Radial EUS vs. Linear EUS in Evaluation of Mediastinal Lymph Nodes in Lung Cancer Staging. a Prospective Double Blind Trial

Abstract

Purpose: Endosonography has recently being used for mediastinal lymph node (MLN) evaluation during staging of lung cancer. The radial endoscopic ultrasound (R-EUS) provides high quality cross sectional images, but cannot guide fine needle aspiration (FNA). Linear EUS (L-EUS) has the ability to guide FNA but has a limited field of view. Use of both endoscopes may improve lymph node detection but is less efficient. In this study, we evaluated the accuracy of radial and linear EUS endoscopes alone and in combination for the detection of mediastinal lymph nodes Methods: Patients suspected of having lung cancer underwent back to back R-EUS and L-EUS evaluation by 1 of 3 experienced endosonographers. Patients were blindly randomized to which procedure would be performed first. If an FNA was required, it would be performed after completing both R-EUS and L-EUS examination. Examinations were recorded in the following order; Liver, Celiac axis, Left Adrenal, and Mediastinal/Esophageal pull through. Recorded procedures were then to be reviewed by 2 different experienced endosonographers; neither of whom had performed the procedure. Both were blinded to the original findings and the alternate procedure results. IRB approval was obtained. Results: To date, a total of 9 patients (study ongoing) underwent evaluation for suspected lung cancer. A total of 13 abnormal MLNs were noted on both procedures. There was agreement on 5/13 (38%) in regards to location (Table 1). Both R-EUS and L-EUS identified a malignant appearing celiac LN. L-EUS picked up a malignant appearing liver lesion. Both R-EUS and L-EUS found 4 malignant appearing MLNs that were not seen by the other examination. There were 8 benign appearing MLNs. There was poor agreement on the location of any benign MLNs (Table 2). There was an adrenal adenoma that was seen on R-EUS only. In total, there was an agreement on the presence of MLNs in 5/21 (24%). Limitations: Small number of patients, Malignant and benign appearing and location decision was based on the endosonographers interpretation recorded imaging of the MLNTable 2: Number of benign appearing mediastinal lymph nodes, according to location, as seen by R-EUS and L-EUSTable 1: Number of Malignant appearing mediastinal Lymph nodes, according to location, as seen by R-EUS and L-EUSConclusion: Based on reviewing recorded R-EUS and L-EUS for MLNs, there is poor agreement in number and location of benign and malignant appearing MLNs. Patients undergoing lung cancer staging should undergo both procedures for proper staging evaluation