Evaluation of Lymph Nodal Staging and Stiffness of Gastrointestinal Cancers by Intraoperative Ultrasound Elastography

Abstract

Introduction: Real-time tissue elastography is a new non-invasive method in ultrasonography that differentiates tissues according to their stiffness. The aim of this study was to define the diagnostic value of the intraoperative ultrasound elastography for the differentiation of benign and metastatic regional lymph nodes (LNs) in patients with gastrointestinal (GI) cancers by comparing this technique with the enhanced CT scan, intraoperative palpation by surgeons, and final pathological findings. Furthermore, we examined the factors which prescribed hardness in GI cancers. Methods: Between 2014 and 2016, a total of 70 patients with resectable GI cancer (28 gastric cancers, 42 colon cancers) who underwent operations were enrolled in this study. The LN metastases judged by ultrasound elastography, CT scans, and intraoperative palpation by surgeons were compared with the postoperative pathological results. Stiffness of tumors evaluated by elastography was compared with various pathological findings. Results: A total of 33 (47%) cancers showed LN metastasis. With a cut-off value of 2.5 for the fat tissueto-LN strain index, the respective values for sensitivity, specificity, and overall accuracy were 97%, 85%, and 89% for intraoperative ultrasound elastography; 53%, 93%, and 74% for CT scan; and 60%, 95%, and 79% for palpation by surgeons. Sensitivity and accuracy were found to be significantly higher for intraoperative ultrasound elastography than for CT scan and intraoperative palpation. No significant differences in tumor stiffness among diseases, tumor size and stage. However, significant differences were found in stroma and histological type of tumors. Conclusion: Nodal diagnosis by intraoperative ultrasound elastography could be a reliable and accurate method in GI cancers when compared to other recent modalities. Our data imply that ultrasound elastography could be the best modality during the intraoperative nodal staging of GI cancers. The factors which prescribed stiffness of tumors were stroma, an invasive style, and a histologic type.