Computed body tomography in inflammatory disease of pancreas

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BODY TOMOGRAPHY IN INFLAMMATORY DISEASE OF PANCREAS BHARAT RAVAL and LEWIS S. CAREY

Department

of Diagnostic

(Receiwd

Radiology,

23 June 1980;

University Hospital. London, Canada receiwd,for

puh/ication

University

of Western

12 Seprrmhrr

Abstract-A radiological classification

of pancreatitis based upon the computed of gas formation, inflammatory mass, pseudocyst formation, calcification. atrophy features is proposed. Computed Body Tomography (CBT) has the advantage over retrograde cholangiocreatography (ERCP) in being sensitive in the detection of occurring either separately or in conjunction in inflammatory disease of pancreas. Computed

Tomography

Pancreas-Pancreatitis

classification-~~Pancreatitis

Ontario,

1980) tomographic appearances or combinations of these ultrasound or endoscopic gas, fluid or calcification

Imaging

modalities

INTRODUCTION Clinically, pancreatitis is classified as acute, recurrent or chronic based upon the duration and reversibility of disease. With the advent of the newer imaging modalities the assessment of pancreas has become readily feasible. The lack of correlation between the radiological appearances and clinical classification prompted a review of our experience and led to the classification proposed here. METHODS Ten millimeter thick continuous slices were obtained through the upper abdomen in the supine position at 1 cm intervals using a GE 7800 Scanner with 4.8 set scanning time. All patients received dilute oral contrast and were scanned during breath holding. Intravenous contrast was used at the discretion of the radiologist monitoring the examination. Reconstruction images in the saggital and coronal planes were obtained in selected patients. Pancreatitis with yasfovmation The presence of gas in pancreatitis has been noted both on plain films [l] and on CBT [2]. It has been equated to a pancreatic abscess although it can also be seen following spontaneous or surgical drainage of a pseudocyst into the gastrointestinal tract. In one of our patients, severe pancreatitis occurred following biliary tract surgery (Fig. 1). Gas formation and diffuse enlargement of the pancreas were noted with several areas of fluid collection. Following a protracted clinical course, the patient expired. At autopsy the radiological diagnosis of pancreatic abscess was confirmed. Pancreatic abscess complicating pancreatitis is an infrequent occurrence with the incidence estimated between 1.5-5% [3-51. It is, however, an important entity to recognize, otherwise the mortality is very high. Early treatment results in an improvement in the outcome [3-61. Pancreatitis

with injlammatory

mass (phlegmon)

Pancreatic enlargement in inflammatory disease can either be localized (Fig. 2A) or diffuse with involvement of the whole gland (Fig. 3). Spread of inflammation occurs along preferred anatomical pathways into the transverse mesocolon, small bowel mesentery, anterior or posterior pararenal space, phrenicocolic or lienorenal ligaments or to more remote sites [7] (Figs 4 and 5). Localized enlargement may simulate a pancreatic carcinoma. Consideration of the CT scan in conjunction with the patient’s clinical status is helpful though not infallible because pancreatitis 43

BHARAT RAVAL and Lfiwls S. CAKtk

44

Fig.

1. Multiple

air bubbles

are seen throughout

Fig. 2A. An inflammatory

a diffusely abscess.

enlarged

pancreas

indicating

mass involves

the head of pancreas.

a pancreatic

Inflammatory

Fig. 2B. 2 weeks

later. the fat planes around the superior mesenteric defined indicating resolution of peripancreatic

Fig. 3. The pancreas

is nonhomogeneous

45

disease of pancreas

and diffusely

enlarged

vessels and the vena cava are better inflammation.

in this patient

with severe pancreatitis.

