Clin J Gastroenterol (2011) 4:15–18 DOI 10.1007/s12328-010-0197-2
CASE REPORT
Diagnosis of gastric antral vascular ectasia by transnasal flexible spectral imaging color enhancement Hakuei Shinhata • Hiroyuki Osawa • Hironori Yamamoto • Tomosuke Hirasawa Hironari Ajibe • Yoshimasa Miura • Kiichi Satoh • Kentaro Sugano
•
Received: 29 August 2010 / Accepted: 23 November 2010 / Published online: 28 December 2010 Ó Springer 2010
Abstract The endoscopic appearance of gastric antral vascular ectasia (GAVE) can be easily misinterpreted as inflammatory changes of gastric mucosa. We report on a case of GAVE that had been missed by conventional transnasal endoscopy but was diagnosed by flexible spectral imaging color enhancement (FICE) with a transnasal endoscope. A 45-year-old woman with severe anemia presented with a 1-month history of increasing fatigue. She was previously diagnosed as having acute antral gastritis by conventional transnasal endoscopy (EG 530N2) because of the presence of reddish mucosal changes on the entire antral rugal fold. However, the FICE images produced using a combination of new processor system (VP4450) and new small-caliber endoscope (EG 530NW), did not show reddish mucosal changes on the entire rugal fold, but gave a clear image of dilated vessels associated with GAVE distinct from the surrounding normal mucosa on the same fold. These findings are useful to differentiate GAVE from ordinary gastritis. The lesions of GAVE were managed with a combination of focal pulse and spray-painting techniques to obliterate the bulk of the disease in two sessions of argon plasma coagulation therapy. Three months later, the patient recovered from iron deficiency anemia with an oral medication of iron tablets. Keywords
FICE GAVE Transnasal endoscopy
H. Shinhata H. Osawa (&) H. Yamamoto T. Hirasawa H. Ajibe Y. Miura K. Satoh K. Sugano Division of Gastroenterology, Department of Internal Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498, Japan e-mail: [email protected]
Introduction Gastric antral vascular ectasia (GAVE) causes bleeding from abnormal gastric vessels and subsequently results in chronic anemia [1]. The endoscopic findings are crucial and the term ‘water melon stomach’ has been coined by Jabbari et al. [2] to describe the characteristic columns of dilated vessels on the ridges of prominent antral rugal folds. These vessels, however, can be easily misinterpreted as moderate to severe gastritis or submucosal hemorrhage caused by acute gastritis [3]. The endoscopic findings of GAVE have not been well documented in the last decade despite such misinterpretations of endoscopic images. Recently, a flexible spectral imaging color enhancement (FICE) system has been developed as a new endoscopic selection system for narrow-band imaging. This system enhances mucosal surface without the use of dyes and provides optimal band images with the same light intensity as conventional endoscopy [4]. Therefore, it is useful for the clear detection of abnormal capillary vessels in depressed or elevated-type early gastric cancer using a normal-caliber endoscope [5, 6]. On the other hand, palisade vessels in Barrett’s esophagus can be detected even with a small-caliber endoscope [7]. The usefulness of this endoscopic system (small-caliber endoscope equipped with FICE) has not been reported in other vascular diseases of the gastrointestinal tract. Here we report a case in which a small-caliber endoscope equipped with FICE gave a clear description of the dilated vessels of GAVE.
