Pancreatic Diseases

1. Pancreatic Diseases

2. Acute Pancreatitis

3. Acute Pancreatitis • Acute pancreatitis (AP) is an acute inflammatory condition of the pancreas that may extend to local and distant extrapancreatic tissues. • The American College of Gastroenterology (ACG) practice guidelines provide acceptable terminology for the classification of AP and its complications. • AP is broadly classified as mild or severe: • Mild AP is often referred to as interstitial pancreatitis, based on its radiographic appearance. • Severe AP implies the presence of organ failure, local complications, or pancreatic necrosis.

4. Acute Pancreatitis The yearly incidence of AP in the United States is approximately 17 new cases per 100,000 population. Acute pancreatitis results in 100,000 hospitalizations per year. 80% of cases of AP are interstitial and mild; the remaining 20% are necrotizing and severe. Approximately 2,000 patients per year die from complications related to AP. • Causes of Acute Pancreatitis (% of Cases) • Gallstones: 45% • Alcohol: 35% • Other 10% • Medications • Hypercalcemia • Hypertriglyceridemia • Obstructive • Post-ERCP • Hereditary • Trauma • Viral Vascular/ischemic • Postcardiac bypass • Idiopathic: 10%

5. Acute Pancreatitis Diagnosis • According to the ACG guidelines, the diagnosis of AP is supported by anelevation of the serum amylase and lipasein excess of three times the upper limit of normal. • Radiologic Studies: • Plain films of the chest and abdomen • Transabdominal ultrasound • Contrast-enhanced computed tomography • Endoscopic ultrasound • MRI and magnetic resonance cholangiopancreatography (MRCP) • Endoscopic retrograde cholangiopancreatography (ERCP)

6. Acute Pancreatitis Plain films • An abdominal radiograph is helpful for excluding other causes of acute abdominal pain, such as obstruction and perforation. • The abdominal (or chest radiograph) is not diagnostic and frequently normal or may demonstrate: • sentinel loop  • colon cut off • diffuse ileus • pleural effusion

7. Acute Pancreatitis Plain films • The abdominal radiograph is not diagnostic and frequently normal or may demonstrate: • sentinel loop  • colon cut off • diffuse ileus • pleural effusion Sentinel loop - afocal dilated proximal jejunal loop in the left upper quadrant

8. Acute Pancreatitis Plain films • The abdominal radiograph is not diagnostic and frequently normal or may demonstrate: • sentinel loop  • colon cut off • diffuse ileus • pleural effusion distention of the colon to the transverse colon with a paucity of gas distal to the splenic flexure

9. Acute Pancreatitis US Findings • Although transabdominal ultrasound is poorly reliable for imaging the pancreas itself, it is the best initial radiographic test for the evaluation of mild AP because: • it detects gallstones as a potential cause, • it rules out acute cholecystitis as a differential cause of pain and hyperamylasemia, and • it detects biliary dilatation suggestive of the need for early endoscopic retrograde cholangiopancreatography (ERCP). The pancreas may appear completely normal in mild cases of acute pancreatitis.

10. Acute Pancreatitis US Findings • In the early stages of acute pancreatitis, the gland may not show swelling. When swelling does occur, the gland is hypoechoic to anechoic because of the increased edema. • On the longitudinal scan, the swollen head of the pancreas may compress the inferior vena cava. • The pancreatic duct may be enlarged secondary to inflammation, spasm, edema, swelling of the papilla, or pseudocyst formation. Image shows that pancreatic echogenicity is within normal limits, but the gland is mildly enlarged. In addition, a complex fluid collection lies anterior to the pancreas, and abnormal sonolucency surrounds the splenic vein.

