A simple phantom for learning EUS-guided FNA

The learning curve for EUS-guided FNA (EUS-FNA) is formidable. Development of a phantom to assist in teaching the technique may be beneficial. This study assessed the feasibility of using a low-cost phantom made of commonly available materials to practice EUS-FNA.

A 2500-mL barium enema bag was modified by running a plastic tube (3-mm inner diameter) through it and sealing one end. One hundred grams of standard agar were suspended in 4 liters of tap water. The broth was heated slowly to boiling. The dissolved agar was then transferred to the barium enema bag after mixing in diced carrots, elbow macaroni, peas, and fingertips of surgical gloves filled with 5 mL of normal saline solution (6 of each) to simulate solid and cystic lesions. Immersion of the phantom in a basin of water provided acoustic coupling. One end of the 3-mm plastic tubing was attached to the nozzle of a water jet device and the other end to its reservoir to create a closed system allowing water recirculation. A linear array echoendoscope and a fine needle were used to perform EUS-FNA. The analysis is descriptive.

The phantom was readily made with inexpensive components (total cost <$50). With refrigeration the phantom was used repetitively during a 4-month period. It produced EUS images with an echotexture comparable with liver. The solid and cystic components resembled hepatic cysts and solid masses encountered when performing EUS in humans. Under EUS-guidance, fine-needle aspirates of selected lesions could be performed allowing targeting, aspiration, and sampling of selected lesions. The Doppler flow effect allowed examination of a simulated vascular structure during FNA.

Once validated, an EUS phantom made of simple components may become an invaluable educational tool for teaching EUS-FNA. Further studies are needed to determine how it affects the skills of gastroenterologists with and without EUS experience.