46

BHARAT RAVAL and LEWIS S. CAREY

Fig. 4. The inflammatory

Fig. 5 A saggital

section

process

spreads

into

the anterior (arrows).

to the left of midline shows spread of inflammation

as well as the posterior

involvement of the left anterior from the pancreas.

pararenal

pararenal

spaces

space

by

Inflammatory

47

disease of pancreas

could be the initial presentation of a carcinoma. In such patients, we have found rescanning as a follow up useful in excluding an underlying malignancy (Fig. 2B). Pancreatitis with pseudocyst formation It is now accepted that pseudocyst formation in pancreatitis is a dynamic process which is commoner than previously assumed. Pseudocysts may undergo spontaneous resolution or occasionally decompress into the gastrointestinal tract or into peritoneum [S, 93. Using ultrasonography in a prospective manner, 50% of patients with acute pancreatitis were found to have pseudocysts [lo]. In the same series, 20% of the pseudocysts underwent spontaneous resolution. A pseudocyst is seen as a well defined area of fluid density that does not enhance following the administration of intravenous urographic contrast media (Figs 6, 7, and 8). Small pseudocysts, multiple pseudocysts or those in unusual locations are readily imaged using CBT (Figs 9, 10, and 11). A preliminary study shows infected pseudocysts are better distinguished by CBT rather than ultrasonography [l 11. Other complications of pseudocysts i.e. hemorrhage or rupture have been demonstrated using computed tomography [12]. Pseudocysts occurring in pancreatitis may be simulated by cystadenoma or cystadenocarcinoma of pancreas, carcinoma of pancreas with necrosis or a pseudocyst distal to ductal obstruction caused by pancreatic carcinoma. Pancreatitis with calci$cation Various authors quote the incidence of calcification in pancreatitis ranging from 31-76x [ 13, 141. A recent study utilising CBT showed pancreatic calcification in 36% of the patients [15]. The calcification seen in pancreatitis occurs in the ductal system. It is commonly associated with pancreatitis secondary to alcohol abuse, but may also be seen in patients with hyperparathyroidism, hyperlipidemia, malnutrition or cystic fibrosis. Occasionally, calcification may occur in a tumor e.g. cystadenoma, cystadenocarcinoma, islet cell tumours or cavernous hemangioma arising in the pancreas [ 161. Pancreatic calcification corresponding to the configuration of pancreatic ductal system is recognizable on computed tomography (Fig. 12). Often a dilated pancreatic duct can be visualized around

Fig. 6. A large

pseudocyst

virtually

replaces

the pancreas and does not enhance graphic contrast.

after

intravenous

uro.

BHARAT RAVAL and LEWIS S. CAKCY

Fig. 7.

Fig. 8 Figs 7 and 8. Coronal

and saggital

sections

show the relationships and aorta.

of the pseudocyst

to the stomach,

Inflammatory

Fig. 9. A pseudocyst

involves

49

disease of pancreas

the portahepatis. CT scanning led to early drainage post-operative follow-up.

and was of value in the

Fig. 10. Only a single pseudocyst in the tail of pancreas was appreciated on ultrasonography The CT shows two additional pseudocysts in the body (arrows) which were confirmed

in this patient at surgery.

BHARAT RAVAL and LEWIS S. CAREY

50

Fig. 11. This pseudocyst

Fig. 12. Pancreatic

arose in the tail of pancreas and dissected left abdominal wall.

calculi

are lined up corresponding

upwards

to the position

to lie between

the spleen and

of the pancreatic

duct

51

Inflammatorydiseaseof pancreas

Fig. 13. The dilated

pancreatic duct (arrow) is readily visualized venous contrast. A pseudocyst lies anterior

by its lack of enhancement to the left kidney.

