Download 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