Differentiating autoimmune pancreatitis from pancreatic adenocarcinoma using dual-phase computed tomography. J Comput Assist Tomogr. 2014;38:146-152. [PMID: 24424563 DOI: 10.1097/rct.0b013e3182a9a431]

Differentiation of autoimmune pancreatitis from pancreatic adenocarcinoma using CT characteristics: a systematic review and meta-analysis

OBJECTIVES

To determine informational CT findings for distinguishing autoimmune pancreatitis (AIP) from pancreatic ductal adenocarcinoma (PDAC) and to review their diagnostic accuracy.

METHODS

A systematic and detailed literature review was performed through PubMed, EMBASE, and the Cochrane library. Similar descriptors to embody the identical image finding were labeled as a single CT characteristic. We calculated the pooled diagnostic odds ratios (DORs) of each CT characteristic using a bivariate random-effects model.

RESULTS

A total of 145 various descriptors from 15 studies (including 562 AIP and 869 PDAC patients) were categorized into 16 CT characteristics. According to the pooled DOR, 16 CT characteristics were classified into three groups (suggesting AIP, suggesting PDAC, and not informational). Seven characteristics suggesting AIP were diffuse pancreatic enlargement (DOR, 48), delayed homogeneous enhancement (DOR, 46), capsule-like rim (DOR, 34), multiple pancreatic masses (DOR, 16), renal involvement (DOR, 15), retroperitoneal fibrosis (DOR, 13), and bile duct involvement (DOR, 8). Delayed homogeneous enhancement showed a pooled sensitivity of 83% and specificity of 85%. The other six characteristics showed relatively low sensitivity (12-63%) but high specificity (93-99%). Four characteristics suggesting PDAC were discrete pancreatic mass (DOR, 23), pancreatic duct cutoff (DOR, 16), upstream main pancreatic duct dilatation (DOR, 8), and upstream parenchymal atrophy (DOR, 7).

CONCLUSION

Eleven CT characteristics were informational to distinguish AIP from PDAC. Diffuse pancreatic enlargement, delayed homogeneous enhancement, and capsule-like rim suggested AIP with the highest DORs, whereas discrete pancreatic mass suggested PDAC. However, pooled sensitivities of informational CT characteristics were moderate.

CLINICAL RELEVANCE STATEMENT

This meta-analysis underscores eleven distinctive CT characteristics that aid in differentiating autoimmune pancreatitis from pancreatic adenocarcinoma, potentially preventing misdiagnoses in patients presenting with focal/diffuse pancreatic enlargement.

KEY POINTS

• Diffuse pancreatic enlargement (pooled diagnostic odds ratio [DOR], 48), delayed homogeneous enhancement (46), and capsule-like rim (34) were CT characteristics suggesting autoimmune pancreatitis. • The CT characteristics suggesting autoimmune pancreatitis, except delayed homogeneous enhancement, had a general tendency to show relatively low sensitivity (12-63%) but high specificity (93-99%). • Discrete pancreatic mass (pooled diagnostic odds ratio, 23) was the CT characteristic suggesting pancreatic ductal adenocarcinoma with the highest pooled DORs.

Contrast-enhanced ultrasound and contrast-enhanced computed tomography for differentiating mass-forming pancreatitis from pancreatic ductal adenocarcinoma: a meta-analysis

BACKGROUND

Patients with mass-forming pancreatitis (MFP) or pancreatic ductal adenocarcinoma (PDAC) presented similar clinical symptoms, but required different treatment approaches and had different survival outcomes. This meta-analysis aimed to compare the diagnostic performance of contrast-enhanced ultrasound (CEUS) and contrast-enhanced computed tomography (CECT) in differentiating MFP from PDAC.

METHODS

A literature search was performed in the PubMed, EMBASE (Ovid), Cochrane Library (CENTRAL), China National Knowledge Infrastructure (CNKI), Weipu (VIP), and WanFang databases to identify original studies published from inception to August 20, 2021. Studies reporting the diagnostic performances of CEUS and CECT for differentiating MFP from PDAC were included. The meta-analysis was performed with Stata 15.0 software. The outcomes included the pooled sensitivity, specificity, positive likelihood ratio (+LR), negative likelihood ratio (-LR), diagnostic odds ratio (DOR), and summary receiver operating characteristic (SROC) curves of CEUS and CECT. Meta-regression was conducted to investigate heterogeneity. Bayesian network meta-analysis was conducted to indirectly compare the overall diagnostic performance.

