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EUS in the detection of early gastric cancer
K Yasuda
EUS in the detection of early gastric cancer Kenjiro Yasuda, MD
Early gastric carcinoma is mainly detected and diagnosed by endoscopic examination with or without biopsy. In general, the diagnosis of early gastric carcinoma is easily accomplished by endoscopic observation and pathologic evaluation of endoscopic biopsy. Endoscopic detection of gastric carcinoma depends on the recognition of visible mucosal changes. However, the final diagnosis is achieved by histopathologic study of biopsy material. Biopsy is very important in obtaining the correct diagnosis of carcinoma, adenoma, hyperplasia, and metaplasia, although it is often possible to distinguish these lesions by the endoscopic characterization of mucosal surface details. Current affiliation: Department of Gastroenterology, Kyoto Second Red Cross Hospital, Kyoto, Japan. Reprint requests: Kenjiro Yasuda, MD, Kyoto Second Red Cross Hospital, Kamanza-dori, Marutamachi-Agaru, Kamagiya-ku, Kyoto, Japan 602 8026. Copyright © 2002 by the American Society for Gastrointestinal Endoscopy 0016-5107/2002/$35.00 + 0 37/0/127705 doi:10.1067/mge.2002.127705 S68
GASTROINTESTINAL ENDOSCOPY
EUS in the detection of early gastric cancer
Endoscopy has been improved from fiberoptic to video-imaging systems that use charged-coupled devices (CCDs). In addition, cross-sectional images can be obtained by using EUS.1-3 The development of magnification endoscopy can show the precise surface pattern. Furthermore, the recent development of endoscopic optical coherence tomography (EOCT) provides a future promise of histologic diagnosis in vivo. HOW TO DETECT EARLY GASTRIC CARCINOMA Careful observation by endoscopy is important for detecting small and early gastric carcinoma. Detecting an abnormal area and performing biopsy can achieve an accurate diagnosis. Theoretically this is easy to say, but practically there are some problems. For detecting early carcinoma of the stomach, endoscopists have to learn how to find early lesions and must be trained to detect abnormal areas by recognizing characteristic color and mucosal pattern abnormalities. For the purpose of training endoscopists to detect early stage gastric carcinoma and to better understand the management of different lesions, the endoscopic classification of early gastric carcinoma was established. VOLUME 56, NO. 4 (SUPPL), 2002
EUS in the detection of early gastric cancer
K Yasuda
B
A
Figure 1. A case of gastric carcinoma type IIc limited to the mucosa. A, Endoscopic finding. B, With indigo carmine dye spraying.
B
A
C
D
Figure 2. A case of type IIa+IIc early gastric cancer limited to the mucosa. A, Endoscopic picture shows redness at the greater curvature of the gastric angularis. B, Close image. C, Dye spraying reveals a clear picture of the lesion. D, EUS image shows a protruded lesion limited to the mucosa. VOLUME 56, NO. 4 (SUPPL), 2002
GASTROINTESTINAL ENDOSCOPY
S69
K Yasuda
EUS in the detection of early gastric cancer
A
A
B
B
C C Figure 3. A case of type lIb early gastric carcinoma in the body of the stomach. A, Endoscopic photo shows whitish flat mucosa and biopsy revealed adenocarcinoma. B and C, US probe with 30-MHz scanner delineates an irregular change in the submucosa (arrow). S70
GASTROINTESTINAL ENDOSCOPY
Figure 4. A case of type IIa early gastric cancer limited to the mucosa. A, Endoscopic finding showing a granular protruded lesion. B, Dye spraying view show the clear margin of the lesion. C, EUS image demonstrates the cystic change behind the lesion but the lesion is limited to the mucosa.
VOLUME 56, NO. 4 (SUPPL), 2002
EUS in the detection of early gastric cancer
K Yasuda
A
B
C
D
Figure 5. Endoscopic mucosectomy (EMR) for type IIc carcinoma at the gastric antrum. EUS reveals the lesion to be limited to the mucosa. A, Endoscopic picture. B, Indigo carmine spraying image. C, Mucosectomy procedure using the cap method. D, Mucosectomy ulcer.
