Книги по МРТ КТ на английском языке / Advanced Imaging of the Abdomen - Jovitas Skucas

ing surgery, endoscopic US can correctly stage 75% to 85% of these tumors; although regional adenopathy is detected, more distant metastases cannot be evaluated. Similar to other imaging, endoscopic US cannot differentiate between benign and malignant adenopathy.

Intraductal US using high-frequency sonographic catheters appears useful in staging papillary cancers. This technique can confirm whether a tumor extends into duodenal submucosa, is limited to Oddi’s muscle, or whether it invades pancreas; intraductal US is less sensitive in detecting lymph node metastases.

High-spatial-resolution MRI should identify most periVaterian tumors, in one study achieving a sensitivity of 88% and specificity of 100% in assessing of tumor invasion (15). PeriVaterian carcinomas are hypointense on precontrast T1-weighted images and enhance less than normal pancreas on immediate postgadolinium SGE images. Tumor conspicuity is greatest on immediate postcontrast images. Magnetic resonance cholangiopancreatography in some of these patients shows varying degrees of common bile duct and pancreatic duct dilation.

At most sites biopsy is necessary to establish a histologic diagnosis. In spite of this advice, some surgeons do not obtain a percutaneous biopsy or even retrograde cholangiopancreatography if an imaging study defines the tumor and its proximal extent, arguing that such preoperative studies do not alter a decision for surgical exploration and, in fact, may cause complications. They believe that visualization by noninvasive imaging should suffice.

Tumor, node, metastasis (TNM) staging for papilla of Vater tumors is outlined in Table 3.2.

Therapy

An ampullectomy has been performed for small benign tumors and T1 carcinomas originating in the papilla of Vater.

Initially performed early in the 20th century, pancreaticoduodenectomy for a periampullary carcinoma was advocated by Whipple in the 1930s, and since then this operation continues to bear his name. Over the years a number of modifications have been introduced, and currently many surgeons opt for a pyloruspreserving variant. The indications for a Whipple procedure have also expanded and

ADVANCED IMAGING OF THE ABDOMEN

Table 3.2. Tumor, node, metastasis (TNM) staging of papilla of Vater tumors

Primary tumor:

Lymph nodes:

Nx Regional nodes cannot be assessed

N0 No regional lymph node metastasis

N1 Metastasis to regional nodes

Distant metastasis:

Mx Distant metastases cannot be assessed M0 No distant metastasis

M1 Distant metastasis

Source: From the AJCC Cancer Staging Manual, 6th edition (2002), published by Springer-Verlag, New York, NY, used with permission of the American Joint Committee on Cancer (AJCC), Chicago, IL.

now include a potentially curable carcinoma in the pancreatic head (complications and imaging of the postoperative Whipple procedure are discussed in Chapter 9). If a Whipple procedure is contraindicated because of metastatic disease or poor patient condition, insertion of a palliative biliary drainage prosthesis is an option.

Potentially, resection of a peri-Vaterian carcinoma should have a high cure rate. Nevertheless, a number of these patients do not undergo curative resection due to age, poor health, or advanced disease. Catheter stenting in poor surgical risk patients is a viable option. Evidence suggests that preoperative biliary drainage in these patients results in decreased morbidity and shorter postoperative hospitalization (16).

DUODENUM

After a Whipple procedure for a peri-Vaterian carcinoma, resection margin tumor involvement is the major prognostic factor for survival. Among consecutive patients who underwent pancreaticoduodenectomy with radical lymphadenectomy for papillary carcinoma, 54% had positive lymph nodes (17); the most common tumor spread was to the posterior pancreaticoduodenal nodes, followed by the inferior pancreaticoduodenal artery nodes and then the paraaortic nodes. Distal metastasis is uncommon for these tumors, at least initially.

Adenoma/Adenocarcinoma

Excepting the periampullary region (discussed above), duodenal adenomas are uncommon. They are considered premalignant. Some contain predominantly a villous component (Fig. 3.5).