RESULTS

Twenty-six studies with 2115 pancreatic masses were included. The pooled sensitivity and specificity of CEUS for MFP were 82% (95% confidence interval [CI], 73%-88%; I2  = 0.00%) and 95% (95% CI, 90%-97%; I2  = 63.44%), respectively; the overall +LR, -LR, and DOR values were 15.12 (95% CI, 7.61-30.01), 0.19 (95% CI, 0.13-0.29), and 78.91 (95% CI, 30.94-201.27), respectively; and the area under the SROC curve (AUC) was 0.90 (95% CI, 0.87-92). However, the overall sensitivity and specificity of CECT were 81% (95% CI, 75-85%; I2  = 66.37%) and 94% (95% CI, 90-96%; I2  = 74.87%); the overall +LR, -LR, and DOR values were 12.91 (95% CI, 7.86-21.20), 0.21 (95% CI, 0.16-0.27), and 62.53 (95% CI, 34.45-113.51), respectively; and, the SROC AUC was 0.92 (95% CI, 0.90-0.94). The overall diagnostic accuracy of CEUS was comparable to that of CECT for the differential diagnosis of MFP and PDAC (relative DOR 1.26, 95% CI [0.42-3.83], P  > 0.05).

CONCLUSIONS

CEUS and CECT have comparable diagnostic performance for differentiating MFP from PDAC, and should be considered as mutually complementary diagnostic tools for suspected focal pancreatic lesions.

Pancreatic cancer, autoimmune or chronic pancreatitis, beyond tissue diagnosis: Collateral imaging and clinical characteristics may differentiate them

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies and is developing into the 2^nd leading cause of cancer-related death. Often, the clinical and radiological presentation of PDAC may be mirrored by other inflammatory pancreatic masses, such as autoimmune pancreatitis (AIP) and mass-forming chronic pancreatitis (MFCP), making its diagnosis challenging. Differentiating AIP and MFCP from PDAC is vital due to significant therapeutic and prognostic implications. Current diagnostic criteria and tools allow the precise differentiation of benign from malignant masses; however, the diagnostic accuracy is imperfect. Major pancreatic resections have been performed in AIP cases under initial suspicion of PDAC after a diagnostic approach failed to provide an accurate diagnosis. It is not unusual that after a thorough diagnostic evaluation, the clinician is confronted with a pancreatic mass with uncertain diagnosis. In those cases, a re-evaluation must be entertained, preferably by an experienced multispecialty team including radiologists, pathologists, gastroenterologists, and surgeons, looking for disease-specific clinical, imaging, and histological hallmarks or collateral evidence that could favor a specific diagnosis. Our aim is to describe current diagnostic limitations that hinder our ability to reach an accurate diagnosis among AIP, PDAC, and MFCP and to highlight those disease-specific clinical, radiological, serological, and histological characteristics that could support the presence of any of these three disorders when facing a pancreatic mass with uncertain diagnosis after an initial diagnostic approach has been unsuccessful.

The value of endoscopic ultrasonography for differential diagnosis in obstructive jaundice of the distal common bile duct

INTRODUCTION

Obstructive jaundice is a common clinical disease of great significance; however, diagnosing it according to etiology, especially in patients with distal obstructive jaundice is difficult. The development of endoscopic ultrasonography has improved diagnostic methods. Endoscopic ultrasonography not only improves the accuracy of conventional endoscopic ultrasound technology in etiological diagnosis, but also offers several special endoscopic ultrasound technologies for diagnosing distal obstructive jaundice of the common bile duct. What's more, endoscopic ultrasonography can be used to treat distal obstructive jaundice of common bile duct.

AREAS COVERED

This review discusses the diagnostic value and applications of endoscopic ultrasonography for obstructive jaundice of the distal common bile duct.

EXPERT OPINION

This article summarizes the value of endoscopic ultrasonography in the etiological diagnosis, relevant treatment applications of distal obstructive jaundice and the limitations of endoscopic ultrasonography in some etiologies due to the lack of clear comparison with other imaging methods. We also provide new data for the future research direction of endoscopic ultrasonography in distal obstructive jaundice.