Case report A 45-year-old woman presented with a 1-month history of increasing fatigue without any other symptoms, including
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Fig. 1 Transnasal endoscopy (EG530 N2) showing several striking reddish changes in the antrum in a distant view (a) and a close-up view (b). Reddish mucosal changes can be seen on the entire rugal
Fig. 2 a Transnasal endoscopy (EG530 NW) showing several striking reddish changes in the antrum without any bleeding or coagula. b The FICE image with a set of wavelengths including 470 nm for blue, 500 nm for green and 550 nm for red enhanced the mucosal changes
Fig. 3 A close-up view. Reddish mucosal changes were not shown on the entire rugal fold in the greater curvature (a) and in the posterior wall (c). The FICE system provided higher color contrasting images between dilated vessels and the surrounding normal mucosa on the same rugal fold in the greater curvature (b) and in the posterior wall (d) than the conventional system
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Clin J Gastroenterol (2011) 4:15–18
folds. Pathological findings of biopsy specimen showed mild inflammatory changes with vascular ectasia near mucosal surface (c) (H&E 940)
Clin J Gastroenterol (2011) 4:15–18
melena. Her previous diagnosis 1 year earlier was acute hemorrhagic gastritis in the antrum. This diagnosis was based on conventional transnasal endoscopic observation (EG530 N2, EPX 4400, Fujifilm Co., Japan) (Fig. 1a, b) showing the presence of reddish mucosal changes on the entire rugal folds, and a biopsy specimen showing mild chronic inflammatory infiltrate in the lamina propria, in spite of the presence of vascular ectasia in the mucosal surface (Fig. 1c). She was not anemic (hemoglobin 11.9 g/dl) and did not take any medication as she was shown to be free from abnormal symptoms and abnormal laboratory findings. In the present laboratory examination, however, she was found to have severe anemia (hemoglobin 6.8 g/dl). Mean cell volume and mean cell hemoglobin concentration were 66.4 fl and 25.1% and serum iron level was 39 lg/dl, suggesting iron deficiency anemia. Serum levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) showed normal levels of 25 and 15 IU/l, respectively. Other chemistry tests also showed normal levels. Fecal occult blood testing was not performed. Transnasal endoscopy (EG530 NW, VP 4450, Fujifilm Co., Japan) showed several striking reddish mucosa in the
17
antrum without any bleeding or coagula (Fig. 2a). These findings were also observed by the FICE image with a set of wavelengths including 470 nm for blue (color gain level 4), 500 nm for green (4) and 550 nm for red (2), resulting in an enhancement of striking reddish mucosal changes (Fig. 2b). However, with a close-up view, the FICE system did not show reddish mucosal changes on the entire rugal fold, but high contrast images between dilated vessels and the surrounding normal mucosa (Fig. 3). The findings suggest that the background mucosa of the dilated vessels on the same fold did not have diffuse gastritis. Based on FICE images, we diagnosed these lesions as GAVE causing gastrointestinal bleeding and severe iron deficiency anemia. Colonoscopy revealed two colonic adenomas of 2 and 3 mm in size, respectively, as well as two hyperplastic polyps. The patient was given oral medication for iron deficiency anemia, and GAVE was treated by an argon plasma coagulation (APC) unit that consisted of a highfrequency electrosurgical generator (VIO 300; ERBE Co., Germany) coupled to an argon gas delivery unit. Electrical power and argon gas flow were set at 20–40 W and 1.0 L/ min, respectively. The APC Probe (ERBE Co., Germany; 300 cm, 2.3 mm) was used. Procedures were performed without sedation. The lesions of GAVE were managed with a combination of focal pulse and spray-painting techniques to obliterate at least 95% of the bulk of the disease in two sessions of APC therapy at each power setting over a 2-week period after admission (Fig. 4). Three months later, the patient recovered from iron deficiency anemia with an oral medication of iron tablets, and had a hemoglobin level of 13 g/dl.