About half of small bowel adenocarcinomas occur in the duodenum; their appearance is similar to that of the rest of the small bowel (Fig. 3.6). Patients with celiac disease have a slightly increased prevalence of duodenal carcinoma than the general population. A duodenal carcinoma developing years after a Billroth gastroduodenostomy is probably unrelated to the original surgery. Patients with hereditary nonpolyposis colorectal cancer are probably not at increased risk for developing a duodenal adenoma or carcinoma.

Figure 3.6. Descending duodenal adenocarcinoma (arrow). (Courtesy of Arunas Gasparaitis, M.D., University of Chicago.)

A retrospective multiinstitution review of patients with duodenal adenocarcinomas found a detection accuracy of 82% for duodenography and 88% for endoscopy (18); almost two thirds of these tumors were in the periampullary region. Detecting an adenocarcinoma in the distal duodenum is beyond endoscopic reach, but it can also be difficult with both barium studies and CT (Fig. 3.7).

The duodenum shares its blood supply with the pancreas. As a result, depending on tumor location and the extent of infiltration, adequate resection often requires a pancreaticoduodenectomy, although occasionally a pancreassparing duodenectomy is feasible.

Endoscopic resection of some duodenal adenomas and carcinomas is practiced in Japan. Saline is injected into the submucosa near the tumor, which is resected using electrocoagulation. Elevated tumors less than 50mm in diameter have been removed using this technique (19). Larger tumors and depressed ones with or without marginal elevation are resected surgically.

Lymphoma/Leukemia

Mucosa-associated lymphoid tissue (MALT) lymphoma rarely affects the duodenum. At times multiple small erosions are detected. One MALT low-grade B-cell lymphoma in the duodenal bulb was detected by a barium study and endoscopy as multiple elevated, irregularly contoured nodules (20).Adult T-cell leukemia led to varioliform polypoid infiltration in the duodenum (21). Sufficient involvement of adjacent lymph nodes will result in duodenal obstruction (Fig. 3.8).

Figure 3.8. Lymphoma obstructing duodenum. Duodenal invasion by an adjacent pancreatic carcinoma or a metastasis to paraaortic nodes has a similar appearance.

Figure 3.9. Duodenal lipoma (arrow). (Courtesy of Arunas Gasparaitis, M.D., University of Chicago.)

Mesenchymal Tumors

Some duodenal stromal tumors are sufficiently undifferentiated to be difficult to characterize. At times even mitotic activity does not distinguish between benign and malignant tumors. Similar to other mesenchymal tumors, a duodenal leiomyoma may bleed or, if large enough, result in obstruction. Presumably some benign tumors eventually undergo sarcomatous degeneration.

A thallium-201 single photon emission computed tomography (SPECT) myocardial perfusion study revealed prominent uptake in a duodenal leiomyosarcoma (22).

The occasional duodenal lipoma is often an incidental finding (Fig. 3.9). Some are huge. Some become pedunculated and even act as a lead point for an intussusception. A rare one erodes and bleeds.

A barium study reveals a lipoma either as an intramural or intraluminal polyp. The primarily fat composition of a lipoma is identified by CT (assuming that the tumor is detected by CT).

Metastasis or Direct Invasion

A malignancy in any adjacent structure readily invades the duodenum and, similar to a metastasis, readily bleeds or obstructs the duodenal lumen (Fig. 3.10). Thus an advanced right renal cell carcinoma and some pancreatic malignan-

DUODENUM

Figure 3.10. Pancreatic carcinoma invading duodenum (arrows). The symmetrical circumferential invasion is somewhat atypical.

cies readily invade the duodenum. A hepatocellular carcinoma spreading to portal lymph nodes will also invade the first or second duodenal segment. Most common metastases involve the pancreaticoduodenal nodes or adjacent paraaortic nodes (Fig. 3.11).

A “bull’s-eye” lesion distal to the bulb rarely represents a benign ulcer; more likely it is a metastatic melanoma (Fig. 3.12) or breast carcinoma. Larger melanomas tend to mimic necrotic mesenchymal tumors.

An inoperable cancer patient presenting with gastric outlet or duodenal obstruction should be considered for palliation with a perorally implanted self-expanding endoprosthesis. Occasionally combined biliary and duodenal obstructions can be bypassed with double stents introduced percutaneously.

