Perfusion CT: can it predict the development of pancreatic necrosis in early stage of severe acute pancreatitis?

Acute pancreatitis and computed tomography: Interest of portal venous phase alone in the initial phase

BACKGROUND

There are no guidelines in the literature for the use of a computed tomography (CT) protocol in the initial phase of acute pancreatitis (AP).

PURPOSE

To evaluate the contribution of single portal venous phase CT compared to triple-phase CT protocol, performed in the initial phase of AP for severity assessment.

MATERIAL AND METHODS

In this retrospective study, a total of 175 patients with acute pancreatitis who underwent initial triple-phase CT protocol (non-contrast, arterial phase, and portal venous phase) between D3 and D7 after the onset of symptoms were included. Analysis of AP severity and complications was independently assessed by two readers using three validated CT severity scores (CTSI, mCTSI, EPIC). All scores were applied to the triple-phase CT protocol and compared to the single portal venous phase. Inter-observer analyses were also performed.

RESULTS

No significant difference whatever the severity score was observed after analysis of the single portal venous phase compared with the triple-phase CT protocol (interstitial edematous pancreatitis: CTSI: 2 vs. 2, mCTSI: 2 vs. 2, EPIC: 1 vs. 1; necrotizing pancreatitis: CTSI: 6 vs. 6, mCTSI: 8 vs. 8, EPIC: 5 vs. 5). Inter-observer agreement was excellent (ICC = 0.96-0.99), whatever the severity score.

CONCLUSION

A triple-phase CT protocol performed at the initial phase of AP was no better than a single portal venous for assessing the severity of complications and could lead to a 63% reduction in irradiation.

Computed tomographic evaluation of pancreatic perfusion in 10 dogs with acute pancreatitis

Severe canine acute pancreatitis can be fatal; imaging features that can predict the clinical course of disease are useful for clinicians. On computed tomography (CT), both pancreatic heterogeneous contrast enhancement and portal vein thrombosis have been correlated with poorer outcome. Perfusion CT is used in human medicine to evaluate pancreatic microcirculation to predict the future development of severe sequela to pancreatitis; this technology has yet to be explored in dogs with acute pancreatitis. The objective of this prospective, case-control study is to evaluate pancreatic perfusion using contrast-enhanced CT in dogs with acute pancreatitis and compare it with previously established values obtained in healthy dogs. Ten client-owned dogs preliminarily diagnosed with acute pancreatitis received a full abdominal ultrasound, specific canine pancreatic lipase (Spec cPL), and perfusion CT. Computer software calculated pancreatic perfusion, peak enhancement index, time to peak enhancement, and blood volume for 3-mm and reformatted 6-mm slices. The data was analyzed using Shapiro-Wilk test, linear mixed model, and Spearman's rho. Values for 3-mm slices were similar to 6-mm slices (all P < 0.05). Dogs with acute pancreatitis had a faster time to peak enhancement than healthy dogs (P = 0.04-0.06). Dogs with acute pancreatitis and homogeneous pancreatic enhancement had higher perfusion, faster time to peak enhancement, and greater blood volume compared to healthy dogs and dogs with acute pancreatitis and heterogeneous pancreatic enhancement (all P = / < 0.05). Pancreatic perfusion decreased with increased pancreatitis severity. No correlation was identified between Spec cPL and pancreatic perfusion (all P > 0.05). These findings preliminarily support perfusion CT in dogs with acute pancreatitis.

New advances in CT imaging of pancreas diseases: a narrative review

Computed tomography (CT) plays a pivotal role as a diagnostic tool in many diagnostic and diffuse pancreatic diseases. One of the major limits of CT is related to the radiation exposure of young patients undergoing repeated examinations. Besides the standard CT protocol, the most recent technological advances, such as low-voltage acquisitions with high performance X-ray tubes and iterative reconstructions, allow for significant optimization of the protocol with dose reduction. The variety of CT tools are further expanded by the introduction of dual energy: the production of energy-selective images (i.e., virtual monochromatic images) improves the image contrast and lesion detection while the material-selective images (e.g., iodine maps or virtual unenhanced images) are valuable for lesion detection and dose reduction. The perfusion techniques provide diagnostic and prognostic information lesion and parenchymal vascularization and interstitium. Both dual energy and perfusion CT have the potential for pushing the limits of conventional CT from morphological evaluation to quantitative imaging applied to inflammatory and oncological diseases. Advances in post-processing of CT images, such as pancreatic volumetry, texture analysis and radiomics provide relevant information for pancreatic function but also for the diagnosis, management and prognosis of pancreatic neoplasms. Artificial intelligence is promising for optimization of the workflow in qualitative and quantitative analyses. Finally, basic concepts on the role of imaging on screening of pancreatic diseases will be provided.

