Advanced imaging techniques for chronic pancreatitis

Multitasking dynamic contrast enhanced magnetic resonance imaging can accurately differentiate chronic pancreatitis from pancreatic ductal adenocarcinoma

Background and aims

Accurate differentiation of chronic pancreatitis (CP) and pancreatic ductal adenocarcinoma (PDAC) is an area of unmet clinical need. In this study, a novel Multitasking dynamic contrast enhanced (DCE) magnetic resonance imaging (MRI) technique was used to quantitatively evaluate the microcirculation properties of pancreas in CP and PDAC and differentiate between them.

Methods

The Multitasking DCE technique was able to acquire one 3D image per second during the passage of MRI contrast agent, allowing the quantitative estimation of microcirculation properties of tissue, including blood flow F_p, plasma volume fraction v_p, transfer constant K^trans, and extravascular extracellular volume fraction v_e. Receiver operating characteristic (ROC) analysis was performed to differentiate the CP pancreas, PDAC pancreas, normal control pancreas, PDAC tumor, PDAC upstream, and PDAC downstream. ROCs from quantitative analysis and conventional analysis were compared.

Results

Fourteen PDAC patients, 8 CP patients and 20 healthy subjects were prospectively recruited. The combination of F_p, v_p, K^trans, and v_e can differentiate CP versus PDAC pancreas with good AUC (AUC [95% CI] = 0.821 [0.654 - 0.988]), CP versus normal pancreas with excellent AUC (1.000 [1.000 - 1.000]), PDAC pancreas versus normal pancreas with excellent AUC (1.000 [1.000 - 1.000]), CP versus PDAC tumor with excellent AUC (1.000 [1.000 - 1.000]), CP versus PDAC downstream with excellent AUC (0.917 [0.795 - 1.000]), and CP versus PDAC upstream with fair AUC (0.722 [0.465 - 0.980]). This quantitative analysis outperformed conventional analysis in differentiation of each pair.

Conclusion

Multitasking DCE MRI is a promising clinical tool that is capable of unbiased quantitative differentiation between CP from PDAC.

Black Pleural Effusion as a Complication of Acute Pancreatitis

Transient and reactive pleural effusion is a known consequence of acute pancreatitis. Usually, the pleural effusion is unilateral, transudate, straw-colored, and self-resolving. We report a rare case of massive left-sided black pleural effusion as a complication of acute pancreatitis with the background of chronic pancreatitis being secondary to alcohol abuse. The pleural effusion resulted in hypoxic respiratory failure. However, the patient had significant improvement after drainage of the pleural effusion and the appropriate management of sepsis with broad-spectrum antibiotics. The patient had a significant improvement and recovery with conservative management without the need for endoscopic therapy or surgical intervention.

T1 signal intensity ratio of the pancreas as an imaging biomarker for the staging of chronic pancreatitis

PURPOSE

Our purpose was to validate the T1 SIR (T1 score) as an imaging biomarker for the staging of CP in a large, multi-institutional, prospective study.

METHODS

The prospective study population included 820 participants enrolled in the PROCEED study from nine clinical centers between June 2017 and December 2021. A radiologist at each institution used a standardized method to measure the T1 signal intensity of the pancreas and the reference organs (spleen, paraspinal muscle, liver), which was used to derive respective T1 scores. Participants were stratified according to the seven mechanistic stages of chronic pancreatitis (MSCP 0-6) based on their clinical history, MRCP, and CT findings.

RESULTS

The mean pancreas-to-spleen T1 score was 1.30 in participants with chronic abdominal pain, 1.22 in those with acute or recurrent acute pancreatitis, and 1.03 in definite CP. After adjusting for covariates, we observed a linear, progressive decline in the pancreas-to-spleen T1 score with increasing MSCP from 0 to 6. The mean pancreas-to-spleen T1 scores were 1.34 (MSCP 0), 1.27 (MSCP 1), 1.21 (MSCP 2), 1.16 (MSCP 3), 1.18 (MSCP 4), 1.12 (MSCP 5), and 1.05 (MSCP 6) (p < 0.0001). The pancreas-to-liver and pancreas-to-muscle T1 scores showed less linear trends and wider confidence intervals.

CONCLUSION

The T1 score calculated by SIR of the pancreas-to-spleen shows a negative linear correlation with the progression of chronic pancreatitis. It holds promise as a practical imaging biomarker in evaluating disease severity in clinical research and practice.

Complications of chronic pancreatitis prior to and following surgical treatment: A proposal for classification

BACKGROUND

Chronic pancreatitis (CP) is a long-lasting disease frequently associated with complications for which there is no comprehensive pathophysiological classification.