Neuroendocrine

Carcinoid

Carcinoid tumors are not uncommon in the duodenum. Most are <1cm in size and benign, and are detected incidentally. Some carcinoids adjacent to the ampulla of Vater are associated with pancreatitis.

Endoscopic US appears to aid in duodenal carcinoid detection and in evaluating the depth of tumor invasion.

High-resolution breath-hold contrastenhanced magnetic resonance imaging (MRI) detected a 10-mm primary duodenal carcinoid (23).

Endoscopic resection is feasible with some superficial carcinoids.

Gastrinoma

Gastrinomas are discussed in more detail in Chapter 9. Duodenal gastrinomas range from single to multiple and some are associated with synchronous pancreatic tumors. They are somewhat prevalent in patients with multiple endocrine neoplasia (MEN) type I syndrome, and among these patients a majority of carcinoids consist of gastrointestinal submucosal nodules; only a minority of patients with sporadic Zollinger-Ellison syndrome have similar submucosal nodules. Clinically, these patients develop hypergastrinemia and gastric acid hypersecretion.

Duodenal gastrinomas are considerably more malignant than those originating in the pancreas; it is not uncommon to find lymph node metastasis at initial presentation even with a

Figure 3.11. Metastatic Merkel cell tumor to third duodenal segment produces partial obstruction (arrow). More common metastases to this location are colon and breast carcinomas.

small primary tumor. Especially among the small ones located submucosally in the first or second part of the duodenum only a minority are identified by preoperative imaging. A 15-mm submucosal gastrinoma palpated at surgery in the posterior duodenal wall had an enlarged peripancreatic lymph node close to the pancreas head as the only positive preoperative imaging finding, although surgery revealed regional lymph node metastases (24).

Clinically these patients develop hypergastrinemia and gastric acid hypersecretion.

At times selective arterial secretin injection aids in localizing these tumors. Fine-needle aspiration cytology has been performed with some of these tumors.

Paraganglioma

Duodenal paragangliomas are rare, usually benign tumors having a predilection for the periampullary region. An occasional one presents with gastrointestinal bleeding. An occasional periampullary paraganglioma is pedunculated, results in obstructive jaundice, or is simply detected as an incidental duodenal polyp on a barium study.

Paragangliomas appear solid and homogeneous on CT, US, and MRI, and enhance homogeneously postcontrast; they contain a prominent vascular network.

Other

Only a rare schwannoma is reported in the duodenum. Use of water as oral contrast during contrast-enhanced CT aids in identifying these hypervascular bleeding schwannoma.

An occasional small superficial insulinoma can be resected endoscopically.

Dilation/Obstruction

Obstruction by an annular pancreas is discussed in Chapter 9. Paraduodenal hernias are covered in Chapter 14.

Gallstone Ileus

A biliary-enteric fistula caused by an eroding gallstone develops to the stomach, duodenum, or even transverse colon. A majority are to the

DUODENUM

duodenum. Rarely, multiple fistulas ensue. Most originate from the gallbladder, with an occasional one evolving from the common bile duct. Once the presence of a fistula is established, the surgeon is interested in whether it communicates with the gallbladder or bile duct, but a surrounding inflammation can make this differentiation difficult at surgery, and often an imaging study will suggest the path of a fistulous communication. An upper gastrointestinal study is generally most helpful with this differentiation, although indirect CT signs, such as whether the gallbladder is contracted and the location of bile duct versus gallbladder gas, can occasionally point toward a correct diagnosis.

Although a gallstone can obstruct anywhere in the gastrointestinal tract, most impact in the distal ileum (but not the terminal ileum); the second most common location is in the duodenum (Bouveret’s syndrome), and the patient then presents with gastric outlet obstruction. In addition to duodenal lumen obstruction, at times a stone also leads to bile duct obstruction, and the patient presents with jaundice. Bouveret’s syndrome is sufficiently rare that no large series have been published, but common enough that numerous single reports exist. It is unfortunate that some of these patients have died without a simple radiologic study being obtained; a barium study or CT should be diagnostic.

