Menoufia Medical Journal

ORIGINAL ARTICLE
Year
: 2019  |  Volume : 32  |  Issue : 3  |  Page : 895--900

Role of contrast-enhanced computed tomography in the evaluation of acute pancreatitis according to the revised Atlanta classification


Adel M El-Wakeel, Waleed A F Mousa, Sara M Sultan 
 Department of Radiology, Faculty of Medicine, Menoufia University, Shebeen El-Kom, Egypt

Correspondence Address:
Sara M Sultan
Department of Radiology, Faculty of Medicine, Menoufia University, Shebeen El-Kom
Egypt

Abstract

Objective The aim of this study was to detect the role of contrast-enhanced computed tomography (CT) in the diagnosis of acute pancreatitis according to the revised Atlanta classification. Background Imaging plays a very important role in the management of pancreatitis. It assists diagnosis and in differentiation of the severity of pancreatitis. Besides, it helps to detect and manage the associated complications through image-guided drainage and aspiration. Contrast-enhanced CT is the most clinically useful study. In 1992, morphological stages of acute pancreatitis were made. Between interstitial pancreatitis and sterile or infected necrosis Atlanta classification was made whereas in the revised Atlanta classification focuses heavily on the morphologic criteria for defining the various manifestations by means of CT. Materials and methods This prospective study was performed on 60 patients. The study was carried out at the Diagnostic Radiology Departments of Menoufia University Hospital and the National Liver Institute. The patients were presenting with acute abdominal pain, mainly epigastric, radiating to the back and the lesions were classified according to the Atlanta classification. Results Forty-two patients were with interstitial pancreatitis, 32 patients were with acute peripancreatic collection and 10 patients were with pseudocysts and 18 patients were with necrotizing pancreatitis, nine patients with acute necrotic collection and nine patients were with walled-off necrosis with statistically significant difference of age between groups (P = 0.014). Conclusion Contrast-enhanced CT is a perfect diagnostic modality to stage the severity of inflammatory process, identify the pancreatic necrosis and describe local complications and grading of severity of acute pancreatitis. Revised Atlanta classification is more accurate for assessing patient mortality and organ failure.



How to cite this article:
El-Wakeel AM, Mousa WA, Sultan SM. Role of contrast-enhanced computed tomography in the evaluation of acute pancreatitis according to the revised Atlanta classification.Menoufia Med J 2019;32:895-900


How to cite this URL:
El-Wakeel AM, Mousa WA, Sultan SM. Role of contrast-enhanced computed tomography in the evaluation of acute pancreatitis according to the revised Atlanta classification. Menoufia Med J [serial online] 2019 [cited 2019 Dec 9 ];32:895-900
Available from: http://www.mmj.eg.net/text.asp?2019/32/3/895/268827


Full Text



 Introduction



Acute pancreatitis was defined as an acute inflammatory process of the pancreas with mutable involvement of other local tissues and remote organ systems. Mild pancreatitis was related to minimal organ dysfunction and an uneventful recovery. Severe pancreatitis was associated with organ failure or local complications for example 'acute' pseudocyst, pancreatic abscess, or else pancreatic necrosis. Both groups were defined as having acute fluid collections early in the course of the disease [1]. The first diagnosis of acute pancreatitis was made clinically from signs and symptoms of acute abdomen and an elevation of pancreatic enzymes, such as lipase and amylase in the blood or urine [2].

Imaging plays a dynamic role in the management of pancreatitis. It enables diagnosis and also differentiation of the severity of this condition. However, it helps to identify and manage the associated complications with image-guided drainage and aspiration. Ultrasound is often the first investigation performed on admission, although it has trivial importance in the diagnosis of pancreatitis or its complications, the early identification of gall stones and biliary dilatation can help identify those patients with a possible stuck calculus in the bile duct [3]. Intervention with Endoscopic retrograde cholangiopancreatography (ERCP) is indicated for persistent choledocholithiasis or acute cholangitis, but it has no role in this morphologic imaging-based classification of acute pancreatitis [4].

Contrast-enhanced computed tomography (CT) is the most clinically useful investigation. A morphologic stage of acute pancreatitis was made in 1992. Atlanta classification is between interstitial pancreatitis and sterile or infected necrosis whereas in the revised Atlanta classification focuses seriously on the morphologic criteria for defining the various manifestations by means of CT. This revision places novel criteria for pancreatic fluid collections and studies some of the clinical criteria and terminology [5].