It is useful to use dye spraying with indigo carmine dye for gastric carcinoma. Of course, this is a complementary technique to the endoscopic detection of a gastric lesion. Figure 1 shows a gastric carcinoma limited to the mucosa with indigo carmine dye spraying. The character and shape of the lesion are distinctly demonstrated. IS EUS EFFECTIVE? EUS diagnosis of early GI tract malignancy is one of the most recent developments in endoscopy. A cross-section of the GI wall can be demonstrated by using EUS. Two types of EUS instruments currently available are useful for this purpose. One is the conventional US endoscope with a radial scan transducer at the tip of endoscope; the other is a US catheter probe with a small radial scan transducer at the tip, which can be used through the working channel of a standard endoscope. The wall of the GI tract can be delineated as a 5 or more layered structure when distended by water in the lumen. The layers of EUS are in good correspondence with histologic wall layers. US scanners of 5.0 to 30 MHz frequency can demonstrate a precise image of the GI tract wall. VOLUME 56, NO. 4 (SUPPL), 2002
The role of EUS is to evaluate the alteration of the GI wall by carcinoma based on the ultrasonic layered structure of GI wall. That means EUS cannot be used to find a lesion, except in the rare case of gastric scirrhous carcinoma, but is used rather to evaluate the changes beneath the mucosa in order to diagnose the depth of carcinoma invasion. This assessment is an important factor in choosing a preferable treatment, such as endoscopic mucosal resection (EMR), laparoscopic surgery, or laparotomy. The diagnostic accuracy of depth of carcinoma invasion is approximately 80%, when lesions are divided into mucosal (m) carcinoma, submucosal (sm) carcinoma, carcinoma invading to the muscularis propria (pm), and carcinoma deeper than the subserosal layer (ss). The EUS diagnosis of a mucosal lesion, which is a good indication for endoscopic mucosectomy, is about 90%. One of the most important diagnostic values of EUS is to identify indications for the endoscopic treatment of early stage GI malignancy. Although EUS can detect the regional metastatic lymph nodes, the rate of detection is unsatisfactory in cases of early gastric carcinoma. GASTROINTESTINAL ENDOSCOPY
S71
K Yasuda
EUS in the detection of early gastric cancer
B
A
C
D
Figure 6. A case of type IIa+IIc early gastric cancer at the anterior wall of the gastric angularis. A, Endoscopic photo. B, Dye spraying picture. C, Magnification view by high-resolution magnification endoscopy shows an irregular area pattern. D, EUS image shows the lesion to be limited to the mucosa.
Figure 2 shows the endoscopic and EUS pictures of gastric carcinoma type IIa+IIc limited to the mucosa. Figure 3 shows the endoscopic finding of type IIb early gastric cancer and its EUS images by 30-MHz US probe invading to the submucosa (arrow). Figure 4 is a case of the type IIa gastric carcinoma limited to the mucosa. EUS demonstrates cystic change beneath the protruded lesion. EUS findings become the evidence to perform EMR (Fig. 5). ROLE OF MAGNIFICATION ENDOSCOPY Based on the advances of technology, highresolution and high-magnification endoscopy has been developed with both fiberoptic and videoimaging systems and is improving. Initial reports with high-resolution and high-magnification endo-
S72
GASTROINTESTINAL ENDOSCOPY
scopes were promising. However, it was not easy to manipulate these endoscopes during ordinary clinical examinations because of the difficulty of focusing and the dark imaging view in magnification mode. NEW HIGH-RESOLUTION AND HIGH-MAGNIFICATION ENDOSCOPES High-magnification endoscopes have a long history. The first models, which were fiberoptic systems, were developed in the late 1960s in the hope that a histologic diagnosis could be achieved without biopsy. However, technical difficulties included a dark visual field and difficulty with focusing. New electronic high-resolution and high-magnification endoscopes may overcome these difficulties. The most advanced videoendoscope for upper GI tract exami-
VOLUME 56, NO. 4 (SUPPL), 2002
EUS in the detection of early gastric cancer
K Yasuda
A
B
C
D
Figure 7. A case of type IIa early gastric cancer at the greater curvature of gastric angularis. A, Endoscopic view showing the whitish flat elevation. B, Dye spraying image. C, Magnification image showing a clearer margin. D, High-magnification picture shows the irregular mucosal and pit patterns.