11. Acute Pancreatitis CT Findings Contrast-enhanced computed tomography (CT) of the abdomenis the preferred testfor evaluating severe pancreatitis and detecting complications. • A CT should not be routinely ordered for all patients with AP; however, The American College of Gastroenterology (ACG)practice guidelines state that: • "a dynamic contrast-enhanced CT is recommended at some point beyond the first 3 days in severe acute pancreatitis (on the basis of a high APACHE score or organ failure) to distinguish interstitial from necrotizing pancreatitis.„ • A CT should also be considered for those in whom a localized pancreatic complication is suspected (eg, pseudocyst, splenic vein thrombosis, splenic artery aneurysm). • CT is also appropriate after resolution of AP to exclude a tumor if the cause of the attack is unclear.

12. Acute Pancreatitis • CT features in interstitialpancreatitis include: • homogenous contrast enhancement; • diffuse or segmental pancreatic enlargement; • irregularity, heterogeneity, and lobularity of the pancreas; • obliteration of the peripancreatic fat planes CT scan obtained with intravenous and oral contrast material shows an enlarged and homogeneously enhancing pancreatic gland. Normal pancreas

13. Acute Pancreatitis CT Findings • Complications of acute pancreatitis may lead to: • necrosis, • hemorrhagic pancreatitis, • phylegmon formation, • abscess, • venous thrombosis • pseudocyst formation • pancreatic pseudoaneurysm NORMAL

14. Acute Pancreatitis The severity of pancreatitis detected on CT may be staged based on the Balthazar system

15. Acute Pancreatitis CT Severity Index The CT severity index is an attempt to improve the early prognostic value of CT in cases of acute pancreatitis. Patients with grade A–E pancreatitis are assigned zero to four points plus two points for necrosis of up to 30%, four points for necrosis of 30%–50%, and six points for necrosis of more than 50%

16. Acute Pancreatitis CT Severity Index There was a statistically significant correlation, with a continuous increasing incidence of morbidity and mortality in patients stratified according to CT severity index groups. Patients who had a severity index of 0 or 1 exhibited a 0% mortality rate and no morbidity, while patients with severity index of 2 had no mortality and a 4% morbidity rate. In contrast, a severity index of 7–10 yielded a 17% mortality rate and a 92% complication rate

17. Acute Pancreatitis CT Findings Transverse nonenhanced CT scan shows a homogeneously enlarged pancreas. There are large heterogeneous peripancreatic fluid collections. peripancreatic fluid collections. Gland necrosis cannot be ruled out. Grade C Severity Index 2 From: AcutePancreatitis: Assessment of Severity with Clinical and CT Evaluation Emil J. Balthazar, MD Radiology 2002;223:603-613.

18. Acute Pancreatitis CT Findings Contrast-enhanced CT scan reveals two zones of liquefied pancreatic necrosis in the neck and tail of the gland. There are residual nodular areas adjacent to the tail of the pancreas, consistent with fat necrosis (curved arrow). Grade D Severity Index 7 From: AcutePancreatitis: Assessment of Severity with Clinical and CT Evaluation Emil J. Balthazar, MD Radiology 2002;223:603-613.

19. Acute Pancreatitis CT Findings CT scans reveal an encapsulated fluid collection associated with liquefied necrosis in the body of the pancreas. The head, part of the body, and the tail of the pancreas are still enhancing. Residual fluid collections and areas of soft-tissue attenuation (curved arrow) consistent with fat necrosis are seen adjacent to the pancreas. f = fluid, N = liquefied gland necrosis, S = stomach. Grade E, Severity Index 10 From: AcutePancreatitis: Assessment of Severity with Clinical and CT Evaluation Emil J. Balthazar, MD Radiology 2002;223:603-613.

20. Acute Pancreatitis Complications A pseudocyst appears as an oval or round water density collection with a thin or thick wall, which may enhance Contrast-enhanced CT scan reveals development of large pseudocysts in the neck and tail of the pancreas. From: AcutePancreatitis: Assessment of Severity with Clinical and CT Evaluation Emil J. Balthazar, MD Radiology 2002;223:603-613.

