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63
Pictorial
H
Jose
.::
.
Endoscopic Tract F. Botet1
and
Sonography Charles
of the Upper Gastrointestinal
Lightdale2
Endoscopic sonography was used to examine the upper gastrointestinal tract of 550 patients referred for evaluation of abnormal findings seen on conventional endoscopy, upper gastrointestinal series, and CT. This essay illustrates the potential uses and limitations of this technique. Special emphasis has been given to the use of landmarks to facilitate orientation of the transducer in both the esophagus and stomach. Specific examples demonstrate involvement of individual layers of the bowel wall in both benign and malignant processes. It is stressed that this is a combined procedure requiring both an endoscopist and a radiologist.
Endoscopic
substantial tract.
sonography
potential
is a valuable
in the evaluation
new
technology
with
of the upper gastrointestinal
Endoscopic combines
sonography
the advantages
is a relatively of direct
new
endoscopic
sonography
with the bowel
wall via a water-filled
balloon
esophagus
or water
the stomach
it possible
filling
makes
Di Magno
et al. [1], who
published
their
preliminary
in 1980.
of esopha-
A, Diagram shows five-layered structure as depicted by endoscopic sonography. 1 = mu-
cosal Interface, highly echogenic; 2 = muscularis mucosa, hypoechoic; 3 = submucosa, highly echogenic; 4 = lamina propria, hypoechoic; 5 = adventitlal interface, highly echogenic; 6 = transducer with inflated balloon. B, Actual cross-sectional image of esophagus as visualized with endoscopic sonography (12MHz transducer). A
B
Received January 31 , 1990: accepted after revision July 9, 1990. Presented in part as an exhibit at the annual meeting of the American Roentgen Ray Society, New Orleans, LA, May 1989. 1 Department of Medical Imaging, Memorial Sloan-Kettering Cancer Center, New York, NY 1 0021 . Address reprint requests 2 Department of Medicine, Gastroenterology Service, Memorial Sloan-Kettering Cancer Center, New York, NY 10021.
January 1991 0361-803x/91/1561-0063
C American
Roentgen
in the to
circumvent the problem air presents with the use of sonography. Some of the earliest work in this field was done by
geal wall.
AJR 156:63-68,
that
visualization
transducer
ences
1.-Endoscopic
technique
of the bowel wall with the capabilities of high-frequency sonography to visualize the layers of the bowel wall and the immediately surrounding spaces. The direct contact of the
Esophagus
Fig.
Essay
Ray Society
to J. F. Botet.
experi-
BOTET
64
AND
LIGHTDALE
AJR:156,
Fig.
2.-Endoscopic
esophagus
January
sonography
of normal
(E) with 12-MHz transducer
A and B, Diagram (A) and upper portion of esophagus.
1991
sonogram Trachea
(T). (B) (TR)
of is
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anterior upper thoracic spine (TS) is posterior. LC = left carotid artery, LS = left subclavian artery. C and D, Diagram (C) and sonogram (D) of middle portion of esophagus. Section just below carina shows both right (RB) and left (LB) main bronchi Note elongation of aorta (A) at beginning of sortie arch; two hypoechoic vascular structures at both sides of aorta are azygous (a) and hemiazygous (h) veins. E and F, Diagram (E) and sonogram (F) of lower portion of esophagus (E). Note close relationship of lower esophagus with left atrium (LA) anteriorly;aorta (A) lies posterioriy.
D
C
LA
,
Technique The instrument used is a side-viewing endoscope measuring 1 3 mm in diameter, with a sonographic transducer at its tip. Two models are currently available, EU-M2 and EU-M3 (Olympus Corp., New Hyde Park, NY). The frequencies used are 7.5 MHz (EU-M2) and both 75 and 1 2 MHz (EU-M3). These mechanical probes provide real-time images with a 1 80#{176} or 360#{176} field of view orthogonal to the plane of the
endoscope. Depth of view with the 7.5-MHz transducer
is a maximum and a 3-cm
of a 7-cm radius radius with the 12-
MHz transducer. The procedures were performed by an endoscopist and a radiologist. The endoscopist introduced and manipulated the endoscope while the radiologist interpreted the images and guided the endoscopist in the positioning of the sonographic transducer.
