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Evaluation of Effect of Fatty Liver on the Severity of Acute Pancreatitis Using Computed Tomography- A Retrospective Study |
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Venkat Kishan Tatikonda, Sindhura Indurti 1. Associate Professor, Department of Radiodiagnosis, Kamineni Institute of Medical Sciences, Narketpally, Nalgonda, Telangana, India. 2. Resident, Department of Radiodiagnosis, Kamineni Institute of Medical Sciences, Narketpally, Nalgonda, Telangana, India. |
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Correspondence Address : Venkat Kishan Tatikonda, 1-2-234/25, Plot No: 12g SBH Colony Domalguda Hyderabad, Hyderabad, Telangana, India. E-mail: venkatkishanresearch@gmail.com |
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ABSTRACT | |||||||||||||||||||||||||||||||||||||||||||
: Fatty Liver (FL) disease is commonly encountered in clinical practice and is frequently seen in patients with Acute Pancreatitis (AP) due to common risk factors such as obesity, alcohol abuse, and insulin resistance among others. Aim: To evaluate the effect of FL on the severity of AP radiologically using Computed Tomography (CT). Materials and Methods: This was a retrospective study, conducted from June 2021 to July 2021 in which plain CT images of patients with AP were reviewed to measure the mean attenuation values of the liver and spleen. A ratio of mean hepatic/splenic Hounsfield Units (HU) <1 was considered as FL. The severity of AP was assessed using the Modified CT Severity Index (CTSI) on Contrast Enhanced Computed Tomography (CECT) scan. Data collected was entered into Microsoft Excel datasheet and frequency (n) and percentages were calculated. Chi-square test was used to calculate the level of significance. Results: A total of 50 patients (44 males and 6 females; mean age 35.58±13.792 years) with AP were included in this study amongst whom FL was found in 23 patients (46%) and non FL in 27 patients (54%). The severity of pancreatitis was significantly greater in patients with FL than patients without FL. AP patients with FL had higher rates of local complications like acute Peripancreatic Fluid Collections (PPFC) (56.5% vs 22.2% p<0.001) and Acute Necrotic Collections (ANC) (26.1% vs 3.7% p<0.001) than those without FL. Conclusion: Fatty liver plays a significant role in the severity acute pancreatitis and can be used as an indicator for the same. Combined plain and contrast CT scans can be used to assess FL and diagnose and predict the severity of AP. | |||||||||||||||||||||||||||||||||||||||||||
Keywords : Acute necrotic collections, Peripancreatic fluid collections, Hepatic-splenic attenuation ratio | |||||||||||||||||||||||||||||||||||||||||||
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INTRODUCTION | |||||||||||||||||||||||||||||||||||||||||||
Acute pancreatitis (AP) is a condition characterised by acute inflammation of the pancreas and peripancreatic tissue. The most common causes are alcohol abuse, gallstones, abdominal surgeries, genetic mutations, infections, hyperlipidemia, hypercalcaemia, autoimmune diseases, pregnancy, and others (1),(2). The CECT is the imaging modality of choice in diagnosing AP and establishing the disease severity (2). The AP usually has a mild course in most patients. However, few patients might develop a severe course which might lead to organ failure and subsequently to Multiple Organ Dysfunction Syndrome (MODS) which is associated with significant mortality and morbidity. In AP, the presence of necrosis carries a poorer prognosis and infected necrosis necessitates active intervention (3). Hence, early diagnosis and prognostication of the severity of AP are necessary. Many scoring systems have been developed to assess the severity of AP and the most widely used is the revised Atlanta classification (2). A common prognostic marker used in AP is serum C-Reactive Protein (serum CRP). Serum CRP level is cheap and easily available, but peaks 72 hrs after onset of symptoms and this delay makes it less useful at admission (4). The FL disease can be alcoholic fatty liver disease or Non Alcoholic Fatty Liver Disease (NAFLD) which may be simple FL or steatohepatitis and further progress to cirrhosis and ultimately to liver failure. The FL, frequently seen in patients with AP, is easily detectable on CT as decreased hepatic attenuation on non contrast images (5). Albeit many studies have been conducted on the same subject, most of them have been conducted in other countries like China (3),(6),(7),(8),(9), Korea (4), USA (10),(11), Mexico (12), Germany (13), and Croatia (14). No studies have been conducted in India regarding the association between the severity of AP and FL. The present study aimed to assess the effect of FL on the severity of AP using CT scan, in a tertiary care centre in India. | |||||||||||||||||||||||||||||||||||||||||||