nation (Olympus GF-Q240Z) can be used easily in standard mode, although focusing remains difficult in maximum magnification. However, this instrument can provide higher-resolution pictures, easier handling, and satisfactory brightness compared with earlier models. The surface mucosal pattern (pit pattern) and capillary structure can be observed by using highmagnification endoscopy. Based on the analysis of mucosal pit pattern obtained by magnification, histologic changes of carcinoma, dysplasia, and adenoma can be suspected. However, it is not easy to diagnose the histologic changes from the magnification pictures. In addition, the whole GI wall cannot be easily scanned in magnified image. Thus the role of high-magnification endoscopy is to magnify a target area in which conventional endoscopy detects an abnormality. Figure 6 shows type IIa+IIc early gastric mucosal carcinoma of the anterior wall of the gastric angle with magnification images. Figure 7 is a case of type IIa, elevated-type early gastric carcinoma limited to the mucosa at the greater curvature
VOLUME 56, NO. 4 (SUPPL), 2002
of the gastric angle, showing an irregular pit pattern of the mucosal surface. IS ENDOSCOPIC OPTICAL COHERENCE TOMOGRAPHY USEFUL FOR HISTOLOGIC DIAGNOSIS? Optical coherence tomography (OCT) is a recently developed technique for demonstrating cross-sectional images in the GI tract with 10 times higher resolution than that of 30-MHz US catheter probe. This system demonstrates images obtained by using broadband width illumination and recording the reflection of the illumination. Microscopic tissue structure can be imaged by this method, but the depth of penetration is limited. The clinical application of OCT has begun to be evaluated by using a prototype OCT probe made by Olympus Co. This probe, which has the same outside and view angle of 360˚ as the high-frequency US probe, can be used through the working channel of a standard endoscope, so this method is called endoscopic optical coherence tomography (EOCT). For EOCT scanning, water injection or balloon contact
GASTROINTESTINAL ENDOSCOPY
S73
K Yasuda
EUS in the detection of early gastric cancer
A
B
C
D
Figure 8. A case of early gastric cancer type IIa involving the mucosa. A, Endoscopic view. B, Indigo carmine dye spraying image. C, Image by endoscopic optical coherence tomography (EOCT). D, Mucosectomy material reveals well-differentiated adenocarcinoma limited to the mucosa.