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Fig. 3.-Endoscopic sonography of benign conditions of esophagus with 7.5-MHz transducer. A, Leiomyoma. Characteristic hypoechoic lesion arising from muscularis mucosa (large arrow). Overlying mucosa (small arrow) is intact. B, Duplication cyst. These usually hypoechoic lesions (arrowheads) may be difterentiated from leiomyomas by their location outside of normal fivelayered esophageal wall (arrow). C, Varices. Submucosal nature of esophageal varices (arrowheads) is not well demonstrated by endosonography because of compression by distended balloon. Extramural component at level of cardia appears as echo-free rounded structures.
Fig. 4.-Endoscopic sonography A, Tumor (12-MHz transducer). surgery. B, Nodes (7.5-MHz transducer).
of malignant processes. T4 tumor (T) of lower esophagus Two
1.4-cm
nodes
Multiple
small
(N) surround
has invaded left subclavian
pericardium. artery
Discontinuity
(a). Although
in pericardial
larger
than
fat (arrow)
1 cm, they
appear
was confirmed hyperechoic;
at
they
were found to be reactive at surgery. C, Small be Involved
nodes (12-MHz transducer). by tumor at surgery.
Fig. 5.-Endoscopic sonography of gastric wall. A, Diagram shows five-layered structure of normal gastric wall in distended stomach. A = mucosa, highly echogenic; B = muscularis mucosa, hypoechoic; = submucosa, highly echogenic; D = lamina propria, hypoechoic; E = serosa, highly echogenic; F = transducer. B, Sonogram of gastric wall (12-MHz transducer) distended with 400 ml of water shows same layers.
(4-6
mm) subcarinal
nodes
(n) with rounded
and relatively
low-level
internal
echoes
were
found
to
66
BOTET
AND
LIGHTDALE
AJA:156,
Fig.
6.-Endoscopic
January
sonography
stomach with 7.5-MHz transducer
1991
of normal
(T)
A and B, Diagram (A) and sonogram (B) of fundus. Left hepatic lobe (L) Is anterior, right hepatic lobe (R) Is to right Left (LHV), middle
(MHV), and right (RHV) hepatic veins drain Into
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inferior
vena cava
= gastric
(IVC).
Aorta
(A) is posterior.
S
fundus.
C and D, Diagram (C) and sonogram (D) of body Note relationship of gastric body to both splenic artery (SPL AR) and splenic vein (SPL
V). S = gastric body. E and F, Diagram (E) and sonogram (F) of antrum. Pancreas body and part of head are seen
posteriorly;
at same
level
splenlc
(SPL
V)
and superior mesenteric (SMV) veins join to form portal vein. Splenic artery (SPL AR) is just anterior. LPV = left portal vein, S = gastric antrum.
Esophagus The normal thickness of the esophageal wall when the lumen is distended with a 3-cm-diameter water-filled balloon is approximately 3 mm and is essentially uniform throughout. Five layers can be identified in the normal esophagus (Fig. 1). Sonographically, the esophagus can be divided into three parts: upper, middle, and lower. The upper portion of the esophagus extends from the oropharynx to the superior
aspect of the aortic arch; the most useful landmarks here are the vertebral column posteriorly and the tracheal air column anteriorly (Fig. 2A). The middle portion of the esophagus extends from the aortic arch to the subcarinal region, where the most useful relationships are the aortic arch and descending aorta posteriorly and the trachea and carina anteriorly (Fig. 2B). The lower portion of the esophagus extends from the subcarinal region to the cardia; the descending aorta is posterior and the left atrium is anterior (Fig. 2C).
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Fig. 7-Endoscopic sonography of benign gastric processes with 12-MHz transducer. A, Gastritis. There is significant thickening of all layers, especially mucosa (white arrow) and submucosa (black arrow), in distended stomach. Overall architecture is maintained. B, Gastric ulcers. There is disruption of mucosal layer (white arrow) and associated inflammatory changes into submucosa and lamina propria (black arrow) in this small ulcer. C, Gastric polyps. These benign hyperplastic polyps (P) arise only from mucosa (straight white arrow), whereas submucosa (straight black arrow) and lamina propria (curved arrows) appear normal.
Fig.
8.-Endoscopic
sonography
of
gastric
varices. A, Gastric
varices
(7.5-MHz
arise within or outside
gastric
transducer)
may
wall. They are
more commonly seen in fundus along greater curvature (v). Anechoic rounded and elongated structures are seen from 10 o’clock to 6 o’clock positions. B, Gastric varices (12-MHz transducer). These large varices are characterized as hypoechoic rounded or elongated structures with strong posterior wall enhancement when imaged with higher-frequency transducer.
