3Acute PancreatitisAcute 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.
4Acute Pancreatitis Causes of Acute Pancreatitis (% of Cases) 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%MedicationsHypercalcemiaHypertriglyceridemiaObstructivePost-ERCPHereditaryTraumaViral Vascular/ischemicPostcardiac bypassIdiopathic: 10%
5Acute Pancreatitis Diagnosis According to the ACG guidelines, the diagnosis of AP is supported by an elevation of the serum amylase and lipase in excess of three times the upper limit of normal.Radiologic Studies:Plain films of the chest and abdomenTransabdominal ultrasoundContrast-enhanced computed tomographyEndoscopic ultrasoundMRI and magnetic resonance cholangiopancreatography (MRCP)Endoscopic retrograde cholangiopancreatography (ERCP)
6Acute 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 offdiffuse ileuspleural effusionThis is a fairly large left pleural effusion. Note that the normal diaphragm boarder as well as the posterior gutter are obscurred by the pleural effusion.
7Acute Pancreatitis Plain films The abdominal radiograph is not diagnostic and frequently normal or may demonstrate:sentinel loop colon cut offdiffuse ileuspleural effusionSentinel loop -a focal dilated proximal jejunal loop in the left upper quadrant
8Acute Pancreatitis Plain films The abdominal radiograph is not diagnostic and frequently normal or may demonstrate:sentinel loop colon cut offdiffuse ileuspleural effusiondistention of the colon to the transverse colon with a paucity of gas distal to the splenic flexure
9Acute 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, andit 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.
10Acute 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.
11Acute Pancreatitis CT Findings Contrast-enhanced computed tomography (CT) of the abdomen is the preferred test for 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.
12Acute Pancreatitis CT features in interstitial pancreatitis include: homogenous contrast enhancement;diffuse or segmental pancreatic enlargement;irregularity, heterogeneity, and lobularity of the pancreas;obliteration of the peripancreatic fat planesCT scan obtained with intravenous and oral contrast material shows an enlarged and homogeneously enhancing pancreatic gland.Normal pancreas
13Acute Pancreatitis CT Findings Complications of acute pancreatitis may lead to:necrosis,hemorrhagic pancreatitis,phylegmon formation,abscess,venous thrombosispseudocyst formationpancreatic pseudoaneurysmNORMAL
14CT Findings (Contrast or Noncontrast) Acute PancreatitisThe severity of pancreatitis detected on CT may be staged based on the Balthazar systemBALTHAZAR Grading System for Severity of Acute Pancreatitis According to CT CriteriaGradeCT Findings (Contrast or Noncontrast)ANormal pancreasBFocal or diffuse glandular enlargement, irregular contour of the gland, heterogeneous attenuation, no peripancreatic inflammationCSame findings as Grade B, with peripancreatic inflammationDSame findings as Grade C, with a single fluid collectionESame findings as Grade C, with multiple fluid collections or abscess formationAdapted from Balthazar EJ, et al. Radiology. 1990:174:331.
15Acute 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%
16Mortality of Acute Pancreatitis CT Severity IndexThere 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 rateMortality of Acute PancreatitisTypeMortality RateInterstitial AP<1%Necrotizing APSterile10%Infected30%
17Acute 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 CSeverity Index 2From: Acute Pancreatitis: Assessment of Severity with Clinical and CT Evaluation Emil J. Balthazar, MD Radiology 2002;223:
18Acute 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 DSeverity Index 7From: Acute Pancreatitis: Assessment of Severity with Clinical and CT Evaluation Emil J. Balthazar, MD Radiology 2002;223:
19Acute 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 10From: Acute Pancreatitis: Assessment of Severity with Clinical and CT Evaluation Emil J. Balthazar, MD Radiology 2002;223:
20Acute Pancreatitis Complications A pseudocyst appears as an oval or round water density collection with a thin or thick wall, which may enhanceContrast-enhanced CT scan reveals development of large pseudocysts in the neck and tail of the pancreas.From: Acute Pancreatitis: Assessment of Severity with Clinical and CT Evaluation Emil J. Balthazar, MD Radiology 2002;223:
21Acute 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:
22Acute 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.Hemorrhagic Phlegmon: One of the complications of acute pancreatitis results in inflammation of the surrounding tissues of the peripancreatic area. These tissues may be edematous with hypoechoic sonographic features, or they may be a more complex striated pattern with hemorrhage.White arrowheads: PhlegmonBlack arrowhead: Pancreatic calcificationLarge Arrow: Peripancreatic fascial infiltrationSt: Stomach
23Acute 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.
