Primary Motility  Disorders of the  Esophagus
 The Esophageal
 Mucosa
 The
 Esophagogastric  Junction
 Barrett's
 Esophagus

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OESO©2015
 
Volume: Barrett's Esophagus
Chapter: Diagnosis
 

Can high frequency ultrasound probes give specific information on esophageal anatomy in Barrett's esophagus?

Y. Murata, S. Suzuki, K. Hayashi, K. Tanigawa, M. Ohta, A. Mitsunaga, H. Ide, K. Takasaki (Tokyo)

In Japan (1994), 32% of esophageal cancer was of superficial type, based on screening examinations by x-ray and endoscopy. The rate of lymph node metastasis of squamous mucosal cancer was 4-8%. Following this fact, a less invasive treatment, such as endoscopic mucosal resection has been introduced for mucosal cancer. In Barrett esophagus, determination of cancer invading more than the mucosa is important because of the difficulty in differentiating high-grade dysplasia from adenocarcinoma on the basis of endoscopic biopsy examination. The pattern and range of lymph node metastasis in Barrett esophageal adenocarcinoma is similar to that of squamous cell carcinoma. In cancer invading the submucosa, the rate of lymph node metastasis is more than 20% [1]. Using conventional endoscopic ultrasonography (EUS) in esophageal lesions, it is difficult to delineate lesions of superficial cancer or small tumors. After high frequency catheter type probes were introduced by Silverstein [2], not only the probe can be scanned under direct view, but also high resolution can be used. Superficial lesions can be delineated by high frequency probes that may suggest the depth of cancer invasion including those with no visible lesion at endoscopy. In case of analysis of the depth of invasion in Barrett esophageal cancer, first the structure of Barrett esophagus should be studied in comparison with normal esophageal wall structure. Second, in diagnosis of short segment Barrett esophagus, the endoscopic definition of esophagogastric junction (EGJ) must be determined. Several criteria of EGJ have existed, such as proximal margin of the gastric folds and the linearly oriented mucosal vessels in the distal esophagus [3]. However, criteria of EGJ by EUS have not been reported yet. Accordingly, the purpose of this paper is first analysis, structure of Barrett esophagus using high frequency probe, and second, EUS definition of EGJ using EUS-3D imaging system.

Equipment, methods and patients

Catheter type probes (20, 30MHz 2.6mm in diameter, Olympus and Fujinon) and 3D imaging system (12MHz 3.6mm in diameter Olympus) were used. Premedication consisted in scopolamine butlybromide, pentazocine and, occasionally, sedative drugs. The patient lying on his or her left side, the two-channel scope is inserted and Barrett esophageal mucosa is observed by direct view. The small probe is inserted through one of the channels and deaerated water is irrigated through the other channel. The scanning is started when the esophageal mucosa is covered with water. In 3D EUS, the probe is inserted through the bigger channel and placed over the EGJ. Scanning is started when the esophagus is filled with. Before scanning is started, the patient is asked to hold his breath. Scanning images are stored into the computer. After examination is finished, the 3D image is reconstructed.

Wall structure of Barrett esophagus

Investigation of wall structure of Barrett esophagus was compared to normal esophageal wall structure. When 20 or 30 MHz are used, the normal esophageal wall is delineated as a 9 layer structure. The 1st and 2nd layer (m1,m2) are the epithelium, the 3rd (m3) is the lamina propria, the 4th hypoechoic layer (m4) is the muscularis mucosa. The 5th hyperechoic layer(s) is the submucosa. From the 6th (p1) to the 8th (p3) are the muscularis propria and the 9th (a) is the adventitia. In Barrett esophagus, the number of layers and basic pattern of layers are similar to normal esophageal structure. A different feature is that the m4 layer (mm) is thicker than the m4 layer in the normal esophageal wall (Figure 1).

Figure 1. Esophageal wall structure of Barrett esophagus. The 1st and 2nd layer (m1,m2) are the epithelium, the 3rd (m3) is the lamina propria, the 4th layer (m4); the hypoechoic layer is the muscularis mucosa, the 5th layer (s); the hyperechoic layer is the submucosa, from the 6th (p1) to the 8th (p3) are the muscularis propria and the 9th (a) is the adventitia.

Structure of the esophagogastric junction in 3D image

The EGJ is best used as the correct term for the static, mural muscular junction between the esophagus and the stomach [3]. Endoscopic EGJ may be defined as the proximal margin of the longitudinal mucosal folds of the gastric cardia, or as a change in the diameter of the lumen. The tubular lumen of the esophagus becomes wider at the cardia. With 3D-EUS, a different diameter of lumens and shapes are demonstrated, and, moreover, the right crus of the diaphragm can be delineated (Figure 2). If there is a concomitant hiatus hernia, it may be difficult to identify the EGJ. A longitudinal image delineates the three muscularis propria layers and notch (Figure 3). 3D-EUS may be used to identify the mural muscular junction between the esophagus and the stomach.

Figure 2. 3Dimage of the esophagogastric junction.

Figure 3. Linear image of the esophagogastric junction.

Conclusion

EUS structure of Barrett esophagus is delineated as 9 layers, similar to normal esophageal wall. Barrett esophagus differs from normal in that the m4 layer (mm) is slightly thicker than in the normal esophagus. The 3D-EUS image may be useful to determine the EGJ.

References

1. Udagawa H, Tsutsumi K, Kinoshita Y, et al. Therapeutic strategy for adenocarcinoma in Barrett esophagus: a study based on a comparison with squamous cell carcinoma. Nippon Geka Gakkai Zasshi 1999;100:261-264.

2. Silverstein FE, Martin RW, Kimmey MB, et al. Experimental evaluation of an endoscopic ultrasound probe:in vitro and in vivo canine studies. Gastroenterology 1989;86:1058-1062.

3. Boyce HW. Endoscopic definition of esophagogastric junction regional anatomy. Gastrointest Endosc 2000;51(5):586592.

4. Murata Y, Suzuki S, Ohta M, et al. Small ultrasonic probes for determination of the depth of superficial esophageal cancer. Gastrointest Endosc 1996;44:23-28.


Publication date: August 2003 OESO©2015