A gallstone does not necessarily need to pass into the duodenal lumen to obstruct. Thus a stone eroding into the duodenal wall but not yet forming a fistulous tract to the lumen will obstruct. An analogy can be made to Mirizzi’s syndrome, where an eroding stone leads to bile duct obstruction. A gallstone impacting in an intraluminal duodenal diverticulum is a rare cause of duodenal lumen obstruction. In addition to lumen obstruction, hemorrhage is a common consequence of a stone eroding into the stomach or duodenum.

Most of these stones are approached surgically. Duodenal obstruction by a gallstone has been treated by endoscopic lithotripsy (25).

Superior Mesenteric

Artery Syndrome

Figure 3.13. Severe superior mesenteric artery syndrome. Oral and intravenous contrast-enhanced CT reveals marked dilation of the descending duodenum and an abrupt cut-off in the third portion (arrow). The superior mesenteric artery and vein had a normal relationship. The patient underwent a duodenojejunostomy. (Courtesy of Patrick Fultz, M.D., University of Rochester.)

mesenteric artery (SMA) is currently rarely encountered. This condition, called SMA syndrome, cast syndrome, and Wilkie’s syndrome, generally develops in thin patients or those suddenly bedridden. A number of patients developed acute SMA syndrome after surgery for severe spinal deformity. It has developed after rapid weight loss due to bowel resection. When fully developed, this syndrome presents a serious management problem; as an extreme, gastric necrosis has ensued.

Although CT and magnetic resonance angiography (MRA) will detect this condition, the diagnosis is generally straightforward with a barium study (Fig. 3.13).

In most patients, subsequent mobility or weight gain is generally curative. An occasional patient requires a duodenojejunostomy, although SMA syndrome has recurred in a rare patient.

Occasionally, a suddenly bedridden patient develops a similar obstruction more distally in the small bowel.

Intussusception

Duodenal obstruction secondary to compression by the adjacent anteriorly located superior

Normally the extraperitoneal duodenal location should prevent intussusception, although large

polyps do predispose to an intussusception. Thus patients with Peutz-Jeghers syndrome, who tend to have large duodenal polyps, are prone to this complication, and it is often recurrent. Intermittent abdominal pain is common.

A barium study or CT in Peutz-Jeghers patients often detects recurrent duodenojejunal intussusception. Eventual almost complete duodenal obstruction requires surgical polypectomy. At times associated bile duct and pancreatic duct obstruction are sequelae of a duodenojejunal intussusception and on a chronic basis have led to pancreatic atrophy.

Extrinsic Causes

Ileocolic intussusception in the very young is a common occurrence. Occasionally such an intussusception and resultant bowel dilation obstruct the adjacently located duodenum.

Other Obstructions

Duodenal obstruction has been caused by a shiitake mushroom (26).

Chronic adynamic ileus (intestinal pseudoobstruction) also affects the duodenum. A hereditary autosomal-dominant form is characterized by visceral myopathy manifesting as a megaduodenum (27); histology identified longitudinal muscle vacuolar degeneration and fibrosis.

Diverticula

Peri-Vaterian

Duodenal diverticula are most common in the papilla of Vater region and most are detected incidentally during barium imaging or ERCP. Their CT and MR appearance can be somewhat confusing (Fig. 3.14). For instance, in one study of patients with periVaterian diverticula, MR cholangiography missed 18% and clearly detected only 35% (28). Their content varies considerably. In an occasional patient such a peri-Vaterian diverticulum becomes infected, bleeds, obstructs adjacent duodenal lumen, or even harbors a malignancy. At times bleeding is massive.Adjacent infection or tumor predispose

ADVANCED IMAGING OF THE ABDOMEN

Figure 3.14. Duodenal diverticulum. CT identifies gas in the pancreatic head (arrow). Initially this gas was believed to be in an abscess in this patient with pancreatitis. (Courtesy of Patrick Fultz, M.D., University of Rochester.)

to perforation and fistula formation from a diverticulum to adjacent structures. Ulcers and even an eroding enterolith within a diverticulum have led to duodenal diverticular perforation (29). These perforations are either into the peritoneal cavity or into an adjacent organ.