after intra-

the calculus, better appreciated by its absence of enhancement after intravenous contrast administration (Fig. 13). We have seen one patient with pancreatic duct calculi where a small carcinoma was not seen on CBT. It is recognized that the incidence of carcinoma of pancreas in patients having pancreatitis with calcification is 4-6x which is higher than the general population [15, 171. Pancreatitis with atrophy Pancreatic atrophy as a change related to advancing years has been described [18]. Thus if atrophy is the sole manifestation of pancreatitis it cannot be djstinguished as such unless the patient is young (Fig. 14). Fortunately atrophy commonly accompanies calcification or an inflammatory mass rendering the diagnosis of pancreatitis easier (Figs 15 and 16). Pancreatitis with combinations The demonstration of more than one of the above features leads to a greater degree of confidence in the diagnosis of pancreatitis. We have encountered pseudocysts occurring distal to pancreatic duct calculi (Fig. 13) or pseudocysts occurring in conjunction with an inflammatory mass. Atrophy of pancreas is often associated with calcification or an inflammatory mass. DISCUSSION Ultrasonography, ERCP and CBT have all been used successfully in imaging inflammatory disease of the pancreas. Ultrasonography has the major advantage of not utilizing ionizing radiation. It is accurate in depicting the majority of pseudocysts [lo, 191. However, obesity or bowel gas may interfere with adequate visualization. Patients with an ileus are thus problematic. As well, ultrasound is not consistently diagnostic for pancreatic calcification or gas formation. It is heavily operator dependent.

BHARAT RAVAL and LEWIS S. CAREY

52

14. In this 4%yr-old

patient

with documented recurrent episodes of pancreatitis, of his disease is a small. atrophic pancreas.

Fig. 15. The head of pancreas

shows calcification

and atrophy

occurring

the only manifestation

concomitantly

Inflammatory

Fig.

16. Pancreatic unchanged

enlargement and calcification in this patient with the clinical

disease

53

of pancreas

have been followed course of pancreatitis

over a 2 yr period and secondary to alcoholism.

remain

ERCP shows the morphology of the pancreatic duct well besides demonstrating the biliary tree. It is generally not undertaken in patients for 46 weeks after an acute episode of pancreatitis [20]. Complications ranging from failure of cannulation to pancreatitis, sepsis, instrumental injury and death have been reported because of the invasive nature of this modality [21]. Skilled personnel are necessary for its performance. Computed Body Tomography is exquisitely sensitive in the detection of gas, fluid or calcification occurring separately or in combination in pancreatitis. It is, however, quite expensive. We undertake CBT in patients with pancreatitis that are severely ill or in patients with upper abdominal pain with a clinical suspicion of pancreatitis that have normal conventional barium studies. A third indication is a patient whose pancreas cannot be adequately assessed by ultrasonography. A new classification of pancreatitis based upon the findings on computed tomography is proposed in the hope that it may lead to a greater understanding of the natural history of inflammatory disease of pancreas. SUMMARY The computed tomographic findings have been utilized to propose a radiological classification of pancreatitis. The merits of CBT over ultrasound and ERCP are discussed to outline the role of CBT in inflammatory disease of pancreas. Acknowledgrmmrs--We wish to thank Marlene Edwards, R.T. for technical assistance, Doris Strathopolous graphic work and the Department of Instructional Resources. University Hospital, for the illustrations.

for the steno-

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by CT: A review of nine cases,

Am. J.

