European Journal of Radiology, 13 ( 199 1) 8 1-87 0 1991 Elsevier Science Publishers B.V. All rights reserved.
EURRAD
81
0720-048X/91/$03.50
00202
Transabdominal ultrasound of the stomach: a pictorial essay Liesbeth S. Sijbrandij and J. Odo Op den Orth Department of Radiology, St. Eiisabethk of Groote Gasthuis,Haarlem, The Netherlands (Received
12 December
Key words: Ultrasound
1990; accepted
study, stomach;
Introduction It is advisable to exclude gross pathology of the stomach during ultrasonography (US) of the upper abdomen. Extensive malignant infiltration of the gastric wall and large leiomyomas are in most instances easily detected. Recently it has been demonstrated that transabdominal US of the stomach, after oral administration of water and injection of a hypotonic agent, may provide detailed and unique information on the normal and abnormal gastric wall [l-3]. In vivo US findings have been compared with surgical specimen studies in a water bath and agreed well. Comparison of specimen studies with histologic sections has been useful for our understanding of in vivo US findings [ 1,2,4]. At our institution, water and glucagon are administered if US findings, such as abnormal thickness of the gastric wall or gastric retention, during routine upper abdominal US suggest gastric pathology. Dedicated gastric US is also employed complementary to the radiologic examination and endoscopy. In this pictorial essay we describe our technique and illustrate preliminary findings in a variety of conditions .
after revision 6 June 1991)
Stomach,
ultrasound
study
of interest. A tilting table that can move between the Trendelenburg and the upright position is an essential accessory. By moving the patient and the table, air is removed from the segment of the stomach under investigation. The distal half of the stomach is, for example, examined in the right-lateral decubitus or right posterior
Technique The employed technique was originally designed to improve US visualization of the pancreas [ 51. After an overnight fast, the patient drinks 600 ml water and gets an intravenous injection of 0.3 mg of glucagon; this provides optimal distension of the stomach which improves visualization of the gastric wall. The position of the patient for the examination depends on the area Address for reprints: E.S. Sijbrandij, M.D., Department ology, St. Elisabeth’s of Groote Gasthuis, Boerhaavelaan AK Haarlem, The Netherlands.
of Radi22, 2000
Fig. 1. Transverse scan with a 7.5 Mhz transducer of the gastric corpus of a patient after water and i.v. glucagon administration. Normal anterior and posterior wall (arrows) of the gastric corpus are shown to good advantage. Diameters are 4 and 5 mm, respectively. 1, interface between fluid and mucosa; 2, mucosa; 3, submucosa; 4, muscularis propria; 5, serosa and subserosal fat. W = water.
82
oblique position with the table top slightly raised. In this position the fluid accumulates in the gastric corpus and antrum, and the gas in the fundus. Graded compression, which can be employed on the distal half of the stomach, frequently allows the use of high-frequency transducers. Scans were obtained with a Toshiba Sonolayer SSA-100A with a 3.15 MHz convex array probe, and an Aloka SSD-650 with a 3.5 MHz convex sector probe, and 5 and 7.5 MHz linear probes. The use of transducers of different frequencies enables both global and detailed visualization of the gastric wall. Normal gastric wall Usually five layers can be distinguished within the gastric wall. They correspond almost directly to the histologic layers, as proved by comparing identical US and histologic sections [ 21. The innermost hyperechoic layer corresponds to the interface between the fluid and the mucosa (Fig. 1). The second hypoechoic layer is caused by the mucosa. The third hyperechoic layer represents the submucosa, and the fourth hypoechoic layer the muscularis propria. Finally, the fifth layer is hyperechoic and is caused by the serosa and subserosal Fig. 3. Transverse scan with a 7.5 MHz transducer, shows thickening of the anterior (black arrows) and posterior wall (white arrows) of the gastric corpus. In the walls no layers can be observed. Findings are compatible with linitis plastica which was proved by pathology. Linitis plastica was caused by metastatic carcinoma of the breast. W = water. White arrows point to the mucosal surface of the posterior wall which is only partly depicted.
fat. We have experienced that the maximum thickness of the normal gastric wall, after administration of water and glucagon, usually does not exceed 7 mm. Abnormal gastric wall
Fig. 2. Scan with a 5 MHz transducer shows extreme thickening of part of the anterior wall of the corpus. The maximum diameter is more than 2 cm (arrowheads); the site where the normal layered gastric wall changes into a hypoechoic thickened wall, with disappearance of all layering, is marked with an asterisk. Water in the stomach is slightly echogenic, because the microbubbles have not yet disappeared. There is also some retained material in the stomach. Endoscopic biopsies demonstrated adenocarcinoma. W = water, still a little echogenic.