methods are not required because air does not interfere with the illumination beam. To discuss the clinical significance of EOCT, 26 cases of GI tract diseases, including 2 cases of early esophageal carcinoma, 14 of early gastric carcinoma, and 1 of early duodenal carcinoma, were examined by EOCT. The lesions were demonstrated by EOCT with high resolution but poor penetration. The depth of imaging penetration was 1.5 to 2.0 mm, but the mucosal glandular structure could not be demonstrated; the lamina propria, muscularis mucosa, and part of submucosa were imaged. The gastric wall is observed as a layered structure, which is different from that of the esophageal wall layers. The surface layer shows a glandular structure, and behind, 3 layers of high, low and high reflective layers, which are thought to be the lamina S74
GASTROINTESTINAL ENDOSCOPY
propria (high reflectivity), muscularis mucosa (low reflectivity), and interface layer of submucosal layer (high reflectivity). Though the resolution was much higher than that of the 30-MHz US scanner, penetration of EOCT was too poor to use this method for assessing the depth of tumor invasion. However, by using this sophisticated instrument, the histologic nature of tissues can be evaluated. EOCT if perfected might be used as a method for optical biopsy in fixture endoscopic examinations. Figure 8 shows endoscopic and EOCT pictures of a type IIa gastric carcinoma. DIAGNOSIS OF EARLY GASTRIC CARCINOMA IN THE FUTURE Detection of small gastric carcinomas is feasible with endoscopic observation with or without dye VOLUME 56, NO. 4 (SUPPL), 2002
EUS in the detection of early gastric cancer
spraying. Furthermore, endoscopy with additional systems such as EUS, magnification endoscopy, and EOCT can evaluate the lesions more completely. The significance of endoscopic detection and staging of early gastric carcinoma is to diagnose small lesions, which can be managed by endoscopic treatments such as mucosectomy. Automatic imaging diagnosis and pathologic diagnosis of early gastric cancer lies in the future by using endoscopy and various techniques, such as EUS and EOCT. For this purpose, the development of automatic pattern recognition systems is required. It seems possible that in the near future there will be auto-
VOLUME 56, NO. 4 (SUPPL), 2002
K Yasuda
matic diagnosis systems based on the analysis of images by information technology. REFERENCES 1. Yasuda K, Nakajima M, Kawai K. Fundamentals of endoscopic laser therapy (ELT) for GI tumors; new aspects with endoscopic ultrasonography (EUS). Endoscopy 1987;19 (Suppl):S2-6. 2. Yasuda K, Nakajima M, Kawai K. Endoscopic diagnosis and treatment of early gastric cancer using endoscopic ultrasonography (EUS). Gastrointest Endosc Clin N Am 1992;2: 495-507. 3. Yasuda K. Gastrointestinal carcinoma. In: The handbook of endoscopic ultrasonography in digestive tract. Tokyo, Japan: Blackwell Science; 2000. p. 54-69.
GASTROINTESTINAL ENDOSCOPY
S75
EUS in the detection of early gastric cancer Kenjiro Yasuda, MD
Early gastric carcinoma is mainly detected and diagnosed by endoscopic examination with or without biopsy. In general, the diagnosis of early gastric carcinoma is easily accomplished by endoscopic observation and pathologic evaluation of endoscopic biopsy. Endoscopic detection of gastric carcinoma depends on the recognition of visible mucosal changes. However, the final diagnosis is achieved by histopathologic study of biopsy material. Biopsy is very important in obtaining the correct diagnosis of carcinoma, adenoma, hyperplasia, and metaplasia, although it is often possible to distinguish these lesions by the endoscopic characterization of mucosal surface details. Current affiliation: Department of Gastroenterology, Kyoto Second Red Cross Hospital, Kyoto, Japan. Reprint requests: Kenjiro Yasuda, MD, Kyoto Second Red Cross Hospital, Kamanza-dori, Marutamachi-Agaru, Kamagiya-ku, Kyoto, Japan 602 8026. Copyright © 2002 by the American Society for Gastrointestinal Endoscopy 0016-5107/2002/$35.00 + 0 37/0/127705 doi:10.1067/mge.2002.127705 S68
GASTROINTESTINAL ENDOSCOPY
EUS in the detection of early gastric cancer
Endoscopy has been improved from fiberoptic to video-imaging systems that use charged-coupled devices (CCDs). In addition, cross-sectional images can be obtained by using EUS.1-3 The development of magnification endoscopy can show the precise surface pattern. Furthermore, the recent development of endoscopic optical coherence tomography (EOCT) provides a future promise of histologic diagnosis in vivo. HOW TO DETECT EARLY GASTRIC CARCINOMA Careful observation by endoscopy is important for detecting small and early gastric carcinoma. Detecting an abnormal area and performing biopsy can achieve an accurate diagnosis. Theoretically this is easy to say, but practically there are some problems. For detecting early carcinoma of the stomach, endoscopists have to learn how to find early lesions and must be trained to detect abnormal areas by recognizing characteristic color and mucosal pattern abnormalities. For the purpose of training endoscopists to detect early stage gastric carcinoma and to better understand the management of different lesions, the endoscopic classification of early gastric carcinoma was established. VOLUME 56, NO. 4 (SUPPL), 2002
EUS in the detection of early gastric cancer
K Yasuda
B
A
Figure 1. A case of gastric carcinoma type IIc limited to the mucosa. A, Endoscopic finding. B, With indigo carmine dye spraying.
