Year : 2006 | Volume
: 16 | Issue : 4 | Page : 433--437
Annular pancreas: MR and MR Pancreaticography a useful tool
AK Sharma, PK Mishra, S Chibber
Department of Radiology and Gastro surgery GB Pant Superspeciality Hospital and MAM College, NOIDA, India
A K Sharma
C10 Kendriya Vihar Sector 51, NOIDA 201307
|How to cite this article:|
Sharma A K, Mishra P K, Chibber S. Annular pancreas: MR and MR Pancreaticography a useful tool.Indian J Radiol Imaging 2006;16:433-437
|How to cite this URL:|
Sharma A K, Mishra P K, Chibber S. Annular pancreas: MR and MR Pancreaticography a useful tool. Indian J Radiol Imaging [serial online] 2006 [cited 2020 Jan 25 ];16:433-437
Available from: http://www.ijri.org/text.asp?2006/16/4/433/32238
Magnetic resonance pancreatography is being used with increasing frequency as a noninvasive alternative to diagnostic endoscopic retrograde pancreaticography in evaluation of the pancreatic duct. This can help to identify the course and drainage pattern of the pancreatic duct and is useful in diagnosing congenital anomalies such as annular pancreas without the risk of inducing pancreatitis.
Annular pancreas is seen in one of every 20,000 autopsies and is characterized by pancreatic tissue completely or incompletely surrounding the duodenum, most commonly the descending duodenum ,. In complete annular pancreas, patients present during the neonatal stage. However patients with incomplete or partial annular pancreas may not present until adulthood. In some instances, incomplete annular pancreas is detected incidently.Although this anomaly may be recognized at conventional radiography, upper GI series, or computed tomography, only ERCP has allowed definitive diagnosis. More recently, annular pancreas has been diagnosed with MR imaging and MR Pancreaticography by identifying the pancreatic annulus and the duct with in the annulus that surrounds all or part of the duodenum . We present a case of annular pancreas with a unique clinical presentation and an unusual anomaly of the malformed pancreatic ducts.
A 40-years-male patient presented with recurrent abdominal pain for the 8 years. He presented several episodes of postprandial epigastric pain,radiating to back with improvements in position intermittent and vomiting. On hospital admission, physical examination was unremarkable. An upper GI examination showed an evidence of narrowing of the second part of duodenum but mucosal pattern was normal [Figure 1].CT scan demonstrated enlargement of the head of pancreas with mild dilation of pancreatic duct encircling the duodenum [Figure 2],[Figure 3],[Figure 4],[Figure 5],[Figure 6].The T1 weighted sequence showed an evidence of enlarged head of pancreas with demonstration of CD and PD encircling the second part of duodenum [Figure 7],[Figure 8],[Figure 9],[Figure 10],[Figure 11],[Figure 12] .MRCP revealed anomalous pancreatic duct without any dilation in the head region of the pancreas [Figure 13].A diagnosis of annular pancreas with pancreatitis was suggested and patient is kept on follow up
With the improvements achieved in imaging techiniques, the diagnosis of AP in adults increased in frequency. Yogi et al classified AP in six types depending on site of drainage of annular duct. The most common variety is type I, in which annular duct flows directly into the main pancreatic duct. In Type II, Wirsung duct encircles the duodenum but still drains at the major papilla. The other four types are much less common. There is sill much controversy on the pathogenesis of AP.Nobukawa postulated that adhesion of the distal tip of the ventral primordium to the duodenal wall, before its migration, orginates the pancreatic obstructing ring, whereas Baldwin persistence and further development of the annular pancreatic tissue is responsible for formation of the annular pancreatic tissue around the duodenum ,,,
Clinical features in infants are characterized by severe duodenal obstruction that requires immediate surgical intervention. In some cases, the obstruction is minimal and patient remains symptom less for life. In adults there is cramping epigastria pain .relieved by vomiting, associated with peptic ulcer disease, acute and chronic pancreatitis, obstructive jaundice and gastric outlet obstruction .
The preoperative diagnosis has evolved considerably due to development of new diagnostic imaging tools.ERCP has been considered the gold standard method in the diagnostic workup, is an invasive method is associated with morbidity, including acute pancreatitis.MRCP has overtaken ERCP as it is noninvasive and is in demonstrating anomalous pancreatic duct and where ERCP fails especially in duodenal obstruction. The main aim of surgical intervention is relieving duodenal or gastric outlet obstruction and bypass surgery of the annulus by dudenojejunostomy or gastrojejunostomy seems to be preferred method of treatment. In recent review of English literature, AP was found concomitantly with 5 cases of ampullary carcinoma and 3 cases of adenocarcinoma.The differential diagnosis of focal pancreatitis in the head of pancreas and pancreatic cancer remains a challenging task for radiologists, pathologists and surgeons. The association of periampullary malignancy must not be overlooked and their coexistence must be considered until its absence is proved.
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