21. Acute Pancreatitis Complications A pancreatic abscess can manifest as a thick-walled low-attenuation fluid collection with gas bubbles or a poorly defined fluid collection with mixed densities/attenuation. CT scan shows large fluid collection containing gas bubbles in pancreatic bed due to abscess complicating acute pancreatitis. Note infiltration of peripancreatic fat and calcified gallstones. From: Cystic Lesions of the Pancreas Terrence C. Demos et al. AJR 2002; 179:1375-1388

22. Acute Pancreatitis Complications A pancreatic phlegmon is an inflammatory mass in and around the pancreas formed by oedema and continued leakage of activated pancreatic enzymes. It may resolve spontaneously, or progress to pseudocyst, necrosis or abscess.

23. Acute Pancreatitis Complications Venous thrombosis can be identified as a failure of the peripancreatic vein (eg, splenic vein, portal vein) to enhance or as an intraluminal filling defect.

24. Acute Pancreatitis Complications A pancreatic pseudoaneurysm is a malformation in the vessels of the pancreas and/or peripancreatic bed. A CT scan with intravenous contrast enhancement within a pancreatic pseudocyst indicating the presence of a pseudoaneurysm. Mesenteric artery angiogram demonstrating contrast extravasating into a pseudoaneurysm

25. Acute Pancreatitis Complications Pancreatic or peripancreatic bleeding is one of the most life-threatening complications of pancreatitis. The standard of care in dealing with pseudoaneurysms has been surgical intervention; recently, many interventional radiologists have reported excellent outcome after angioembolization. Preembolization angiogram depicting a splenic artery pseudoaneurysm. Postembolization angiogram depicting successful coil embolization of the pseudoaneurysm.

26. Acute Pancreatitis Diagnosis • According to the ACG guidelines, the diagnosis of AP is supported by anelevation of the serum amylase and lipasein excess of three times the upper limit of normal. • Radiologic Studies: • Plain films of the chest and abdomen • Transabdominal ultrasound • Contrast-enhanced computed tomography • Endoscopic ultrasound • MRI and magnetic resonance cholangiopancreatography (MRCP) • Endoscopic retrograde cholangiopancreatography (ERCP)

27. Acute Pancreatitis MRI Findings MRI is an alternative in situations in which CECT is contraindicated, such as in patients with contrast allergy or renal insufficiency. Acute necrotizing pancreatitis. In A, a distal common bile duct stricture (arrow), abnormal pancreatic duct side branches (solid arrowheads) and indirect signs of duodenal wall thickening (open arrowheads) are visualized. The peripancreatic fluid collections detected in B (arrows) are not detected in A, because of the shorter T2 relaxation time of the fluid in the peripancreatic collections. From: MR Imaging of the Pancreas: A Pictorial Tour C. Matos et al. Radiographics. 2002;22:e2.

28. Acute Pancreatitis MRI Findings MRI was found to be equivalent to CECT in helping assess the location and extent of peripancreatic inflammatory changes and fluid collections. In addition, MRI was found to be equivalent in helping assess the degree of pancreatic necrosis. Patient with acute pancreatitis and peripancreatic exudate. Non-fat-suppressed (A, C) and fat-suppressed (B, D) T2-weighted images. Increased signal intensity of peripancreatic fat tissues (arrows) is better demonstrated in B and D. From: MR Imaging of the Pancreas: A Pictorial Tour C. Matos et al. Radiographics. 2002;22:e2.

29. Acute Pancreatitis Endoscopic retrograde cholangiopancreatography (ERCP) ERCP allows identification and removal of common-bile-duct stones in suspected gallstone pancreatitis. Because of its invasive nature and the inherent risk of worsening pancreatitis, it should be performed only in the setting of ongoing biliary obstruction and cholangitis. Slightly dilated common bile duct with calculus and normal pancreatic duct are shown

30. Chronic Pancreatitis

31. Chronic Pancreatitis Chronic pancreatitis represents a continuous, prolonged, inflammatory and fibrosing process of the pancreas with irreversible morphologic changes resulting in permanent endocrine and exocrine pancreatic dysfunction. Acute pancreatitis and chronic pancreatitis are assumed to be different disease processes, and most cases of acute pancreatitis do not result in chronic disease.