The role of artificial intelligence in pancreatic surgery: a systematic review

Artificial intelligence (AI), including machine learning (ML), is being slowly incorporated in medical practice, to provide a more precise and personalized approach. Pancreatic surgery is an evolving field, which offers the only curative option for patients with pancreatic cancer. Increasing amounts of data are available in medicine: AI and ML can help incorporate large amounts of information in clinical practice. We conducted a systematic review, based on PRISMA criteria, of studies that explored the use of AI or ML algorithms in pancreatic surgery. To our knowledge, this is the first systematic review on this topic. Twenty-five eligible studies were included in this review; 12 studies with implications in the preoperative diagnosis, while 13 studies had implications in patient evolution. Preoperative diagnosis, such as predicting the malignancy of IPMNs, differential diagnosis between pancreatic cystic lesions, classification of different pancreatic tumours, and establishment of the correct management for each of these lesions, can be facilitated through different AI or ML algorithms. Postoperative evolution can also be predicted, and some studies reported prediction models for complications, including postoperative pancreatic fistula, while other studies have analysed the implications for prognosis evaluation (from predicting a textbook outcome, the risk of metastasis or relapse, or the mortality rate and survival). One study discussed the possibility of predicting an intraoperative complication-massive intraoperative bleeding. Artificial intelligence and machine learning models have promising applications in pancreatic surgery, in the preoperative period (high-accuracy diagnosis) and postoperative setting (prognosis evaluation and complication prediction), and the intraoperative applications have been less explored.

Computed tomography-based radiomics approach in pancreatic tumors characterization

Radiomics (or texture analysis) is a new imaging analysis technique that allows calculating the distribution of texture features of pixel and voxel values depend on the type of ROI (3D or 2D), their relationships in the image. Depending on the software, up to several thousand texture elements can be obtained. Radiomics opens up wide opportunities for differential diagnosis and prognosis of pancreatic neoplasias. The aim of this review was to highlight the main diagnostic advantages of texture analysis in different pancreatic tumors. The review describes the diagnostic performance of radiomics in different pancreatic tumor types, application methods, and problems. Texture analysis in PDAC is able to predict tumor grade and associates with lymphovascular invasion and postoperative margin status. In pancreatic neuroendocrine tumors, texture features strongly correlate with differentiation grade and allows distinguishing it from the intrapancreatic accessory spleen. In pancreatic cystic lesions, radiomics is able to accurately differentiate MCN from SCN and distinguish clinically insignificant lesions from IPMNs with advanced neoplasia. In conclusion, the use of the CT radiomics approach provides a higher diagnostic performance of CT imaging in pancreatic tumors differentiation and prognosis. Future studies should be carried out to improve accuracy and facilitate radiomics workflow in pancreatic imaging.

Artificial intelligence in gastrointestinal radiology: A review with special focus on recent development of magnetic resonance and computed tomography

Artificial intelligence (AI), particularly the deep learning technology, have been proven influential to radiology in the recent decade. Its ability in image classification, segmentation, detection and reconstruction tasks have substantially assisted diagnostic radiology, and has even been viewed as having the potential to perform better than radiologists in some tasks. Gastrointestinal radiology, an important subspecialty dealing with complex anatomy and various modalities including endoscopy, have especially attracted the attention of AI researchers and engineers worldwide. Consequently, recently many tools have been developed for lesion detection and image construction in gastrointestinal radiology, particularly in the fields for which public databases are available, such as diagnostic abdominal magnetic resonance imaging (MRI) and computed tomography (CT). This review will provide a framework for understanding recent advancements of AI in gastrointestinal radiology, with a special focus on hepatic and pancreatobiliary diagnostic radiology with MRI and CT. For fields where AI is less developed, this review will also explain the difficulty in AI model training and possible strategies to overcome the technical issues. The authors’ insights of possible future development will be addressed in the last section.