Diffuse thickening of the gastric wall with disappearance of the layers, which are generally visible at US, may be caused by either malignant, for example adenocarcinoma (Figs. 2 and 3), or malignant lymphoma (Fig. 4), or benign, for example peptic ulcer (Fig. 5), conditions. An echogenic focus within a thickened gastric wall is usually caused by necrotic material at the bottom of an ulcer [ 41. Selective involvement of one or two layers may suggest the histologic origin of a lesion. A myogenic tumor (Fig. 6a, b and c). a submucosal module caused by heterotopic pancreatic tissue (Fig. 6d), mucosal hyperplasia (Fig. 6e) and epithelial polyps (Fig. 6f) can therefore usually be identitied. At our institution, transabdominal gastric US also proved useful complementary to radiography and endo-
a
Fig. 4. Transverse scan with a 7.5 MHz transducer demonstrates thickening of anterior (arrowheads) and posterior (arrows) gastric wall; in the posterior wall no layers can be observed. Mucosal surface is very coarse and irregular which suggested malignant lymphoma rather than linitis plastica, which was confirmed by endoscopic biopsies. W = water.
scopy in differentiating between benign and malignant causes underlying an abnormal mucosal relief (Figs. 7, 8 and 9). Discussion US of the stomach may provide important information on the gastric wall, which cannot be obtained with other imaging methods. Currently two routes are employed: (1) in endoscopic US the probe is introduced in the stomach which allows routinely the use of high-frequency transducers, (2) in transabdominal US the employment of high-frequency transducers is usually only possible for those parts of the stomach which can be reached by graded compression. Although the gastric fundus can in most instances be examined with a 3.5 MHz transducer, tiny lesions in the fundus can easily be missed. Endoscopic US is an expensive and invasive technique often necessitating heavy sedation; it is therefore only employed on specific indications, usually rather late in the work-up of a gastric problem.
b Fig. 5. (a) Routine transverse scan with a 3.5 MHz transducer of a fasting patient reveals retained material (r) in the stomach. The lateral wall of the antrum (black arrows) is not thickened and shows normal layered appearance. Media1 wall of antrum is thickened and hypoechoic; within this thickened wall an echogenic focus (white arrow) is apparent. (b) Transverse scan of the gastric antrum with a 7.5 MHz transducer shows the five layers ofthe ventral and dorsal wall (black arrows) to good advantage. The medial wall is hypoechoic and thickened (white >); the layered structure is lost and within the medial wall an echogenic focus (white arrow) is again observed. Barium examination and endoscopy demonstrated an ulcer in the medial wall of the antrum; endoscopic biopsies and follow-up made malignancy highly improbable. r = retained material.
a Fig. 7. (a) Double-contrast study shows a very irregular mucosal relief. (b) Scan with a 5 MHz transducer after water and i.v. glucagon administration shows a normal thickness ofthe gastric wall. The abnormal relief is apparently caused by unusually undulating gastric mucosa (arrows); a malignant lesion is highly improbable. The patient refused gastroscopy. W = water.
In contrast, the non-invasive transabdominal US technique can be employed in a much greater population with (suspected) gastric pathology. In the future, relative indications for endoscopic and transabdominal US will have to be worked out. In contrast to endoscopic US there is only very limited information available in the literature on transabdominal US. The interpretation of findings with transabdominal US is, however, the same as of those obtained with endoscopic US. Specific layer involvement often suggests the underlying pathology; however; this modality does not enable a definite histologic diagnosis. Especially if ulceration is present, differentiation between carcinomatous infiltration,
t
b
inflammatory
infiltration
and fibrosis is not possible
[91. Acknowledgements The authors thank Willem Dekker, M.D., and Jaap Ferwerda, M.D., for their cooperation and excellent endoscopic feedback.