AIM

The aims of this study were to: Propose a pathophysiological classification of the complications of CP; evaluate their prevalence in a surgical cohort prior to, and following surgical management; and assess the impact of the surgical treatment on the occurrence of new complications of CP during follow-up. We hypothesized that optimal surgical treatment can resolve existing complications and reduce the risk of new complications, with the exclusion of pancreatic insufficiency. The primary outcomes were prevalence of complications of CP at baseline (prior to surgical treatment) and occurrence of new complications during follow-up.

METHODS

After institutional review board approval, a prospective observational cohort study with long-term follow-up (up to 20.4 years) was conducted. All consecutive single-center adult patients (≥ 18 years of age) with CP according to the criteria of the American Pancreas Association subjected to surgical management between 1997 and 2021, were included. The prevalence of CP complications evaluated, according to the proposed classification, in a surgical cohort of 166 patients. Development of the pathophysiological classification was based on a literature review on the clinical presentation, course, and complications of CP, as well a review of previous classification systems of CP.

RESULTS

We distinguished four groups of complications: Pancreatic duct complications, peripancreatic complications, pancreatic hemorrhages, and pancreatic insufficiency (exocrine and endocrine). Their baseline prevalence was 20.5%, 23.5%, 10.2%, 31.3%, and 27.1%, respectively. Surgical treatment was highly effective in avoiding new complications in the first and third groups. In the group of peripancreatic complications, the 15-year Kaplan-Meier prevalence of new complications was 12.1%. The prevalence of pancreatic exocrine and endocrine insufficiency increased during follow-up, being 66.4% and 47.1%, respectively, at 15 years following surgery. Pancreatoduodenal resection resulted optimal results in avoiding new peripancreatic complications, but was associated with the highest rate of pancreatic exocrine insufficiency.

CONCLUSION

The proposed complication classification improves the understanding of CP. It could be beneficial for clinical decision making, as it provides an opportunity for more comprehensive judgement on patient’s needs on the one hand, and on the pros and cons of the treatment under consideration, on the other. The presence of complications of CP and the risk of development of new ones should be among the main determinants of surgical choice.

Radiomics and Its Applications and Progress in Pancreatitis: A Current State of the Art Review

Radiomics involves high-throughput extraction and analysis of quantitative information from medical images. Since it was proposed in 2012, there are some publications on the application of radiomics for (1) predicting recurrent acute pancreatitis (RAP), clinical severity of acute pancreatitis (AP), and extrapancreatic necrosis in AP; (2) differentiating mass-forming chronic pancreatitis (MFCP) from pancreatic ductal adenocarcinoma (PDAC), focal autoimmune pancreatitis (AIP) from PDAC, and functional abdominal pain (functional gastrointestinal diseases) from RAP and chronic pancreatitis (CP); and (3) identifying CP and normal pancreas, and CP risk factors and complications. In this review, we aim to systematically summarize the applications and progress of radiomics in pancreatitis and it associated situations, so as to provide reference for related research.

Histopathologic correlation of pancreatic fibrosis with pancreatic magnetic resonance imaging quantitative metrics and Cambridge classification

PURPOSE

To determine the correlation of the T1-weighted signal intensity ratio (T1 SIR, or T1 Score) and arterial-to-delayed venous enhancement ratio (ADV ratio) of the pancreas with pancreatic fibrosis on histopathology.

METHODS

Sixty consecutive adult CP patients who had an MRI/MRCP study prior to pancreatic surgery were analyzed. Three blinded observers measured T1 SIR of pancreas to spleen (T1 SIR p/s), pancreas-to-paraspinal muscle (T1 SIR p/m), ADV ratio, and Cambridge grade. Histopathologic grades were given by a gastrointestinal pathologist using Ammann's fibrosis score. Statistical analysis included Spearman's correlation coefficient of the T1 SIR, ADV ratio, Cambridge grade with the fibrosis score, and weighted kappa for interobserver agreement.

RESULTS

The study population included 31 female and 29 male patients, with an average age of 52.1 (26-78 years). Correlations between fibrosis score and T1 SIR p/s, T1 SIR p/m, and ADV ratio were ρ = - 0.54 (p = 0.0001), ρ = - 0.19 (p = 0.19), and ρ = - 0.39 (p = 0.003), respectively. The correlation of Cambridge grade with fibrosis score was ρ = 0.26 (p = 0.07). There was substantial interobserver agreement (weighted kappa) for T1 SIR p/s (0.78), T1 SIR p/m (0.71), and ADV ratio (0.64). T1 SIR p/s of ≤ 1.20 provided a sensitivity of 74% and specificity of 50% (AUC: 0.74), while ADV ratio of ≤ 1.10 provided a sensitivity of 75% and specificity of 55% (AUC: 0.68) to detect a fibrosis score of ≥ 6.