Patients with a peri-Vaterian diverticulum probably have impaired sphincter of Oddi function, presumably secondary to compression of the adjacent distal bile duct, and many case reports have suggested an increased risk for choledocholithiasis, cholangitis, and pancreatitis in the presence of a peri-Vaterian diverticulum. Yet a retrospective study of 1115 patients undergoing ERCP detected only a moderate, but not statistically significant, relationship between presence of a peri-Vaterian diverticulum and common bile duct stones (30). Several other studies have reached similar conclusions, and if there is an increased risk of choledocholithiasis in patients with a peri-Vaterian diverticulum, it is small.

Some patients with Ehlers-Danlos syndrome develop a large duodenal diverticulum. A peri-Vaterian diverticulum filled with a food bezoar occasionally results in common bile duct obstruction.

Ultrasonography reveals a peri-Vaterian diverticulum as a collection of persistent bright linear or concave echoes close to the pancreatic head.

DUODENUM

Intraluminal

Most intraluminal diverticula (also described as a wind-sock sign) develop in the second part of the duodenum and most manifest in young adults. Whether all of these diverticula are congenital in origin is conjecture, although some are associated with other duodenal congenital anomalies, including ampulla of Vater malposition. In an occasional patient the ampulla is located in the diverticulum or on its rim. Small ones tend to be incidental findings, but duodenal obstruction, stasis, bleeding, and pancreatitis are occasional sequelae of larger ones.

Whether all of these diverticula are congenital in origin is conjecture, although some are associated with other duodenal congenital anomalies, including ampulla of Vater malposition. At times the ampulla is located on the diverticular rim.

The diagnosis is straightforward with a barium study. Other imaging modalities detect these diverticula if an intraluminal collection of contrast can be identified surrounded by a thin radiolucent line. Their connection to the main lumen ranges from a focal neck to an almost circumferential opening. Their classic windsock appearance is pathognomonic, although diagnostic problems occur if the diverticulum is already filled with secretions and little contrast enters its lumen.

Locating the ampulla is obviously important if diverticular excision is contemplated.

Other Diverticula

Most diverticula in the third and fourth portions of the duodenum are incidental findings (Fig. 3.15). Although stasis within such a diverticulum is common, the volume involved is sufficiently small that clinical malabsorption rarely develops.

Bleeding, at times massive, is occasionally encountered from distal duodenal diverticula. Most endoscopy does not reach much beyond the second duodenal segment and simply detects intraluminal blood without identifying a site of bleeding. With active bleeding either a technetium-99m (Tc-99m) red blood cell study or arteriography is the study of choice.

Figure 3.15. Giant diverticulum (arrows) at ligament of Treitz region. (Courtesy of Thomas Miller, M.D., San Louis Obispo, California.)

Melanosis

Occasionally endoscopy reveals melanin-like black or brown spots within the duodenum, usually within the first and second parts. Although such a finding can be secondary to a melanoma, more often no tumor is found. These melanin-like spots represent iron deposition within macrophages. This condition, also known as pseudomelanosis duodeni, is more common in the elderly and those with chronic illnesses, and in some appears related to hypertension or antihypertensive medications.

Perforation/Fistula

Although considerably less common than in years past, the most common cause of duodenal perforation in adults continues to be peptic ulcer disease. An acute perforated ulcer is one of the causes of an acute abdomen and usually requires surgical correction. An occasional impacted fish bone results in duodenal perforation, a rare event.

A laparoscopic approach is feasible to treat duodenal perforations. A retrospective study of laparoscopic repair of perforated duodenal ulcers in 35 patients found that conversion to

laparotomy was necessary in 23%, with the causes being a fragile perforation edge, a perforation that could not be identified, and extensive intraabdominal adhesions (31).

Vascular Lesions (Bleeding)

Vascular fistulas are discussed in Chapter 17.

Dieulafoy Lesion

Dieulafoy lesions are rarely described in the duodenum. Their endoscopic appearance is similar to those seen in the stomach.