24Acute 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
25Preembolization angiogram depicting a splenic artery pseudoaneurysm. Acute PancreatitisComplicationsPancreatic 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.
26Acute Pancreatitis Diagnosis According to the ACG guidelines, the diagnosis of AP is supported by an elevation of the serum amylase and lipase in excess of three times the upper limit of normal.Radiologic Studies:Plain films of the chest and abdomenTransabdominal ultrasoundContrast-enhanced computed tomographyEndoscopic ultrasoundMRI and magnetic resonance cholangiopancreatography (MRCP)Endoscopic retrograde cholangiopancreatography (ERCP)
27Acute 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.
28Acute 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.
29Acute PancreatitisEndoscopic 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
31Chronic PancreatitisChronic 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.
32Chronic PancreatitisThe 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 pancreatitisOther conditions: hyperlipidemia, hyperparathyroidism, uremia, drug use, hereditary causes, autoimmune conditions, congenital causes (a congenital abnormality of fusion, pancreas divisum)
33Chronic PancreatitisChronic 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
34Chronic Pancreatitis Signs and symptoms Preferred Examination 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 ExaminationPlain film of the abdomenCTUltrasonographyMRI, particularly MRCPERCP
35Chronic 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.
36Chronic 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
37Chronic 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, andbile duct involvementare depicted well on CT scans.
38Chronic 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.
39Chronic 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 structure of pancreatic tissue.
40Chronic 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
41Chronic PancreatitisEndoscopic 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.
42Chronic PancreatitisEndoscopic retrograde cholangiopancreatography (ERCP)Mild pancreatitis may present with minimal dilation of the main pancreatic duct and some clubbing of the side branches of the duct
43Chronic PancreatitisEndoscopic retrograde cholangiopancreatography (ERCP)The patient with moderately-staged chronic pancreatitis shows 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
44Chronic PancreatitisEndoscopic 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
45Chronic Pancreatitis MRI Findings Groove pancreatitisMRI, 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.Groove pancreatitis is an uncommon type of focal chronic pancreatitis affecting the groove between the head of the pancreas, the duodenum, and the common bile duct.(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.
46Chronic 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.
47Chronic Pancreatitis MRCP and ERCP By contrast, a pancreatic carcinoma usually results in an abrupt transition of 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.
48Chronic Pancreatitis Complications of chronic pancreatitis include: pseudocyst formationfistula formationpseudoaneurysms of large arteries close to the pancreasstenosis of the common bile ductsplenic and/or portal venous obstructionDiabetes can develop in 70-90% of patients with chronic calcific pancreatitis
49Cystic 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 diagnosisFrom: Cystic Lesions of the Pancreas Terrence C. Demos et al. AJR 2002; 179:
50PseudocystPanceatic 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 liningA typical pseudocyst, however, is a uniform, low-attenuation fluid collection with a thin uniform wall that enhances after the administration of IV contrast materialFrom: Cystic Lesions of the Pancreas Terrence C. Demos et al. AJR 2002; 179:
51PseudocystOn CT, 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.On sonography, uncomplicated pseudocysts are generally hypoechoic with variable through-transmission, but hemorrhage or necrotic debris will produce internal echogenicity.From: Cystic Lesions of the Pancreas Terrence C. Demos et al. AJR 2002; 179:
52When cysts are chronic, the cyst wall can calcify PseudocystWhen cysts are chronic, the cyst wall can calcifyCT scan shows pseudocyst with calcified wall in head of pancreas.From: Cystic Lesions of the Pancreas Terrence C. Demos et al. AJR 2002; 179:
53PseudocystSymptoms related to complications of pseudocyst include jaundice due to extrahepatic bile duct obstruction and signs of duodenal obstruction.Upper GI tract barium study shows displacement and stretching of duodeno-jejunal junction.A catheter in a dilated common bile duct.
54Mucinous adenocarcinoma Adenocarcinoma is the most common pancreatic neoplasm.Mucinous adenocarcinoma is an uncommon variant of adenocarcinoma.This neoplasm produces a large volume of mucin that results in a cystic appearance on imaging studiesCT scan shows well-defined cystic component of mass in tail of pancreas. Note liver metastasis (arrow).From: Cystic Lesions of the Pancreas Terrence C. Demos et al. AJR 2002; 179: