CT Imagine of Acute Pancreatitis
Transcript of CT Imagine of Acute Pancreatitis
CT Imaging of Acute Pancreatitis
Erin Rikard
Radiology
December 2007
Outline
• Definition• Epidemiology• Causal Factors• Pathophysiology• CT Evaluation and Findings – Normal and
abnormal• Complications• Management• Prognosis
Definition
Definition
Acute Pancreatitis -
Inflammation of
pancreas with
potential for
complete healing
Epidemiology
Epidemiology
• 79.8/100,000 per year → 185,000 new cases annually in U.S.
• Peak incidence in 6th decade
Causal Factors
Causal Factors
Etiology Incidence
Cholelithiasis 30-60%
Alcohol 15-30%
Iatrogenic 2-5%
Trauma/Surgery --
Metabolic Disorders --
Viral Infection --
Pathophysiology
Pathophysiology
• Pancreatic autodigestion, with activated pancreatic enzymes escaping the ductal system and lysing tissue of pancreas and adjacent structures
• Lack of capsule facilitates spread
Normal CT Findings
Normal Anatomy by CT
• Pancreas arcing anteriorly over spine
• Head adjacent to duodenum
• Tail extending toward spleen
• Splenic vein posterior to body and tail
• Portal vein confluence immediately posterior & left of pancreatic neck
Normal Morphology by CT
• Pancreatic acini → lobulated contour• No capsule• AP dimensions
Head 2-2.5 cm Body and tail 1-2 cm
• Pancreatic duct Maximal diameter 3 mm in adults (5 mm in
elderly) Empties into ampulla of Vater, along medial aspect
of 2nd portion of duodenum
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CT scans of normal kidneys and pancreas
Spleen
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Liver
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Pancreas
Evaluation by CT
Evaluation of Acute Pancreatitis
• Contrast-enhanced CT is imaging modality of choice
• Oral and IV contrast differentiate pancreatic tissue from adjacent blood vessels and duodenum
Recommendations for Contrast-Enhanced CT
• Clinical diagnosis in doubt
• Severe clinical pancreatitis
• Ranson score > 3
• APACHE score > 8
• Failure to rapidly improve within 72 hours of beginning conservative medical therapy
• Initial improvement with later deterioration
Ranson Criteria
At admission
• Age > 55• WBC > 16,000• Blood glucose > 200• Serum AST > 250• Serum LDH > 350
After 48 hours
• Hematocrit ↓ > 10%• ↑ BUN ≥ 1.8 after
rehydration• Serum calcium < 8.0• PO2 < 60• Base deficit > 4 • Estimated fluid
sequestration > 6L
Abnormal CT Findings
• Peripancreatic inflammation
• Diffuse or focal pancreatic edema
• Poor definition and heterogeneity of gland
• Fluid collections
• Necrosis
• Thickening of pararenal fascia
Abnormal CT Findings
Spectrum of Disease
• Mild Cases May be normal or
show only mild gland enlargement
• Severe Cases May reveal
peripancreatic fluid &/or pancreatic necrosis and phlegmon
Peripancreatic Inflammation/ Pancreatic Edema/
Fluid Collections
Transverse CT scan obtained with intravenous and oral contrast material reveals a large, edematous, homogeneously attenuating (73-HU) pancreas (1) and peripancreatic inflammatory changes (white arrows). Although the attenuation values are low, there is no pancreatic necrosis. Calcified gallstones are seen in gallbladder (black arrow). 2 = liver (140 HU).
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Infection?• Gallium-67 SPECT (perfusion studies)
• ? with (+) findings had infection at intervention – 78% of all patients
• No false (+)
• No correlation between gallium uptake and presence or absence of necrosis
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47-year-old man with severe pancreatitis
Fluid collection replacing pancreatic body and tail
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647-year-old man with severe pancreatitis
47-year-old man with severe pancreatitis who had true-positive finding for 47-year-old man with severe pancreatitis who had true-positive finding for infection on gallium study. Fusion image of CT scan and gallium study was infection on gallium study. Fusion image of CT scan and gallium study was helpful in localizing infection. helpful in localizing infection.
Necrosis
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57-year-old man with acute necrotizing pancreatitis and severe back pain
Large region of unenhancement (necrosis) involving most of body and tail of pancreas. Inflammatory fluid is present in anterior pararenal space. Note ascites around liver.
50 year-old woman with acute pancreatitis (1st view)
(a, b) Transverse CT scans obtained with intravenous and oral contrast material reveal an encapsulated fluid collection associated with liquefied necrosis (large straight arrows) in the body of the pancreas. The head, part of the body, and the tail of the pancreas are still enhancing (small straight arrows). N = liquefied gland necrosis, S = stomach.
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(a, b) Transverse CT scans obtained with intravenous and oral contrast material. The head, part of the body, and the tail of the pancreas are still enhancing (straight arrows). 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.
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Complications
Complications
• Pancreatic Pseudocysts
• Abscess
• Hemorrhagic Pancreatitis
• Splenic Artery Pseudoaneurysm formation or rupture/ Splenic Venous Thrombosis
Pancreatic Pseudocyst
• Fluid collection surrounded by fibrous capsule but not lined by epithelium
• Occurs in 10% of cases
• Significant % will not resolve spontaneously
• Seen within pancreas and potential spaces with which gland is continuous (lesser sac and left pararenal space)
28 year-old man with pseudocyst
Image demonstrates a pseudocyst (arrow) in the tail of the pancreas surrounded by a thick enhancing wall. The lesion appears heterogeneous with central areas of higher attenuation, which is suggestive of fresh hemorrhage. Note infiltration (arrowheads) of the peripancreatic fat.
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Axial CT scan obtained with intravenous contrast material demonstrates calcifications from chronic pancreatitis in the head of the pancreas. A high-attenuation focus of blood (arrow) is seen within the low-attenuation pseudocyst, a finding that is consistent with hemorrhage.
44 year-old man with acute abdominal pain – hemorrhagic pseudocyst
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Abscess
• 1 in 20 cases and fatal in ¾ of cases
• Suspected clinically with fever and septicemia
• Pathognomonic finding → presence of gas bubbles in pancreatic bed
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Pancreatic abscess containing gas in 54-year-old man
Large fluid collection containing gas bubbles in pancreatic bed due to abscess complicating acute pancreatitis. Note infiltration of peripancreatic fat and calcified gallstones.
Hemorrhagic Pancreatitis
• Rare• Noted clinically by ↓ in
hematocrit
CT scan demonstrates hemorrhagic pancreatitis as a heterogeneous mass in the area of the pancreatic bed (*). Arrow indicates active extravasation (hemorrhage).
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Splenic Artery Pseudoaneurysm
• Presents similarly to hemorrhagic pancreatitis with a ↓ in hematocrit
Axial CT scan with intravenous contrast material reveals a pseudoaneurysm (arrow) projecting from the splenic artery.
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Management
Management
• Acute pancreatitis usually self-limited Inflammation ↓ within 3-7 days in 90% of
cases
• Medical therapy Analgesics IV hydration Decrease PO intake → Decreased pancreatic
secretionAntimicrobials in severe necrotizing
pancreatitis
• Presence of abscess or necrosis indicates need for intervention
• Percutaneous drainage of abscess
• Surgical debridement (necrosectomy) of infected necrotic tissue when conservative treatment has failed
Management
Prognosis
Prognosis
• Mortality ↓ over last 20 years 5% for all cases20% for severe cases
Reasons for Reduced Mortality• Initially - Recognition and application of
severity signs• 1990s – More selective endoscopic or
surgical debridement of infected tissue, endoscopic cyst drainage, and angiographic control of GI bleeding
• Later – Improved nutritional support by jejunal feeding, earlier use of antibiotic therapy, gut sterilization, early ERCP for common bile duct stones, and necrosectomy for necrotic tissue
Resources
Resources• Balthazar, Emil J. “Acute Pancreatitis: Assessment of Severity With
Clinical and CT Evaluation.” Radiology. 2002; 223: 603-613.• Banu, S., P. Singh, N. Pooran, and B. Stark. “Evaluation of Factors
That Have Reduced Mortality from Acute Pancreatitis Over the Past 20 Years.” Journal of Clinical Gastroenterology. 2002 July; 35: 50-60.
• Bennett, William F., Kuldeep Vaswani, and Kenneth Vitellas. “Case 1: Parenchymal Lymphoma.” American Journal of Roentgenology. 2000; 175: 882-883.
• Cohen-Scali, Frank, et al. “Discrimination of Unilocular Macrocystic Serous Cystadeoma from Pancreatic Pseudocyst and Mucinous Cystadenoma with CT: Initial Observations.” Radiology. 2003; 228: 727-733.
• Demos, Terrence C., et al. “Cystic Lesions of the Pancreas.” American Journal of Roentgenology. 2002; 179: 1375-1388.
• Gore, Richard M., et al. “ Helical CT in the Evaluation of the Acute Abdomen.” American Journal of Roentgenology. 2000; 174: 901-913.
Resources Continued• Gunderman, Richard B. Essential Radiology. 1998.• Greenberger, Norton J. and Phillip P. Toskes. “Acute and Chronic
Pancreatitis.” Harrison’s Internal Medicine. • Mitchell, RM, MF Byrne, and J. Baillie. “Pancreatitis.” Lancet. 2003
Apr 26; 361: 1447-1455.• Novelline, Robert A. Squire’s Fundamentals of Radiology. 6th ed.
2004.• Pretorius, E. Scott and Jeffrey A. Solomon. Radiology Secrets. 2nd
ed. 2006. • Ranson, JH, et al. “Prognostic Signs and the Role of Operative
Management in Acute Pancreatitis.” Surgery, Gynecology, and Obstetrics.
• Tang, Linda J., Stan Zipser, and Young S. Kang. “Temporary Spontaneous Thrombosis of a Splenic Artery Pseudoaneurysm in Chronic Pancreatitis During Intravenous Octreotide Administration.” Journal of Vascular Interventional Radiology. 2005; 16: 863-866.
Resources Continued• Urban, Bruce A. and Elliot K. Fishman. “Tailored Helical CT
Evaluation of Acute Abdomen.” Radiographics. 2000; 20: 725-749.• West, Jeffrey H., Stephen B. Vogel, and Walter E. Drane. “Gallium
Uptake in Complicated Pancreatitis.” American Journal of Roentgenology. 2002; 178: 841-846.