CONCLUSION

There is a moderate negative correlation between the T1 Score (SIR p/s) and ADV ratio with pancreatic fibrosis and a substantial interobserver agreement. These parenchymal metrics show a higher correlation than the Cambridge grade.

T1 relaxation times and MR elastography-derived stiffness: new potential imaging biomarkers for the assessment of chronic pancreatitis

PURPOSE

Non-invasive imaging methods to detect morphological changes of the pancreas in patients with mild chronic pancreatitis (CP) are needed. This study aimed to compare magnetic resonance imaging-based parameters, pancreatic volume, T1 mapping, magnetic resonance elastography (MRE), and proton density fat fraction between CP patients and controls, and determine the diagnostic performance for diagnosing different stages of CP.

METHODS

Nineteen patients with mild CP (Cambridge grade 2 or less or recurring acute pancreatitis; n = 19), 30 with moderate/severe CP (Cambridge grade 3 and 4), and 35 healthy controls underwent pancreatic magnetic resonance imaging to assess the above mentioned magnetic resonance imaging-based parameters. The diagnostic performance of each parameter for detecting any mild and moderate/severe CP was determined using receiver operating characteristic analysis.

RESULTS

Pancreatic volume, T1 relaxation times, MRE-derived stiffness, and proton density fat fraction differed significantly between patients with mild CP, moderate/severe CP, and healthy controls (all p < 0.05). T1 mapping and MRE showed a very high diagnostic performance for distinguishing the mild CP group from the control group (T1 mapping: receiver operating characteristic area under the curve (ROC-AUC): 0.94; sensitivity: 84%; specificity: 91%, MRE: ROC-AUC: 0.93; sensitivity: 89%; specificity: 94%). T1 mapping and MRE also had the highest performance for diagnosing the presence of any CP from the control group (ROC-AUCs of 0.98 and 0.97, respectively).

CONCLUSION

Quantitative assessments of T1 relaxation time and MRE-derived stiffness had high performance in detecting mild CP and could probably reflect the early fibrotic changes in CP.

Role of standardized reporting and novel imaging markers in chronic pancreatitis

PURPOSE OF REVIEW

This article reviews recent efforts about standardized imaging features and reporting of chronic pancreatitis and recently published or ongoing imaging studies, which aim to establish novel imaging biomarkers for detection of parenchymal changes seen in chronic pancreatitis.

RECENT FINDINGS

New novel MRI techniques are being developed to increase the diagnostic yield of chronic pancreatitis specifically in the early stage. T1 relaxation time, T1 signal intensity ratio and extracellular volume fraction offer potential advantages over conventional cross-sectional imaging, including simplicity of analysis and more objective interpretation of observations allowing population-based comparisons. In addition, standardized definitions and reporting guidelines for chronic pancreatitis based on available evidence and expert consensus have been proposed. These new imaging biomarkers and reporting guidelines are being validated for prognostic/therapeutic assessment of adult patients participating in longitudinal studies of The Consortium for the Study of Chronic Pancreatitis, Diabetes and Pancreatic Cancer.

SUMMARY

New imaging biomarkers derived from novel MRI sequences promise a new chapter for diagnosis and severity assessment of chronic pancreatitis; a cross-sectional imaging-based diagnostic criteria for chronic pancreatitis combining ductal and parenchymal findings. Standardized imaging findings and reporting guidelines of chronic pancreatitis would enhance longitudinal assessment of disease severity in clinical trials and improve communication between radiologists and pancreatologists in clinical practice.

Pancreatic cystic neoplasms and post-inflammatory cysts: interobserver agreement and diagnostic performance of MRI with MRCP

PURPOSE

We aimed to answer several clinically relevant questions; (1) the interobserver agreement, (2) diagnostic performance of MRI with MRCP for (a) branch duct intraductal papillary mucinous neoplasms (BD-IPMN), mucinous cystic neoplasms (MCN) and serous cystic neoplasms (SCN), (b) distinguishing mucinous (BD-IPMN and MCN) from non-mucinous cysts, and (c) distinguishing three pancreatic cystic neoplasms (PCN) from post-inflammatory cysts (PIC).

METHODS

A retrospective analysis was performed at a tertiary referral center for pancreatic diseases on 71 patients including 44 PCNs and 27 PICs. All PCNs were confirmed by surgical pathology to be 17 BD-IPMNs, 13 MCNs, and 14 SCNs. Main duct and mixed type IPMNs were excluded. Two experienced abdominal radiologists blindly reviewed all the images.

