Quantitative evaluation of pancreatic tumor fibrosis using shear wave elastography

Point-shear wave elastography generated by acoustic radiation force impulse in chronic pancreatitis

BACKGROUND

Transcutaneous point-shear wave elastography (p-SWE) performed using an acoustic radiation force impulse can be used to quantify pancreatic stiffness in chronic pancreatitis (CP). We aimed to evaluate its usefulness to diagnose and monitor CP.

METHODS

175 participants were included in this prospective study including patients with CP (n = 65), liver cirrhosis (LC; n = 60), alcohol abuse (n = 10) and healthy controls (n = 40). Point-shear wave elastography of the pancreas was performed and quantified as median shear wave velocity (SWV). In the same way, p-SWE of the spleen served as a marker of portal hypertension. The M-ANNHEIM Severity score was used as global marker for disease activity in CP.

RESULTS

Compared to healthy controls, pancreatic SWV was significantly elevated in CP (1.38 vs. 0.96 m/s; p < 0.0001, MWU-test). Pancreatic SWV was increased in alcoholic CP but not in hereditary CP. Receiver operating characteristic analysis revealed 1.2 m/s as the optimal cut-off to identify non-heredity-CP subjects (90% specificity; 81% sensitivity; 92% positive predictive value). Pancreatic SWV correlated significantly with the M-ANNHEIM Severity score, severity of CP-typical complications (both p < 0.05, linear regression analysis), morphological changes of the pancreas and need for hospital treatment (both p < 0.05, MWU-test) but not with exocrine or endocrine insufficiency. Pancreatic SWV >1.7 m/s was identified to predict M-ANNHEIM Severity score ≥11 points. Pancreatic SWV was also elevated in LC (1.42 m/s; p < 0.001), correlating with increased splenic SWV.

CONCLUSION

Transcutaneous pancreatic p-SWE represents a bedside, cost-effective and non-invasive tool which adds valuable information to the process of diagnosing and monitoring CP. By portal hypertension, an increased pancreatic SWV must be expected.

Contrast-enhanced ultrasound (CEUS) and shear wave elastography (SWE) features for characterizing serous microcystic adenomas (SMAs): In comparison to pancreatic neuroendocrine tumors (pNETs)

Objectives

Serous microcystic adenoma (SMA), a primary benign pancreatic tumor which can be clinically followed-up instead of undergoing surgery, are sometimes mis-distinguished as pancreatic neuroendocrine tumor (pNET) in regular preoperative imaging examinations. This study aimed to analyze preoperative contrast-enhanced ultrasound (CEUS) and shear wave elastography (SWE) features of SMAs in comparison to pNETs.

Material and methods

In this retrospective study, patients with imaging-diagnosed pancreatic lesions were screened between October 2020 to October 2022 (ethical approval No. B2020-309R). Performing by a Siemens Sequoia (Siemens Medical Solutions, Mountain View, CA, USA) equipped with a 5C-1 curved array transducer (3.0-4.5 MHz), CEUS examination was conducted to observe the microvascular perfusion patterns of pancreatic lesions in arterial phase, venous/late phases (VLP) using SonoVue® (Bracco Imaging Spa, Milan, Italy) as the contrast agent. Virtual touch tissue imaging and quantification (VTIQ) - SWE was used to measure the shear wave velocity (SWV, m/s) value to represent the quantitative stiffness of pancreatic lesions. Multivariate logistic regression was performed to analyze potential ultrasound and clinical features in discriminating SMAs and pNETs.

Results

Finally, 30 SMA and 40 pNET patients were included. All pancreatic lesions were pathologically proven via biopsy or surgery. During the arterial phase of CEUS, most SMAs and pNETs showed iso- or hyperenhancement (29/30, 97 % and 31/40, 78 %), with a specific early honeycomb enhancement pattern appeared in 14/30 (47 %) SMA lesions. During the VLP, while most of the SMA lesions remained iso- or hyperenhancement (25/30, 83 %), nearly half of the pNET lesions revealed an attenuated hypoenhancement (17/40, 43 %). The proportion of hypoenhancement pattern during the VLP of CEUS differed significantly between SMAs and pNETs (P = 0.021). The measured SWV value of SMAs was significantly higher than pNETs (2.04 ± 0.70 m/s versus 1.42 ± 0.44 m/s, P = 0.002). Taking a SWV value > 1.83 m/s as a cutoff in differentiating SMAs and pNETs, the area under the receiver operating characteristic curve (AUROC) was 0.825, with sensitivity, specificity and likelihood ratio (+) of 85.71 %, 72.73 % and 3.143, respectively. Multivariate logistic regression revealed that SWV value (m/s) of the pancreatic lesion was an independent variable in discriminating SMA and pNET.

Conclusion

By comprehensively evaluating CEUS patterns and SWE features, SMA and pNET may be well differentiated before the operation. While SMA typically presents as harder lesion in VTIQ-SWE, exhibiting a specific honeycomb hyperenhancement pattern during the arterial phase of CEUS, pNET is characterized by relative softness, occasionally displaying a wash-out pattern during the VLP of CEUS.

Application of ultrasound shear wave elastography in pre-operative and quantitative prediction of clinically relevant post-operative pancreatic fistula after pancreatectomy: a prospective study for the investigation of risk evaluation model

OBJECTIVES

The aim of this study was to modify recognized clinically relevant post-operative pancreatic fistula (CR-POPF) risk evaluation models with quantitative ultrasound shear wave elastography (SWE) values and identified clinical parameters to improve the objectivity and reliability of the prediction.

METHODS

Two prospective, successive cohorts were initially designed for the establishment of CR-POPF risk evaluation model and the internal validation. Patients who scheduled to receive pancreatectomy were enrolled. Virtual touch tissue imaging and quantification (VTIQ)-SWE was used to quantify pancreatic stiffness. CR-POPF was diagnosed according to 2016 International Study Group of Pancreatic Fistula standard. Recognized peri-operative risk factors of CR-POPF were analyzed, and the independent variables selected from multivariate logistic regression were used to build the prediction model.

RESULTS

Finally, the CR-POPF risk evaluation model was built in a group of 143 patients (cohort 1). CR-POPF occurred in 52/143 (36%) patients. Constructed from SWE values and other identified clinical parameters, the model achieved an area under the receiver operating characteristic curve of 0.866, with sensitivity, specificity, and likelihood ratio of 71.2%, 80.2%, and 3.597 in predicting CR-POPF. Decision curve of modified model revealed a better clinical benefit compared to the previous clinical prediction models. The models were then examined via internal validation in a separate collection of 72 patients (cohort 2).

CONCLUSIONS

Risk evaluation model based on SWE and clinical parameters is a potential non-invasive way to pre-operatively, objectively predict CR-POPF after pancreatectomy.

CLINICAL RELEVANCE STATEMENT

Our modified model based on ultrasound shear wave elastography may provide an easy access in pre-operative and quantitative evaluating the risk of CR-POPF following pancreatectomy and improve the objectivity and reliability of the prediction compared to previous clinical models.

KEY POINTS

• Modified prediction model based on ultrasound shear wave elastography (SWE) provides an easy access for clinicians to pre-operatively, objectively evaluate the risk of clinically relevant post-operative pancreatic fistula (CR-POPF) following pancreatectomy. • Prospective study with validation showed that the modified model provides better diagnostic efficacy and clinical benefits compared to previous clinical models in predicting CR-POPF. • Peri-operative management of CR-POPF high-risk patients becomes more possible.

The Role of Transabdominal Ultrasound Elastography in Gastrointestinal Non-Liver Diseases: Current Application and Future Prospectives

Ultrasound imaging is the first-line investigation for patients with abdominal symptoms, as it effectively depicts the gastrointestinal tract and enables the diagnosis of multiple pathological conditions. Among different recent ultrasound technological advancements, elastography enables the evaluation of various tissue characteristics, such as neoplastic transformation or fibroinflammatory status. In recent years, ultrasound elastography has been utilized extensively for the study of liver diseases and in numerous other clinical settings, including gastrointestinal diseases. Current guidelines suggest the use of transabdominal ultrasound elastography to characterize bowel wall lesions, to assess gastrointestinal contractility, to diagnose and grade chronic pancreatitis; however, no specific indications are provided. In the present paper, we summarize the evidence concerning the application of different ultrasound elastography modalities in gastrointestinal non-liver diseases.

Evaluation of Tumor Fibrosis in Pancreatic Ductal Adenocarcinoma by 2-D Shear Wave Elastography: A Pilot Study

OBJECTIVE

The aim of the work described here was to investigate the association of the stromal proportion with the elasticity obtained by 2-D shear wave elastography (SWE) and the diagnostic value of elasticity in evaluating tumor stromal fibrosis in pancreatic ductal adenocarcinoma (PDAC).

METHODS

Patients who met inclusion criteria underwent pre-operative 2-D SWE examination and intra-operative determination of hardness by palpation from July 2021 to November 2022, and the post-operative specimens were used to evaluate pathological features including the tumor stromal proportion. A receiver operating characteristic curve was created to evaluate its diagnostic value in differentiating the degree of tumor stromal fibrosis.

RESULTS

The 2-D SWE measurements in pancreatic lesions were successful in 62 of 69 patients (89.9%). A total of 52 eligible participants were enrolled for subsequent correlation analysis. Elasticity correlated well with tumor stromal proportion (r_s = 0.646) and number of tumor cells (r_s = -0.585) in PDAC. Moreover, pancreatic elasticity determined by 2-D SWE, palpation-determined hardness and tumor stromal proportion were well correlated with each other. Two-dimensional SWE could clearly distinguish mild and severe stromal fibrosis, and its diagnostic performance was better than that determined by palpation even though the difference was not statistically significant (p = 0.103).

CONCLUSION

The elasticity of PDAC obtained using 2-D SWE was closely related to stromal proportion and tumor cellularity and could clearly be used to diagnose the degree of stromal fibrosis, which indicates that 2-D SWE can be a non-invasive predictive imaging biomarker in personalization of therapy and monitoring of treatment.

Endoscopic Ultrasound Guided Shear Wave Elastography Is Safe With High Feasibility and Reproducibility When Used in the Pancreas: Findings From a Prospective Cohort

OBJECTIVES

The aim of this study was to assess the safety, feasibility, and reproducibility of endoscopic ultrasound shear wave elastography (EUS-SWE) in the pancreas.

METHODS

This is a prospective registry of consecutive patients undergoing clinically indicated EUS. Ten readings of SWE velocities (Vs [distance/time, m/s]) were obtained in the head (HOP), body, and tail of pancreas to quantify tissue stiffness. Each Vs score was accompanied by a reliability measurement VsN (%) with VsN >50% considered reliable. Safety was evaluated by perioperative complications rate. Feasibility was determined by technical success of obtaining measurements. Reproducibility was evaluated using intraclass correlation coefficient analysis.

RESULTS

Total of 3320 EUS-SWE measurements were performed on 117 patients without perioperative complications. Measurement success rate was 100% across all locations. Reliable measurements were more common in the HOP (953/1120 [85.1%]) followed by body (853/1130 [75.5%]) and tail of pancreas (687/1070 [64.2%]) (P < 0.001). The analysis showed good reproducibility in all locations (intraclass correlation coefficient range, 0.80-0.89).

CONCLUSIONS

Endoscopic ultrasound-SWE is safe, has 100% technical success rate, and is highly reproducible when used in the pancreas. Our study suggests that SWE measurements in the HOP offer the highest reliability, likely because of large study area and less respiratory artifact.

Fibrosis in Liver and Pancreas: a Review on Pathogenic Significance, Diagnostic Options, and Current Management Strategies

Inflammation is one of the most natural ways of the body's biological response against invading foreign pathogens or injured cells which eventually can lead to a chronic or acute productive response. Fibrosis is an end-stage event associated with an inflammatory response addressed with tissue hardening, discoloration, and most importantly overgrowth of associated tissue. Various organs at different diseased conditions are affected by fibrosis including the liver, pancreas, brain, kidney, and lung. Etiological factors including internal like inflammatory cytokines, growth factors, and oxidative stress and external like alcohol and viruses contribute to the development of fibrosis in both the liver and pancreas. More frequently, these organs are associated with pathogenic progression towards fibrosis from acute and chronic conditions and eventually fail in their functions. The pathogenesis of the organ-fibrotic events mainly depends on the activation of residential stellate cells; these cells help to accumulate collagen in respective organs. Various diagnostic options have been developed recently, and various therapeutic options are in trial to tackle fibrosis. In this review, an overview on fibrosis, the pathogenesis of fibrosis in the liver and pancreas, various diagnostic options developed in recent years, and possible present therapeutic measures to overcome options of fibrosis in the liver and pancreas; thus, restoring the functional status of organs is discussed.

Two-dimensional shear wave elastography of the pancreas: measurement success rate, repeatability, and factors affecting measurement values

PURPOSE

We aimed to evaluate the success rate, repeatability, and factors affecting the measurement values of two-dimensional ultrasonic shear wave elastography (2D-SWE) for measuring pancreatic stiffness.

METHODS

This prospective study recruited 100 healthy participants. 2D-SWE was performed on the pancreatic head, body, and tail. We compared the success rates of pancreatic stiffness measurements of different body positions and ultrasonic scans, with and without probe pressurization, as well as the effects of sex, age, body mass index (BMI), and region of interest (ROI) depth on measurement values. Intra- and inter-operator repeatabilities were assessed in 20 participants. The influence of ROI depth was verified using a tissue-like phantom.

RESULTS

The median 2D-SWE measurements of the pancreatic head, body, and tail were 1.44, 1.45, and 1.56 m/s, respectively. The success rates for the pancreatic head and body were significantly higher than that of the tail. The success rate for the semi-recumbent position was higher than that of the supine position (P < 0.001). The intra-operator values for same-day and inter-operator reliability were excellent. Univariate analyses showed that probe pressurization, age, BMI, and ROI depth were correlated with pancreatic shear wave velocity (SWV) (P < 0.05); only ROI depth had a significant effect on SWV values. The inclusion phantom showed that the SWV value increased as the ROI depth increased.

CONCLUSIONS

2D-SWE had a high success rate and good repeatability for measuring pancreatic head and body stiffness. The ROI depth was the main factor affecting pancreatic SWV, which increased with ROI depth.

Evaluation of the Elasticity of the Pancreas Using Acoustic Radiation Force Impulse Elastography in Patients with Acute Pancreatitis: A Systematic Review and Meta-Analysis

Acoustic radiation force impulse (ARFI) elastography has been used to diagnose acute pancreatitis (AP). The present study aimed to assess the effectiveness of ARFI elastography in the diagnosis of AP. Studies examining the efficacy of ARFI elastography in AP were selected by searching MEDLINE, EMBASE, CENTRAL, ICTRP, and ClinicalTrial.gov. until September 2021. Meta-analyses were performed using random effects models. The Grading of Recommendations, Assessment, Development, and Evaluation approach was used to assess the certainty of the evidence. Eight case-control studies (994 patients) were included in the meta-analysis. The ARFI-Virtual Touch Quantification value (or ARFI shear wave propagation velocity) of the AP patient group was 0.83 m/s higher (95% confidence interval [CI]: 0.36-1.3) than that in the control group (95% CI: 1.0-1.28). The sensitivity and specificity of ARFI elastography for diagnosing AP were 98.3% (95% CI: 92.6-96.6%) and 95.5% (95% CI: 87.5-98.5%), respectively. The results showed that physicians could use ARFI elastography to accurately diagnose patients with AP. Additional well-designed studies are necessary to validate the efficacy of ARFI elastography in patients with AP.

Transabdominal ultrasonographic diagnosis of relatively rare pancreatic neoplasms

There are various types of pancreatic neoplasms, and their prognosis and treatment methods are different. Therefore, accurate diagnosis is important to determine the best treatment strategy. Transabdominal ultrasonography is frequently used as a screening examination for diagnostic imaging of pancreatic neoplasms. In this review, we have focused on the characteristics of ultrasonic findings for relatively rare pancreatic neoplasms.

Validation of a three-dimensional printed dry lab pancreaticojejunostomy model in surgical assessment: a cross-sectional study

OBJECTIVES

Until now, there have been few tools to evaluate whether a surgeon was technically ready to perform a safe pancreaticojejunostomy (PJ). In the current study, we aimed to evaluate whether a three-dimensional model could mimic a real surgical situation and distinguish between surgeons of different levels of experiences.

DESIGN

A three-dimensional PJ dry laboratory model was printed. Eight experienced pancreatic surgeons were tasked to evaluate the appearance and tactile sensation of the model. Proficiency was scored based on 15 surgeons with various levels of pancreatic experience performing a PJ on the three-dimensional model. Additionally, the time of manipulation and NASA Task Load Index (NASA-TLX) scores were recorded for each operation.

SETTING

Our study was conducted in multimedical centre in China.

RESULTS

Compared with real surgical situations, this model had similar appearance (3.96±0.55 out of five points) and tactile sensation (3.85±0.46 out of five points) according to the expert evaluation. Additionally, the chief surgeon group scored the best in proficiency (based on NASA-TLX scores and operative time), and there were statistical differences for performances among surgeons of various levels (p<0.05).

CONCLUSION

The three-dimensional PJ model could mimic a real surgical situation and can distinguish between surgeons of different levels of experiences.

Evaluation of ulcerative colitis activity using transabdominal ultrasound shear wave elastography

BACKGROUND

Transabdominal ultrasound (US) has been reported to be effective in the evaluation of ulcerative colitis (UC). US can measure shear wave elastography (SWE) and shear wave dispersion (SWD), which may be correlated with inflammation and necrosis. We aimed to investigate the relationship between UC activity and SWE and SWD.

METHODS

Patients with UC who underwent US within 2 days before or after a colonoscopy between April 2019 and March 2020 were included. SWE and SWD were measured in the sigmoid colon; the correlations of SWE and SWD with the Lichtiger index and the Ulcerative Colitis Endoscopic Index of Severity (UCEIS) were investigated. We also compared SWE and SWD between patients with mucosal healing and those in the active phase according to the UCEIS.

RESULTS

Twenty-six UC patients were enrolled. The median Lichtiger index, UCEIS, SWE values, and SWD values were 8 [interquartile range (IQR), 5.3-10.8], 4 (IQR, 3.3-5), 1.69 (IQR, 1.49-2.16) m/s, and 11.9 (IQR, 10.9-13.3) (m/s)/kHz, respectively. The Lichtiger index and UCEIS were negatively correlated with the SWE values (rs=-0.404 and rs=-0.506) but not with the SWD values (rs=0.004 and rs=0.002). The SWE values differed significantly between the mucosal healing and active phase groups [2.40 (IQR, 2.18-3.38) vs. 1.62 (IQR, 1.44-1.95) m/s, P=0.007], whereas the SWD values did not [13.1 (IQR, 7.05-21.6) vs. 11.9 (IQR, 11.1-13.2) (m/s)/kHz, P=0.918].

CONCLUSIONS

SWE may be useful for the evaluation of UC activity and could be a noninvasive method of assessing disease severity.

Current status of the diagnosis of chronic pancreatitis by ultrasonographic elastography

Chronic pancreatitis (CP) is pathologically characterized by the loss of exocrine pancreatic parenchyma, irregular fibrosis, cellular infiltration, and ductal abnormalities. Diagnosing CP objectively is difficult because standard diagnostic criteria are insufficient. The change of parenchymal hardness is the key factor for the diagnosis and understanding of the severity of CP. The ultrasonography (US) or endoscopic ultrasonography (EUS) elastography have been used to diagnose pancreatic diseases. Both strain elastography (SE) and shear wave elastography are specific diagnostic techniques for measuring tissue hardness. Most previous studies were conducted with SE. There are three methods of interpreting SE; the method of recognizing the patterns in SE distribution images in the region of interest, the method of using strain ratio to compare the hardness of adipose tissue or connective tissue with that of the lesion, and the method of evaluating the hardness distribution of a target by histogram analysis. These former two methods have been used primarily for neoplastic diseases, and histograms analysis has been used to assess hardness distribution in the evaluation of CP. Since the hardness of the pancreas increases with aging, it is necessary to consider the age in the diagnosis of pancreatic disorders using US or EUS elastography.

Prediction of pancreatic fistula after pancreatectomy by virtual touch tissue imaging and quantification (VTIQ) technology

OBJECTIVES

The aim of this study was to quantitatively evaluate the stiffness of pancreatic parenchyma and solid focal pancreatic lesions (FPLs) by virtual touch tissue imaging and quantification (VTIQ) technique and to investigate the potential usefulness of VTIQ method in the prediction of post-operative pancreatic fistula (POPF) after pancreatectomy.

METHODS

In this prospective study, patients who scheduled to undergo pancreatectomy were initially enrolled and received VTIQ assessment within one week before surgery. VTIQ elastography (Siemens ACUSON Sequoia, 5C-1 transducer) was used to measure the shear wave velocity (SWV) value of FPLs and the body part pancreatic parenchyma. The palpation stiffness of pancreas was qualitatively evaluated during operation by surgeons. POPF was finally diagnosed and graded through a three-weeks post-operative follow-up according to international study group of pancreatic fistula (ISGPF). SWV values were compared between POPF positive and negative group. Receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic efficacy of SWV value in predicting POPF.

RESULTS

From December 2020 to June 2021, 44 patients were finally enrolled in this study, among which, 26 patients were identified to develop POPF after pancreatectomy. The SWV value of pancreatic parenchyma in POPF positive group was significantly lower than that in POPF negative group (P = 0.001). However, there was no significant difference in palpation stiffness between the two groups (P = 0.124). Besides, neither the SWV value of FPL nor the SWV ratio between FPL to surrounding pancreatic parenchyma differ significantly between POPF positive and negative group (P > 0.05). Taking SWV value of pancreatic parenchyma >1.10 m/s as a cut-off value for predicting POPF, area under the receiver operating characteristic curve (AUROC) was 0.864 with 72.2% sensitivity, 92.3% specificity, 86.7% positive predictive value (PPV) and 82.8% negative predictive value (NPV), respectively.

CONCLUSIONS

VTIQ technique might be a potential non-invasive imaging method to predict POPF before pancreatectomy in future clinical practice.

Imaging diagnosis of autoimmune pancreatitis using endoscopic ultrasonography

The diagnosis of autoimmune pancreatitis (AIP) is challenging and should be achieved through the comprehensive evaluation of clinical, radiological, serological, and pathological evidence, as there is currently no single reliable diagnostic modality. Endoscopic ultrasonography (EUS) can reveal pancreatic parenchymal and ductal features in much more detail than any other existing imaging modality. In this article, we focused on three applications of EUS, i.e., conventional EUS imaging, EUS elastography (EUS-EG), and contrast-enhanced harmonic EUS (CEH-EUS), for the diagnosis of AIP. Diffuse hypoechoic areas, diffuse enlargement, bile duct wall thickening, and peripancreatic hypoechoic margins on conventional EUS are characteristic features of AIP, and the frequencies of these findings are significantly higher in AIP than in pancreatic cancer (PC). EUS-EG of the pancreatic parenchyma in AIP showed homogenous stiffness and that the elasticity of the pancreas may change after steroid therapy. CEH-EUS revealed focal or diffuse iso-enhancement in most AIP cases and hypo-enhancement in most PC cases. However, some AIP cases show a contrast enhancement pattern similar to that of PC. It should be noted that EUS findings of AIP may differ depending on its stage or disease activity. Differentiation from PC has become an increasingly important issue in the process of diagnosing AIP, and EUS, including elastography and contrast enhancement, could be a promising imaging modality for this purpose.

The course and prognostic value of increased pancreas stiffness detected by ultrasound elastography during acute pancreatitis

BACKGROUND

In this study, we determined the pancreatic stiffness (PS) changes in the course of acute pancreatitis (AP) by ultrasound elastography and evaluated its relation with prognosis.

MATERIAL/METHODS

Pancreatic shear wave velocity measurements (SWM) were evaluated at the time of admission to the hospital, following clinical improvement, and one-month after for AP patients and compared to healthy volunteers. Its relationship with clinical severity indexes was evaluated.

RESULTS

The pancreatic SWM value in the healthy group was 7.72 ± 2.50 kPa, and in AP group was 10.97 ± 2.26 kPa (p = 0.000). There was no difference between mild and severe pancreatitis. The mean SWM was 8.96 ± 1.53 kPa after disease remission, and 8.83 ± 1.24 kPa after 1-month.

CONCLUSIONS

PS increases significantly during AP and decreases with clinical improvement, but this was still higher than controls, and it kept its elevation after 1-month. We think that larger, long-term studies are needed to determine the clinicopathological significance of this.