Discussion
Fig. 4 At least 95% of lesion of GAVE were obliterated with a combination of focal pulse and spray-painting techniques in two sessions of APC therapy
In this case, we showed that vascular ectasia was clearly visible with the use of new endoscopic technology. Conventional endoscopy through the transnasal route revealed reddish mucosal changes on the entire antral rugal fold, but FICE images clearly showed them as vascular ectasia,
Fig. 5 Magnified images of GAVE in patients with liver cirrhosis. The conventional image a shows dilated capillaries surrounding and beneath the gastric pits. The FICE system provides a higher contrast between the capillaries and surrounding areas (b)
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distinct from the surrounding normal area on the same fold, resulting in a precise diagnosis of GAVE. This is the first report showing the advantage of transnasal FICE in the diagnosis of GAVE. Inferior image quality associated with transnasal endoscopy, which is now widely used for screening purposes due to better tolerance by patients, has been reported [8]. The FICE system with the transnasal endoscope could detect dilated vessels more clearly than the conventional system. In our case, GAVE had been missed by conventional transnasal endoscopic observation because of the presence of reddish mucosal changes on the entire rugal fold in a distant view. The endoscopic diagnosis of reddish mucosal change in the stomach is sometimes difficult and may vary from mucosal inflammation to cancer or vascular diseases [9]. The FICE system would help to detect the suspicious areas of various diseases. Interestingly, the FICE images seen on the current endoscopy, using a combination of new processor system (VP4450) and new endoscope (EG530 NW), did not show reddish mucosal changes on the entire rugal fold, but a clear picture of both dilated vessels and the surrounding normal mucosa on the same fold, enabling us to differentiate GAVE from gastritis. Moreover, it is important to note that such FICE images are available even with a transnasal endoscope. We investigated diagnostic methods for GAVE that have been reported over the past decade. Ringold and Banerjee [10] reported that FICE improved visualization of gastrointestinal vascular ectasia. They observed vascular ectasia of gastric body using a set of wavelengths including 405, 500 and 520 nm in a distant view, but did not show it in a close-up view. Also, FICE images with such a set of wavelengths seemed to be darker than those with the current set of wavelengths. On the other hand, Hayashi and Saeki [11] reported that the magnified narrow-band imaging (NBI) method is useful for the diagnosis of GAVE, showing dilated capillaries surrounding and beneath the gastric pits. Recently, we observed another case of GAVE related to liver cirrhosis using a magnified FICE system, resulting in a similar endoscopic appearance as NBI (Fig. 5). In the FICE system, magnified images may be useful for the diagnosis of GAVE as well as transnasal endoscopic images. The laminar structures and blood flow of the alimentary tract mucosa are altered by inflammation or neoplasia, acting as a scattering element and interfering with the reflectance spectrum [12]. A specific set of wavelengths including 470, 500 and 550 nm are useful for the diagnosis of early gastric cancer [5, 6]. In addition, this set of wavelengths using a small-caliber endoscope could enhance palisade vessels in Barrett’s esophagus [7]. These characteristics may allow the enhancement of small vascular ectasia, distinct from the surrounding area, using the
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Clin J Gastroenterol (2011) 4:15–18
new small-caliber endoscope (EG-530NW). Recently, the resolution of the small-caliber endoscope has improved (although it is still inferior to that of the normal-caliber endoscope), leading to higher contrast FICE images than those provided by earlier models of small-caliber endoscopes. The combination of new small-caliber endoscope and FICE system may resolve the diagnostic problems of GAVE sometimes misclassified as gastric inflammation [3]. In conclusion, conventional endoscopy using the transnasal route failed to diagnose striking reddish lesions on the entire antral rugal fold as GAVE, but the combination of small-caliber endoscope and FICE system showed them as dilated ectatic vessels distinct from the surrounding normal area on the same rugal fold, resulting in a precise diagnosis of GAVE.