Prediction of the progression of walled-off necrosis in patients with acute pancreatitis on whole pancreatic perfusion CT

BACKGROUND/PURPOSE

This study investigated whether measuring pancreatic blood volume (PBV) on whole pancreatic perfusion computed tomography (P-CT) can predict the progression of walled-off necrosis (WON) in patients with acute pancreatitis (AP).

METHODS

A single-center, retrospective cohort study was conducted between December 2015 and December 2016. The participants were divided into two groups: 14 patients with WON and 15 patients without WON. PBV was measured within 72 hours after the diagnosis of AP, and the final diagnosis of WON was made by contrast-enhanced CT (CE-CT) or endoscopic ultrasonography (EUS) 4 weeks after the onset of AP.

RESULTS

The minimum CT value did not differ significantly between the two groups. On the other hand, the minimum PBV was significantly lower in the WON group than in the without WON group (1.4 (0.9-9.9) vs 19.8 (8.2-21.7) mL/100 mL, respectively; P = .02). The cutoff value of the minimum PBV for WON was 16.5 mL/100 mL (sensitivity 100%, specificity 67%, AUC 0.85; P = .001).

CONCLUSIONS

Whole pancreatic P-CT can evaluate pancreatic ischemia visually and quantitatively. The minimum PBV measurement on whole pancreatic P-CT within 72 hours after the diagnosis of AP contributes to the prediction of progression of WON.

Computed tomographic evaluation of pancreatic perfusion in healthy dogs

OBJECTIVE

To evaluate the feasibility of contrast-enhanced CT for assessment of pancreatic perfusion in healthy dogs.

ANIMALS

6 healthy purpose-bred female Treeing Walker Coonhounds.

PROCEDURES

Contrast-enhanced CT of the cranial part of the abdomen was performed with 3-mm slice thickness. Postprocessing computer software designed for evaluation of human patients was used to calculate perfusion data for the pancreas and liver by use of 3-mm and reformatted 6-mm slices. Differences in perfusion variables between the pancreas and liver and differences in liver-specific data of interest were evaluated with the Friedman test.

RESULTS

Multiple pancreatic perfusion variables were determined, including perfusion, peak enhancement index, time to peak enhancement, and blood volume. The same variables as well as arterial, portal, and total perfusion and hepatic perfusion index were determined for the liver. Values for 6-mm slices appeared similar to those for 3-mm slices. The liver had significantly greater median perfusion and peak enhancement index, compared with the pancreas.

CONCLUSIONS AND CLINICAL RELEVANCE

Measurement of pancreatic perfusion with contrast-enhanced CT was feasible in this group of dogs. Hepatic arterial and pancreatic perfusion values were similar to previously published findings for dogs, but hepatic portal and hepatic total perfusion measurements were not. These discrepancies might have been attributable to physiologic differences between dogs and people and related limitations of the CT software intended for evaluation of human patients. Further research is warranted to assess reliability of perfusion variables and applicability of the method for assessment of canine patients with pancreatic abnormalities.

