fluorodeoxyglucose positron emission tomography–computed tomography (FDG-PET/CT) in predicting lymph node status in node-negative endometrial cancer on preoperative magnetic resonance imaging (MRI). Methods: Patients with endometrial cancer who underwent both preoperative MRI and FDG-PET/CT and then underwent hysterectomy and lymphadenectomy were included. MRI and FDG-PET/CT images were independently reviewed by 2 radiologists and 2 nuclear medicine physicians blinded to the clinical and pathologic information and the results of FDG-PET/CT or MRI. Lymph nodes smaller than 1 cm in short axis diameter were defined as negative lymph nodes on MRI. Lymph nodes were divided into 8 lymph node stations in each patient. The diagnostic performance of PET-CT in predicting lymph node metastasis was calculated in a patient-by-patient analysis and lymph node station-by-station analysis. Results: A total of 362 patients did not have lymph node metastasis on preoperative MRI. All patients underwent pelvic lymph node dissection, and 118 patients underwent para-aortic lymph node dissection. A total of 10,238 lymph nodes were retrieved from 2,099 lymph node stations. Twenty-seven patients had lymph node metastasis on pathologic examination. PET-CT diagnosed only 5 patients (18.5%) with lymph node metastasis. The sensitivity of FDG-PET/CT was 18.5% in patient-by-patient analysis. Lymph node metastasis was found in 49 lymph node stations on pathologic examination. PET-CT diagnosed only 8 lymph node stations (16.3%) with lymph node metastasis. The sensitivity of FDG-PET/CT was 16.3% in lymph node station-by-station analysis. The median diameter of false-negative metastatic lymph nodes was 6 mm (range, 1–22 mm) in long axis and 3 mm (range, 1–11 mm) in short axis. Conclusions: This study indicates the low value of preoperative FDG-PET/CT in predicting lymph node metastasis in node-negative endometrial cancer on preoperative MRI.