References 1. Pastershank SP, Chappell EW, Buchan DJ, Chow KC. Arteriovenous malformation of the stomach. Can Med Assoc J. 1974; 110:57–8. 2. Jabbari M, Cherry R, Lough JO, Daly DS, Kinnear DG, Goresky CA. Gastric antral vascular ectasia: the watermelon stomach. Gastroenterology. 1984;37:1165–70. 3. Gouldesbrough DR, Pell AC. Gastric antral vascular ectasia: a problem of recognition and diagnosis. Gut. 1991;32:954–5. 4. Miyake Y, Sekiya T, Kubo S, Hara T. A new spectrophotometer for measuring the spectral reflectance of gastric mucous membrane. J Photogr Sci. 1989;37:134–8. 5. Osawa H, Yoshizawa M, Yamamoto H, Kita H, Satoh K, Ohnishi H, et al. Optima band imaging system can facilitate detection of change in depressed type early gastric cancer. Gastrointest Endosc. 2008;67:226–34. 6. Yoshizawa M, Osawa H, Yamamoto H, Kita H, Nakano H, Satoh K, et al. Diagnosis of elevated-type early gastric cancer by optimal band imaging system. Gastrointest Endosc. 2009;69:19–28. 7. Osawa H, Yamamoto H, Yamada N, Yoshizawa M, Sunada K, Kita H, et al. Diagnosis of endoscopic Barrett’s esophagus by transnasal flexible spectral imaging color enhancement. J Gastroenterol. 2009;44:1125–32. 8. Birkner B, Fritz N, Schatke W, Hasford J. A prospective randomized comparison of unsedated ultrathin versus standard esophagogastroduodenoscopy in routine outpatient gastroenterology practice: does it work better through the nose? Endoscopy. 2003;35:647–51. 9. Mori M, Adachi Y, Kakeji Y, Korenaga D, Sugimachi K, Motooka M, et al. Superficial flat-type early gastric carcinoma of the stomach. Cancer. 1992;69:306–13. 10. Ringold DA, Banerjee B. High-contrast imaging (FICE) improves visualization of gastrointestinal vascular ectasias. Endoscopy. 2008;40:E26. 11. Hayashi S, Saeki S. Endoscopic microvascular architecture of the portal hypertensive gastric mucosa on narrow band imaging. Dig Endosc. 2007;19:116–23. 12. Yao K, Yao T, Matsui T, Iwashita A, Oishi T. Hemoglobin content in intramucosal gastric carcinoma as a marker of histologic differentiation: a clinical application of quantitative electronic endoscopy. Gastrointest Endosc. 2000;52:241–5.
CASE REPORT
Diagnosis of gastric antral vascular ectasia by transnasal flexible spectral imaging color enhancement Hakuei Shinhata • Hiroyuki Osawa • Hironori Yamamoto • Tomosuke Hirasawa Hironari Ajibe • Yoshimasa Miura • Kiichi Satoh • Kentaro Sugano
•
Received: 29 August 2010 / Accepted: 23 November 2010 / Published online: 28 December 2010 Ó Springer 2010
Abstract The endoscopic appearance of gastric antral vascular ectasia (GAVE) can be easily misinterpreted as inflammatory changes of gastric mucosa. We report on a case of GAVE that had been missed by conventional transnasal endoscopy but was diagnosed by flexible spectral imaging color enhancement (FICE) with a transnasal endoscope. A 45-year-old woman with severe anemia presented with a 1-month history of increasing fatigue. She was previously diagnosed as having acute antral gastritis by conventional transnasal endoscopy (EG 530N2) because of the presence of reddish mucosal changes on the entire antral rugal fold. However, the FICE images produced using a combination of new processor system (VP4450) and new small-caliber endoscope (EG 530NW), did not show reddish mucosal changes on the entire rugal fold, but gave a clear image of dilated vessels associated with GAVE distinct from the surrounding normal mucosa on the same fold. These findings are useful to differentiate GAVE from ordinary gastritis. The lesions of GAVE were managed with a combination of focal pulse and spray-painting techniques to obliterate the bulk of the disease in two sessions of argon plasma coagulation therapy. Three months later, the patient recovered from iron deficiency anemia with an oral medication of iron tablets. Keywords
FICE GAVE Transnasal endoscopy
H. Shinhata H. Osawa (&) H. Yamamoto T. Hirasawa H. Ajibe Y. Miura K. Satoh K. Sugano Division of Gastroenterology, Department of Internal Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498, Japan e-mail: [email protected]