54

BHARAT RAVAL and LEWIS S. CAREY

3. R. A. Steedman, R. Doering and R. Carter, Surgical aspects of pancreatic abscess, Surg. Gyn. Obs. 125, 757-762 (1976). 4. S. J. Camer, E. C. G. Tan, K. W. Warren and J. W. Braasch. Pancreatic abscess: A critical analvsis of 113 cases. Am. J. Sury. 129, 426431 (1975). 5. J. L. Holden, T. V. Berne and L. Rosoff, Pancreatic abscess following acute pancreatitis, Arch. Surg. 111, 858.-861 (1976). 6. D. Palovan. D. Simonowitz and R. J. Bates. Guidelines in the management of oatients with nancreatic abscess. Am. J. Gastroe;t. 69, 97-100 (1978). 7. M. A. Meyers and J. A. Evans, Effects of pancreatitis on the small bowel and colon: Spread along mesenteric planes, Am. J. Roentg. 119, 151-165 (1973). 8. D. A. Sarti, Rapid development and spontaneous regression of pancreatic pseudocysts documented by ultrasound. Radiology 125, 187-793 (1977). 9. J. L. Clements, E. L. Bradley and S. B. Eaton, Spontaneous internal drainage of pancreatic pseudocysts, Am. J. Rocwtg. 126, 985-991 (1976). 10. A. C. Gonzalez, E. L. Bradley and J. L. Clements, Pseudocyst formation in acute pancreatitis: Ultrasonographic evaluation of 99 cases, Am. J. Roentg. 127, 315.~317 (1976). I 1. H. Y. Kressel, A. R. Margulis, G. W. Gooding, R. A. Filly, A. A. Moss and M. Korobkin, CT scanning and ultrasound in the evaluation of pancreatic pseudocysts: A preliminary comparison, Radiology 126, 153-157 (1978). 12. G. F. Pistolesi, G. P. Marzoli, P. Q. Colosso, P. Pederzoli and C. Procacci, Computed tomography in surgical pancreatic emergencies. J. Comput. assist. Tomogr. 2, 165-169 (1978). 13. K. W. Warren and M. Veidenheimer, Pathological considerations in the choice of operation for chronic relapsing pancreatitis. New Engl. J. Med. 266, 323-329 (1962). 14. H. Sarles, J. Sarles, R. Camatte, R. Muratore, M. Gaini, C. Guien, J. Pastor and F. LeRoy, Observations on 205 confirmed cases of acute pancreatitis, recurring pancreatitis and chronic pancreatitis, Gut 6, 545-559 (1965). 15. J. T. Ferrucci. J. Wittenberg, E. B. Black, R. H. Kirkpatrick and D. A. Hall, Computed body tomography in chronic pancreatitis, Radiology 130, 175-182 (1979). 16. E. J. Ring, S. B. Eaton, J. T. Ferrucci and W. F. Short, Differential diagnosis of pancreatic calcification, Am. J. Rorntg. 117, 44-52 (1973). 17. J. R. Johnson and Z. A. Zintel, Pancreatic calcification and cancer of the pancreas, Surg. Gynrc. Ohs. 117,585%588 (1963). 18. L. Kreel. M. Haertel and D. Katz, Computed tomography of the normal pancreas, J. Comput. assist. Tomogr. 1, 290-299 (1977). 19. G. R. Leopold, Pancreatic echography: A new dimension in the diagnosis of pseudocyst, Radiology 104. 365 -369 (1972). 20. J. T. Ferrucci, Radiology of the pancreas 1976. Radial. Clin. Norfh Am. 14, 543-561 (1976). 21. M. K. Bilbao. C. T. Dotter, T. G. Lee and R. M. Katon, Complications of endoscopic retrograde cholangiopancreatography (ERCP): A study of 10,000 cases. Gastroenterology 70, 314-320 (1976).

About the Author-BHARAT RAVAL was born in Kakira. Uganda and received his M.B., Ch.B. from Makerere University Medical School, Kampala, Uganda in 1971. He undertook internship and residency training at St. Michael’s Hospital, Toronto and was awarded the Diploma of American Board of Radiology in 1977 and F.R.C.P.(C) in 1978. Currently he is an Assistant Professor at the University of Western Ontario and Staff Radiologist at University Hospital, London, Canada. He is the author of several papers on applications of computed tomography to liver, endocrine and chest diseases and an active member of various radiological societies. About the Author-LEwrs S. CAREY graduated in Medicine from Queen’s University, Kingston, Ontario. He spent a year in Anatomy followed by a rotating internship, 4 yr in Surgery and 2 yr in Radiology at the Mayo Clinic, He is currently Chairman of Diagnostic Radiology and Nuclear Medicine, University of Western Ontario with interests in CT Scanning and Telecommunications.