Novel low echo reduction function reduces artifacts in endoscopic ultrasound observation of the gallbladder

Endoscopic ultrasonography (EUS), with its high spatial resolution, is indispensable for diagnosing the nature and invasiveness of gallbladder lesions [1] [2] [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 to THE. 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]).

Fig. 1 Endoscopic ultrasound (EUS) images of the gallbladder obtained using a radial-type scope (GF-UE290; Olympus) and a new EUS processor (EVIS EUS EU-ME3; Olympus) showing the appearance on: a B-mode 6 MHz; b tissue harmonic echo (THE) mode; c THE with increasing low echo reduction (LER) at Lv.7, which suppresses low echo areas while maintaining high echo areas, thereby improving contrast without whiteout.

Video 1 Low echo reduction, a novel endoscopic ultrasound function, is used to suppress multiple reflection artifacts during gallbladder observation, making it easy to recognize the gallbladder wall and lesions.

Fig. 2 Endoscopic ultrasound (EUS) images of the gallbladder showing the appearance on: a tissue harmonic echo (THE) mode; b THE with increasing low echo reduction (LER) at Lv.8, which suppresses multiple reflection artifacts and makes it easy to recognize the boundaries of the gallbladder wall and lesions. Although LER has a risk of missing small findings or lesions, small polyps are not obscured.

Fig. 3 Endoscopic ultrasound (EUS) images of the gallbladder showing the appearance on: a tissue harmonic echo (THE) mode; b THE with increasing low echo reduction (LER) at Lv.8, which suppresses the artifacts and makes it easier to see the edges of the lesion in situations where artifacts are covering the lesion, making it difficult to see its edges.

In situations where artifacts prevent close evaluation of the interior of hollow organs with EUS, LER may reduce artifacts and improve visibility.

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Competing interests

Dr. Katanuma has received a lecture fee from Olympus Co., Tokyo, Japan. The remaining authors declare that they have no conflicts of interest.

• References

• 1 Tanaka K, Katanuma A, Hayashi T. et al. Role of endoscopic ultrasound for gallbladder disease. J Med Ultrason (2001) 2021; 48: 187-198
• 2 Hashimoto S, Nakaoka K, Kawabe N. et al. The role of endoscopic ultrasound in the diagnosis of gallbladder lesions. Diagnostics (Basel) 2021; 11: 1789
• 3 Toyonaga H, Hayashi T, Ueki H. et al. An intact boundary between the tumor and inner hypoechoic layer discriminates T1 lesions among sessile elevated gallbladder cancers. J Hepatobiliary Pancreat Sci 2021; 28: 1121-1129

Publication History

Article published online:
09 March 2023