~____
Fig. 6. (a) Scan with a 3.5 MHz transducer shows a hypoechoic mass (m) in the proper muscle layer ofthe posterior wall (white arrows). Barium examination and endoscopy were compatible with a small prepyloric leiomyoma. W = water; black arrows = normal gastric wall. (b) Routine transverse scan with a 3.75 Hhz transducer of the upper abdomen shows a hypoechoic mass (m) with a diameter of several centimeters. ao = aorta, arrow points to the gastric wall. (c) Scan with a 7.5 MHz transducer after water and i.v. glucagon administration demonstrates that the mass (m), which has the same echogenicity as the proper muscle layer, is covered by the three superficial layers of the gastric wall (white arrows). Findings suggest a myogenic tumor. W = water; black arrows = normal gastric wall. (d) Scan with a 5 MHz transducer demonstrates a primarily hyperechoic mass (M), located in the submucosa of the posterior wall (arrows) of the prepyloric region. Endoscopic findings were compatible with aberrant pancreatictissue. W = water. (e) Transverse scan with a ~-MHZ transducer of a patient, in whom a barium examination showed multiple coarse rigid,folds. Thickening of the gastric wall is restricted to the mucosal layer ( 2_,). Findings are compatible with mucosal hyperplasia. Multiple endoscopic biopsies however did not lead to a specific mucosal hyperplasia, for example Menetrier’s disease. W = water; pw = posterior wall. (f) Dedicated pancreatic US revealed multiple lesions projecting from the gastric mucosal surface into the lumen of the stomach. This transverse scan with a 7.5 MHz transducer shows an anterior and a posterior wall lesion. The layered structure of these polypoid lesions and the relation to the normal gastric wall are shown to good advantage; findings are compatible with epithelial polyps. Our files revealed that earlier endoscopic intervention had demonstrated hyperplastic polyps. W = water.
86
a b Fig. 8. (a) Double-contrast study shows an irregular mucosal relief. (b) Scan with a 3.75 MHz transducer after water and glucagon administration demonstrates a normal diameter of the posterior gastric wall (VA); even with this transducer an indication of the normal layered structure can be observed. The anterior wall (aw), however, is hypoechoic and measures more than 1 cm; there is no indication of a layered structure. Endoscopic biopsies demonstrated adenocarcinoma; the resected specimen demonstrated infiltration through all wall layers. w = water.
a Fig. 9. (a) Double-contrast study of the gastric wall mainly caused thickening of the submucosa; the hypertrophic gastritis. w = water,
b demonstrates filling defect at the lesser curvature. (b) Scan with a 5 MHz transducer shows local thickening by an increased diameter of the mucosa; the echogenicity of the mucosa is normal. There is also slight proper muscle layer is normal. An early carcinoma cannot be excluded. Endoscopic biopsies demonstrated m = mass caused by selective thickening of the mucosa. The normal anterior gastric wall is numbered as in Fig. 1; arrowheads = posterior gastric wall.
References 1 Miyamoto Y, Tsujimoto F, Shimpei T. Ultrasonographic diagnosis of submucosal tumors of the stomach. The ‘bridging layers’ sign. J Clin Ultrasound 1988; 16: 251-258. 2 Miyamoto Y, Nakatani M, Ida M et al. Ultrasonographic find-
ings in gastric cancer: in vitro and in vivo studies. J Clin Ultrasound 1989; 17: 309-318. 3 Worlicek H, Dunz D, Engelhard K. Ultrasonic examination of the wall of the fluid-filled stomach. J Clin Ultrasound 1989; 17: 5-14. 4 Martinez-Noguera A, Mata J, Matias-Guiu X et al. Echogenic
87
focus in the gastrointestinal wall as sign of ulceration. Gastrointest Radio1 1989; 14: 295-299. 5 Op den Orth JO. Tubeless hypotonic duodenography with water: simple aid in sonography of the pancreatic head. Radiology 1985; 154: 826. 6 Smithuis RHM, Op den Orth JO. Gastric fluid detected by sonography in fasting patients: relation to duodenal ulcer disease and gastric outlet-obstruction. AJR 1989; 153: 731-733. 7 Yashuda K, Nakajima M, Yoshida S et al. The diagnosis of sub-
mucosal tumors of the stomach by endoscopic ultrasonography. Gastrointest Endosc 1989; 35: IO-15 8 Nakazawa S, Yoshino J, Nakamura T et al. Endoscopic ultrasonography of gastric myogenic tumor, a comparative study between histology and ultrasonography. J Ultrasound Med 1989; 8: 353-359 9 Ohashi S, Nakazawa S, Yoshino J. Endoscopic ultrasonography in the assessment of invasive gastric cancer. Scan J Gastroenterol 1989; 24: 1039-1048.