The modifications divide acute pancreatitis into interstitial edematous pancreatitis and necrotizing pancreatitis, distinguish an early phase ( first week) and a late phase (after the first week), and stress on systemic inflammatory response syndrome and multisystem organ failure [6].

According to the revised Atlanta classification, contrast-enhanced CT is the main tool for assessing the imaging-based criteria because it is widely accessible for these acutely ill patients and has a high degree of precision [7],[8], helping to assess complications, and monitoring of treatment response through follow-up studies. CT should be carried out in patients who develop severe acute pancreatitis or complications. The ideal time for assessing these complications with CT is after 72 h from the start of symptoms [4].

The imaging based revised Atlanta classification involves cautious assessment for CT images of collection of fluid and/or non liquefied material inside and around the pancreas (areas of pancreatic parenchymal and peripancreatic necrosis) [9]. It also outlines other significant findings such as the causes of pancreatitis, as well as cholecystolithiasis and choledocholithiasis, and complications related to acute pancreatitis, plus extra hepatic biliary dilatation, portal, splenic, and mesenteric venous thrombosis, varices, arterial pseudoaneurysm, pleural effusion, and also ascites. Furthermore, other intra-abdominal results caused by pancreatic secretions need to be described [10]. The aim of this study was to detect the role of contrast-enhanced CT in the diagnosis of acute pancreatitis according to the revised Atlanta classification.

 Materials and Methods



This prospective study was conducted on 60 patients referred to the Diagnostic Radiology Departments of Menofia University Hospital and National Liver Institute. The patient at the hospital underwent: (a) clinical history and examination, for example, acute abdominal pain (epigastric pain radiating to the back), (b) laboratory investigation, for example, serum lipase and amylase levels three or more times normal, and (c) ultrasonography, followed by contrast-enhanced CT examination after obtaining detailed clinical history, explanation of the procedure, and getting informed consent in a written form.

Inclusion criteria

Patients suffering from acute abdominal pain, mainly epigastric, radiating to back.

Patients presenting with elevated serum amylase and lipase level.

Exclusion criteria

Pregnant and lactating patients.

Renal impairment (serum creatinine value above the standard level).

Cardiac failure.

Previous allergic reaction to contrast media.

Ethical considerations

Approval from the research ethics committee was taken before starting the field work.

All the procedures of the study were approved by the Diagnostic Radiology Department.

Agreement of the participant without obligation.

Confidentiality of data was preserved.

Explanation of this project to the participants.

An informed permission was taken from the patients to contribute in the study, after clarifying the aim of the study.

Statistical analysis

The collected data were organized, tabulated, and statistically analyzed using the statistical package for the social sciences (SPSS), version 16 (SPSS Inc., Chicago, Illinois, USA), running on an IBM-compatible computer.

Quantitative data were represented as mean and SD. Qualitative data were represented as relative frequency and percentage. Comparison between groups was done by Student' t-test samples for quantitative and for qualitative data using Pearson's χ2 and Fisher's-exact test.

Data were presented in the form of graphs, tables, and numeric presentations. A P value less than or equal to 0.05 was considered statistically significant.

 Results



All patients with interstitial edematous pancreas have normal enhancement [Figure 1]. Half of them have mild fat infiltration and the other half are severe. About two-third of them have moderate pancreatic swelling. One-third of the patients with necrotizing pancreatitis have mild necrosis of the pancreatic parenchyma [Figure 2], 33.3% had moderate, and 33.3% had severe. About one-third of them have mild necrosis of the peripancreatic tissue and the others are moderate. All patients with acute peripancreatic fluid collection of the pancreas have a homogeneous content with partial capsulation and duration of less than 4 weeks. Also, all patients with pancreatic pseudocysts have a heterogeneous content with complete capsulation and duration of more than 4 weeks. Moreover, all patients with acute necrotic collection of pancreas have a homogeneous content with partial capsulation and duration less than 4 weeks with necrosis. In addition, all patients with walled-off necrosis (WON) of the pancreas have a heterogeneous content with complete capsulation and duration of more than 4 weeks with necrosis [Table 1].{Figure 1}{Figure 2}{Table 1}

Most of the patients (22) were with acute peripancreatic fluid collection [Figure 3], seven with pseudocysts, and two with acute necrotic fluid collection resolved with conservative treatment with less than 2 weeks. Two cases were with pseudocyst and WON that need early fine needle aspiration and [Figure 4] percutaneous drainage. Only one case was with WON that needed surgical intervention [Table 2] and [Figure 5].{Figure 3}{Figure 4}{Table 2}{Figure 5}

There was statistical significance about the difference of type of lesion regarding the age group (P = 0.014) as a P value of less than 0.05 was considered statistically significant [Table 3].{Table 3}

 Discussion



Consistent with the revised Atlanta classification, contrast-enhanced CT is the main tool for evaluating the imaging-based criteria because it is commonly available for these severely ill patients and has a high degree of accuracy [6].