32. Chronic Pancreatitis • The main causes of chronic pancreatitis include the following: • Alcoholism: Alcoholism is associated with chronic pancreatitis in 60-90% of patients. • Cholelithiasis: Cholelithiasis is a common cause of acute pancreatitis, but it probably is associated with chronic pancreatitis in 20-25% of patients. • Idiopathic: Etiology is idiopathic in 10-40% of patients. • Cystic fibrosis: This disease is associated with pancreatic atrophy and chronic pancreatitis • Other conditions: hyperlipidemia, hyperparathyroidism, uremia, drug use, hereditary causes,autoimmune conditions, congenital causes (a congenital abnormality of fusion, pancreas divisum)

33. Chronic Pancreatitis • Chronic pancreatitis can be classified into 3 categories: • Chronic calcifying pancreatitis is invariably related to alcoholism. • In chronic obstructive pancreatitis, the prominent histologic changes are periductal fibrosis and subsequent ductal dilatation. These changes are much more focal than those in the other forms, and in most patients, the changes involve only the portion of the pancreas in which ductal drainage is impaired. Diffuse changes may occur, in which the main pancreatic duct or ampulla is obstructed. • Chronic inflammatory pancreatitis is rare and can affect elderly persons without a previous history of alcohol excess. The main duct of the pancreas is dilated and contains calcified secretions

34. Chronic Pancreatitis • Signs and symptoms • Chronic pancreatitis is a relapsing condition that presents with abdominal pain,occurring in 95% of cases. • Pain can be episodic, lasting hours to days, or it can persist for months or even years. The pain is characteristically steady in the epigastrium, and it frequently radiates to the back. • Weight loss and signs of exocrine and endocrine dysfunction are also common symptoms. Preferred Examination • Plain film of the abdomen • CT • Ultrasonography • MRI, particularly MRCP • ERCP

35. Chronic Pancreatitis Plain films • Pancreatic calcifications are shown in 25-59% of patients. • This feature is pathognomonic for chronic pancreatitis. • Calcification is punctate or coarse, and it may have a focal, segmental, or diffuse distribution. chronic pancreatitis with marked calcification of the pancreatic parenchyma.

36. Chronic Pancreatitis Upper GI tract barium series The anatomic proximity of the pancreatic head and stomach antrum is constant, and enlargement of the pancreatic head usually causes effacement of the antrum. This finding has been termed the pad sign. Upper gastrointestinal tract barium study shows a reverse 3 in the duodenum due to chronic pancreatitis. Pancreatic carcinoma can have a similar appearance

37. Chronic Pancreatitis CT Findings • Currently, CT is regarded as the imaging modality of choice for the initial evaluation of suggested chronic pancreatitis. • The diagnostic features of: • pancreatic enlargement, • pancreatic calcifications, • pancreatic ductal dilatation, • thickening of the peripancreatic fascia, and • bile duct involvement • are depicted well on CT scans.

38. Chronic Pancreatitis CT Findings The sensitivity of plain film for detection of pancreatic calcifications is about 80 %, which is higher than that of sonography but lower than that of CT.

39. Chronic Pancreatitis Ultrasound • Ultrasonography is the first modality to be used in patients presenting with upper abdominal pain, although the direct diagnosis of chronic pancreatitis is not always possible. • In early disease, the pancreas may be enlarged and hypoechoic, with ductal dilatation. Later, the pancreas becomes heterogeneous, with areas of increased echogenicity and focal or diffuse enlargement. Chronic pancreatitis in phase of exacerbation - an uneven outline of the gland and heterogeneous structureof pancreatic tissue.

40. Chronic Pancreatitis Ultrasound • In late stages of the disease, the pancreas becomes atrophic and fibrotic, and it shrinks. These changes result in a small, echogenic pancreas with a heterogeneous echotexture. • Pseudocysts may occur, and focal hypoechoic inflammatory masses may mimic pancreatic neoplasia. • Calculi and calcification in the gland result in densely echogenic foci, which may show shadow

41. Chronic Pancreatitis Endoscopic retrograde cholangiopancreatography (ERCP) ERCP is the most sensitive and specific technique in the investigation of chronic pancreatitis, although it is invasive and may cause an acute episode of pancreatitis and ascending cholangitis. ERCP of normal pancreatic and biliary ducts.