ADVANCED IMAGING OF THE ABDOMEN

a mesenteric arteriovenous fistula results in isolated duodenal varices and portal hypertension. A bleeding duodenal varix developed in a setting of splenic vein thrombosis and chronic pancreatitis (32).

Fluoroscopy shows that duodenal varices tend to decrease in size with inspiration.

Devascularization or percutaneous transhepatic obliteration of the varix in question is often the treatment of choice for these varices. Other options for controlling bleeding from these bleeding varices include endoscopic ligation, endoscopic injection sclerotherapy, and transjugular intrahepatic portosystemic shunt (TIPS).

Varices

Duodenal varices are less common than in the esophagus or stomach. Most of these varices are part of an esophagogastric variceal complex, but an occasional patient develops only isolated duodenal varices. Isolated portal vein thrombosis appears to predispose to duodenal varices that are part of a retroperitoneal portosystemic shunt system. They have been reported throughout the duodenum. The feeding vessel is either the superior or inferior pancreaticoduodenal vein or superior mesenteric vein. Efferent veins drain into the inferior vena cava.

Although most duodenal varices are secondary to portal hypertension, occasionally

Angiodysplasia/ Telangiectasia

A duodenal angiodysplasia bleeding site is least common in the gastrointestinal tract. An occasional duodenal site is found in patients with hereditary hemorrhagic telangiectasia. Some of these angiodysplasias are related either to the major or minor papilla.

Therapy

Endoscopy is often the initial examination performed in patients with upper gastrointestinal bleeding. In some patients, however, endoscopic therapy is not successful in stopping bleeding from a duodenal site, and in these patients arte-

DUODENUM

riography and subsequent transcatheter arterial embolization should be considered. Embolization successfully achieves hemostasis in most patients, although the success rate is less than with lower gastrointestinal bleeding (Fig. 3.16). Occasionally single-vessel embolization will not arrest bleeding, and embolization of both gastroduodenal and inferior pancreaticoduodenal arteries is necessary. In spite of the rich duodenal blood supply, such synchronous embolization should be undertaken with caution because of the possible induction of duodenal or pancreatic ischemia.

References

1.Alvarez C, Rueda O,Vicente JM, Fraile E. Gastric emphysema in a child with congenital duodenal diaphragm. Pediatr Radiol 1997;27:915–917.

2.Thiefin G, Barraya R, Ramaholimihaso F, Diebold MD. [Duodenal diaphragm induced by aspirin.] [French] Presse Med 2000;29:1351–1352.

3.Rha SE, Lee JH, Lee SY, Park SM. Duodenal diaphragm associated with long-term use of nonsteroidal antiinflammatory drugs: a rare cause of duodenal obstruction in an adult. AJR 2000;175:920–921.

4.Sollfrank M, Koch W, Waldner H, Rudisser K. [Intramural duodenal hematoma after endoscopic biopsy.] [German] Rofo Fortschr Geb Rontgenstr Neuen Bildgeb Verfahr 2001;173:157–159.

5.Shah P, Applegate KE, Buonomo C. Stricture of the duodenum and jejunum in an abused child. Pediatr Radiol 1997;27:281–283.

6.McWilliams RG, Blakeborough A, Johnson MI, Weston

M.Case report: the “veiled right kidney sign”—an ultrasound finding in retroperitoneal perforation of the duodenum. Br J Radiol 1996;69:1061–1063.

7.Long FR, Kramer SS, Markowitz RI, Liacouras CA. Duodenitis in children: correlation of radiologic findings with endoscopic and pathologic findings. Radiology 1998;206:103–108.

8.Naouri C, Menecier P, Naouri A, Levenq P. [Duodenal tuberculosis: a difficult diagnosis.] [French] Presse Med 1997;26:805–806.

9.Vullierme MP, Vilgrain V, Flejou JF, et al. Cystic dystrophy of the duodenal wall in the heterotopic pancreas: radiopathological correlations. J Comput Assist Tomogr 2000;24:635–643.

10.Causeret S, Francois Y, Griot JB, Flourie B, Gilly FN, Vignal J. Prophylactic pancreaticoduodenectomy for premalignant duodenal polyposis in familial adenomatous polyposis. Int J Colorectal Dis 1998;13:39–42.