The Extracellular Matrix in Pancreatic Cancer: Description of a Complex Network and Promising Therapeutic Options

The stroma is a relevant player in driving and supporting the progression of pancreatic ductal adenocarcinoma (PDAC), and a large body of evidence highlights its role in hindering the efficacy of current therapies. In fact, the dense extracellular matrix (ECM) characterizing this tumor acts as a natural physical barrier, impairing drug penetration. Consequently, all of the approaches combining stroma-targeting and anticancer therapy constitute an appealing option for improving drug penetration. Several strategies have been adopted in order to target the PDAC stroma, such as the depletion of ECM components and the targeting of cancer-associated fibroblasts (CAFs), which are responsible for the increased matrix deposition in cancer. Additionally, the leaky and collapsing blood vessels characterizing the tumor might be normalized, thus restoring blood perfusion and allowing drug penetration. Even though many stroma-targeting strategies have reported disappointing results in clinical trials, the ECM offers a wide range of potential therapeutic targets that are now being investigated. The dense ECM might be bypassed by implementing nanoparticle-based systems or by using mesenchymal stem cells as drug carriers. The present review aims to provide an overview of the principal mechanisms involved in the ECM remodeling and of new promising therapeutic strategies for PDAC.

An initial trial of quantitative evaluation of autoimmune pancreatitis using shear wave elastography and shear wave dispersion in transabdominal ultrasound

BACKGROUND/OBJECTIVES

We aimed to examine therapeutic efficacy and prognosis prediction of autoimmune pancreatitis (AIP) using shear wave elastography (SWE) and shear wave dispersion (SWD) in transabdominal ultrasound (US).

METHODS

The subjects were 23 patients with diffuse type 1 AIP who underwent SWE and SWD, and 34 controls with a normal pancreas. Elasticity and dispersion were defined as the pancreatic elastic modulus (PEM) and dispersion slope, respectively. PEM and dispersion slope were compared between AIP and control cases, and the short-term therapeutic effect and long-term prognosis were examined.

RESULTS

PEM (30.9 vs. 6.6 kPa, P < 0.001) and dispersion slope (15.3 vs. 13.0 (m/sec)/kHz, P = 0.011) were significantly higher in AIP cases than in controls. Among the 17 AIP patients followed-up in two weeks after treatment, these parameters were 12.7 kPa and 10.5 (m/sec)/kHz with median decrease rate of 37.2% and 32.8%, respectively, which were significantly higher than the change in the size of pancreatic parenchyma (14.4%, P = 0.026). Fourteen of these subjects were followed up for >12 months, during which 2 had relapse; diabetes improved in 5 and worsened in 2; in 60% of cases, the pancreatic parenchyma was atrophied. The % change in PEM after two weeks was tended to be higher in non-atrophy cases.

CONCLUSION

SWE and SWD measurement in US may be useful for quantitative assessment of AIP and evaluation of short-term treatment efficacy.

Evaluation of Pancreatic Fibrosis Grading by Multi Parametric Quantitative Magnetic Resonance Imaging

BACKGROUND

Early detection and grading of pancreatic fibrosis (PF) are important and challenging clinical goals.

PURPOSE

To determine main pancreatic duct (MPD) diameter, pancreatic thickness, and grades of PF via magnetic resonance elastography (MRE), T1 mapping, and intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI), assessing respective diagnostic performances.

STUDY TYPE

Prospective.

SUBJECTS

Histopathologic and imaging records (MRE, T1 mapping, and IVIM-DWI) generated by 144 patients between December 2018 and May 2020 were collected for analysis. Grades of PF were distributed as follows: F0, 82; F1, 22; F2, 22; and F3, 18.

FIELD STRENGTH/SEQUENCE

3 T pancreatic MRI, encompassing MRE, T1 mapping, and IVIM-DWI.

ASSESSMENT

In all patients, T1 relaxation times, pancreatic stiffness values, IVIM-DWI parameters, MPD diameter, and pancreatic thickness were measured.

STATISTICAL TESTS

Receiver operating characteristic (ROC) analysis served to assess imaging parameters useful in diagnosing PF. To identify relations between specific parameters and grades of PF, logistic regression analysis was invoked.

RESULTS

Both pancreatic stiffness (r = 0.754; P < 0.001) and T1 relaxation time (r = 0.433; P < 0.001) correlated significantly with PF (%). To determine PF grades ≥F1, a combined model (area under the curve [AUC] = 0.906) performed significantly better than pancreatic stiffness (AUC = 0.855; P < 0.001) or T1 relaxation time (AUC = 0.754; P < 0.001) alone. For PF grades ≥F2 or grade F3, both the combined model (≥F2: AUC = 0.910; F3: AUC = 0.939) and pancreatic stiffness (≥F2: AUC = 0.906; F3: AUC = 0.929) outperformed T1 relaxation time (≥F2: AUC = 0.768 [P = 0.005 and P = 0.004, respectively]; F3: AUC = 0.816 [both P < 0.005]). All IVIM-DWI parameters generated AUC values <0.700.

DATA CONCLUSION

A combination of MRE and T1 mapping seems promising in diagnosing various grades of PF, particularly at an early stage.

LEVEL OF EVIDENCE

1 TECHNICAL EFFICACY: Stage 2.

Variability measurements provide additional value to shear wave elastography in the diagnosis of pancreatic cancer

Shear wave elastography (SWE) is a technique to non-invasively and quantitatively evaluate tissue stiffness. We aimed to investigate whether we can differentiate pancreatic cancer (PC) from normal pancreatic parenchyma (NPP) by SWE using transabdominal ultrasound. We investigated a total of 106 patients (84 with NPP and 22 with PC) whose pancreatic elastic modulus was measured by two-dimensional SWE (2D-SWE). Intra-rater reliability in this study was examined, and three measurements were sufficiently reliable. There were no differences between the two groups in factors that could affect SWE measurements. The median value of the elastic modulus was 5.70 kPa in the PC patients and 5.66 kPa in the NPP group, which was not significantly different (P = 0.785). On the contrary, the range was 8.64 kPa and 4.72 kPa, with a significantly greater range in the PC patients (P = 0.001). In conclusion, the median elastic modulus measured by 2D-SWE was not significantly different between PC and NPP, and evaluating the obtained elastic modulus itself is not useful in differentiation. However, the variability was significantly greater in PC than in NPP. Evaluating the range of elasticities will provide additional information in SWE, which may be useful in the diagnosis of PC.

Acoustic radiation force impulse imaging of pancreas in patients with early onset idiopathic recurrent acute pancreatitis

BACKGROUND AND AIMS

Patients with recurrent acute pancreatitis (RAP) may progress to chronic pancreatitis (CP). A critical step in this progression is the development of fibrosis. Elastography has been used to assess degree of fibrosis by measurement of shear wave velocity (SWV). The aim of this study was to measure the stiffness of pancreas as a surrogate for pancreatic fibrosis in patients with RAP and compare it with a group of individuals without any history of pancreatic disorders.

