Elastography of the Pancreas, Current View

Basic Principles and Role of Endoscopic Ultrasound in Diagnosis and Differentiation of Pancreatic Cancer from Other Pancreatic Lesions: A Comprehensive Review of Endoscopic Ultrasound for Pancreatic Cancer

Pancreatic cancer is one of the leading causes of cancer-related deaths worldwide. Pancreatic lesions consist of both neoplastic and non-neoplastic lesions and often pose a diagnostic and therapeutic challenge due to similar clinical and radiological features. In recent years, pancreatic lesions have been discovered more frequently as incidental findings due to the increased utilization and widespread availability of abdominal cross-sectional imaging. Therefore, it becomes imperative to establish an early and appropriate diagnosis with meticulous differentiation in an attempt to balance unnecessary treatment of benign pancreatic lesions and missing the opportunity for early intervention in malignant lesions. Endoscopic ultrasound (EUS) has become an important diagnostic modality for the identification and risk stratification of pancreatic lesions due to its ability to provide detailed imaging and acquisition of tissue samples for analysis with the help of fine-needle aspiration/biopsy. The recent development of EUS-based technology, including contrast-enhanced endoscopic ultrasound, real-time elastography-endoscopic ultrasound, miniature probe ultrasound, confocal laser endomicroscopy, and the application of artificial intelligence has significantly augmented the diagnostic accuracy of EUS as it enables better evaluation of the number, location, dimension, wall thickness, and contents of these lesions. This article provides a comprehensive overview of the role of the different types of EUS available for the diagnosis and differentiation of pancreatic cancer from other pancreatic lesions while discussing their key strengths and important limitations.

Revolutionizing the Pancreatic Tumor Diagnosis: Emerging Trends in Imaging Technologies: A Systematic Review

Background and Objectives: The pancreas, ensconced within the abdominal cavity, requires a plethora of sophisticated imaging modalities for its comprehensive evaluation, with ultrasonography serving as a primary investigative technique. A myriad of pancreatic pathologies, encompassing pancreatic neoplasia and a spectrum of inflammatory diseases, are detectable through these imaging strategies. Nevertheless, the intricate anatomical confluence and the pancreas's deep-seated topography render the visualization and accurate diagnosis of its pathologies a formidable endeavor. The objective of our paper is to review the best diagnostic imagistic tools for the pancreas. Materials and Methods: we have gathered several articles using Prisma guidelines to determine the best imagistic methods. The imperative of pancreatic scanning transcends its diagnostic utility, proving to be a pivotal element in a multitude of clinical specialties, notably surgical oncology. Within this domain, multidetector computed tomography (MDCT) of the pancreas holds the distinction of being the paramount imaging modality, endorsed for its unrivaled capacity to delineate the staging and progression of pancreatic carcinoma. In synergy with MDCT, there has been a notable advent of avant-garde imaging techniques in recent years. These advanced methodologies, including ultrasonography, endoscopic ultrasonography, contrast-enhanced ultrasonography, and magnetic resonance imaging (MRI) conjoined with magnetic resonance cholangiopancreatography (MRCP), have broadened the horizon of tumor characterization, offering unparalleled depth and precision in oncological assessment. Other emerging diagnostic techniques, such as elastography, also hold a lot of potential and promise for the future of pancreatic imaging. Fine needle aspiration (FNA) is a quick, minimally invasive procedure to evaluate lumps using a thin needle to extract tissue for analysis. It is less invasive than surgical biopsies and usually performed as an outpatient with quick recovery. Its accuracy depends on sample quality, and the risks include minimal bleeding or discomfort. Results, guiding further treatment, are typically available within a week. Elastography is a non-invasive medical imaging technique that maps the elastic properties and stiffness of soft tissue. This method, often used in conjunction with ultrasound or MRI, helps differentiate between hard and soft areas in tissue, providing valuable diagnostic information. It is particularly useful for assessing liver fibrosis, thyroid nodules, breast lumps, and musculoskeletal conditions. The technique is painless and involves applying gentle pressure to the area being examined. The resulting images show tissue stiffness, indicating potential abnormalities. Elastography is advantageous for its ability to detect diseases in early stages and monitor treatment effectiveness. The procedure is quick, safe, and requires no special preparation, with results typically available immediately. Results: The assembled and gathered data shows the efficacy of various techniques in discerning the nature and extent of neoplastic lesions within the pancreas. Conclusions: The most common imaging modalities currently used in diagnosing pancreatic neoplasms are multidetector computed tomography (MDCT), endoscopic ultrasound (EUS), and magnetic resonance imaging (MRI), alongside new technologies, such as elastography.

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.

Feasibility and Measurement Value of Pancreatic 2-D Shear Wave Elastography in Healthy Adults: Evaluation, Influencing Factors, Reference Range, Measurement Stability and Reproducibility

OBJECTIVE

The present study was aimed at assessing the success rate and measurement value, determining the influencing factors and reference range and examining the intra-operator stability and inter-operator reproducibility of pancreatic 2-D shear wave elastography (SWE) measurement in healthy adults.

