Pancreatic MRI An Electronic Atlas of Pancreatic Imaging

1. Pancreatic MRIAn Electronic Atlas of Pancreatic Imaging Bonnie Garon, MD Howard Youngworth, MD Lusine Tumyan, MD Miriam Romero, MD Suzanne Palmer, MD Keck School of Medicine University of Southern California

2. Purpose Understand the role of routine MRI, MR Pancreatography, and Secretin stimulation MRI in evaluation of pancreatic pathology Review normal anatomy and common variants as demonstrated by MRI Demonstrate the MRI characteristics of various pathological conditions with their clinical presentations and correlative imaging

3. Pancreas arises from two diverticula of the primitive foregut Ventral (anterior) bud � develops into the hepatobiliary system gives off a small bud from the bile duct close to the duodenum (ventral pancreatic bud) which eventually forms the uncinate process and inferior portion of the head of the pancreas Dorsal (posterior) bud � forms the body, tail and part of the head of the pancreas Pancreatic Embryology

4. Pancreatic Duct Main Pancreatic duct of Wirsung Formed from distal portion of embryologic dorsal duct and ventral duct Drains through major papilla Maximum diameter 2-3 mm Major drainage in 90% Accessory Pancreatic Duct of Santorini Proximal portion of embryologic dorsal duct Drains through minor papilla Present in 44% CBD drains via major papilla in 100%

5. Pancreatic Divisum

6. Pancreatic Anatomy Located in the anterior pararenal space Vascular landmarks Splenic artery and vein Superior mesenteric artery and vein 12-15 cm long Vascular supply Gastroduodenal artery, pancreatico-duodenal artery and splenic artery Imaging Appearance High T1 signal intensity and low T2 signal intensity, similar to liver

7. Advantages Therapeutic and diagnostic procedure Direct inspection of the papilla of Vater and ampullary tumors ERCP can be superior in diagnosis of intraductal papillary mucinous tumors Disadvantages Technically difficult with a failed cannulation rate of up to 11% Invasive procedure with complication rate of 5-7 % and mortality rate of 0.2 % Limited in evaluation of tumor extension Cannot be performed in patients with pancreatico-enteric anastomosis Endoscopic Retrograde Cholangiopancreatography

8. Computerized Axial Tomography Advantages More manageable in severely ill patients Cost and availability relative to MRI and ERCP High spatial resolution Air and calcification are easily recognizable Disadvantages Irradiation Iodinated contrast media

9. Ultrasound Advantages Noninvasive, portable, widely available and economical Color doppler evaluation of peripancreatic vascular structures allows determination of tumor resectability Disadvantages Operator and patient dependent Enteric gas limits evaluation

10. MR Cholangiopancreaticography Advantages Noninvasive alternative to diagnostic ERCP Useful in proximal obstruction where ERCP is limited May be performed in post operative patient Improved tissue characterization when compared to CT Disadvantages Patient dependent Artifacts may obscure areas of interest Poor visualization of calcifications Cost

11. Routine Pancreatic MRI Technique NPO Phased-array surface coil Breath held with ultra fast sequences May be performed with or without MRCP sequences imaging IV Contrast

12. Routine Pancreatic MRI Technique

13. MRCP Technique Thick Slab Heavily T2 weighted images Stationary, slow flowing liquids high SI Fat suppression to allow higher SNR and contrast noise ratio Background tissue SI very low or absent TR 3000, TE 1100 3D Slab thickness 60-80 mm Sat band over CSF FOV large enough to prevent wrap around Multiple planes of acquisition Coronal and coronal oblique Pin wheel around central axis Acquisition time 2-3sec

14. NSF Prevention Calculate GFR in patients with high risk for renal insufficiency Over age 65 Diabetes, Hypertension Kidney disease, dialysis Choice of contrast based on GFR > 60 � Contrast agent of choice (Magnevist) 30-60 (moderate kidney impairment) Should not exceed recommended dose of contrast, Multihance preferred at our institution <30 (severe kidney impairment) Use of contrast should be carefully considered If contrast is absolutely necessary, must sign �MR contrast in Renal dysfunction/ Dialysis patient� consent If on dialysis, must receive dialysis immediately after

15. Dynamic MR Pancreatography with Secretin Improves visualization of pancreatic ductal system Improves the detection of: Normal ducts, pancreatic divisum, ductal stricture, chronic pancreatitis associated with marked ductal dilatation Mechanism of Secretin Exogenous administration of secretin stimulates the secretion of fluid and bicarbonate by the exocrine pancreas Manometric studies show an increase in duct pressure at 1 minute and return to basal pressure at 5 minutes Increases fluid secretion by ductal cells and simultaneously increases sphincter of Oddi tone

16. Dynamic MR Pancreatography with Secretin Dosing and Technique IV administration of 1 mL of secretin per 10 kg of body weight Image before and repeat every 2 minutes for 16 minutes after administering secretin Abnormal if duct remains greater than 1 mm above baseline after 6 minutes FDA-Risks and Side effects Some common side effects with secretin include: Nausea, flushing, abdominal pain, vomiting Secretin may cause an allergic reaction A test dose of secretin should be given to check for an allergic reaction

17. Secretin Stimulation in a Normal Pancreatic Duct

18. Acute Pancreatitis Most common benign disease involving pancreas Most common cause is choledocholithiasis and alcohol use Temporary process with potential for restoration of normal anatomy Complications include acute fluid collections, psuedocyst formation, pancreatic abscess and pancreatic necrosis Imaging Imaging used to detect cause or complications Increased T2/Decreased T1 signal from edema Normal MRI appearance is seen in 29% of patients with acute pancreatitis

20. Necrotizing Pancreatitis Complication of severe acute pancreatitis Focal/diffuse area of nonviable pancreas Tends to affect body/tail, spares head due to abundant vascular supply Imaging Areas of absent enhancement Heterogeneous signal intensity

21. Chronic Pancreatitis Continued inflammatory disease of pancreas characterized by irreversible damage to anatomy and function Mainly caused by alcohol abuse Calcifying or Obstructive Focal chronic pancreatitis is difficult to differentiate from adenocarcinoma due to similar imaging findings Imaging Loss of fat signal on fat suppressed images Diminished contrast enhancement Multifocal dilatation and stenosis of duct due to fibrosis Focal areas of decreased signal on T1 and T2 images from calcifications

22. Dynamic Imaging of Chronic Pancreatitis Visualization of the minor duct and the side branches is significantly improved Pitfalls Pre-existing ductal strictures Ducts greater than 5 mm prior to secretin administration Negative predictive value increases from 84% to 98% using dynamic pancreatography Study confidently shows that patients with suspected pancreatic disease did not have the disease, which may prevent the need for ERCP

23. Pancreatic Pathology: Cystic Fibrosis Autosomal recessive, 1 in 2000-2500 live births Dysfunction of exocrine glands forming thick tenacious material Multisystem disease that affects lungs, GI tract, liver, biliary tract, pancreas, and reproductive tract Presentation Steatorrhea, malabsorption Pancreatitis Diabetes Mellitus Imaging Diffuse pancreatic atrophy Complete/Partial fatty replacement Calcific chronic pancreatitis Loss of lobular contour

24. Three imaging patterns Enlarged, lobulated pancreas with complete fatty replacement Atrophic pancreas with partial fatty replacement Atrophic pancreas without fatty replacement Pancreatic Pathology: Cystic Fibrosis

25. Primary Hemochromatosis Autosomal recessive Excessive absorption and parenchymal retention of dietary Fe that favors accumulation within non-RES organs Clinical Manifestations Cirrhosis, glucose intolerance, heart failure, abdominal pain, arthropathy, and skin discoloration Complications HCC, liver failure, cardiomyopathy, diabetes Imaging Decreased SI (DI) on T1 and T2 weighted images in pancreas and liver due to paramagnetic effect of iron Changes most conspicuous on gradient echo imaging Spleen and bone marrow spared

26. Secondary Hemochromatosis/Hemosiderosis Iron deposition due to iron overload and RES cell deposition Pancreas does not contain RES cells and usually not effected Estimated RES cell capacity = 10 gm, which corresponds with 40 units of blood After RES cell saturated, parenchymal cell deposition will occur, causing decreased signal within the pancreas

