LAUSR

Endoscopic ultrasonography (EUS), with its high spatial resolution, is indispensable for diagnosing the nature and invasiveness of gallbladder lesions [1–3]. The gallbladder and bile ducts are hollow organs that do not originally have internal echo sources and are susceptible to multiple reflections and other artifacts. Recently, a new endoscopic ultrasound (EUS) processor (EVIS EUS EU-ME3; Olympus, Tokyo, Japan) was launched that is equipped with a novel anti-artifact function called low echo reduction (LER). LER suppresses low echo areas while maintaining high echo areas, thereby improving contrast without whiteout. LER is usually set at Lv.3 and ranges from 1 (lowest) to 20 (highest). The tissue harmonic echo (THE) mode can reduce artifacts in B-mode images, but LER can provide further artifact reduction, in addition toTHE. The LER level can be changed both when the EUS screen is live or paused. We usually evaluate the gallbladder using a radial-type scope (GF-UE290; Olympus) with THE mode, setting at gain Lv.10 and contrast at Lv.4. LER was able to suppress multiple reflection artifacts, making it easy to recognize the boundaries of the gallbladder wall and lesions (▶Fig. 1; ▶Video 1). It should be noted that LER suppresses even minute signal changes, and there is a risk of missing small findings or lesions; however, small polyps were not obscured (▶Fig. 2). LER also suppressed artifacts and made it easier to see lesions in cases where they were covered by artifacts (▶Fig. 3). In situations where artifacts prevent close evaluation of the interior of hollow organs with EUS, LER may reduce artifacts and improve visibility.