42. Chronic Pancreatitis Endoscopic retrograde cholangiopancreatography (ERCP) Mild pancreatitismay present with minimal dilation of the main pancreatic duct and some clubbing of the side branches of the duct

43. Chronic Pancreatitis Endoscopic retrograde cholangiopancreatography (ERCP) The patient withmoderately-staged chronic pancreatitisshows moderate dilation of the main pancreatic duct (1.5 times the normal size) This is accompanied by moderate clubbing of the side branches of the main pancreatic duct

44. Chronic Pancreatitis Endoscopic retrograde cholangiopancreatography (ERCP) A characteristic "chain of lakes" appearance of the main pancreatic duct can be noted on ERCP in patients with severe chronic pancreatitis. The main pancreatic duct is enlarged (greater than 1.5 times) with increased tortuosity. There is severe clubbing and dilation of the side branches. Stone formation and occlusion of the pancreatic duct may occur in this stage of the disease

45. Chronic Pancreatitis MRI Findings Groove pancreatitis MRI, particularly MRCP, is a noninvasive technique. The combination of pancreatic parenchyma imaging sequences with MR angiography and secretin-enhanced MRCP offers the possibility of a comprehensive examination within a single diagnostic modality for evaluation of the full range of pancreatic diseases. (A) MRCP demonstrates a "double duct" stricture with proximal dilatation of the common bile duct and pancreatic duct (arrow). A cystic lesion is seen between the common bile duct and the duodenal wall. (B) Fat-suppressed TSE T1-weighted image. Unenhanced (C) and delayed gadolinium-enhanced (D) T1-weighted images, demonstrate diffuse enhancement of the sheetlike mass, which corresponded to fibrotic tissue.

46. Chronic Pancreatitis MRCP and ERCP • Involvement of the common bile duct may be visualized as a gradually tapering of the lumen of the obstructed common bile duct. MRCP image in patient with chronic pancreatitis shows reduced duodenal filling.

47. Chronic Pancreatitis MRCP and ERCP • By contrast, a pancreatic carcinoma usually results in an abrupt transitionof the common bile duct. Dynamic MRCP images in a patient with an ampullary tumor shows an increase in the caliber of the pancreatic duct. Associated biliary tract dilatation is seen - double-duct sign.

48. Chronic Pancreatitis • Complications of chronic pancreatitis include: • pseudocyst formation • fistula formation • pseudoaneurysms of large arteries close to the pancreas • stenosis of the common bile duct • splenic and/or portal venous obstruction • Diabetes can develop in 70-90% of patients with chronic calcific pancreatitis

49. Cystic Lesions of the Pancreas Cystic pancreatic lesions are regularly encountered on imaging studies of patients who are symptomatic or as unexpected abnormalities in patients who are being examined for other reasons. A wide variety of cystic lesions of the pancreas are seen, but pseudocysts are by far most common. Cystic neoplasms are often misdiagnosed as pseudocysts. This indicates the difficulty in diagnosis and at the same time emphasizes the need to obtain clinical information to provide the most accurate diagnosis From: Cystic Lesions of the Pancreas Terrence C. Demos et al. AJR 2002; 179:1375-1388

50. Pseudocyst Panceatic and parapancreatic fluid collections are most often complications of pancreatitis. These fluid collections can resolve spontaneously, but those that do not are recognized as pseudocysts on imaging studies when a well-defined wall becomes visible. This wall consists of fibrous tissue, but unlike true cysts, lymphoepithelial cysts, and most cystic neoplasms, a pseudocyst has no epithelial lining A typical pseudocyst, however, is a uniform, low-attenuation fluid collection with a thin uniform wall that enhances after the administration of IV contrast material From: Cystic Lesions of the Pancreas Terrence C. Demos et al. AJR 2002; 179:1375-1388