Introduction Gastric antral vascular ectasia (GAVE) causes bleeding from abnormal gastric vessels and subsequently results in chronic anemia [1]. The endoscopic findings are crucial and the term ‘water melon stomach’ has been coined by Jabbari et al. [2] to describe the characteristic columns of dilated vessels on the ridges of prominent antral rugal folds. These vessels, however, can be easily misinterpreted as moderate to severe gastritis or submucosal hemorrhage caused by acute gastritis [3]. The endoscopic findings of GAVE have not been well documented in the last decade despite such misinterpretations of endoscopic images. Recently, a flexible spectral imaging color enhancement (FICE) system has been developed as a new endoscopic selection system for narrow-band imaging. This system enhances mucosal surface without the use of dyes and provides optimal band images with the same light intensity as conventional endoscopy [4]. Therefore, it is useful for the clear detection of abnormal capillary vessels in depressed or elevated-type early gastric cancer using a normal-caliber endoscope [5, 6]. On the other hand, palisade vessels in Barrett’s esophagus can be detected even with a small-caliber endoscope [7]. The usefulness of this endoscopic system (small-caliber endoscope equipped with FICE) has not been reported in other vascular diseases of the gastrointestinal tract. Here we report a case in which a small-caliber endoscope equipped with FICE gave a clear description of the dilated vessels of GAVE.
Case report A 45-year-old woman presented with a 1-month history of increasing fatigue without any other symptoms, including
123
16
Fig. 1 Transnasal endoscopy (EG530 N2) showing several striking reddish changes in the antrum in a distant view (a) and a close-up view (b). Reddish mucosal changes can be seen on the entire rugal
Fig. 2 a Transnasal endoscopy (EG530 NW) showing several striking reddish changes in the antrum without any bleeding or coagula. b The FICE image with a set of wavelengths including 470 nm for blue, 500 nm for green and 550 nm for red enhanced the mucosal changes
Fig. 3 A close-up view. Reddish mucosal changes were not shown on the entire rugal fold in the greater curvature (a) and in the posterior wall (c). The FICE system provided higher color contrasting images between dilated vessels and the surrounding normal mucosa on the same rugal fold in the greater curvature (b) and in the posterior wall (d) than the conventional system
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Clin J Gastroenterol (2011) 4:15–18
folds. Pathological findings of biopsy specimen showed mild inflammatory changes with vascular ectasia near mucosal surface (c) (H&E 940)
Clin J Gastroenterol (2011) 4:15–18
melena. Her previous diagnosis 1 year earlier was acute hemorrhagic gastritis in the antrum. This diagnosis was based on conventional transnasal endoscopic observation (EG530 N2, EPX 4400, Fujifilm Co., Japan) (Fig. 1a, b) showing the presence of reddish mucosal changes on the entire rugal folds, and a biopsy specimen showing mild chronic inflammatory infiltrate in the lamina propria, in spite of the presence of vascular ectasia in the mucosal surface (Fig. 1c). She was not anemic (hemoglobin 11.9 g/dl) and did not take any medication as she was shown to be free from abnormal symptoms and abnormal laboratory findings. In the present laboratory examination, however, she was found to have severe anemia (hemoglobin 6.8 g/dl). Mean cell volume and mean cell hemoglobin concentration were 66.4 fl and 25.1% and serum iron level was 39 lg/dl, suggesting iron deficiency anemia. Serum levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) showed normal levels of 25 and 15 IU/l, respectively. Other chemistry tests also showed normal levels. Fecal occult blood testing was not performed. Transnasal endoscopy (EG530 NW, VP 4450, Fujifilm Co., Japan) showed several striking reddish mucosa in the
17