Multifactorial Scores and Biomarkers of Prognosis of Acute Pancreatitis: Applications to Research and Practice

Acute pancreatitis (AP) is a severe inflammation of the pancreas presented with sudden onset and severe abdominal pain with a high morbidity and mortality rate, if accompanied by severe local and systemic complications. Numerous studies have been published about the pathogenesis of AP; however, the precise mechanism behind this pathology remains unclear. Extensive research conducted over the last decades has demonstrated that the first 24 h after symptom onset are critical for the identification of patients who are at risk of developing complications or death. The identification of these subgroups of patients is crucial in order to start an aggressive approach to prevent mortality. In this sense and to avoid unnecessary overtreatment, thereby reducing the financial implications, the proper identification of mild disease is also important and necessary. A large number of multifactorial scoring systems and biochemical markers are described to predict the severity. Despite recent progress in understanding the pathophysiology of AP, more research is needed to enable a faster and more accurate prediction of severe AP. This review provides an overview of the available multifactorial scoring systems and biochemical markers for predicting severe AP with a special focus on their advantages and limitations.

Dynamic Contrast-Enhanced MRI for Measuring Pancreatic Perfusion in Acute Pancreatitis: A Preliminary Study

RATIONALE AND OBJECTIVES

To assess the characteristics of pancreatic perfusion in normal pancreas and acute pancreatitis (AP) by using dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI).

METHOD AND MATERIALS

Eighty-One AP patients and 26 normal subjects underwent DCE-MRI. The Omitk-Tool was used to analyze perfusion parameters such as K^trans, V_p^, and AUC. The parameters of pancreas between AP and control groups were compared. In AP patients, the parameters were compared between edematous and necrotizing pancreatitis and among different grades of AP as determined by MR severity index (MRSI) and the 2012 Revised Atlanta Classification of AP.

RESULTS

The K^trans, V_p^, and AUC values of AP were lower than those of the control group (p = 0.007, 0.000, and 0.025). According to MRSI, the K^trans and AUC values were significantly different between mild and moderate (p = 0.000, 0.000) and between mild and severe (p = 0.008, 0.016) AP but not between moderate and severe AP (p = 0.218, 0.217). Based on the 2012 Revised Atlanta Classification, the K^trans values were significantly different between mild and moderately severe (p = 0.000) and between mild and severe (p = 0.005) AP, but not between moderately severe and severe AP (p = 0.619). The K^trans values were significantly different between edematous and necrotizing pancreatitis (p = 0.03).

CONCLUSION

The application of DCE-MRI to evaluate pancreatic perfusion contributes to the diagnosis of AP and its severity grade. Pancreatic perfusion is lower in AP patients than in patients with a normal pancreas, and pancreatic perfusion tends to decrease as the severity of AP increases.

Can Disturbed Liver Perfusion Revealed in p-CT on the First Day of Acute Pancreatitis Provide Information about the Expected Severity of the Disease?

Background

The aim of the study was to evaluate the prognostic properties of perfusion parameters of liver parenchyma based on computed tomography (CT) of patients with acute pancreatitis (AP) made on the first day of onset of symptoms, to assess their usefulness in identifying patients with increased risk of the development of severe AP.

Methods

79 patients with clinical symptoms and biochemical criteria indicative of AP underwent perfusion computed tomography (p-CT) within 24 hours after onset of the symptoms. Perfusion parameters in 41 people who developed a severe form of AP were compared with parameters in 38 patients in whom the course of AP was mild.

Results

Statistical differences in the liver perfusion parameters between the group of patients with mild and severe AP were shown. The permeability-surface area product was significantly lower, and the hepatic arterial fraction was significantly higher in the group of patients with progression of AP.

Conclusions

Based on the results, it seems that p-CT performed on the first day from the onset of AP is a method that, by revealing disturbances in hepatic perfusion, can help in identifying patients with increased risk of the development of severe AP.

Predictive factors for the mortality of acute pancreatitis on admission

Background and aims

The revised Atlanta classification is widely used for the evaluation of acute pancreatitis (AP) severity. However, this classification cannot be used within 48 hours of AP onset. The aim of this study was to investigate the predictive factors of mortality in patients with AP on admission.

Methods

We evaluated the association between AP mortality and clinical parameters at the time of admission in patients with AP from April 2013 to December 2017 at one university hospital and one tertiary care referral center.