EURRAD
81
0720-048X/91/$03.50
00202
Transabdominal ultrasound of the stomach: a pictorial essay Liesbeth S. Sijbrandij and J. Odo Op den Orth Department of Radiology, St. Eiisabethk of Groote Gasthuis,Haarlem, The Netherlands (Received
12 December
Key words: Ultrasound
1990; accepted
study, stomach;
Introduction It is advisable to exclude gross pathology of the stomach during ultrasonography (US) of the upper abdomen. Extensive malignant infiltration of the gastric wall and large leiomyomas are in most instances easily detected. Recently it has been demonstrated that transabdominal US of the stomach, after oral administration of water and injection of a hypotonic agent, may provide detailed and unique information on the normal and abnormal gastric wall [l-3]. In vivo US findings have been compared with surgical specimen studies in a water bath and agreed well. Comparison of specimen studies with histologic sections has been useful for our understanding of in vivo US findings [ 1,2,4]. At our institution, water and glucagon are administered if US findings, such as abnormal thickness of the gastric wall or gastric retention, during routine upper abdominal US suggest gastric pathology. Dedicated gastric US is also employed complementary to the radiologic examination and endoscopy. In this pictorial essay we describe our technique and illustrate preliminary findings in a variety of conditions .
after revision 6 June 1991)
Stomach,
ultrasound
study
of interest. A tilting table that can move between the Trendelenburg and the upright position is an essential accessory. By moving the patient and the table, air is removed from the segment of the stomach under investigation. The distal half of the stomach is, for example, examined in the right-lateral decubitus or right posterior
Technique The employed technique was originally designed to improve US visualization of the pancreas [ 51. After an overnight fast, the patient drinks 600 ml water and gets an intravenous injection of 0.3 mg of glucagon; this provides optimal distension of the stomach which improves visualization of the gastric wall. The position of the patient for the examination depends on the area Address for reprints: E.S. Sijbrandij, M.D., Department ology, St. Elisabeth’s of Groote Gasthuis, Boerhaavelaan AK Haarlem, The Netherlands.
of Radi22, 2000
Fig. 1. Transverse scan with a 7.5 Mhz transducer of the gastric corpus of a patient after water and i.v. glucagon administration. Normal anterior and posterior wall (arrows) of the gastric corpus are shown to good advantage. Diameters are 4 and 5 mm, respectively. 1, interface between fluid and mucosa; 2, mucosa; 3, submucosa; 4, muscularis propria; 5, serosa and subserosal fat. W = water.
82
oblique position with the table top slightly raised. In this position the fluid accumulates in the gastric corpus and antrum, and the gas in the fundus. Graded compression, which can be employed on the distal half of the stomach, frequently allows the use of high-frequency transducers. Scans were obtained with a Toshiba Sonolayer SSA-100A with a 3.15 MHz convex array probe, and an Aloka SSD-650 with a 3.5 MHz convex sector probe, and 5 and 7.5 MHz linear probes. The use of transducers of different frequencies enables both global and detailed visualization of the gastric wall. Normal gastric wall Usually five layers can be distinguished within the gastric wall. They correspond almost directly to the histologic layers, as proved by comparing identical US and histologic sections [ 21. The innermost hyperechoic layer corresponds to the interface between the fluid and the mucosa (Fig. 1). The second hypoechoic layer is caused by the mucosa. The third hyperechoic layer represents the submucosa, and the fourth hypoechoic layer the muscularis propria. Finally, the fifth layer is hyperechoic and is caused by the serosa and subserosal Fig. 3. Transverse scan with a 7.5 MHz transducer, shows thickening of the anterior (black arrows) and posterior wall (white arrows) of the gastric corpus. In the walls no layers can be observed. Findings are compatible with linitis plastica which was proved by pathology. Linitis plastica was caused by metastatic carcinoma of the breast. W = water. White arrows point to the mucosal surface of the posterior wall which is only partly depicted.
fat. We have experienced that the maximum thickness of the normal gastric wall, after administration of water and glucagon, usually does not exceed 7 mm. Abnormal gastric wall
Fig. 2. Scan with a 5 MHz transducer shows extreme thickening of part of the anterior wall of the corpus. The maximum diameter is more than 2 cm (arrowheads); the site where the normal layered gastric wall changes into a hypoechoic thickened wall, with disappearance of all layering, is marked with an asterisk. Water in the stomach is slightly echogenic, because the microbubbles have not yet disappeared. There is also some retained material in the stomach. Endoscopic biopsies demonstrated adenocarcinoma. W = water, still a little echogenic.