MATERIAL AND METHODS | |||||||||||||||||||||||||||||||||||||||||||
This was a retrospective study conducted at the Department of Radiodiagnosis, Kamineni Institute of Medical Sciences, Narketpally, Nalgonda, Telangana, India, on 50 patients diagnosed with AP referred for CECT of the abdomen, during a period from May 2019 to May 2021. Data was studied and analysed from June 2021 to July 2021 for a period of 2 months. Inclusion criteria: All male and female patients, aged 5 years to 75 years, diagnosed with AP referred to the Department of Radiodiagnosis were included in the study. The presence of at least two of the following criteria was considered diagnostic for AP (6): (i) acute abdominal pain consistent with AP (ii) raised serum lipase and/ or serum amylase levels more than three times the upper limit of normal and (iii) CT findings typical of AP. Exclusion criteria: Those patients with history of pancreatic disease or with chronic liver disease, splenectomised patients or those with any history of malignancy were excluded from the study. Study Procedure The Modified Computed Tomography Severity Index (CTSI) used to assess the severity of pancreatitis was based on the Revised Atlanta classification for pancreatitis (Table/Fig 1) (15). AP was classified into Acute Interstitial Edematous Pancreatitis (AIEP) and Acute Necrotising Pancreatitis (ANP), based on CECT findings and the existence of pancreatic necrosis (16). Local complications included were acute Peripancreatic Fluid Collections (PPFC), Acute Necrotic Collections (ANC), Walled-Off Necrosis (WON), and Pancreatic Pseudocyst (PP). Other local complications considered were vascular complications like splenic or portal vein thrombosis. Systemic complications that were included were ascites and pleural effusion. Plain CT images of the study population were retrospectively reviewed. The hepatic attenuation was normally higher than the splenic attenuation. Reversal of hepatic-splenic attenuation ratio is seen in patients with FL (5),(17). The mean attenuation values (HU) were measured for Regions Of Interest (ROIs) of area 400-500 mm2 in the liver and spleen in two contiguous axial plain CT sections. In each section, three ROIs were placed in the liver (two in the right lobe of the liver and one in the left lobe) and one ROI was placed in the spleen (Table/Fig 2). The mean hepatic HU and the mean splenic HU were calculated by averaging the values from both slices. The mean hepatic-splenic attenuation ratio was calculated and a ratio of less than 1 was regarded as FL. STATISTICAL ANALYSIS Data was entered into a Microsoft Excel datasheet and was analysed using Statistical Software for Social Sciences (SPSS) version 22.0 (IBM SPSS Statistics, Somers NY, USA) software. Categorical data was represented in the form of Frequencies and proportions. The Chi-square test was used as a test of significance for qualitative data. Continuous data was represented as mean and standard deviation. The p-value (probability that the result is true) of <0.05 was considered as statistically significant after assuming all the rules of statistical tests. | |||||||||||||||||||||||||||||||||||||||||||
RESULTS | |||||||||||||||||||||||||||||||||||||||||||
A total of 66 patients underwent CECT for pancreatitis at the study centre during the given study period. Sixteen patients were excluded from the study: 7 patients had a previous history of pancreatitis or pancreatic disease, 4 patients had a history of chronic liver disease, 3 patients had undergone chemotherapy for malignancy and 2 patients were splenectomised. Out of the 50 patients examined, 44 patients were male and 6 were female. The mean age of subjects was 35.58±13.792 years. The majority of subjects were in the age group 31 to 40 years (36%) (Table/Fig 3). A total of 33 patients (66%) had AIEP, and 17 patients (34%) had ANP based on the revised Atlanta classification (Table/Fig 4). Based on the modified CT severity score, patients were classified into mild disease, moderately severe disease, and severe disease. Mild pancreatitis