B
A
C
D
Figure 2. A case of type IIa+IIc early gastric cancer limited to the mucosa. A, Endoscopic picture shows redness at the greater curvature of the gastric angularis. B, Close image. C, Dye spraying reveals a clear picture of the lesion. D, EUS image shows a protruded lesion limited to the mucosa. VOLUME 56, NO. 4 (SUPPL), 2002
GASTROINTESTINAL ENDOSCOPY
S69
K Yasuda
EUS in the detection of early gastric cancer
A
A
B
B
C C Figure 3. A case of type lIb early gastric carcinoma in the body of the stomach. A, Endoscopic photo shows whitish flat mucosa and biopsy revealed adenocarcinoma. B and C, US probe with 30-MHz scanner delineates an irregular change in the submucosa (arrow). S70
GASTROINTESTINAL ENDOSCOPY
Figure 4. A case of type IIa early gastric cancer limited to the mucosa. A, Endoscopic finding showing a granular protruded lesion. B, Dye spraying view show the clear margin of the lesion. C, EUS image demonstrates the cystic change behind the lesion but the lesion is limited to the mucosa.
VOLUME 56, NO. 4 (SUPPL), 2002
EUS in the detection of early gastric cancer
K Yasuda
A
B
C
D
Figure 5. Endoscopic mucosectomy (EMR) for type IIc carcinoma at the gastric antrum. EUS reveals the lesion to be limited to the mucosa. A, Endoscopic picture. B, Indigo carmine spraying image. C, Mucosectomy procedure using the cap method. D, Mucosectomy ulcer.
It is useful to use dye spraying with indigo carmine dye for gastric carcinoma. Of course, this is a complementary technique to the endoscopic detection of a gastric lesion. Figure 1 shows a gastric carcinoma limited to the mucosa with indigo carmine dye spraying. The character and shape of the lesion are distinctly demonstrated. IS EUS EFFECTIVE? EUS diagnosis of early GI tract malignancy is one of the most recent developments in endoscopy. A cross-section of the GI wall can be demonstrated by using EUS. Two types of EUS instruments currently available are useful for this purpose. One is the conventional US endoscope with a radial scan transducer at the tip of endoscope; the other is a US catheter probe with a small radial scan transducer at the tip, which can be used through the working channel of a standard endoscope. The wall of the GI tract can be delineated as a 5 or more layered structure when distended by water in the lumen. The layers of EUS are in good correspondence with histologic wall layers. US scanners of 5.0 to 30 MHz frequency can demonstrate a precise image of the GI tract wall. VOLUME 56, NO. 4 (SUPPL), 2002
The role of EUS is to evaluate the alteration of the GI wall by carcinoma based on the ultrasonic layered structure of GI wall. That means EUS cannot be used to find a lesion, except in the rare case of gastric scirrhous carcinoma, but is used rather to evaluate the changes beneath the mucosa in order to diagnose the depth of carcinoma invasion. This assessment is an important factor in choosing a preferable treatment, such as endoscopic mucosal resection (EMR), laparoscopic surgery, or laparotomy. The diagnostic accuracy of depth of carcinoma invasion is approximately 80%, when lesions are divided into mucosal (m) carcinoma, submucosal (sm) carcinoma, carcinoma invading to the muscularis propria (pm), and carcinoma deeper than the subserosal layer (ss). The EUS diagnosis of a mucosal lesion, which is a good indication for endoscopic mucosectomy, is about 90%. One of the most important diagnostic values of EUS is to identify indications for the endoscopic treatment of early stage GI malignancy. Although EUS can detect the regional metastatic lymph nodes, the rate of detection is unsatisfactory in cases of early gastric carcinoma. GASTROINTESTINAL ENDOSCOPY
S71
K Yasuda
EUS in the detection of early gastric cancer
B
A
C
D
Figure 6. A case of type IIa+IIc early gastric cancer at the anterior wall of the gastric angularis. A, Endoscopic photo. B, Dye spraying picture. C, Magnification view by high-resolution magnification endoscopy shows an irregular area pattern. D, EUS image shows the lesion to be limited to the mucosa.