Results

A total of 203 consecutive patients were enrolled. Nine patients (4.4%) died despite multidisciplinary treatment. In a multivariable analysis, hematocrit ≥ 40% (odds ratio [OR], 1.07; 95% confidence interval [CI], 1.01–1.13; P = 0.021), blood urea nitrogen (BUN) ≥ 40 mg/dL (OR, 1.26; 95% CI, 1.11–1.42; P < 0.001), base excess < -3.0 mmol/L (OR, 1.15; 95% CI, 1.04–1.26; P = 0.004), and inflammation extending to the rectovesical excavation (OR, 1.19; 95% CI, 1.10–1.30; P < 0.001) on admission were significantly associated with mortality.

Conclusion

Among the imaging findings, inflammation extending to the rectovesical excavation was the only independent predictive factor for mortality in AP. This simple finding, obtained on computed tomography without contrast agent on admission, might be a promising prognostic factor for AP.

Functional imaging in pancreatic disease

In addition to the classical morphological evaluation of pancreatic disease, the constant technological advances in imaging techniques based fundamentally on computed tomography and magnetic resonance imaging have enabled the quantitative functional and molecular evaluation of this organ. In many cases, this imaging-based information results in substantial changes to patient management and can be a fundamental tool for the development of biomarkers. The aim of this article is to review the role of emerging functional and molecular techniques based on computed tomography and magnetic resonance imaging in the evaluation of pancreatic disease.

The association between portal system vein diameters and outcomes in acute pancreatitis

BACKGROUND/OBJECTIVES

Acute pancreatitis (AP) progresses to necrotizing pancreatitis in 15% of cases. An important pathophysiological mechanism in AP is third spacing of fluids, which leads to intravascular volume depletion. This results in a reduced splanchnic circulation and reduced venous return. Non-visualisation of the portal and splenic vein on early computed tomography (CT) scan, which might be the result of smaller vein diameter due to decreased venous flow, is associated with infected necrosis and mortality in AP. This observation led us to hypothesize that smaller diameters of portal system veins (portal, splenic and superior mesenteric) are associated with increased severity of AP.

METHODS

We conducted a post-hoc analysis of data from two randomized controlled trials that included patients with predicted severe and mild AP. The primary endpoint was AP-related mortality. The secondary endpoints were (infected) necrotizing pancreatitis and (persistent) organ failure. We performed additional CT measurements of portal system vein diameters and calculated their prognostic value through univariate and multivariate Poisson regression.

RESULTS

Multivariate regression showed a significant inverse association between splenic vein diameter and mortality (RR 0.75 (0.59-0.97)). Furthermore, there was a significant inverse association between splenic and superior mesenteric vein diameter and (infected) necrosis. Diameters of all veins were inversely associated with organ failure and persistent organ failure.

CONCLUSIONS

We observed an inverse relationship between portal system vein diameter and morbidity and an inverse relationship between splenic vein diameter and mortality in AP. Further research is needed to test whether these results can be implemented in predictive scoring systems.

The Accuracy of Pancreatic Perfusion Computed Tomography and Angiography in Predicting Necrotizing Pancreatitis: A Systematic Review

Early prediction of necrotizing pancreatitis is important for tailoring treatment, but current scoring systems have moderate accuracy and can be calculated only 24 to 48 hours after disease onset. Evaluation of (micro)circulatory changes in acute pancreatitis at admission by perfusion computed tomography (PCT) or angiography could predict necrosis earlier. Our aim was to systematically review the evidence for angiographic and PCT prediction of necrotizing pancreatitis. We performed a systematic review and searched MEDLINE and Embase. We included cohort studies addressing pancreatic perfusion for prognostication of severity of acute pancreatitis and assessed study quality with a tool specific for diagnostic accuracy studies. Six prospective cohorts with 334 patients were included. Sensitivity of PCT for predicting necrosis ranged from 71% to 100% and specificity from 74% to 100%. The only study directly comparing PCT and angiography found a similar sensitivity (100%) but higher specificity for PCT (90% vs 72%). The included studies had moderate quality. Current studies consistently demonstrate excellent sensitivity and specificity of PCT for early prediction of necrosis. The performance found in our review should be confirmed in larger prospective cohorts as published studies have moderate quality. Furthermore, it should be investigated whether early PCT improves disease course.

Early diagnosis of pancreatic necrosis based on perfusion CT to predict the severity of acute pancreatitis

BACKGROUND

Perfusion CT can diagnose pancreatic necrosis in early stage of severe acute pancreatitis, accurately. However, no study to date has examined whether early diagnosis of pancreatic necrosis is useful in predicting persistent organ failure (POF).

METHODS

We performed a multi-center prospective observational cohort study to investigate whether perfusion CT can predict the development of POF in the early stage of AP, based on early diagnosis of the development of pancreatic necrosis (PN). From 2009 to 2012, we examined patients showing potential early signs of severe AP (n = 78) on admission. Diagnoses for the development of PN were made prospectively by on-site physicians on the admission based on perfusion CT (diagnosis 1). Blinded retrospective reviews were performed by radiologists A and B, having 8 and 13 years of experience as radiologists (diagnosis 2 and 3), respectively. Positive diagnosis for the development of PN were assumed equivalent to positive predictions for the development of POF. We then calculated the area under the curve (AUC) of the receiver operating characteristic for POF predictions.

RESULTS

Fourteen (17.9%) and 23 patients (29.5%) developed PN and POF, respectively. For diagnoses 1, 2, and 3, AUCs for POF predictions were 74, 68, and 73, respectively.

CONCLUSIONS

Perfusion CT diagnoses pancreatic necrosis and on that basis predicts the development of POF; http://www.umin.ac.jp/ctr/index-j.htm,UMIN000001926 .

Perfusion CT - Can it resolve the pancreatic carcinoma versus mass forming chronic pancreatitis conundrum?

OBJECTIVES

To evaluate the utility of perfusion CT (PCT) in differentiating pancreatic adenocarcinoma from mass forming chronic pancreatitis (MFCP).

METHODS

In this ethically approved study, PCT was performed in 122 patients with pancreatic masses of which 42 patients had pancreatic adenocarcinoma and 13 had MFCP on histopathology. Perfusion parameters studied included blood flow (BF), blood volume (BV), permeability surface area product (PS), time to peak (TTP), peak enhancement intensity (PEI) and mean transit time (MTT). Twenty five controls with no pancreatic pathology were also studied.

RESULTS

Amongst the perfusion parameters BF and BV were found to be the most reliable for differentiating between adenocarcinoma and mass forming pancreatitis. Although they were reduced in both pancreatic adenocarcinoma (BF- 16.6 ± 13.1 ml/100 ml/min and BV- 5 ± 3.5 ml/100 ml) and MFCP (BF- 30.4 ± 8.7 ml/100 ml/min and BV- 8.9 ± 3.1 ml/100 ml) as compared to normal controls (BF- 94.1 ± 24 ml/100 ml/min and BV- 36 ± 10.7 ml/100 ml) but the extent of reduction was greater in pancreatic adenocarcinoma than in MFCP. Based on ROC analysis cut off values of 19.1 ml/100 ml/min for BF and 5 ml/100 ml for BV yielded optimal sensitivity and specificity for differentiating pancreatic adenocarcinoma from MFCP.

CONCLUSIONS

PCT may serve as an additional paradigm for differentiating pancreatic adenocarcinoma from mass forming chronic pancreatitis and a useful tool for detecting masses which are isodense on conventional CT.

Defining post-operative pancreatitis as a new pancreatic specific complication following pancreatic resection

INTRODUCTION

Post-operative pancreatic fistula has been well defined. However the underlying aetiology remains poorly understood. The aim of this review was to investigate whether the underlying aetiology for a proportion of patients suffering from post-operative pancreatic fistula was due to post-operative pancreatitis.

METHOD

A systematic literature review according to the PRISMA guidelines. The date range was from 2005 to 2016. The search strategy included the terms: post-operative pancreatitis, pathophysiology, post-operative pancreatic fistula, pancreaticoduodenectomy, ischaemic pancreatitis, microcirculation and pancreatitis, serum and drain amylase and lipase. The data was summarised without quantitative or qualitative analysis.

RESULTS

There exists significant physiological, biochemical, clinical and histological evidence in the literature that a proportion of post-operative pancreatic fistula is due to post-operative pancreatitis. A new definition of post-operative pancreatitis based on the presence of biochemical evidence for pancreatic inflammation (urinary trypsinogen-2 >50 ug/L or serum amylase/lipase > upper limit of normal) between post-operative days 0-2. Predicted severity is based on C-reactive protein with a cut-off of 180 mg/L at post-operative day 2. The proposed grading of severity is in line with previous work by international study group of pancreatic surgery.