RESULTS

Sensitivity of two radiologists for BD-IPMN, MCN and SCN was 88-94%, 62-69% and 57-64%, specificity of 67-78%, 67-78% and 67-78%, and accuracy of 77-82%, 65-75% and 63-73%, respectively. There was 80% sensitivity, 63-73% specificity, 70-76% accuracy for distinguishing mucinous from non-mucinous neoplasms, and 73-75% sensitivity, 67-78% specificity, 70-76% accuracy for distinguishing all PCNs from PICs. There was moderate-to-substantial interobserver agreement (Cohen's kappa: 0.65).

CONCLUSION

Two experienced abdominal radiologists had moderate-to-high sensitivity, specificity, and accuracy for BD-IPMN, MCN, and SCN. The interobserver agreement was moderate-to-substantial. MRI with MRCP can help workup of incidental pancreatic cysts by distinguishing PCNs from PICs, and premalignant mucinous neoplasms from cysts with no malignant potential.

Comprehensive review of diagnostic modalities for early chronic pancreatitis

Chronic pancreatitis (CP) is a progressive condition caused by several factors and characterised by pancreatic fibrosis and dysfunction. However, CP is difficult to diagnose at an early stage. Various advanced methods including endoscopic ultrasound based elastography and confocal laser endomicroscopy have been used to diagnose early CP, although no unified diagnostic standards have been established. In the past, the diagnosis was mainly based on imaging, and no comprehensive evaluations were performed. This review describes and compares the advantages and limitations of the traditional and latest diagnostic modalities and suggests guidelines for the standardisation of the methods used to diagnose early CP.

Pancreatic atrophy and exocrine insufficiency associate with the presence of diabetes in chronic pancreatitis patients, but additional mediators are operative

OBJECTIVES

Diabetes mellitus is a frequent complication of chronic pancreatitis (CP) and has traditionally been considered to develop as a consequence of pancreatic islet cell loss. However, additional mechanisms may be operative including accumulation of pancreatic fat and fibrosis. We used advanced magnetic resonance imaging (MRI) to study pancreatic morphology and exocrine function in a reference population and in CP patients with and without diabetes.

METHODS

This was a cross-sectional mono centre study. All subjects underwent advanced MRI including assessment of pancreatic ductal parameters (Cambridge classification and main pancreatic duct diameter), parenchymal parameters (DIXON technique and diffusion weighted imaging as proxies for pancreatic fat content and fibrosis, as well as pancreatic volume segmentation). Pancreatic exocrine function was determined as duodenal secretion following secretin stimulation and by the faecal elastase test.

RESULTS

The study included 76 patients with definite CP of whom 23 (30.1%) had diabetes and 23 sex- and age matched healthy volunteers. Compared to their non-diabetic counterparts, diabetic patients were characterised by a low pancreatic volume (20 vs. 36 ml; p = .02) and impaired pancreatic exocrine function (faecal elastase 19 vs. 48 µg/g; p = .008), while no difference between patients with and without diabetes were seen in relation to MRI derived proxies for fibrosis and pancreatic fat accumulation and pancreatic duct parameters. A large proportion of non-diabetic patients (49%) had similar morphological and functional characteristics as patients with diabetes.

CONCLUSION

Pancreatic atrophy and exocrine insufficiency are present in most CP patients with diabetes, but additional mediators seem to be operative in post pancreatitis diabetes mellitus.

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.

Coexistence of alcohol-related pancreatitis and alcohol-related liver disease: A systematic review and meta-analysis

BACKGROUND

Available estimates of coexistent alcohol-related pancreatitis (ALP) and alcohol-related liver disease (ALD) vary widely, and factors that determine coexistent disease are largely unknown. We performed a systematic review of published literature with the primary aim to generate robust estimates for coexistent alcohol-related chronic pancreatitis (ACP) and alcohol-related cirrhosis (ALC).

METHODS

We searched PubMed, EMBASE, and Web of Science databases from inception until February 2018. Studies included were those in English-language, sample size ≥25 and allowed calculation of the coexistent disease. Pooled estimates were calculated using a random-effects model approach.