antrum without any bleeding or coagula (Fig. 2a). These findings were also observed by the FICE image with a set of wavelengths including 470 nm for blue (color gain level 4), 500 nm for green (4) and 550 nm for red (2), resulting in an enhancement of striking reddish mucosal changes (Fig. 2b). However, with a close-up view, the FICE system did not show reddish mucosal changes on the entire rugal fold, but high contrast images between dilated vessels and the surrounding normal mucosa (Fig. 3). The findings suggest that the background mucosa of the dilated vessels on the same fold did not have diffuse gastritis. Based on FICE images, we diagnosed these lesions as GAVE causing gastrointestinal bleeding and severe iron deficiency anemia. Colonoscopy revealed two colonic adenomas of 2 and 3 mm in size, respectively, as well as two hyperplastic polyps. The patient was given oral medication for iron deficiency anemia, and GAVE was treated by an argon plasma coagulation (APC) unit that consisted of a highfrequency electrosurgical generator (VIO 300; ERBE Co., Germany) coupled to an argon gas delivery unit. Electrical power and argon gas flow were set at 20–40 W and 1.0 L/ min, respectively. The APC Probe (ERBE Co., Germany; 300 cm, 2.3 mm) was used. Procedures were performed without sedation. The lesions of GAVE were managed with a combination of focal pulse and spray-painting techniques to obliterate at least 95% of the bulk of the disease in two sessions of APC therapy at each power setting over a 2-week period after admission (Fig. 4). Three months later, the patient recovered from iron deficiency anemia with an oral medication of iron tablets, and had a hemoglobin level of 13 g/dl.
Discussion
Fig. 4 At least 95% of lesion of GAVE were obliterated with a combination of focal pulse and spray-painting techniques in two sessions of APC therapy
In this case, we showed that vascular ectasia was clearly visible with the use of new endoscopic technology. Conventional endoscopy through the transnasal route revealed reddish mucosal changes on the entire antral rugal fold, but FICE images clearly showed them as vascular ectasia,
Fig. 5 Magnified images of GAVE in patients with liver cirrhosis. The conventional image a shows dilated capillaries surrounding and beneath the gastric pits. The FICE system provides a higher contrast between the capillaries and surrounding areas (b)
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18
distinct from the surrounding normal area on the same fold, resulting in a precise diagnosis of GAVE. This is the first report showing the advantage of transnasal FICE in the diagnosis of GAVE. Inferior image quality associated with transnasal endoscopy, which is now widely used for screening purposes due to better tolerance by patients, has been reported [8]. The FICE system with the transnasal endoscope could detect dilated vessels more clearly than the conventional system. In our case, GAVE had been missed by conventional transnasal endoscopic observation because of the presence of reddish mucosal changes on the entire rugal fold in a distant view. The endoscopic diagnosis of reddish mucosal change in the stomach is sometimes difficult and may vary from mucosal inflammation to cancer or vascular diseases [9]. The FICE system would help to detect the suspicious areas of various diseases. Interestingly, the FICE images seen on the current endoscopy, using a combination of new processor system (VP4450) and new endoscope (EG530 NW), did not show reddish mucosal changes on the entire rugal fold, but a clear picture of both dilated vessels and the surrounding normal mucosa on the same fold, enabling us to differentiate GAVE from gastritis. Moreover, it is important to note that such FICE images are available even with a transnasal endoscope. We investigated diagnostic methods for GAVE that have been reported over the past decade. Ringold and Banerjee [10] reported that FICE improved visualization of gastrointestinal vascular ectasia. They observed vascular ectasia of gastric body using a set of wavelengths including 405, 500 and 520 nm in a distant view, but did not show it in a close-up view. Also, FICE images with such a set of wavelengths seemed to be darker