METHODS

In 2022, 387 healthy adults were prospectively recruited. Logistic regression and linear regression analyses were used to explore the factors influencing the success rate and the measurement value of pancreatic 2-D SWE measurement, respectively. A two-sided 95% reference range was estimated accordingly. The intraclass correlation coefficient was calculated to evaluate the intra-operator stability and inter-operator reproducibility of the pancreatic 2-D SWE measurement.

RESULTS

The pancreatic body (89.6%) bore the highest while the tail (72.8%) bore the lowest success rate of pancreatic 2-D SWE measurement. Sex and body mass index (BMI) were the independent factors influencing measurement success rate in all three parts of the pancreas. Mean measurement values (Emean) were not the same in the three parts of the pancreas of the same participant. BMI and image depth were the independent factors influencing Emean in the pancreatic body, while region of interest depth and BMI were the only independent factors influencing Emean in the pancreatic head and tail, respectively. The intra-operator stability of pancreatic 2-D SWE measurement was found to be excellent, whereas its inter-operator reproducibility was poor to good.

CONCLUSION

Pancreatic 2-D SWE is a reliable technique for evaluating pancreatic stiffness in healthy adults, but its success rate and measurement value are influenced by multiple factors.

Normal value of virtual touch imaging quantification elastography in measurements of pancreas

OBJECTIVE

To evaluate pancreatic tissue stiffness and provide a normal reference shear wave velocity (SWV) value of pancreas from healthy adults by Virtual Touch Imaging Quantification (VTIQ) measurements.

METHODS

Healthy adult volunteers without known history of hepatobiliary or pancreatic diseases were included. VTIQ elastography (Siemens ACUSON Sequoia, 5C-1 transducer) was used. SWV values were measured at the cephalic, corpus and tail of pancreas and replicated different operators' obtained data. Subgroups were classified according to the volunteers' gender, age, body mass index (BMI), depth of measurements and the echogenicity of the pancreas.

RESULTS

From February 2023 to July 2023, 33 healthy adult volunteers were included. The success rate of VTIQ measurements in cephalic, corpus and tail regions was 90.90 % (30/33), 96.97 % (32/33) and 90.90 % (30/33) respectively. The color elastograms of healthy adult pancreas showed uniform blue or simultaneously blue and green. The average SWV values were 0.97±0.26 m/s for cephalic, 0.91±0.24 m/s for corpus and 0.97±0.25 m/s for pancreatic tail respectively (P = 0.198). The mean SWV values of pancreas did not show significant difference with age, gender or depth (P > 0.05). BMI was an influence factor in the measurements of SWV values of cephalic and tail of pancreas (P < 0.05). Pancreas with hyperechoic parenchyma showed higher mean SWV values (P < 0.05). The intra-observer (ICC = 0.938 [95% CI: 0.869-0.971]) and the inter-observer (ICC = 0.887 [95% CI: 0.760-0.947]) agreements of VTIQ measurements were excellent.

CONCLUSIONS

The mean SWV value of the pancreas in healthy adults was 0.96±0.20 m/s (range: 0.52-1.74 m/s). VTIQ technique can be used in pancreatic stiffness measurements with good reliability.

Risk Factors of Postoperative Acute Pancreatitis and Its Impact on the Postoperative Course after Pancreaticoduodenectomy-10 Years of Single-Center Experience

BACKGROUND

Clinically relevant acute postoperative pancreatitis (CR-PPAP) after pancreaticoduodenectomy (PD) is a complication that may lead to the development of local and systemic consequences. The study aimed to identify risk factors for CR-PPAP and assess the impact of CR-PPAP on the postoperative course after PD.

METHODS

The study retrospectively analyzed data from 428 consecutive patients who underwent PD at a single center between January 2013 and December 2022. The presence of increased amylase activity in plasma, above the upper limit of normal 48 h after surgery, was checked. CR-PPAP was diagnosed when accompanied by disturbing radiological features and/or symptoms requiring treatment. We investigated the relationship between the occurrence of CR-PPAP and the development of postoperative complications after PD, and possible predictors of CR-PPAP.

RESULTS

The postoperative follow-up period was 90 days. Of the 428 patients, 18.2% (n = 78) had CR-PPAP. It was associated with increased rates of CR-POPF, delayed gastric emptying, occurrence of intra-abdominal collections, postoperative hemorrhage, peritonitis, and septic shock. Patients who developed CR-PPAP were more often reoperated (37.17% vs. 6.9%, p < 0.0001)) and had increased postoperative mortality (14.1% vs. 5.74%, p < 0.0001). Soft pancreatic parenchyma, intraoperative blood loss, small diameter of the pancreatic duct, and diagnosis of adenocarcinoma papillae Vateri were independent risk factors for CR-PPAP and showed the best performance in predicting CR-PPAP.

CONCLUSIONS

CR-PPAP is associated with an increased incidence of postoperative complications after PD, worse treatment outcomes, and an increased risk of reoperation and mortality. Pancreatic consistency, intraoperative blood loss, width of the duct of Wirsung, and histopathological diagnosis can be used to assess the risk of CR-PPAP. Amylase activity 48 h after surgery > 161 U/L is highly specific in the diagnosis of CR-PPAP.

