4

Dilatation of the Pancreatic Duct

4

Pancreas

Marginal diameters of 2–3 mm occur as a postprandial functional response, but often they are based on a disease of the biliary system. In the case of somewhat blurred ducts, it is well worth the effort to take a look at the gallbladder and to trace the CBD all the way to the papilla of Vater. In many cases, ductal dilatation is nothing more than postcholecystectomy, often preceded by recurrent colics (with accompanying pancreatitis?). The underlying cause must be increased intraductal pressure (Fig. 4.62).

Fig. 4.62 Dilated pancreatic duct (arrows) in postcholecystectomy. K = venous confluence; AO = aorta; L = liver.

Fig. 4.63

a Pancreatic duct of marginal diameter (0.28 cm, cursors) in histologically proven IPMN.

b Slightly dilated pancreatic duct in carcinoma of the pancreatic head (uncinate process, hypoechoic mass).

Chronic Pancreatitis

Dilatation of the pancreatic duct in chronic pancreatitis tends to be quite marked rather than marginal. The obstruction may be caused by intraductal calculi, prepapillary gallstones, protein plugs, and in a few rare cases a slowgrowing malignancy. Fibrosis of the adjacent tissue can result in a tortuous duct with varying diameter, beaded irregularities, and twisting, mostly in an advanced state (Fig. 4.64).

Periampullary Cancer, Cancer of thePancreaticHead

Here, dilatation of the pancreatic duct is normal and in the advanced stage quite marked. Cancer of the tail of the pancreas will not result in ductal dilatation, while cancer of the uncinate process will sometimes do so. Cancer in the head of the pancreas is usually accompanied by dilatation of the CBD (Fig. 4.65).

4

Dilatation of the Pancreatic Duct

Fig. 4.65 Dilated prepapillary ducts.

a Transverse epigastric view: cross-sectional view of the pancreatic duct (DP) and CBD (CH) (double duct sign); periampullary ductal cancer of the pancreas. The carcinoma could not be demonstrated on ultrasound or CT. AO = aorta; VC = vena cava; VL = splenic vein; P = pancreas.

b ERCP film with tumorous void in the pancreatic duct.

Marked Dilatation

Chronic Pancreatitis

Intraductal Mass

Pancreatic Cancer

Acute relapsing pancreatitis or persistent pain in chronic pancreatitis are often caused by stones obstructing the pancreatic duct. The calculi will be visualized when following the duct sonographically to the papilla of Vater. One

treatment option is ultrasound-guided lithotripsy following papillotomy (Fig. 4.66a,b).

Prominent dilatation of the pancreatic duct with no obstruction seen on ultrasound or endoscopy is also found in the rare patient with

chronic autoimmune pancreatitis. In these cases, it is of vital importance that possible neoplasms (look out for IPMN) and malignancy be ruled out for certain (Fig. 4.66c,d, Fig. 4.67).

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Pancreas

Fig. 4.69 Pancreatic duct (DP) with prestenotic dilatation and ductal cut-off without direct visualization of the tumor; but, together with the cut-off (arrow), the diffuse ill-defined enlarged head of the pancreas suggests the malignancy. AO = aorta.

Table 4.11 Differential diagnosis of the pancreatic duct with prestenotic dilatation

Pancreas divisum ● Ductal cut-o in the head/body without definite cause

●Conspicuously enlarged head of the pancreas

●Demonstration of two ductal systems in the pancreatic head

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Dilatation of the Pancreatic Duct

Fig. 4.70 Small cancer (T) of the pancreatic head; duct (DP) with prestenotic dilatation; dilated CBD (DHC) and cystic duct (DCY). “Double duct sign”.

Fine-needle biopsy and cytohistology is of no benefit in the case of suspected carcinoma in chronic pancreatitis because of the high rate of false-negative results. However, if pain is persistent in chronic pancreatitis, the possibility of carcinoma must be a primary consideration.

Fig. 4.71 Cancer (T) of the uncinate process. AO = aorta; VC = venous confluens; VL = splenic vein.

a With invasion of the pancreatic duct (arrow, DP).

The cumulative risk of pancreatic cancer in chronic pancreatitis is 1.8% after 10 years, and 4% after 20 years.15 Therefore, chronic pancreatitis is considered a precancer. When the symptoms persist, cancer cannot be ruled out and the issue has to be settled by surgery (Figs. 4.69, 4.70, 4.71).

b CDS: invasion of the splenic vein. The invasive spread confirms malignancy and rules out surgery as an option.

Table 4.11 summarizes the differential diagnosis of the pancreatic duct with prestenotic dilatation.