The goal of the radiologists, surgeons, and pathologists is to use the revised classifications to systematize imaging terminology to assist treatment planning and to enable accurate comparison of the results between different departments and institutions [8].

In this study, men (73.7%) are more affected than women (26.3%) and most of them are above 40 years old (68.2%). The mean age of the patients 48 ± 18.21 ranged from 21 to 70 years with statistically significant difference between the type of lesion and age of the patients (P = 0.014). That is close to Peery et al. [11] study in which 63.6% of the patients were men with a mean age of 38 ± 11.85 years.

In this study upper abdominal pain is the most common symptom (100%) among all patients. This is matching with Ammann and Muellhaupt [12] who found that the most common symptom associated with pancreatitis is pain localized to the upper-to-middle abdomen. Patients often report that their pain radiates to the back.

Most of the patients presented with a history of smoking (63.6%), history of gall stone (54.5%), and alcoholism (18.2%). That is similar to Du et al. [13] who found that the most common cause of acute pancreatitis is cholelithiasis (35–40%), followed by alcohol (30%).

All patients in the current study have elevated serum amylase. Most of the patients have elevated serum lipase (63.6%) and elevated serum triglycerides (27.3%). This differs from Banks et al. [14] who found that in acute pancreatitis, the plasma lipase levels increase within 4–8 h, peak at 24 h to more than 2 times × the upper limit of normal 24 h and may remain elevated for 10–14 days.

In this study, 42 of the 60 patients have interstitial edematous pancreatitis (IEP). All patients with IEP have normal enhancement and half of them have mild fat infiltration and the other half are severe. About two-third of them have moderate pancreatic swelling without necrosis. This is similar to Bharwani et al. [15] who found IEP as localized or diffuse enlargement of the pancreas, with normal homogeneous enhancement or slightly heterogeneous enhancement of the pancreatic parenchyma related to edema.

In this study, one-third of the patients with necrotizing pancreatitis have mild necrosis of pancreatic parenchyma, 33.3% had moderate, and 33.3% had severe. About one-third of them have mild necrosis of peripancreatic tissue and the others are moderate. This is different from the Bollen et al. [9] study which found that the necrotizing pancreatitis is similar to interstitial edematous pancreatitis.

In this study, all patients with pancreatic pseudocysts have a heterogeneous content with complete capsulation and duration of more than 4 weeks. This is different from the Kim and Kim [16] study in which observed that about 50% of pseudocysts persist asymptomatic, and there are no reliable signs, for example, size or duration, to expect which will develop symptomatically and actually need treatment.

Regarding this study, all patients with WON of pancreas have a heterogeneous content with complete capsulation and duration of more than 4 weeks with necrosis. That is consistent with the study by Thoeni who identified that WON grows when necrotic tissues and acute necrotic collections become mature and then form a capsule. This process frequently involves at least 4 weeks [15].

In this study, all patients with WON of pancreas have a heterogeneous content with complete capsulation and duration of more than 4 weeks with necrosis. This is matching with Bharwani et al. [15] who found that any encapsulated fluid-containing collection within the pancreas, with discontinuation of the parenchyma, of more than 4 weeks after the onset of acute necrotizing pancreatitis is very likely WON [17].

In this study, most of the patients (22) were with acute peripancreatic fluid collection, seven with pseudocysts, and two were with acute necrotic fluid collection resolved with conservative treatment with less than 2 weeks. Two cases were with pseudocyst and WON that need early fine needle aspiration and percutaneous drainage. Only one case was with WON that needs surgical intervention and this is close to Singh et al. [18] who found that invasive intervention for complications associated with acute pancreatitis is indicated in the presence of symptoms or secondary infection in patients for whom conservative management has failed or who are not sufficiently stable for conservative management.

 Conclusion



Contrast-enhanced CT is a perfect diagnostic modality to determine the severity of inflammatory process, identify the pancreatic necrosis, and to show local complications and grading of severity of acute pancreatitis. Revised Atlanta classification is more accurate for assessing patient mortality and organ failure.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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