Pre-Operative Imaging and Pathological Diagnosis of Localized High-Grade Pancreatic Intra-Epithelial Neoplasia without Invasive Carcinoma

Pancreatic ductal adenocarcinoma (PDAC) arises from precursor lesions, such as pancreatic intra-epithelial neoplasia (PanIN) and intraductal papillary mucinous neoplasm (IPMN). The prognosis of high-grade precancerous lesions, including high-grade PanIN and high-grade IPMN, without invasive carcinoma is good, despite the overall poor prognosis of PDAC. High-grade PanIN, as a lesion preceding invasive PDAC, is therefore a primary target for intervention. However, detection of localized high-grade PanIN is difficult when using standard radiological approaches. Therefore, most studies of high-grade PanIN have been conducted using specimens that harbor invasive PDAC. Recently, imaging characteristics of high-grade PanIN have been revealed. Obstruction of the pancreatic duct due to high-grade PanIN may induce a loss of acinar cells replaced by fibrosis and lobular parenchymal atrophy. These changes and additional inflammation around the branch pancreatic ducts (BPDs) result in main pancreatic duct (MPD) stenosis, dilation, retention cysts (BPD dilation), focal pancreatic parenchymal atrophy, and/or hypoechoic changes around the MPD. These indirect imaging findings have become important clues for localized, high-grade PanIN detection. To obtain pre-operative histopathological confirmation of suspected cases, serial pancreatic-juice aspiration cytologic examination is effective. In this review, we outline current knowledge on imaging characteristics of high-grade PanIN.

Focal Autoimmune Pancreatitis: A Simple Flow Chart for a Challenging Diagnosis

Autoimmune pancreatitis is a chronic fibroinflammatory autoimmune mediated disease of the pancreas. Clinically, obstructive painless jaundice and upper abdominal pain are the main symptoms. Focal AIP is characterized by segmental involvement of pancreatic parenchyma and it is often radiologically represented by a pancreatic mass. In these cases, the diagnosis can be very challenging, since it may be easily confused with pancreatic cancer. Therefore, we suggest a combined approach of imaging tests as the diagnostic workup. EUS study combined with CEUS and elastography, if available, increases the accuracy of the method to rule out cancer. Moreover, the lesion should always be sampled under EUS guidance to obtain a cyto/histological diagnosis. The diagnostic workup should also include the use of diagnostic clinical criteria (extrapancreatic lesions, steroid response) and laboratory findings (CA 19.9 and IgG4 evaluations).

Atypical enhanced computed tomography signs of pancreatic cancer and its differential diagnosis from autoimmune pancreatitis

Background

To analyze the atypical enhanced computed tomography (CT) signs of pancreatic cancer (PC) and compare them with those of autoimmune pancreatitis (AIP) to explore the differential diagnosis value of CT.

Methods

The clinical data of 36 AIP (AIP group) and 38 PC patients (PC group), who were admitted to our hospital from January 2013 to June 2020 and confirmed by surgical biopsy or hormone therapy, were retrospectively analyzed. Participants in both groups were examined by CT, the imaging signs of the 2 groups were analyzed, and the results of CT examination were compared.

Results

In the PC group, the density of the lesions on the CT scan was mostly reduced, the pancreas was not swollen, and the kidneys were not involved. The bile duct wall was thickened with a sausage-like appearance, enveloped edges were rare, blood vessels were invaded, lymph nodes were enlarged, and the pancreatic duct was truncated. The findings of the AIP group were the opposite. The difference in the proportion of participants with the above-mentioned CT features between the 2 groups was statistically significant (P<0.05). The shape of the lesions in the AIP group was mainly elongated, of uneven density, and the density of enhanced scanning was medium to high. The predominant shape of the lesions in PC participants was spherical, and the density was uniform. The enhanced scan was mainly low-density. The difference in shape and density between the 2 groups was also statistically significant (P<0.05). The CT values of the plain scan, intravenous phase, and delayed phase in the AIP group were significantly higher than those in the PC group (P<0.05).

Conclusions

The imaging signs of AIP and PC overlap. Examination with CT is of great value in the differential diagnosis between AIP and PC. Familiarity with and mastery of the CT signs of AIP and PC can help to improve the accuracy of clinical diagnosis and provide a reliable basis for patients' follow-up treatment.

Distinguishing pancreatic cancer and autoimmune pancreatitis with in vivo tomoelastography

OBJECTIVES

To prospectively investigate the stiffness and fluidity of pancreatic ductal adenocarcinoma (PDAC) and autoimmune pancreatitis (AIP) with tomoelastography, and to evaluate its diagnostic performance in distinguishing the two entities.