MATERIAL AND METHODS

Using acoustic radiation force impulse (ARFI) imaging SWV was calculated in 31 patients with idiopathic RAP having disease onset ≤30 years. A control group of 31 individuals with no history pancreatic disorder and no features of CP on endosonography was selected for comparison. ARFI imaging was done by a single radiologist who was blinded to the cases and controls RESULTS:: Mean age of patients with RAP was 24.8 (SD 9.86) years, disease duration was 3.45 (interquartile range 1-5) years, mean number of episodes 4.9 (SD 2.72). There was a significant difference in SWV between patients (1.27 ± 0.50 m/s) and controls (1.00 ± 0.17 m/s) (P = 0.001)). There was a positive correlation between SWV and number of pain episodes (P = 0.026) and negative correlation with BMI (P = 0.002).

CONCLUSION

SWV was high in patients with RAP indicating a stiff pancreas. The stiffness increases with the number of episodes of pancreatitis.

Intraoperative Ultrasound Elastography Is Useful for Determining the Pancreatic Texture and Predicting Pancreatic Fistula After Pancreaticoduodenectomy

OBJECTIVES

Pancreatic fistula (PF) is one of the most common complications after pancreaticoduodenectomy (PD). The soft pancreatic texture is known to be an important predictive factor for PF after PD. However, its evaluation is dependent on the sense of touch by the operator during operation, thus not objective. The aim of this study was to investigate the relationship between mean elasticity via intraoperative ultrasound elastography and histological pancreatic hardness, as well as predictive factor of PF after PD.

METHODS

Forty-eight patients who underwent ultrasound elastography during PD and had pancreatic parenchyma histologically evaluated were included.

RESULTS

Pancreatic fistula was noted in 20 patients. There were significant differences in the histological pancreatic fibrosis rate between soft pancreas group (8.2%) and hard pancreas group (28.4%, P < 0.05) and in the mean elasticity between soft pancreas group (1.94 m/s) and hard pancreas group (3.17 m/s, P < 0.05). The mean elasticity was significantly correlated with pancreatic fibrosis rate (P < 0.05). A multivariate analysis revealed that the mean elasticity of less than 2.2 m/s was a significant predictor of PF after PD (P = 0.003).

CONCLUSIONS

Intraoperative ultrasound elastography could predict pancreatic texture objectively. The mean elasticity of less than 2.2 m/s was a significant predictor of PF after PD.

The Physical Microenvironment of Tumors: Characterization and Clinical Impact

The tumor microenvironment plays a critical role in tumorigenesis and metastasis. As tightly controlled extracellular matrix homeostasis is lost during tumor progression, a dysregulated extracellular matrix can significantly alter cellular phenotype and drive malignancy. Altered physical properties of the tumor microenvironment alter cancer cell behavior, limit delivery and efficacy of therapies, and correlate with tumorigenesis and patient prognosis. The physical features of the extracellular matrix during tumor progression have been characterized; however, a wide range of methods have been used between studies and cancer types resulting in a large range of reported values. Here, we discuss the significant mechanical and structural properties of the tumor microenvironment, summarizing their reported values and clinical impact across cancer type and grade. We attempt to integrate the values in the literature to identify sources of reported differences and commonalities to better understand how aberrant extracellular matrix dynamics contribute to cancer progression. An intimate understanding of altered matrix properties during malignant transformation will be crucial in effectively detecting, monitoring, and treating cancer.

Endoscopic Ultrasound-Guided Management of Chronic Pancreatitis

PURPOSE OF REVIEW

The purpose of this review is to discuss the role of endoscopic ultrasound (EUS) in the diagnosis and treatment of chronic pancreatitis (CP).

RECENT FINDINGS

EUS has evolved and become invaluable in diagnosing early CP with the use of elastography and contrast enhancement. Lumen-apposing metal stents have allowed for easier transmural drainage and necrosectomy for pancreatic pseudocyst and walled of necrosis. EUS-guided pancreatic duct drainage is being utilized for pancreatic duct complications including stenosis, stones, and duct disruptions that are not amendable to endoscopic retrograde cholangiopancreatography. EUS is an effective tool that assists with the diagnosis and treatment of CP. The technology continues to evolve allowing for diagnosis of CP in earlier stages, which enables more effective therapy. The development of new EUS-guided tools and techniques has improved the treatment of complications from CP.

The Propagation Display Method Improves the Reproducibility of Pancreatic Shear Wave Elastography

Evaluation of the pancreatic elastic modulus (PEM) using shear wave elastography (SWE) requires at least 5 measurements to ensure reproducibility. The aim of this study was to evaluate improvement in reproducibility of SWE, using the propagation display method in normal pancreas ([NP] phase 1) and to examine the differences in PEM between NP and chronic pancreatitis (CP), intraductal papillary mucinous neoplasm (IPMN) and autoimmune pancreatitis ([AIP] phase 2). In phase 1, the measurement success rate, median PEM in repeated measurements and appropriate number of SWE measurements were determined in 109 cases with NP. In phase 2, PEM was measured in CP (n = 10), IPMN (n = 31) and AIP (n = 5), using the required number of SWE measurements determined in phase 1. In phase 1, the measurement success rate was 93.9% (92/109 cases). The median PEM for NP was 14.6 kPa and the appropriate number of SWE measurements was at least 3. In phase 2, the median PEMs in CP, IPMN and AIP were 19.6, 18.1 and 17.2 kPa, respectively, with significant differences between NP and CP (p = 0.0133) and between NP and IPMN (p = 0.0436). Use of the propagation display method in SWE improves the reproducibility of measurement of PEM.

Elastography of the Pancreas, Current View

Ultrasound elastography (USE) of the pancreas allows pancreatic tissue stiffness assessment by virtual palpation. Two main types of USE are used. For the pancreas strain elastography applying by endoscopic ultrasound has been established for the characterisation of small solid pancreatic lesions (SPL). In larger SPL >30 mm the results are less convincing mainly due to the heterogenicity of the lesions but also by concomitant changes of the surrounding pancreatic parenchyma. The current role of shear wave elastography has to be determined. This article reviews the current use of elastography of the pancreas.

Increased hardness of the underlying pancreas correlates with the presence of intraductal papillary-mucinous neoplasm in a limited number of cases

PURPOSE

Pancreatic fibrosis or fibrosing reactions have been reported in intraductal papillary-mucinous neoplasm (IPMN) patients. We assessed whether a higher elastic modulus (EM) measured using shear wave elastography (SW-EG) correlated with the existence of branch-duct (BD) IPMN.