CONCLUSION

Post-operative pancreatitis should be recognised as a separate pancreatic specific complication following pancreatic resection. Improved recognition may allow better understanding of potential methods of prevention, treatment and prediction of severity.

Perfusion-CT--Can We Predict Acute Pancreatitis Outcome within the First 24 Hours from the Onset of Symptoms?

PURPOSE

Severe acute pancreatitis (AP) is still a significant clinical problem which is associated with a highly mortality. The aim of this study was the evaluation of prognostic value of CT regional perfusion measurement performed on the first day of onset of symptoms of AP, in assessing the risk of developing severe form of acute pancreatitis.

MATERIAL AND METHODS

79 patients with clinical symptoms and biochemical criteria indicative of acute pancreatitis (acute upper abdominal pain, elevated levels of serum amylase and lipase) underwent perfusion CT within 24 hours after onset of symptoms. The follow-up examinations were performed after 4-6 days to detect progression of the disease. Perfusion parameters were compared in 41 people who developed severe form of AP (pancreatic and/or peripancreatic tissue necrosis) with parameters in 38 consecutive patients in whom course of AP was mild. Blood flow, blood volume, mean transit time and permeability surface area product were calculated in the three anatomic pancreatic subdivisions (head, body and tail). At the same time the patient's clinical status was assessed by APACHE II score and laboratory parameters such as CRP, serum lipase and amylase, AST, ALT, GGT, ALP and bilirubin were compared.

RESULTS

Statistical differences in the perfusion parameters between the group of patients with mild and severe AP were shown. Blood flow, blood volume and mean transit time were significantly lower and permeability surface area product was significantly higher in patients who develop severe acute pancreatitis and presence of pancreatic and/or peripancreatic necrosis due to pancreatic ischemia. There were no statistically significant differences between the two groups in terms of evaluated on admission severity of pancreatitis assessed using APACHE II score and laboratory tests.

CONCLUSIONS

CT perfusion is a very useful indicator for prediction and selection patients in early stages of acute pancreatitis who are at risk of developing pancreatic and/or peripancreatic necrosis already on the first day of the onset of symptoms and can be used for treatment planning and monitoring of therapy of acute pancreatitis. Early suspicion of possible pancreatic necrosis both on the basis of scores based on clinical status and laboratory tests have low predictive value.

Acute Pancreatitis-Progress and Challenges: A Report on an International Symposium

An international symposium entitled "Acute pancreatitis: progress and challenges" was held on November 5, 2014 at the Hapuna Beach Hotel, Big Island, Hawaii, as part of the 45th Anniversary Meeting of the American Pancreatic Association and the Japanese Pancreas Society. The course was organized and directed by Drs. Stephen Pandol, Tooru Shimosegawa, Robert Sutton, Bechien Wu, and Santhi Swaroop Vege. The symposium objectives were to: (1) highlight current issues in management of acute pancreatitis, (2) discuss promising treatments, (3) consider development of quality indicators and improved measures of disease activity, and (4) present a framework for international collaboration for development of new therapies. This article represents a compilation and adaptation of brief summaries prepared by speakers at the symposium with the purpose of broadly disseminating information and initiatives.

Treating acute pancreatitis: what's new?

The medical treatment of acute pancreatitis continues to focus on supportive care, including fluid therapy, nutrition, and antibiotics, all of which will be critically reviewed. Pharmacologic agents that were previously studied were found to be ineffective likely due to a combination of their targets and flaws in trial design. Potential future pharmacologic agents, particularly those that target intracellular calcium signaling, as well as considerations for trial design will be discussed. As the incidence of acute pancreatitis continues to increase, greater efforts will be needed to prevent hospitalization, readmission and excessive imaging in order to reduce overall healthcare costs. Primary prevention continues to focus on post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis and secondary prevention on cholecystectomy for biliary pancreatitis as well as alcohol and smoking abstinence.