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Pancreas

Tips, tricks, and pitfalls

General

●The pancreas is more easily detectable in abdominal ultrasound than is generally assumed; it is of great value to have a “second look” when intestinal gas interferes with the detection of the organ. Peristalsis, compression, palpation, decubitus position, inspiration, or expiration favor a better visual situation.

●The normal visual point in a transverse scan direction is through the deep inspirated left liver lobe, and for the tail a scan direction through the spleen.

References

[1]Etemad B, Whitcomb DC. Chronic pancreatitis: diagnosis, classification, and new genetic developments. Gastroenterology 2001; 120(3):682–707

[2]Wermke W. 32. Dreiländertreffen Davos 2008

[3]Dellinger EP, Forsmark CE, Layer P, et al. De- terminant-based classification of acute pancreatitis severity: an international multidisciplinary consultation. Ann Surg 2012;256: 875-880

[4]Sarner M, Cotton PB. Classification of pancreatitis. Gut 1984;25(7):756–759

[5]D’Onofrio M, Zamboni G, Tognolini A, et al. Mass-forming pancreatitis: value of contrastenhanced ultrasonography. World J Gastroenterol 2006;12(26):4181–4184

[6]Kim KP, Kim MH, Kim JC, Lee SS, Seo DW, Lee SK. Diagnostic criteria for autoimmune

●Fluid collection in the stomach improves the visualization of the pancreas, so a breakfast that includes a drink may lead to better conditions.

●Dynamic criteria: displacement of the organ is detectable on inspiration.

●Consistency: normally, compression of the soft pancreatic head by the caval pulsation can be observed.

Special

●In diminished parenchyma (aging pancreas, cachexia) a lot of vessels are close together; in this case the gastroduodenal artery becomes a leading structure.

chronic pancreatitis revisited. World J Gastroenterol 2006;12(16):2487–2496

[7]Catalano MF, Lahoti S, Geenen JE, Hogan WJ. Prospective evaulation of endoscopic ultrasonography, endoscopic retrograde pancreatography, and secretin testin in the diagnosis of chronic pancreatitis. Gastrointest Endosc 1998;48:11–17

[8]Jenssen C, Dietrich CF. Endosonographie bei chronischer Pankreatitis [Endoscopic ultrasound in chronic pancreatitis]. Z Gastroenterol 2005;43(8):737–749

[9]Claudon M, Cosgrove D, Albrecht T, et al; EFSUMB Study Group et al. Guidelines and good clinical practice recommendations for contrast enhanced ultrasound (CEUS)—up- date 2008. Ultraschall Med 2008;29(1): 28–44

[10]Will U. in: Schmidt G, Görg C. Kursbuch Ultraschall. 5. ed Stuttgart, New York: Thieme; 2008

[11]DeWitt J, Devereaux B, Chriswell M, et al. Comparison of endoscopic ultrasonography

●Hyperechoic fluid or stones in the pancreatic duct conceal a duct dilatation; branches of the main duct are only exceptionally demonstrable (Fig. 4.72; see also Fig. 4.66 d).

The duodenum enclosing the pancreas is, like the jejunum, a small and poorly visible part of the intestine. This situation changes in case of inflammation; in a functional state such as diabetic vegetative neuropathy, intramural fluid collection alters the situation. In this case, the duodenum is demonstrable around the head of the pancreas, because the descending duodenum runs not only strictly caudally (as seen in anatomy) but also in a dorsal direction.

Fig. 4.72

a Chronic atrophic pancreatitis. Echogenic pancreatic duct with stenosis between the stomach (MA) and the splenic vein (VL).

b Atrophic chronic pancreatitis. Dilated hyoechoic duct (DP) with a calculus in the head and visible branches of the main duct (arrows).

and multidetector computed tomography for detecting and staging pancreatic cancer. Ann Intern Med 2004;141(10):753–763

[12]Taniguchi T, Seko S, Azuma K, et al. Autoimmune pancreatitis detected as a mass in the tail of the pancreas. Am J Gastroenterol 1995; 90:1834–1837

[13]Riede UN, Werner M. Color atlas of pathology. Stuttgart: Thieme, 2004

[14]Klöppel G, Kosmahl M. Cystic lesions and neoplasms of the pancreas. Pancreatology 2001;1:648–655

[15]Lowenfels AB, Maisonneuve P, Cavallini G, et al; International Pancreatitis Study Group. Pancreatitis and the risk of pancreatic cancer. N Engl J Med 1993;328(20):1433–1437

[16]D’Egidio A, Schein M; D’Egidio A. Pancreatic pseudocysts: a proposed classification and its management implications. Br J Surg 1991;78 (8):981–984