PREDICTION OF LYMPH NODE METASTASIS FROM 18F-FDG PET/CT RADIOMICS OF CERVICAL CANCER

1521 Objectives: Cervical cancer is one of the most frequent forms of neoplasm in women and one of the leading causes of cancer death in this group. An appropriate preoperative staging, particularly focused on the eventual lymph nodes involvement, is crucial to ensure the most appropriate treatment and to obtain the best outcome. In locally advanced disease, 18F-FDG PET/CT already demonstrated a prognostic role. In the present study is evaluated its putative role in the preoperative setting in the prediction of lymph node metastasis through the analysis of radiomic features of the primary cervical lesion. Methods: A subset of 74 patients with early stage cervical cancer that underwent surgery with pelvic lymphadenectomy and available preoperative 18F-FDG PET/CT have been retrospectively (March 2006 - April 2019) evaluated. Histology was used as a standard reference. PET cervical lesions were contoured with PETVCAR (GE Healthcare) using an iterative threshold. SUVmax, SUVmean, MTV, TLG and radiomics features were computed inside tumor contours using standard Image Biomarker Standardization Initiative (IBSI) methods. Radiomics features associated with lymph-node metastases were identified by Mann-Whitney test. Receiver operating characteristic (ROC) curves and area under the curve (AUC) values were computed and optimal cut-of (Youden index) was assessed. Results: Fourteen out of 74 (18.9%) patients had histologically proved nodal metastases, 5 of which identified by PET/CT (9 false negative cases). PET/CT for pelvic nodal metastases demonstrated a sensitivity, specificity, accuracy, positive predictive value and negative predictive of 36%, 93%, 82%, 55%, 86%, respectively. The presence of nodal metastasis significantly correlated with MTV (p value= 0,013; AUC= 0,72 ; cut-of= 17ml). The most significant radiomics feature was Inverse Difference-Grey Level Co-occurrence Matrix (an homogeneity index), that demonstrated a correlation with the presence of nodal metastases (p value=0,03, AUC=0,76, cut-of =0,17). No significant correlation was found for SUV parameters. Conclusions: PET/CT demonstrated low sensitivity, high specificity and high NPV in detecting pelvic nodal metastases in preoperative staging of cervical cancer. These preliminary data suggest a promising application of radiomics PET for predicting the presence of nodal metastases in cervical cancer; further studies on larger populations are needed.