was seen in 15 patients (30%), moderately severe pancreatitis in 21 patients (42 %), and severe pancreatitis was seen in 14 patients (28%). Of the total study population, FL was found in 23 patients (46%) of which 13 patients had AIEP (56.5%) and 10 had ANP (43.5%). A higher incidence of severe acute pancreatitis (OR 4.42, 95% CI) was found in patients with FL than those without FL. In the FL group, two patients had mild disease (8.6%), 11 patients had moderately severe disease (47.8%) and 10 had severe disease (43.5%). In the non FL group, 13 patients had mild disease (48.2%), 10 had moderately severe disease (37%) and four patients had severe disease (14.8%) (Table/Fig 5). The number of patients with PPFC (Table/Fig 6), ANC (Table/Fig 7), WON (Table/Fig 8), and PP (Table/Fig 9) were 19 (38%), 7 (14%), 1 (2%), and 2 (4%), respectively in the study population (Table/Fig 10). In the present study, the number of patients with ascites, pleural effusions, splenic vein thrombosis and portal vein thrombosis (Table/Fig 11) were 29 (58), 19 (38%), 9 (18%), and 1 (2%), respectively. In patients with FL, 17 patients (73.9%) had ascites, 12 (52.2%) patients had pleural effusions and 7 patients (30.4%) had splenic vein thrombosis. In patients without FL, 12 patients (44.4%) had ascites, seven patients (25.9%) had pleural effusions, one patient (3.7%) had portal vein thrombosis, and two patients (7.4%) had splenic vein thrombosis. | |||||||||||||||||||||||||||||||||||||||||||
DISCUSSION | |||||||||||||||||||||||||||||||||||||||||||
The present study was done to analyse the effect of fatty liver on the severity of acute pancreatitis radiologically using CT and depicted a significant association between the two. Patients with FL had a higher incidence of severe acute pancreatitis (OR 4.42, 95% CI) than those without FL which is similar to studies conducted by Xu C et al., Yoon S et al., Wu D et al., and Mikolasevic I et al., (3),(4),(6),(14). In the present study, acute pancreatitis patients with FL also had higher rates of local complications like acute PPFCs (56.5% vs 22.2% p<0.01) and ANC (26.1% vs 3.7% p<0.02) than patients without FL which is similar to findings by Yoon S et al., who found that acute PPFCs (52.9% vs 24.1%, p<0.001) and ANC ( 20.9% vs 10.5%, p=0.046) were higher in the FL group than the Non FL group (4). However, there was no significant difference in the occurrence of PP (4.3% vs 3.7%, p>0.05) in this study between the patients with FL and the patients without FL which differs from the findings of Yoon S et al., who found significantly higher rates of PP (44.8% vs 20.3%, p<0.001) and WON (14.9% vs 3%, p=0.006) in the FL group than the Non FL group (4). In a meta-analysis conducted by Váncsa S et. al., (18) the authors found that the odds of moderately severe acute pancreatitis and severe acute pancreatitis (OR=3.14, CI 1.87-5.25) and severe acute pancreatitis alone (OR=2.67, CI 2.01-3.56)were higher in the FL group compared to the Non FL group (18). The authors also found that the proportion of acute PPFCs (44.55% vs 17.73%) and ANC (34.83% vs 15.75%) were higher in the FL group than the Non FL group. These findings are identical to the findings of the current study. The pathophysiology as to why FL is associated with a more severe course of acute pancreatitis is yet to be studied. Raised levels of CRP have been found in patients with FL [19,20]. Hence, patients with FL are in a chronic pro-inflammatory state which might aggravate the course of AP. In the early stage of AP, FL can be diagnosed by CT scan, thus predicting the delayed peak of serum CRP, which can lead to early intervention and thereby help in decreasing morbidity and mortality. Limitation(s) Firstly, the current study being a retrospective study, the sample size was small. Second, it was a single centre study and there is a need for further research and verification in the future. | |||||||||||||||||||||||||||||||||||||||||||
CONCLUSION | |||||||||||||||||||||||||||||||||||||||||||
Fatty liver is associated with a severe course of disease in acute pancreatitis patients and is also associated with a higher incidence of local complications, thereby increasing morbidity and mortality. CT scans are routinely performed in patients with acute pancreatitis, and fatty liver which can be detected in unenhanced phase images could serve as a useful prognostic marker. | |||||||||||||||||||||||||||||||||||||||||||
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