Endoscopic Ultrasound Placement of Preloaded Fiducial Markers Shortens Procedure Time Compared to Back-Loaded Markers

Abstract

Background & aims: Fiducial markers are inert radiopaque gold or carbon markers implanted in or near pancreatic tumor to demarcate areas for image-guided radiation therapy. Endoscopic ultrasound (EUS) pre-loaded fiducial needles (PLNs) have been developed to circumvent technical issues associated with traditional back-loaded fiducials (BLNs). We performed a randomized controlled trial to compare procedure times in patients with pancreatic adenocarcinoma undergoing EUS-guided placement of BLNs vs PLNs.

Methods: In a prospective study, 44 patients with pancreatic adenocarcinoma referred for fiducial marker placement at 2 tertiary care centers were assigned to groups that received PLNs (n = 22) or BLNs (n = 22); each group had the same proportion of patients with tumors of different locations (head or neck vs body or tail).The procedure was standardized among all endoscopists and placement of a minimum of 3 markers inside the tumor was defined as technical success. The times for procedure and fiducial placement were recorded, total number of fiducial markers used documented, and grade of procedure difficulty ranked by passing the needle or deploying the fiducials. Other recorded variables included tumor characteristics, fluoroscopy use, and the number of fiducials clearly seen by EUS and fluoroscopy. The primary aim was to compare the duration of EUS-guided fiducial insertion of BLNs vs PLNs.

Results: The median placement time was significantly shorter in the PLN group (9 min) than the BLN group (16 min) (P < .001). However, the 44% reduction in time did not reach pre-specified levels (≥60%). Similar results were found after stratifying by tumor location. Deployment of BLNs was easier than deployment of PLNs (P = .03). There was no significant difference between groups in technical success, number of fiducials placed, EUS or fluoroscopic visualization, or adverse events. During simulation computed tomography and image-guided radiation therapy, there was no difference between groups in visualization of fiducials, migration rate, or accuracy of placement.

Conclusions: In a randomized controlled trial of 44 patients with pancreatic adenocarcinoma, we found EUS-guided placement of PLNs to require less time and produce similar results compared with BLNs. Further refinements in PLN delivery system are needed to increase the ease of deployment. Clinicaltrials.gov no: NCT02332863.

Keywords: Fiducial Markers; Outcomes; Pancreatic Cancer; Radiation Therapy.