Retrocrural Lymph Node Metastasis Disclosed by 18F-FDG PET/CT: A Predictor of Supra-diaphragmatic Spread in Ovarian Cancer

Retrocrual lymph nodes (RCLNs) communicate with retroperitoneal and posterior mediastinal LNs. It is possible that, when RCLNs are involved, supra diaphragmatic extension will occur in abdomino pelvic cancers. The authors investigated performance of 18F FDG PET/CT to diagnose RCLN metastasis and whether RCLN metastases were associated with supra diaphragmatic lymphatic metastases of ovarian cancer. Sixty seven patients with stage IV ovarian cancer who had undergone 18F FDG PET/CT were included in this retrospective study. Diagnostic performance of 18F FDG PET/CT for RCLN metastasis was evaluated. Patients were divided into two groups by presence or absence of supra diaphragmatic LN metastasis. The prevalences of RCLN metastasis between the two groups were compared and the odds ratio was calculated. Sensitivity and specificity of 18F FDG PET/CT for RCLN metastasis were 96.3 and 100%, respectively. Of the 67 study subjects, 27 patients had RCLN metastases (40.3%). Fifty patients had supra diaphragmatic LN metastases. 18F FDG PET/CT showed 26 RCLN metastases in patients with supra diaphragmatic LN metastases (54.5%), and only 1 in patients without supra diaphragmatic LN metastasis (5.9%), and the difference between two groups was statistically significant (P<0.05). The odds ratio that patients with RCLN metastasis would have supra diaphragmatic LN metastasis was 17.3 (95% confidence interval=2.1 to 140.9, P=0.008). Performance of 18F FDG PET/CT to diagnose RCLN metastasis was excellent. RCLN metastasis revealed by 18F FDG PET/CT was strongly associated with supra diaphragmatic LN spread of ovarian cancer. Thus, RCLN metastasis could be used as a predictor of supra diaphragmatic lymphatic metastasis of ovarian cancer