A
Fig. 9.-Endoscopic sonography A, Adenocarcinoma. Tumor (T) B, Nodes. Multiple small nodes and hypoechoic nodes were found C, Gastric lymphoma. Folds (L)
B
of malignant gastric processes with 12-MHz transducer. involves all layers of gastric wall extending beyond serosa but not involving any adjacent structure. (n) in gastrohepatic ligament region, largest two measuring 5 and 6 mm at 1 1 and 12 o’clock positions. to be involved by tumor at surgery. are thickened and prominent and there is circumferential involvement.
These
round
68
BOTET
AND
LIGHTDALE
AJA:156,
January
1991
Fig. 10.-Endoscoplc sonography of tumor recurrences with 7.5-MHz transducer. A, Esophageal recurrence at anastomosis
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after pull-up surgery. Two areas of recurrence (R) are Identified at 7 and 10 o’clock posftlons. B, Gastric recurrence(R)after partial gastrectomy. There are a double set of layers at esophagogastric anastomosls at 3 o’clock position, and nodularlty with disruption of normal layers between 7 and 12 o’clock positions. Biopsy proved this to be a recurrence of original gastric tumor.
Typical benign processes include leiomyomas (Fig. 3A), duplication cysts (Fig. 3B), and varices (Fig. 3C). Sonograms of esophageal carcinoma are characterized by disruption of the layers of the esophageal wall, beginning with the mucosa, and possibly extending to involve all layers and invade the surrounding structures (Fig. 4A). Metastasis to lymph nodes as small as 2 mm in diameter can be visualized (Figs. 4B and 4C) [2]. On the basis of our experience in over 600 cases examined with endoscopic sonography, we have defined three criteria that suggest nodal involvement: Nodes that appear round are more likely to be malignant than those that appear elongated. Nodes that are hype- or isoechoic with respect to the primary tumor also are more likely to be malignant. Those nodes that are hyperechoic are more commonly benign. Size is the least reliable predictor of malignant/ benign involvement: nodes in the 3- to 5-mm range have been proved to be malignant, while nodes as large as 3 cm have been proved to be benign.
the pancreas to the left and posteriorly (Fig. 6B). Sonograms of the antrum of the stomach show the left hepatic lobe anteriorly and the pancreas, splenic vein, and portal vein posteriorly. In the very distal antrum the gallbladder can be seen to the right (Fig. 6C). Typical benign gastric lesions include gastritis (Fig. 7A), ulcer (Fig. 7B), polyps (Fig. 7C), and varices (Fig. 8). Sonograms in cases of gastric carcinoma show disruption of the wall beginning with the mucosa (Fig. 9A). Nodal involvement of the gastric drainage areas may be shown by endoscopic sonography (Fig. 9B). Gastric involvement by lymphoma is not uncommon in the non-Hodgkin family of tumors; it arises from the lamina propria of the mucosa, which is rich in lymphoid tissue. Bolondi et al. [3] suggest that it may be differentiated on the basis of endoscopic sonography from carcinoma, because carcinoma may be more echogenic than lymphoma (Fig. 9C). Recurrences from both gastric and esophageal tumors can be detected by endoscopic sonography (Fig. 1 0) [4].
Stomach The normal thickness of the gastric wall varies according to the degree of gastric distension. In a fully distended waterfilled stomach the thickness is approximately 3 mm. Sonograms show the five layers of the gastric wall (Fig. 5). The stomach can be divided into the fundus, the body, and the antrum. The sonographic landmarks of the fundus are the aorta with the celiac axis posteriorly; the left hepatic lobe is seen to the right and the spleen is seen to the left (Fig. 6A). Sonograms of the body of the stomach will show the left hepatic lobe to the right and anteriorly, the body and tail of
REFERENCES 1 . Di Magno EP, Aegan PT, Clam JE, et al. Human endoscopic ultrasonography. Gastroenterology 1982:83:824-829 2. Tic TL, Cohen P, Coene P, et al. Endosonography and computed tornography of esophageal carcinoma. Gastroenterology 1989:96: 1478-1 486 3. Bolondi L, Casanova P, Caletti GC, Grigioni W, Zani L, Barbara L. Primary gastric lymphoma versus gastric carcinoma: endoscopic US evaluation. Radiology 1987:165:821-826 4. Ughtdale cJ, Botet JF, Brennan M, Kelsen DP, Tumbull AD. Diagnosis of recurrent gastric cancer at the surgical anastomosis by endoscopic ultrasonography. Gastrointest Endosc 1989:35:407-412