METHODS

Tomoelastography provided high-resolution maps of shear wave speed (c in m/s) and phase angle (φ in rad), allowing mechanical characterization of the stiffness and fluidity properties of the pancreas. Forty patients with untreated PDAC and 33 patients with untreated AIP who underwent diagnostic pancreatic MRI at 3-T together with multifrequency MR elastography and tomoelastography data processing were prospectively enrolled. Ten healthy volunteers served as controls. Two radiologists and a technician measured pancreatic stiffness and fluidity independently. The two radiologists also independently evaluated the patients' conventional MR sequences using the following diagnostic score: 1, definitely PDAC; 2, probably PDAC; 3, indeterminate; 4, probably AIP; and 5, definitely AIP. Interobserver agreement was assessed. Stiffness and fluidity of PDAC, AIP, and healthy pancreas, as well as diagnostic performance of tomoelastography and conventional MRI, were compared.

RESULTS

AIP showed significantly lower stiffness and fluidity than PDAC and significantly higher stiffness and fluidity than healthy pancreas. Pancreatic fluidity was not influenced by secondary obstructive changes. The intraclass correlation coefficient for pancreatic stiffness and fluidity by the 3 readers was near-perfect (0.951-0.979, all p < 0.001). Both stiffness and fluidity allowed distinguishing PDAC from AIP. AUCs were 0.906 for stiffness, 0.872 for fluidity, and 0.842 for conventional MRI.

CONCLUSIONS

Pancreatic stiffness and fluidity both allow differentiation of PDAC and AIP with high accuracy.

KEY POINTS

• AIP showed significantly lower stiffness and fluidity than PDAC and significantly higher stiffness and fluidity than healthy pancreas. • Both stiffness and fluidity allowed distinguishing PDAC from AIP. • Pancreatic fluidity could distinguish malignancy from non-malignant secondary obstructive changes.

Steroid-responsive pancreatitides

Autoimmune pancreatitis has received considerable attention, especially due to the marked effect of corticosteroid therapy on its clinical course. Knowledge, especially regarding type 1 autoimmune pancreatitis, has significantly increased over the last decades, and despite significant differences in pathophysiology and outcomes, both type 1 and 2 autoimmune pancreatitis are still considered different types of the same disease. Some have proposed a different nomenclature reflecting these differences. Although the term steroid-responsive pancreatitides may be interpreted as synonymous to type 1 and 2 autoimmune pancreatitis, these are not the only pancreatic conditions that show a response to steroid therapy. Acute pancreatitis caused by vasculitis and connective tissue diseases and acute pancreatitis secondary to checkpoint inhibitors or programmed cell death receptor antibody-mediated blockage cancer therapy may also benefit from steroid treatment. This review presents current concepts on these disorders, aiming to increase awareness, analyze similarities and differences, and propose a new nomenclature that reflects their specific particularities, clustering them under the term “steroid-responsive pancreatitides”.

Partial Pancreatic Parenchymal Atrophy Is a New Specific Finding to Diagnose Small Pancreatic Cancer (≤10 mm) Including Carcinoma in Situ: Comparison with Localized Benign Main Pancreatic Duct Stenosis Patients

BACKGROUND

This study aimed to evaluate and identify the specific CT findings by focusing on abnormalities in the main pancreatic duct (MPD) and pancreatic parenchyma in patients with small pancreatic cancer (PC) including carcinoma in situ (CIS).

METHODS

Nine CT findings indicating abnormalities of MPD and pancreatic parenchyma were selected as candidate findings for the presence of small PC ≤ 10 mm. The proportions of patients positive for each finding were compared between small PC and benign MPD stenosis groups. Interobserver agreement between two independent image reviewers was evaluated using kappa statistics.

RESULTS

The final analysis included 24 patients with small PC (including 11 CIS patients) and 28 patients with benign MPD stenosis. The proportion of patients exhibiting partial pancreatic parenchymal atrophy (PPA) corresponding to the distribution of MPD stenosis (45.8% vs. 7.1%, p < 0.01), upstream PPA arising from the site of MPD stenosis (33.3% vs. 3.6%, p = 0.01), and MPD abrupt stenosis (45.8% vs. 14.3%, p = 0.03) was significantly higher in the small PC group than in the benign MPD stenosis group.