Figure 2 shows the endoscopic and EUS pictures of gastric carcinoma type IIa+IIc limited to the mucosa. Figure 3 shows the endoscopic finding of type IIb early gastric cancer and its EUS images by 30-MHz US probe invading to the submucosa (arrow). Figure 4 is a case of the type IIa gastric carcinoma limited to the mucosa. EUS demonstrates cystic change beneath the protruded lesion. EUS findings become the evidence to perform EMR (Fig. 5). ROLE OF MAGNIFICATION ENDOSCOPY Based on the advances of technology, highresolution and high-magnification endoscopy has been developed with both fiberoptic and videoimaging systems and is improving. Initial reports with high-resolution and high-magnification endo-
S72
GASTROINTESTINAL ENDOSCOPY
scopes were promising. However, it was not easy to manipulate these endoscopes during ordinary clinical examinations because of the difficulty of focusing and the dark imaging view in magnification mode. NEW HIGH-RESOLUTION AND HIGH-MAGNIFICATION ENDOSCOPES High-magnification endoscopes have a long history. The first models, which were fiberoptic systems, were developed in the late 1960s in the hope that a histologic diagnosis could be achieved without biopsy. However, technical difficulties included a dark visual field and difficulty with focusing. New electronic high-resolution and high-magnification endoscopes may overcome these difficulties. The most advanced videoendoscope for upper GI tract exami-
VOLUME 56, NO. 4 (SUPPL), 2002
EUS in the detection of early gastric cancer
K Yasuda
A
B
C
D
Figure 7. A case of type IIa early gastric cancer at the greater curvature of gastric angularis. A, Endoscopic view showing the whitish flat elevation. B, Dye spraying image. C, Magnification image showing a clearer margin. D, High-magnification picture shows the irregular mucosal and pit patterns.
nation (Olympus GF-Q240Z) can be used easily in standard mode, although focusing remains difficult in maximum magnification. However, this instrument can provide higher-resolution pictures, easier handling, and satisfactory brightness compared with earlier models. The surface mucosal pattern (pit pattern) and capillary structure can be observed by using highmagnification endoscopy. Based on the analysis of mucosal pit pattern obtained by magnification, histologic changes of carcinoma, dysplasia, and adenoma can be suspected. However, it is not easy to diagnose the histologic changes from the magnification pictures. In addition, the whole GI wall cannot be easily scanned in magnified image. Thus the role of high-magnification endoscopy is to magnify a target area in which conventional endoscopy detects an abnormality. Figure 6 shows type IIa+IIc early gastric mucosal carcinoma of the anterior wall of the gastric angle with magnification images. Figure 7 is a case of type IIa, elevated-type early gastric carcinoma limited to the mucosa at the greater curvature
VOLUME 56, NO. 4 (SUPPL), 2002
of the gastric angle, showing an irregular pit pattern of the mucosal surface. IS ENDOSCOPIC OPTICAL COHERENCE TOMOGRAPHY USEFUL FOR HISTOLOGIC DIAGNOSIS? Optical coherence tomography (OCT) is a recently developed technique for demonstrating cross-sectional images in the GI tract with 10 times higher resolution than that of 30-MHz US catheter probe. This system demonstrates images obtained by using broadband width illumination and recording the reflection of the illumination. Microscopic tissue structure can be imaged by this method, but the depth of penetration is limited. The clinical application of OCT has begun to be evaluated by using a prototype OCT probe made by Olympus Co. This probe, which has the same outside and view angle of 360˚ as the high-frequency US probe, can be used through the working channel of a standard endoscope, so this method is called endoscopic optical coherence tomography (EOCT). For EOCT scanning, water injection or balloon contact
GASTROINTESTINAL ENDOSCOPY
S73
K Yasuda
EUS in the detection of early gastric cancer
A
B
C
D
Figure 8. A case of early gastric cancer type IIa involving the mucosa. A, Endoscopic view. B, Indigo carmine dye spraying image. C, Image by endoscopic optical coherence tomography (EOCT). D, Mucosectomy material reveals well-differentiated adenocarcinoma limited to the mucosa.
