Analysis of the Layer Structure of the Gallbladder Wall Delineated by Endoscopic Ultrasound Using the Pinning Method

Abstract

The gallbladder is a suitable target of endoscopic ultrasound (EUS). However, the interpretation of the layer structure of the gallbladder wall delineated by EUS is still controversial. To confirm the relationship between the layers demonstrated by EUS and the histological structure, we performed a study using the pinning method. In most slices, the gallbladder wall was demonstrated to be a two‐or three‐layer structure, consisting of a low echoic layer, sometimes with an overlying hyperechoic layer, and a high echoic layer from the mucosal side. The slices were pierced with pins at random depths. Among the twelve pin echoes demonstrated in the low echoic layer, four were located in the muscularis propria, two in the border between the muscularis propria and the subserosa, three in the fibrous layer of the upper portion of the subserosa, and three in the adipose layer of the lower portion of the subserosa. The three sites where the pin echoes were seen at the border between the low echoic and high echoic layers were located in the fibrous layer, the border between the fibrous layer and the adipose layer, and in the adipose layer, respectively. The twelve sites at which pin echoes were observed in the high echoic layer were confirmed to be in the adipose layer. These results indicate that the inner hypoechoic layer includes not only the muscularis propria but also the fibrous layer of the subserosa. This should be kept in mind when assessing the depth of invasion of a gallbladder carcinoma.

Abnormal arrangement of the pancreato-biliary ductal system associated with advanced gallbladder cancer diagnosed 3 years after follow-up ultrasonography

“…EUS has high accuracy in diagnosing not only AAPB but also gallbladder cancer, due to its high spatial resolution. 15,16 Once this anomaly is suspected, EUS should be carried out for the evaluation of the presence/absence of biliary malignancies, to determine the treatment strategy.…”

Intraductal ultrasonography (IDUS) for the diagnosis of biliopancreatic diseases

“…The normal bile duct wall is visualised as a twolayer structure, that is, the inner hypoechoic layer and the outer hyperechoic layer (Fig. 4), and histological components of each layer have been clarified [24,43] using the same experimental method as that in analysing the components of the layer structure delineated by endoscopic ultrasonography (EUS) of the gallbladder wall [44]. Occasionally, an interface echo is visualised between the bile and the inner hypoechoic layer.…”

EUS in Bile Duct, Gallbladder, and Ampullary Lesions

“…The outer hyperechoic layer represents the subserosal fat layer and serosa. [193][194][195][196] In some cases, a hyperechoic layer is demonstrated on the inner hypoechoic layer. This is considered to be mainly an interface echo.…”