CONCLUSIONS

The presence of partial PPA, upstream PPA, and MPD abrupt stenosis on a CT image was highly suggestive of the presence of small PCs including CIS.

Comparison of diagnostic performance between CT and MRI in differentiating non-diffuse-type autoimmune pancreatitis from pancreatic ductal adenocarcinoma

OBJECTIVES

To intraindividually compare the diagnostic performance of CT and MRI in differentiating non-diffuse-type autoimmune pancreatitis (AIP) from pancreatic ductal adenocarcinoma (PDA).

METHODS

Sixty-one patients with non-diffuse-type AIP and 122 patients with PDA, who underwent dynamic contrast-enhanced CT and MRI with MR pancreatography, were included. Two blinded radiologists independently rated their confidence in differentiating the two diseases on a 5-point scale, and the diagnostic performances of CT and MRI were compared. The presence of key imaging features to differentiate AIP and PDA were compared between CT and MRI.

RESULTS

The area under the receiver operating characteristic curve was significantly greater on MRI (0.993-0.995) than on CT (0.953-0.976) for both raters (p≤0.035). The sensitivities of MRI were higher than those of CT for the diagnosis of AIP (88.5-90.2% vs. 77-80.3%, p≤0.07) and PDA (97.5-99.2% vs. 91.8-94.3%, p≤0.031) for both raters, although the difference for AIP was statistically marginal (p=0.07) for rater 1. In AIP, multiple pancreatic masses, delayed homogeneous enhancement of the pancreatic mass, and multiple main pancreatic duct (MPD) strictures were observed significantly more frequently using MRI than CT (p≤0.008). In PDA, discrete pancreatic mass and MPD stricture were observed significantly more frequently using MRI than CT (p≤0.012).

CONCLUSIONS

The diagnostic performance of MRI is better for differentiating non-diffuse-type AIP from PDA, which is due to the superiority of MRI over CT in demonstrating the key distinguishing features of both diseases.

KEY POINTS

• Imaging differential diagnosis of non-diffuse-type AIP and PDA is challenging. • MRI has better diagnostic performance than CT in differentiating non-diffuse-type AIP from PDA. • MRI is superior to CT in demonstrating key distinguishing features of non-diffuse-type AIP and PDA.

Abdominal manifestations of IgG4-related disease: a pictorial review

In the last decade, autoimmune pancreatitis has become recognised as part of a wider spectrum of IgG4-related disease, typically associated with elevated serum IgG4 levels and demonstrating a response to corticosteroid therapy. Radiologically, there is imaging overlap with other benign and neoplastic conditions. This pictorial review discusses the intra-abdominal manifestations of this disease on cross-sectional imaging before and after steroid treatment and the main radiological features which help to distinguish it from other key differentials.

TEACHING POINTS

• Autoimmune pancreatitis is part of a spectrum of IgG4-related disease. • Diagnosis is based on raised serum IgG4, clinical, radiological and histopathological findings. • Cross-sectional imaging can demonstrate the typical findings of abdominal IgG4-related disease. • Cross-sectional imaging can be used to monitor response to corticosteroid treatment.

Focal autoimmune pancreatitis and chronic sclerosing sialadenitis mimicking pancreatic cancer and neck metastasis

Type 1 autoimmune pancreatitis (AIP) or chronic sclerosing sialadenitis (Küttner’s tumour) is an uncommon disorder that has recently been confirmed as an IgG4-related disease. Here, we describe a rare case of a 53-year-old male patient who primarily presented with pancreatic body mass, left neck mass and several lumps in his lower lip mimicking pancreatic cancer (PC) and neck metastasis. The patient underwent pancreatic body mass and labial gland lumps resection as well as an ultrasound-guided biopsy of the left neck mass. He was diagnosed with IgG4-related focal type of AIP (f-AIP) and Küttner’s tumour by immunohistochemistry. The patient responded well to corticosteroid therapy and remains healthy with no signs of recurrence at one year follow-up. The differentiation of f-AIP from PC is very important to avoid unnecessary pancreatic resection.