Diffuse thickening of the gastric wall with disappearance of the layers, which are generally visible at US, may be caused by either malignant, for example adenocarcinoma (Figs. 2 and 3), or malignant lymphoma (Fig. 4), or benign, for example peptic ulcer (Fig. 5), conditions. An echogenic focus within a thickened gastric wall is usually caused by necrotic material at the bottom of an ulcer [ 41. Selective involvement of one or two layers may suggest the histologic origin of a lesion. A myogenic tumor (Fig. 6a, b and c). a submucosal module caused by heterotopic pancreatic tissue (Fig. 6d), mucosal hyperplasia (Fig. 6e) and epithelial polyps (Fig. 6f) can therefore usually be identitied. At our institution, transabdominal gastric US also proved useful complementary to radiography and endo-
a
Fig. 4. Transverse scan with a 7.5 MHz transducer demonstrates thickening of anterior (arrowheads) and posterior (arrows) gastric wall; in the posterior wall no layers can be observed. Mucosal surface is very coarse and irregular which suggested malignant lymphoma rather than linitis plastica, which was confirmed by endoscopic biopsies. W = water.
scopy in differentiating between benign and malignant causes underlying an abnormal mucosal relief (Figs. 7, 8 and 9). Discussion US of the stomach may provide important information on the gastric wall, which cannot be obtained with other imaging methods. Currently two routes are employed: (1) in endoscopic US the probe is introduced in the stomach which allows routinely the use of high-frequency transducers, (2) in transabdominal US the employment of high-frequency transducers is usually only possible for those parts of the stomach which can be reached by graded compression. Although the gastric fundus can in most instances be examined with a 3.5 MHz transducer, tiny lesions in the fundus can easily be missed. Endoscopic US is an expensive and invasive technique often necessitating heavy sedation; it is therefore only employed on specific indications, usually rather late in the work-up of a gastric problem.
b Fig. 5. (a) Routine transverse scan with a 3.5 MHz transducer of a fasting patient reveals retained material (r) in the stomach. The lateral wall of the antrum (black arrows) is not thickened and shows normal layered appearance. Media1 wall of antrum is thickened and hypoechoic; within this thickened wall an echogenic focus (white arrow) is apparent. (b) Transverse scan of the gastric antrum with a 7.5 MHz transducer shows the five layers ofthe ventral and dorsal wall (black arrows) to good advantage. The medial wall is hypoechoic and thickened (white >); the layered structure is lost and within the medial wall an echogenic focus (white arrow) is again observed. Barium examination and endoscopy demonstrated an ulcer in the medial wall of the antrum; endoscopic biopsies and follow-up made malignancy highly improbable. r = retained material.
a Fig. 7. (a) Double-contrast study shows a very irregular mucosal relief. (b) Scan with a 5 MHz transducer after water and i.v. glucagon administration shows a normal thickness ofthe gastric wall. The abnormal relief is apparently caused by unusually undulating gastric mucosa (arrows); a malignant lesion is highly improbable. The patient refused gastroscopy. W = water.
In contrast, the non-invasive transabdominal US technique can be employed in a much greater population with (suspected) gastric pathology. In the future, relative indications for endoscopic and transabdominal US will have to be worked out. In contrast to endoscopic US there is only very limited information available in the literature on transabdominal US. The interpretation of findings with transabdominal US is, however, the same as of those obtained with endoscopic US. Specific layer involvement often suggests the underlying pathology; however; this modality does not enable a definite histologic diagnosis. Especially if ulceration is present, differentiation between carcinomatous infiltration,
t
b
inflammatory
infiltration
and fibrosis is not possible
[91. Acknowledgements The authors thank Willem Dekker, M.D., and Jaap Ferwerda, M.D., for their cooperation and excellent endoscopic feedback.