11.Bradford D, Levine MS, Hoang D, Sachdeva RM, Einhorn

E.Early duodenal cancer: detection on double-contrast upper gastrointestinal radiography. AJR 2000;174:1564– 1566.

12.Ligorred L, Morollon MJ, Aragon J, et al. [Obstructive jaundice from an adenomyoma of the ampulla of Vater.] [Spanish] Rev Esp Enferm Dig 1997;89:411–412.

13.Hamissa S, Rahmouni A, Coffin C, Wolkenstein P. CT detection of an ampullary somatostatinoma in a patient with von Recklinghausen’s disease. AJR 1999;173: 503–504.

14.Smith TR, Berkowitz D, Frost A. Prolapse of the common bile duct with small ampullary villous adenocarcinoma into third part of the duodenum. AJR 2003; 181:599–600.

15.Sugita R, Furuta A, Ito K, Fujita N, Ichinohasama R, Takahashi S. Periampullary tumors: High-spatial- resolution MR imaging and histopathologic findings in ampullary region specimens. Radiology 2004; 231:767–774.

16.Marcus SG, Dobryansky M, Shamamian P, et al. Endoscopic biliary drainage before pancreaticoduodenectomy for periampullary malignancies. J Clin Gastroenterol 1998;26:125–129.

17.Shirai Y, Ohtani T, Tsukada K, Hatakeyama K. Patterns of lymphatic spread of carcinoma of the ampulla of Vater. Br J Surg 1997;84:1012–1016.

18.Santoro E, Sacchi M, Scutari F, Carboni F, Graziano F. Primary adenocarcinoma of the duodenum: treatment and survival in 89 patients. Hepatogastroenterology 1997;44:1157–1163.

19.Hirasawa R, Iishi H, Tatsuta M, Ishiguro S. Clinicopathologic features and endoscopic resection of duodenal adenocarcinomas and adenomas with the submucosal saline injection technique. Gastrointest Endosc 1997;46:507–513.

20.Kawai T, Tada T, Yokoyama, Joh T, Itoh M. Lymphoma arising in mucosa-associated lymphoid tissue of the duodenal bulb. J Gastroenterol 1998;33:97–101.

21.Gakiya I, Kugai Y, Hayashi S, et al. Varioliform mucosal polypoid lesions in intestinal tract in a patient with adult T-cell leukemia. J Gastroenterol 1997;32:553– 557.

22.Shuke N, Tonami N, Takahashi I, et al. Prominent uptake of Ti-201 by duodenal leiomyosarcoma after exercise myocardial perfusion study. Clin Nucl Med 1995;20: 299–301.

23.Whitfill CH, Siegelman ES, Rosato EF, Furth EE. Primary carcinoid of the duodenum: detection and characterization by magnetic resonance imaging. J Magn Reson Imaging 1998;8:1175–1176.

24.Takasu A,Shimosegawa T,Fukudo S,et al. Duodenal gas- trinoma—clinical features and usefulness of selective arterial secretin injection test. J Gastroenterol 1998;33: 728–733.

25.Dumonceau JM, Delhaye M, Deviere J, Baize M, Cremer M. Endoscopic treatment of gastric outlet obstruction caused by a gallstone (Bouveret’s syndrome) after extracorporeal shock-wave lithotripsy. [Review] Endoscopy 1997;29:319–321.

26.Hitosugi M, Kitamura O, Takatsu A, Yoshino Y. Autopsy case of duodenal obstruction from impacted mushroom. [Review] J Gastroenterol 1998;33:562–565.

27.Basilisco G. Hereditary megaduodenum. [Review] Am J Gastroenterol 1997;92:150–153.

28.Tsitouridis I, Emmanouilidou M, Goutsaridou F, et al. MR cholangiography in the evaluation of patients with duodenal periampullary diverticulum. Eur J Radiol 2003; 47:154–160.

29.Tsukamoto T, Hasegawa I, Ohta Y, et al. [Perforated duodenal diverticulum caused by enterolith.] [Review]