27. Pancreatic Ductal Adenocarcinoma 5th leading cause of cancer deaths Diabetes and smoking doubles the risk Most frequent cause of malignant obstructive jaundice New onset diabetes in 25 � 50% Imaging Tumor most visible on T1 post Gd Enhances less than adjacent pancreatic tissue on arterial and portal venous phases Delayed phase enhancement is variable due to desmoplastic reaction

28. Mucinous Cystadenoma 10% of pancreatic cysts, 1% pancreatic neoplasms Low malignant potential, usually in pancreatic tail/body Commonly asymptomatic, but may present with pain, anorexia Treatment- surgical resection due to invariable transformation into cystadenocarcinoma Imaging Well demarcated hypovascular thick wall mass of 2-36 cm with high T2 SI and low T1 SI Multi/unilocular large cysts with thin septa, usually less than 6 cysts. May contain peripheral calcifications Nodules may indicate malignant transformation

29. Intraductal Papillary Mucinous Tumor Rare intraductal tumor originating from epithelial lining with large amounts of mucinous secretions Recurrent episodes of dull pain/acute pancreatitis Low grade malignancy with better prognosis than adenocarcinoma Treatment- Whipple

30. Intraductal Papillary Mucinous Tumor Main Duct IPMT Dilatation of main pancreatic duct, branch ducts and papilla Pancreatic atrophy Segmental Cyst in body/tail with normal remaining pancreas Cyst in pancreatic head with dilatation of duct Branch Duct IPMT Mainly in uncinate process Severe pancreatic atrophy Complications: seeding to main pancreatic duct resulting in main duct IPMT

31. Carcinoid Metastatic carcinoid to the pancreas is rare MR imaging low signal intensity on T1-weighted images high signal intensity (HS) on T2-weighted due to complex cystic nature

32. Insulinoma Most common functioning islet cell tumor Single benign adenoma 80 to 90% No predilection for any part of the pancreas 70% less than 1.5 cm Low signal intensity on fat-suppressed T1W1 Hyperintense on dynamic contrast enhanced

33. Insulinoma

34. Pancreatic Trauma Present with laceration in pancreas or hematoma Due to blunt trauma (MVA) or due trauma in region like surgical intervention close to pancreas

35. Pancreatic Transplantation Used to manage certain cases of complicated type 1 diabetes mellitus Susceptible to postoperative complications like arterial and venous thrombosis Artery and venous supply usually anastomosed to iliac vessels Imaging-hyperintense to adjacent organs on T1-fat suppressed images, avidly enhances

36. Pancreatic Arteriovenous Malformation

37. References C Matos, O Cappeliez, C Winant, E Coppens, J Devi�re, T Metens. MR Imaging of the Pancreas: A Pictorial Tour. RadioGraphics, Jan 2002; 22: 2. D Wolfgnang. Radiology Review Manuel. 5th ed. Philadelphia: Lippincott, Williams and Wilkins, 2003. K.J. Mortel�, P.R. Ros. Cystic Focal Liver Lesions in the Adult: Differential CT and MR Imaging Features. RadioGraphics, Jul 2001; 21: 895 - 910. Mergo et al. Pancreatic Neoplasms: MR Imaging and Pathologic Correlation. Radiographics, March 1997; 17:281-201. E.S. Siegalman. Body MRI. Philadelphia, Pa: Elsevier Saunders, 2005. Food and Drug Administration, Human Secretin 7/13/04, viewed 10/01/07, http://www.fda.gov/cder/consumerinfo/druginfo/Human_Secretin.HTM Clinical Correlations, FDA advises caution with gadolinium based contrast 12/27/06, NYU School of Medicine, viewed 10/15/07, http://www.clinicalcorrelations.org/wp-content/uploads/nfd.jpg Thailand Cyber University, Digestive Tract 1, viewed 10/10/07, http://www.thaicyberu.go.th/OfficialTCU/main/digestivesystem1/Content/211.gif Leyendecker et al. MR Cholangiopacreatography: Spectrum of Pancreatic Duct Abnormalities. Radiology, December 2002; 179:1465-1471. Minami et al. Cystic Neoplasms of the Pancreas: Comparison of MR Imaging with CT. Radiology, April 1989;171:53-56. Brugge et al. Cystic Neoplasms of the Pancreas. New England Journal of Medicine, September 16, 2004; 351: 1218-26.