RESULTS

Twenty-nine (including 5 autopsy studies) of 2000 eligible studies met inclusion criteria. Only 6.9% included patients were female. Fifteen studies enabled calculation of ACP in ALC, and 11 for ALC in ACP. Pooled prevalence of ACP in ALC was 16.2% (95% CI 10.4-24.5) overall, and 15.5% (95% CI 8.0-27.7) when data were limited to clinical studies. Corresponding prevalence for ALC in ACP was 21.5% (95% CI 12.0-35.6) and 16.9% (95% CI 11.5-24.3), respectively. There was significant heterogeneity among studies (I² - 65-92%). Pooled prevalence for ALP in ALD or ALD in ALP in clinical studies were 15.2% and 39%, respectively. None of the studies reported outcomes in patients with coexistent disease.

CONCLUSION

A sizeable fraction of patients with ACP or ALC have coexistent disease. Future studies should define the prevalence of coexistent disease in women and minority populations, and the consequences of coexistent disease on clinical presentation and short- and long-term outcomes.

Advanced MR Imaging of the Pancreas

MR imaging can be optimized to evaluate a spectrum of pancreatic disorders with advanced sequences aimed to provide quantitative results and increase MR diagnostic capabilities. The pancreas remains a challenging organ to image because of its small size and location deep within the body. Besides its anatomic limitations, pancreatic pathology can be difficult to identify in the early stages. For example, subtle changes in ductal anatomy and parenchymal composition seen in early chronic pancreatitis are imperceptible with other modalities, such as computed tomography. This article reviews the application of MR imaging techniques and emerging MR sequences used in pancreas imaging.

Pancreatic magnetic resonance imaging texture analysis in chronic pancreatitis: a feasibility and validation study

PURPOSE

This feasibility and validation study addresses the potential use of magnetic resonance imaging (MRI) texture analysis of the pancreas in patients with chronic pancreatitis (CP).

METHODS

Extraction of 851 MRI texture features from diffusion weighted imaging (DWI) of the pancreas was performed in 77 CP patients and 22 healthy controls. Features were reduced to classify patients into subgroups, and a Bayes classifier was trained using a tenfold cross-validation forward selection procedure. The classifier was optimized to obtain the best average m-fold accuracy, sensitivity, specificity, and positive predictive value. Classifiers were: presence of disease (CP vs. healthy controls), etiological risk factors (alcoholic vs. nonalcoholic etiology of CP and tobacco use vs. no tobacco use), and complications to CP (presumed pancreatogenic diabetes vs. no diabetes and pancreatic exocrine insufficiency vs. normal pancreatic function).

RESULTS

The best classification performance was obtained for the disease classifier selecting only five of the original features with 98% accuracy, 97% sensitivity, 100% specificity, and 100% positive predictive value. The risk factor classifiers obtained good performance using 9 (alcohol: 88% accuracy) and 10 features (tobacco: 86% accuracy). The two complication classifiers obtained similar accuracies with only 4 (diabetes: 83% accuracy) and 3 features (exocrine pancreatic function: 82% accuracy).

CONCLUSION

Pancreatic texture analysis demonstrated to be feasible in patients with CP and discriminate clinically relevant subgroups based on etiological risk factors and complications. In future studies, the method may provide useful information on disease progression (monitoring) and detection of biomarkers characterizing early-stage CP.

Progression of parenchymal and ductal findings in patients with chronic pancreatitis: A 4-year follow-up MRI study

PURPOSE

Knowledge of the underlying mechanisms behind progression of chronic pancreatitis (CP) is needed to identify targets for new mechanism-based treatments. There is an urgent need for imaging biomarkers that can detect early morphological and functional pancreatic damage in order to initiate intervention and reduce the progression of CP at an early stage. The aim of our study was to assess and explore the potential role of structural magnetic resonance imaging (MRI) biomarkers for characterisation of disease progression in a CP patient cohort over a 4-year period.

METHODS

This longitudinal MRI study included twenty-five patients with definitive CP. Assessments of morphological imaging parameters at baseline and after 4 years included pancreatic gland volume, apparent diffusion coefficient (ADC) values, fat signal fraction (FSF) and main pancreatic duct (MPD) diameter. Patients were classified according to the modified Cambridge classification.

RESULTS

CP patients developed significantly reduced pancreatic gland volume, which decreased from mean 50.3 ± 19.6 ml at baseline to 43.5 ± 20.8 ml at follow-up (P < 0.001), decreased ADC values, meaning a higher degree of fibrosis (P < 0.001), increased FSF, meaning more fat infiltration (P < 0.001) and higher Cambridge classification scores (P = 0.033). The MPD diameter in the pancreatic head, body and tail did not change significantly over time (all P > 0.05). Only few, but no clear and systematic, associations were found between the progressions of the individual MRI measures.

CONCLUSIONS

Morphological progression in patients with established CP seems to be primarily parenchymal-related. The different parenchymal changes were mostly unrelated and probably reflect diverse pathophysiological processes.