METHODS

In total, 183 normal pancreas (NP) and 123 BD-IPMN cases were enrolled. First, we assessed the difference in pancreatic EM (PEM) at different sites (head or tail side of the cyst). Second, a comparison was done between the median PEM of the NP and the BD-IPMN cases. Receiver-operating characteristic analysis was performed to determine the BD-IPMN diagnostic capabilities. Finally, in patients whose cyst was not visualized, the test-positive rate was determined.

RESULTS

No significant difference was seen between the cyst head side PEM (4.61 kPa) and the tail side PEM (5.35 kPa) (P = 0.471). Among these cases matched by age, 73 were selected each from NP and BD-IPMN cases (median age 65 years). The median PEM of the BD-IPMN cases (5.18 kPa) was significantly higher than that of the NP cases (3.17 kPa) (P < 0.001). When the cut-off value was set at 4.75 kPa, the sensitivity, specificity, PPV, NPV, and accuracy were 75.3%, 64.4%, 72.3%, 67.9%, and 69.9%, respectively. The cut-off value of 4.75 kPa helped for the indirect selection of BD-IPMN patients (10/17, 58.8%) whose cyst was not detected on B-mode ultrasonography.

CONCLUSION

SW-EG measurement of the underlying pancreatic parenchyma may correlate with the presence of BD-IPMN.

Feasibility and usefulness of endoscopic ultrasonography-guided shear-wave measurement for assessment of autoimmune pancreatitis activity: a prospective exploratory study

Purpose

To assess the feasibility and the clinical usefulness of a newly developed endoscopic ultrasonography (EUS) shear-wave elastography technique (EUS shear-wave measurement: EUS-SWM) in the diagnosis and treatment of autoimmune pancreatitis (AIP).

Methods

Tissue elasticity was measured in the pancreas in 160 patients. The success rate of EUS-SWMs, the velocity of the shear wave (Vs, m/s), and the reliability index of the Vs measurement (VsN) were evaluated, and the elasticity (median Vs) was compared between AIP patients (n = 14) and normal controls.

Results

A total of 3837 EUS-SWMs were performed without adverse events. Overall, 97.6% (3743/3837) were successful. The median VsN was 74%. The median Vs values of the pancreas were as follows: 2.22 m/s in the pancreatic head (push position), 2.36 m/s in the head (pull position), 1.99 m/s in the body, and 2.25 m/s in the tail. The median Vs of the AIP group (2.57 m/s) was significantly higher than that of the normal controls (1.89 m/s) (P = 0.0185). The mean Vs significantly decreased from 3.32 m/s to 2.46 m/s after steroid therapy (n = 6) (P = 0.0234).

Conclusion

EUS-SWM is feasible and generates credible results. EUS-SWM was a useful method for assessment of the effect of steroid therapy in AIP patients.

Electronic supplementary material

The online version of this article (10.1007/s10396-019-00944-4) contains supplementary material, which is available to authorized users.

Usefulness of shear wave elastography as a quantitative diagnosis of chronic pancreatitis

BACKGROUND AND AIM

Chronic pancreatitis (CP) is sometimes diagnosed at the progressed stage. For the early diagnosis of CP, endoscopic ultrasonography (EUS) may be a useful method, but its diagnostic criteria is based on subjective judgment. Shear wave elastography (SW-EG) using transabdominal ultrasonography, which quantifies tissue elasticity as an absolute value, may be an objective and noninvasive method for the diagnosis of CP.

METHODS

Eighty-five patients with known or suspected CP who underwent both EUS and SW-EG from October 2012 to July 2016 were included in this study. Patients were categorized into four stages using Rosemont classification and into three stages using Japan Pancreas Society clinical diagnostic criteria 2009 that was EUS-based criteria for the diagnosis of CP. SW-EG was measured five times in the pancreatic parenchyma, and the median value was defined as the pancreatic elastic modulus (PEM).

RESULTS

Pancreatic elastic modulus was significantly positively correlated with Rosemont classification stage (r_s  = 0.54), Japan Pancreas Society stage (r_s  = 0.41), and the number of EUS features (r_s  = 0.47). Area under the receiver operating characteristic curve for the accuracy of SW-EG (consistent with CP and suggestive of CP vs normal and indeterminate for CP) was 0.77 (sensitivity 77.1%, specificity 64.9%). In a multivariate linear regression analysis including various EUS features related to PEM, hyperechoic foci with shadowing and lobularity with honeycombing were independent features related to PEM.

CONCLUSIONS

Chronic pancreatitis may be diagnosed noninvasively and objectively using SW-EG without performing EUS.

Viscoelastic properties of human pancreatic tumors and in vitro constructs to mimic mechanical properties

Pancreatic ductal adenocarcinoma (PDAC) is almost universally fatal, in large part due to a protective fibrotic barrier generated by tumor-associated stromal (TAS) cells. This barrier is thought to promote cancer cell survival and confounds attempts to develop effective therapies. We present a 3D in vitro system that replicates the mechanical properties of the PDAC microenvironment, representing an invaluable tool for understanding the biology of the disease. Mesoscale indentation quantified viscoelastic metrics of resected malignant tumors, inflamed chronic pancreatitis regions, and histologically normal tissue. Both pancreatitis (2.15 ± 0.41 kPa, Mean ± SD) and tumors (5.46 ± 3.18 kPa) exhibit higher Steady-State Modulus (SSM) than normal tissue (1.06 ± 0.25 kPa; p < .005). The average viscosity of pancreatitis samples (63.2 ± 26.7 kPa·s) is significantly lower than that of both normal tissue (252 ± 134 kPa·s) and tumors (349 ± 222 kPa·s; p < .005). To mimic this remodeling behavior, PDAC and TAS cells were isolated from human PDAC tumors. Conditioned medium from PDAC cells was used to culture TAS-embedded collagen hydrogels. After 7 days, TAS-embedded gels in control medium reached SSM (1.45 ± 0.12 kPa) near normal pancreas, while gels maintained with conditioned medium achieved higher SSM (3.38 ± 0.146 kPa) consistent with tumors. Taken together, we have demonstrated an in vitro system that recapitulates in vivo stiffening of PDAC tumors. In addition, our quantification of viscoelastic properties suggests that elastography algorithms incorporating viscosity may be able to more accurately distinguish between pancreatic cancer and pancreatitis.