~____
Fig. 6. (a) Scan with a 3.5 MHz transducer shows a hypoechoic mass (m) in the proper muscle layer ofthe posterior wall (white arrows). Barium examination and endoscopy were compatible with a small prepyloric leiomyoma. W = water; black arrows = normal gastric wall. (b) Routine transverse scan with a 3.75 Hhz transducer of the upper abdomen shows a hypoechoic mass (m) with a diameter of several centimeters. ao = aorta, arrow points to the gastric wall. (c) Scan with a 7.5 MHz transducer after water and i.v. glucagon administration demonstrates that the mass (m), which has the same echogenicity as the proper muscle layer, is covered by the three superficial layers of the gastric wall (white arrows). Findings suggest a myogenic tumor. W = water; black arrows = normal gastric wall. (d) Scan with a 5 MHz transducer demonstrates a primarily hyperechoic mass (M), located in the submucosa of the posterior wall (arrows) of the prepyloric region. Endoscopic findings were compatible with aberrant pancreatictissue. W = water. (e) Transverse scan with a ~-MHZ transducer of a patient, in whom a barium examination showed multiple coarse rigid,folds. Thickening of the gastric wall is restricted to the mucosal layer ( 2_,). Findings are compatible with mucosal hyperplasia. Multiple endoscopic biopsies however did not lead to a specific mucosal hyperplasia, for example Menetrier’s disease. W = water; pw = posterior wall. (f) Dedicated pancreatic US revealed multiple lesions projecting from the gastric mucosal surface into the lumen of the stomach. This transverse scan with a 7.5 MHz transducer shows an anterior and a posterior wall lesion. The layered structure of these polypoid lesions and the relation to the normal gastric wall are shown to good advantage; findings are compatible with epithelial polyps. Our files revealed that earlier endoscopic intervention had demonstrated hyperplastic polyps. W = water.
86
a b Fig. 8. (a) Double-contrast study shows an irregular mucosal relief. (b) Scan with a 3.75 MHz transducer after water and glucagon administration demonstrates a normal diameter of the posterior gastric wall (VA); even with this transducer an indication of the normal layered structure can be observed. The anterior wall (aw), however, is hypoechoic and measures more than 1 cm; there is no indication of a layered structure. Endoscopic biopsies demonstrated adenocarcinoma; the resected specimen demonstrated infiltration through all wall layers. w = water.
a Fig. 9. (a) Double-contrast study of the gastric wall mainly caused thickening of the submucosa; the hypertrophic gastritis. w = water,
b demonstrates filling defect at the lesser curvature. (b) Scan with a 5 MHz transducer shows local thickening by an increased diameter of the mucosa; the echogenicity of the mucosa is normal. There is also slight proper muscle layer is normal. An early carcinoma cannot be excluded. Endoscopic biopsies demonstrated m = mass caused by selective thickening of the mucosa. The normal anterior gastric wall is numbered as in Fig. 1; arrowheads = posterior gastric wall.
References 1 Miyamoto Y, Tsujimoto F, Shimpei T. Ultrasonographic diagnosis of submucosal tumors of the stomach. The ‘bridging layers’ sign. J Clin Ultrasound 1988; 16: 251-258. 2 Miyamoto Y, Nakatani M, Ida M et al. Ultrasonographic find-
ings in gastric cancer: in vitro and in vivo studies. J Clin Ultrasound 1989; 17: 309-318. 3 Worlicek H, Dunz D, Engelhard K. Ultrasonic examination of the wall of the fluid-filled stomach. J Clin Ultrasound 1989; 17: 5-14. 4 Martinez-Noguera A, Mata J, Matias-Guiu X et al. Echogenic
87
focus in the gastrointestinal wall as sign of ulceration. Gastrointest Radio1 1989; 14: 295-299. 5 Op den Orth JO. Tubeless hypotonic duodenography with water: simple aid in sonography of the pancreatic head. Radiology 1985; 154: 826. 6 Smithuis RHM, Op den Orth JO. Gastric fluid detected by sonography in fasting patients: relation to duodenal ulcer disease and gastric outlet-obstruction. AJR 1989; 153: 731-733. 7 Yashuda K, Nakajima M, Yoshida S et al. The diagnosis of sub-
mucosal tumors of the stomach by endoscopic ultrasonography. Gastrointest Endosc 1989; 35: IO-15 8 Nakazawa S, Yoshino J, Nakamura T et al. Endoscopic ultrasonography of gastric myogenic tumor, a comparative study between histology and ultrasonography. J Ultrasound Med 1989; 8: 353-359 9 Ohashi S, Nakazawa S, Yoshino J. Endoscopic ultrasonography in the assessment of invasive gastric cancer. Scan J Gastroenterol 1989; 24: 1039-1048.
