Eur. Radiol. 4, 476-478 (1994) © Springer-Verlag1994

European Radiology

Gastrointestinal radiology Pancreatic pseudoaneurysm: CT features A. A. Ghiatas 1, R. Hollis 2, E J. Rivera 1 1Department of Radiology,7703 Floyd Curl Drive, San Antonio,TX 78284-7800, USA 2Departments of Gastroenterology,Universityof TexasHealth Science Center, San Antonio,Texas78284-7800, USA Received 17 May 1993; Revisionreceived 19 November 1993; Accepted25 January 1994

Introduction Delay in the diagnosis of pancreatic pseudoaneurysm may cause serious and perhaps fatal complications. The role of CTis important in its early and accurate diagnosis.

Case report A 48-year-old man with a history of chronic alcoholic pancreatitis was admitted because of a 4-day history of mild epigastric pain and melena. On physical examination he was tachycardic and hypotensive. His abdomen was non-distended with normal bowel sounds and mild diffuse abdominal tenderness. No mass or hepatosplenomegaly was present. Rectal examination revealed hemoccult-positive brown stools. Nasogastric tube lavage was negative. The haematocrit was 14.6 and the liver function tests normal. Serum amylase was 115 mg/dl (normal = 40-140 mg/dl) and lipase was 41 mg/dl (normal = 4-24 mg/dl). Oesophagoduodenoscopy as well as colonoscopy were performed and did not reveal any abnormalities. CT of the abdomen was performed after the oral and during the intravenous administration of 100 ml contrast medium (due to patient's poor-quality veins the enhancement was performed by hand injection) with 10 mm slice thickness and 10 mm interslice intervals. The study was performed using a Picker International Correspondence to: A. A. Ghiatas

1200 SX CT unit (Highland Heights, Ohio). The study revealed a pancreatic pseudocyst involving the head of the pancreas with a nodular mass within, of the same density as that of the aorta (Fig. 1). The CT study was compared with a previous one performed 9 weeks earlier, on the same CT unit and using the same protocol, revealing that the pancreatic pseudocyst had been present before and was unchanged in size. However, the enhanced nodular mass within the pancreatic pseudocyst had not been present previously (Fig. 2). The new finding of an enhanced nodular mass in the clinical setting of chronic pancreatitis with gastrointestinal bleeding was felt to be highly suspicious of a pseudoaneurysm and was reported as such. A few hours following the CT examination the patient developed acute epigastric crampying pain followed by (maroon) haematochezia, his haematocrit was further decreased and the serum lipase, transaminase and alkaline phosphatase levels were acutely increased. The patient was transfused with 2 units of packed red blood cells and urgent upper endoscopy was performed which revealed fresh blood spurting from the ampulla of Vater. Emergent coeliac and superior mesenteric arteriography was performed which revealed a pseudoaneurysm of moderate size in the area of the head of the pancreas supplied by the posterior pancreaticoduodenal artery (Fig. 3). The pseudoaneurysm was successfully embolised using coils and Gelfoam (Fig. 4). The patient's condition was stabilised without any further gastrointestinal bleeding and he underwent elective Roux-en-Y pancreatic cystojejunostomy 8 weeks later.

Discussion The causes of gastrointestinal bleeding in patients with pancreatitis are usually non-pancreatic such as gastroenteritis, peptic ulcer, oesophageal varices and MalloryWeis tears. Haemorrhage due to direct involvement of pancreatic or peripancreatic vessels, although not very

A. A. Ghiatas et al.: Pancreatic pseudoaneurysm: CT features

Fig. 1. Enhanced CT scan at the level of the pancreatic head showing a pancreatic pseudocyst (white arrows) eontaining a nodular mass (black arrow). Small, less-enhanced loci within the pseudocyst are thought to represent fresh coagulated blood (small white arrows) Fig.2. Enhanced CT scan at the level of pancreatic head showing a pancreatic pseudocyst (white arrows) Fig.3. Arteriogram showing a pseudoaneurysm arising from the posterior pancreaticoduodenal artery (black arrow) Fig.4. Arteriogram showing embolisation coils (black arrows) in the area where the pseudoaneurysm in Fig. 3 was present

common, is (well) known and usually associated with high mortality. As the pseudocyst progresses it may involve a vessel which becomes necrosed due to the effects of pancreatic enzymes. Involvement of a vein may lead to thrombosis, while involvement of an artery may cause the development of a pseudoaneurysm into the pseudocyst [1]. It has been estimated that in chronic pancreatitis aneurysmal degeneration of pancreatic/peripancreatic vessels approaches 10 % [2]. The arteries most commonly involved are the splenic, pancreaticoduodenals and gastroduodenal [3]. If the pseudoaneurysm enlarges

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it may rupture and cause significant haemorrhage into the peritoneal or reptroperitoneal space. Communication of the pseudoaneurysm with the pancreatic duct and bleeding into the d u o d e n u m (through the pancreatic duct) is called haemosuccus pancreaticus [4]. The haemorrhage is usually significant, causing rapid hypotension. Accurate preoperative diagnosis is essential for improvement of the survival rate. The survival rate is 58 % when the diagnosis of bleeding pseudoaneurysm is made preoperatively in comparison with 43 % when the diagnosis is made intraoperatively [5]. Angiography is the standard imaging modality for diagnosing pseudoaneurysm in pancreatitis; however, it is an invasive m e t h o d and is performed in cases of suspected pseudoaneurysm. CT is a fast, non-invasive imaging modality which provides an accurate diagnosis of pancreatic pseudoaneurysm even in cases where the diagnosis is not suspected. The appearance of a pancreatic pseudoaneurysm has previously been described as a low attenuating mass within a pseudocyst on a non-enhanced CT scan which shows marked enhancement (similar to aorta) on a bolus-enhanced CT scan [6]. In our case, in addition to the presence of an enhanced (similar to aorta) mass within the pseudocyst, the appearance of a new nodular mass (in comparison with a recent previous CT examination)

478 within a pseudocyst in a case of chronic pancreatitis with gastrointestinal bleeding was highly suggestive of a pancreatic p s e u d o a n e u r y s m . We believe that the finding described here of a new nodular mass within a pseudocyst is useful as being highly suggestive of the presence of a pseudoaneurysm.

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A. A. Ghiatas et al.: Pancreatic pseudoaneurysm: CT features 3. Walter JF, Chuang VR Bookstein J J, Reuter SR, Cho KJ, Pulmono MC (1977) Angiography of massive hemorrhage secondary to pancreatic disease. Radiology 124:337-342 4. Sandblom P (1970) Gastrointestinal hemorrhage through the pancreatic duct. Ann Surg 171:61-66 5. Eckhauser FE, Stanley JC, Zelenock GB, Borlaza GS, Freier DT, Lindenauer SM (1980) Gastroduodenal and pancreatico-duodenal aneurysms: a complication of pancreatitis causing spontaneous gastrointestinal hemorrhage. Surgery 88:335-344 6. Kopecky KK, Ellis JH, Bies JR, Madura JA (1984) Computed tomography diagnosis of pancreatic pseudoaneurysm. Comput Radiol 8:361-364