than those with the current set of wavelengths. On the other hand, Hayashi and Saeki [11] reported that the magnified narrow-band imaging (NBI) method is useful for the diagnosis of GAVE, showing dilated capillaries surrounding and beneath the gastric pits. Recently, we observed another case of GAVE related to liver cirrhosis using a magnified FICE system, resulting in a similar endoscopic appearance as NBI (Fig. 5). In the FICE system, magnified images may be useful for the diagnosis of GAVE as well as transnasal endoscopic images. The laminar structures and blood flow of the alimentary tract mucosa are altered by inflammation or neoplasia, acting as a scattering element and interfering with the reflectance spectrum [12]. A specific set of wavelengths including 470, 500 and 550 nm are useful for the diagnosis of early gastric cancer [5, 6]. In addition, this set of wavelengths using a small-caliber endoscope could enhance palisade vessels in Barrett’s esophagus [7]. These characteristics may allow the enhancement of small vascular ectasia, distinct from the surrounding area, using the
123
Clin J Gastroenterol (2011) 4:15–18
new small-caliber endoscope (EG-530NW). Recently, the resolution of the small-caliber endoscope has improved (although it is still inferior to that of the normal-caliber endoscope), leading to higher contrast FICE images than those provided by earlier models of small-caliber endoscopes. The combination of new small-caliber endoscope and FICE system may resolve the diagnostic problems of GAVE sometimes misclassified as gastric inflammation [3]. In conclusion, conventional endoscopy using the transnasal route failed to diagnose striking reddish lesions on the entire antral rugal fold as GAVE, but the combination of small-caliber endoscope and FICE system showed them as dilated ectatic vessels distinct from the surrounding normal area on the same rugal fold, resulting in a precise diagnosis of GAVE.
References 1. Pastershank SP, Chappell EW, Buchan DJ, Chow KC. Arteriovenous malformation of the stomach. Can Med Assoc J. 1974; 110:57–8. 2. Jabbari M, Cherry R, Lough JO, Daly DS, Kinnear DG, Goresky CA. Gastric antral vascular ectasia: the watermelon stomach. Gastroenterology. 1984;37:1165–70. 3. Gouldesbrough DR, Pell AC. Gastric antral vascular ectasia: a problem of recognition and diagnosis. Gut. 1991;32:954–5. 4. Miyake Y, Sekiya T, Kubo S, Hara T. A new spectrophotometer for measuring the spectral reflectance of gastric mucous membrane. J Photogr Sci. 1989;37:134–8. 5. Osawa H, Yoshizawa M, Yamamoto H, Kita H, Satoh K, Ohnishi H, et al. Optima band imaging system can facilitate detection of change in depressed type early gastric cancer. Gastrointest Endosc. 2008;67:226–34. 6. Yoshizawa M, Osawa H, Yamamoto H, Kita H, Nakano H, Satoh K, et al. Diagnosis of elevated-type early gastric cancer by optimal band imaging system. Gastrointest Endosc. 2009;69:19–28. 7. Osawa H, Yamamoto H, Yamada N, Yoshizawa M, Sunada K, Kita H, et al. Diagnosis of endoscopic Barrett’s esophagus by transnasal flexible spectral imaging color enhancement. J Gastroenterol. 2009;44:1125–32. 8. Birkner B, Fritz N, Schatke W, Hasford J. A prospective randomized comparison of unsedated ultrathin versus standard esophagogastroduodenoscopy in routine outpatient gastroenterology practice: does it work better through the nose? Endoscopy. 2003;35:647–51. 9. Mori M, Adachi Y, Kakeji Y, Korenaga D, Sugimachi K, Motooka M, et al. Superficial flat-type early gastric carcinoma of the stomach. Cancer. 1992;69:306–13. 10. Ringold DA, Banerjee B. High-contrast imaging (FICE) improves visualization of gastrointestinal vascular ectasias. Endoscopy. 2008;40:E26. 11. Hayashi S, Saeki S. Endoscopic microvascular architecture of the portal hypertensive gastric mucosa on narrow band imaging. Dig Endosc. 2007;19:116–23. 12. Yao K, Yao T, Matsui T, Iwashita A, Oishi T. Hemoglobin content in intramucosal gastric carcinoma as a marker of histologic differentiation: a clinical application of quantitative electronic endoscopy. Gastrointest Endosc. 2000;52:241–5.
