Objective evaluation of the resistance forces of 22-gauge EUS-FNA and fine-needle biopsy needles.

BACKGROUND AND OBJECTIVES: EUS-guided tissue acquisition is routinely performed for the diagnosis of gastrointestinal tract and adjacent organ lesions. Recently, various types of needles have been developed. However, how the shape of the needle tip and echoendoscope tip angle affect puncturability, has not been clarified. The aim of this experimental study was to compare the puncturability of several 22-gauge EUS-FNA and EUS-guided fine-needle biopsy (EUS-FNB) needles, and to evaluate the effects of the needle tip shape and echoendoscope tip angle on tissue puncturability.

MATERIALS AND METHODS: The following six major FNA and FNB needles were evaluated: SonoTip® ProControl, EZ Shot 3 Plus, Expect™ Standard Handle, SonoTip® TopGain, Acquire™ , and SharkCore™ . The mean maximum resistance force against needle advancement was evaluated and compared under several conditions using an echoendoscope.

RESULTS: The mean maximum resistance force of the needle alone was higher for the FNB needles than for the FNA needles. The mean maximum resistance force of the needle in the echoendoscope with free angle demonstrated that the resistance forces were between 2.10 and 2.34 Newton (N). The mean maximum resistance force increased upon increases in angle of the tip of echoendoscope, particularly in the FNA needles. Among the FNB needles, SharkCore™ had the lowest resistance force (2.23 N). The mean maximum resistance force of the needle alone, the needle in the echoendoscope with free angle, and the needle in the echoendoscope with full-up angle for SonoTip® TopGain were all similar to that of Acquire™ .

CONCLUSION: SonoTip® TopGain had similar puncturability to Acquire™ in all tested situations. Regarding the puncturability, SharkCore™ is most suitable for insertion into target lesions, when tight echoendoscope tip angle is necessary.