methods are not required because air does not interfere with the illumination beam. To discuss the clinical significance of EOCT, 26 cases of GI tract diseases, including 2 cases of early esophageal carcinoma, 14 of early gastric carcinoma, and 1 of early duodenal carcinoma, were examined by EOCT. The lesions were demonstrated by EOCT with high resolution but poor penetration. The depth of imaging penetration was 1.5 to 2.0 mm, but the mucosal glandular structure could not be demonstrated; the lamina propria, muscularis mucosa, and part of submucosa were imaged. The gastric wall is observed as a layered structure, which is different from that of the esophageal wall layers. The surface layer shows a glandular structure, and behind, 3 layers of high, low and high reflective layers, which are thought to be the lamina S74
GASTROINTESTINAL ENDOSCOPY
propria (high reflectivity), muscularis mucosa (low reflectivity), and interface layer of submucosal layer (high reflectivity). Though the resolution was much higher than that of the 30-MHz US scanner, penetration of EOCT was too poor to use this method for assessing the depth of tumor invasion. However, by using this sophisticated instrument, the histologic nature of tissues can be evaluated. EOCT if perfected might be used as a method for optical biopsy in fixture endoscopic examinations. Figure 8 shows endoscopic and EOCT pictures of a type IIa gastric carcinoma. DIAGNOSIS OF EARLY GASTRIC CARCINOMA IN THE FUTURE Detection of small gastric carcinomas is feasible with endoscopic observation with or without dye VOLUME 56, NO. 4 (SUPPL), 2002
EUS in the detection of early gastric cancer
spraying. Furthermore, endoscopy with additional systems such as EUS, magnification endoscopy, and EOCT can evaluate the lesions more completely. The significance of endoscopic detection and staging of early gastric carcinoma is to diagnose small lesions, which can be managed by endoscopic treatments such as mucosectomy. Automatic imaging diagnosis and pathologic diagnosis of early gastric cancer lies in the future by using endoscopy and various techniques, such as EUS and EOCT. For this purpose, the development of automatic pattern recognition systems is required. It seems possible that in the near future there will be auto-
VOLUME 56, NO. 4 (SUPPL), 2002
K Yasuda
matic diagnosis systems based on the analysis of images by information technology. REFERENCES 1. Yasuda K, Nakajima M, Kawai K. Fundamentals of endoscopic laser therapy (ELT) for GI tumors; new aspects with endoscopic ultrasonography (EUS). Endoscopy 1987;19 (Suppl):S2-6. 2. Yasuda K, Nakajima M, Kawai K. Endoscopic diagnosis and treatment of early gastric cancer using endoscopic ultrasonography (EUS). Gastrointest Endosc Clin N Am 1992;2: 495-507. 3. Yasuda K. Gastrointestinal carcinoma. In: The handbook of endoscopic ultrasonography in digestive tract. Tokyo, Japan: Blackwell Science; 2000. p. 54-69.
GASTROINTESTINAL ENDOSCOPY
S75