EUS‐guided hydrogel microparticle injection in a cadaveric model

Abstract

Background and Aims A potential method to reduce gastrointestinal toxicity during radiation therapy in pancreatic head cancer is to create a physical space between the head of the pancreas (HOP) and the duodenum. To date, there have been early reports on the feasibility of endoscopic ultrasound (EUS)‐guided hydrogel injection into the interface between the HOP and the duodenum to increase the peri‐pancreatic space for radiotherapy. We aimed to evaluate the technical feasibility of EUS‐guided hydrogel injection for the creation of space at the peri‐pancreatic interface in a cadaveric model. Methods Baseline abdominal computerized tomography (CT) was performed on three unfixed cadaveric specimens. The hydrogel was injected transduodenally into the interface between the HOP and duodenum using linear‐array EUS and a 19G needle for fine needle aspiration (FNA). This procedure was repeated along the length of the HOP. CT imaging and gross dissection were performed after the procedure to confirm the localization of the hydrogel and to measure the distance between the HOP and the duodenum. Results All cadavers underwent successful EUS‐guided injection of the hydrogel. Cadavers 1, 2, and 3 were injected with 9.5, 27, and 10 cc of hydrogel, respectively; along the HOP, the formation of the peri‐pancreatic space was a maximum size of 11.77, 13.20, and 12.89 mm, respectively. The hydrogel injections were clearly visualized as hyperechoic bullae during EUS and on post‐procedure CT images without any artifacts in all cases. Conclusions We demonstrated that EUS‐guided delivery of hydrogel is feasible, and that it increases the peri‐pancreatic space in a cadaveric model. The polyethylene glycol (PEG) hydrogel was clearly visible on EUS and CT, without significant artifacts. This may lead to new treatment approaches for pancreatic carcinomas.

Demonstrating the benefits of corrective intraoperative feedback in improving the quality of duodenal hydrogel spacer placement

“…Our group has shown that injection of hydrogel spacer between the head of pancreas (HOP) and duodenum increases the duodenal sparing, and therefore, makes the dose escalation more feasible. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] However, the success of the spacer placement procedure is highly uncertain. Previous studies on rectal spacer have shown that hydrogel spacer injection is associated with risk of infection, inflammation, and softtissue wall infiltration.…”

“…However, the effectiveness of dose escalation is limited due to the proximity of organs at risk (OAR), mainly the duodenum. Our group has shown that injection of hydrogel spacer between the head of pancreas (HOP) and duodenum increases the duodenal sparing, and therefore, makes the dose escalation more feasible 3–17 …”

Systematic study of the iodinated rectal hydrogel spacer material discrepancy on accuracy of proton dosimetry

“… 8 , 9 , 10 , 11 , 12 Recent studies have shown that hydrogel spacer resulted in a significant reduction of rectal dose during PT. 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 However, the standard rectal hydrogel spacer is not visible on planning computed tomography (CT) and intraoperative cone‐beam CT that lack the adequate resolution and contrast to distinguish between the soft tissue (prostate and rectum) and hydrogel. 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 Thus, magnetic resonance imaging (MRI) is required to localize the hydrogel spacer, but anatomical changes, patient intolerance, MRI‐incompatible hardware, and the extra cost and time raise the need for an alternative spacer localization method.…”

A phantom-based analysis for tracking intra-fraction pancreatic tumor motion by ultrasound imaging during radiation therapy

“…Respiration). However, this larger margin will result in delivering greater radiation doses to the area around the tumor, thereby inherently causing toxicities to normal tissues (17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31). In this case, it is not possible to apply dose escalation without margin reduction (32)(33)(34)(35).…”