STATEMENT OF SIGNIFICANCE

Understanding tumor-stroma crosstalk in pancreatic ductal adenocarcinoma (PDAC) is challenged by a lack of stroma-mimicking model systems. To design appropriate models, pancreatic tissue must be characterized with a method capable of evaluating in vitro models as well. Our indentation-based characterization tool quantified the distinct viscoelastic signatures of inflamed resections from pancreatitis, tumors from PDAC, and otherwise normal tissue to inform development of mechanically appropriate engineered tissues and scaffolds. We also made progress toward a 3D in vitro system that recapitulates mechanical properties of tumors. Our in vitro model of stromal cells in collagen and complementary characterization system can be used to investigate mechanisms of cancer-stroma crosstalk in PDAC and to propose and test innovative therapies.

Usefulness of endoscopic ultrasonography-elastography as a predictive tool for the occurrence of pancreatic fistula after pancreatoduodenectomy

BACKGROUND

Pancreatic fistula (PF) is a major complication following pancreatoduodenectomy (PD). Pancreatic texture is a risk factor for PF, but its evaluation depends on the subjective judgment. The aim of this study was to investigate whether preoperative endoscopic ultrasonography-elastography (EUS-EG), which objectively assesses tissue elasticity, predict the development of PF following PD.

METHODS

Fifty-nine patients who underwent EUS-EG before PD and had pancreas parenchyma histologically evaluated were included. Using histogram analysis, mean elasticity (ME), which represents tissue elasticity and is inversely correlated with pancreatic fibrosis, was calculated.

RESULTS

Among 59 patients, 19 developed PF (32.2%). The ME in patients with PF was significantly higher than that in patients without PF (85.4 vs. 55.6, P < 0.001). Area under the receiver operating characteristic curve for the accuracy of pancreatic texture and ME for predicting PF were 0.718 and 0.846, respectively. When a ME of 70.0 was used as a cut-off value for predicting PF, the sensitivity and specificity were 84.2% and 80.0%, respectively. In a multivariate logistic regression analysis, only a ME of >70.0 was an independent predictor of PF (odds ratio 10.02, P = 0.008).

CONCLUSIONS

Endoscopic ultrasonography-elastography may be an accurate and objective method for predicting PF following PD.

Endoscopic ultrasound elastography for solid pancreatic lesions

Elastography is one of technologies assisting diagnosis of solid pancreatic lesions (SPL). This technology has been previously used for measuring the stiffness of various organs based on a principle of “harder the lesions, higher chance for malignancy”. Two elastography techniques; strain and shear wave elastography, are available. For endoscopic ultrasound (EUS), only the former is existing. To interpret results of EUS elastography for SPL, 3 methods are used: (1) pattern recognition; (2) strain ratio; and (3) strain histogram. Based on results of existing studies, these 3 techniques provide high sensitivity but low to moderate specificity and accuracy rate. This review will summarize all available information in order to update current situation of using elastography for an evaluation of SPLs to readers.

Point shear-wave elastography in chronic pancreatitis: A promising tool for staging disease severity

BACKGROUND

Objectives: ElastPQ^®-pSWE is an ultrasound technique developed to stage disease severity in patients with chronic liver diseases. Little data is available about its application to the pancreas. We aimed to assess the feasibility and reproducibility of pancreatic stiffness (PS) measurements in patients with chronic pancreatitis and their relationship with clinical and laboratory data.

MATERIAL AND METHODS

52 consecutive patients with chronic pancreatitis (CP) (40 males; median age 60 years) underwent hepatic and pancreatic pSWE. Liver stiffness was measured by transient elastography, 42 healthy subjects being controls (25 males; median age 54 years). Pancreatic pSWE inter-observer agreement was analyzed by intraclass correlation coefficient (ICC). The effects of clinical, laboratory and US data on PS measurements were evaluated by linear regression.

RESULTS

pSWE was feasible in all the CP patients, but one. Pancreatic stiffness was significantly higher in CP patients than healthy controls (4.3 ± SD 2.4 vs. 2.8 ± SD 1.1 kPa, respectively, p = 0.001). Significantly higher values in the CP group were observed in patients with longer disease duration (>10 vs. ≤10 years) (5.8 ± SD 4 vs. 3.9 ± SD 1.5 kPa, respectively, p = 0.01), on chronic analgesic drugs (6.0 vs. 3.5 kPa, p < 0.05) and with lower body weight (p < 0.05, r = -0.38). At multivariate analysis all the three variables resulted independently associated to the pancreatic stiffness value. The ICC for PS was 0.77.

CONCLUSIONS

ElastPQ^®-pSWE is promising and reproducible in assessing pancreatic stiffness, which mainly reflects disease length and severity. Accordingly, its use is of potential value in stratifying CP patients by identifying those with a more serious degree of disease.

Chronic pancreatitis

Chronic pancreatitis is defined as a pathological fibro-inflammatory syndrome of the pancreas in individuals with genetic, environmental and/or other risk factors who develop persistent pathological responses to parenchymal injury or stress. Potential causes can include toxic factors (such as alcohol or smoking), metabolic abnormalities, idiopathic mechanisms, genetics, autoimmune responses and obstructive mechanisms. The pathophysiology of chronic pancreatitis is fairly complex and includes acinar cell injury, acinar stress responses, duct dysfunction, persistent or altered inflammation, and/or neuro-immune crosstalk, but these mechanisms are not completely understood. Chronic pancreatitis is characterized by ongoing inflammation of the pancreas that results in progressive loss of the endocrine and exocrine compartment owing to atrophy and/or replacement with fibrotic tissue. Functional consequences include recurrent or constant abdominal pain, diabetes mellitus (endocrine insufficiency) and maldigestion (exocrine insufficiency). Diagnosing early-stage chronic pancreatitis is challenging as changes are subtle, ill-defined and overlap those of other disorders. Later stages are characterized by variable fibrosis and calcification of the pancreatic parenchyma; dilatation, distortion and stricturing of the pancreatic ducts; pseudocysts; intrapancreatic bile duct stricturing; narrowing of the duodenum; and superior mesenteric, portal and/or splenic vein thrombosis. Treatment options comprise medical, radiological, endoscopic and surgical interventions, but evidence-based approaches are limited. This Primer highlights the major progress that has been made in understanding the pathophysiology, presentation, prevalence and management of chronic pancreatitis and its complications.