Contrast Enhanced EUS for Predicting Solid Pancreatic Neuroendocrine Tumor Grade and Aggressiveness

Pancreatic neuroendocrine tumor (PNET) behavior assessment is a daily challenge for physicians. Modern PNET management varies from a watch-and-wait strategy to surgery depending on tumor aggressiveness. Therefore, the aggressiveness definition plays a pivotal role in the PNET work-up. The aggressiveness of PNETs is mainly based on the dimensions and histological grading, with sometimes a lack of specificity and sensibility. In the last twenty years, EUS has become a cornerstone in the diagnostic phase of PNET management for its high diagnostic yield and the possibility of obtaining a histological specimen. The number of EUS applications in the PNET work-up has been rapidly increasing with new and powerful possibilities. The application of contrast has led to an important step in PNET detection; in recent years, it has been gaining interesting applications in aggressiveness assessment. In this review, we underline the latest experiences and opportunities in the behavior assessment of PNETs using contact-enhanced EUS and contested enhanced harmonic EUS with a particular focus on the future application and possibility that these techniques could provide.

Diagnostic performance of endoscopic ultrasound elastography for differential diagnosis of solid pancreatic lesions: A propensity score-matched analysis

BACKGROUND

Endoscopic ultrasound-elastography (EUS-EG) is a non-invasive complementary diagnostic method for differential diagnosis of solid pancreatic lesions (SPL). However, the optimal strain ratio (SR) value and diagnostic performance of EUS-EG have not yet been determined in pancreatic neuroendocrine neoplasm (PNEN), mass-forming pancreatitis (MFP), and pancreatic ductal adenocarcinoma (PDAC). We aimed to determine the optimal SR value in EUS-EG for differential diagnosis of SPLs.

METHODS

Patients who underwent EUS-EG for SPL evaluation between July 2016 and June 2019 were retrospectively investigated. Patients were divided into three groups based on the final diagnosis (PNEN, MFP, or PDAC). Patient demographics, characteristics of SPL, and EUS-EG were compared.

RESULTS

The mean (± standard deviation) SR value for each group were 11.85 ± 7.56 (PNEN, n = 10), 11.45 ± 5.97 (MFP, n = 37), and 22.50 ± 13.19 (PDAC, n = 87). Multinomial logistic regression analysis revealed that an increase of SR value was significantly associated with PDAC (PNEN versus PDAC, p = 0.0216; MFP versus PDAC, p = 0.0006). The optimal cut-off value for differential diagnosis was confirmed as 17.14 after propensity score matching.

CONCLUSIONS

We provided the optimal cut-off SR values for differential diagnosis between MFP and PDAC. EUS-EG can be used as a supplementary diagnostic method in the diagnosis of SPLs. (Clinical trial registration number: https://cris.nih.go.kr/cris: KCT0002082).

Early detection of pancreatic tumors by advanced EUS imaging

The early detection of pancreatic ductal adenocarcinoma (PDAC) dramatically improves outcome. All available state-of-the-art imaging methods allow early detection with EUS being the best technique for exclusion of PDAC and detection of very early PDAC. Etiological differentiation of small SPL is important to guide individually tailored patients' management including radical surgery in resectable PDAC, medical (neoadjuvant or palliative intended) treatment in patients with non-resectable malignancy, pancreatic parenchyma saving strategies in some non-PDAC, and follow-up in particular in low-grade PanNEN or other small benign lesions. Multimodality EUS imaging including B-Mode assessment, elastography, contrast-enhancement and EUS-guided sampling is the most appropriate technique for diagnosis and risk assessment of small SPL. We present a review discussing modern (endoscopic) ultrasound imaging techniques including contrast enhanced ultrasound and elastography for the early detection and characterization of solid pancreatic lesions.

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.

Applications of endoscopic ultrasound elastography in pancreatic diseases: From literature to real life

Elastography is a non-invasive method widely used to measure the stiffness of the tissues, and it is available in most endoscopic ultrasound machines, using either qualitative or quantitative techniques. Endoscopic ultrasound elastography is a tool that should be applied to obtain a complementary evaluation of pancreatic diseases, together with other imaging tests and clinical data. Elastography can be informative, especially when studying pancreatic masses and help the clinician in the differential diagnosis between benign or malignant lesions. However, further studies are necessary to standardize the method, increase the reproducibility and establish definitive cut-offs to distinguish between benign and malignant pancreatic masses. Moreover, even if promising, elastography still provides little information in the evaluation of benign conditions.

Diagnostic Performance of Point Shear Wave Elastography (pSWE) Using Acoustic Radiation Force Impulse (ARFI) Technology in Mesenteric Masses: A Feasibility Study

Purpose: To evaluate the diagnostic performance of ultrasound point shear wave elastography (pSWE) using acoustic radiation force impulse (ARFI) technology in different benign and malignant mesenteric masses (MMs). Methods: A total of 69 patients with MMs diagnosed from September 2018 to November 2021 were included retrospectively in the study. The inclusion criteria were (1) an MM over 1 cm; (2) valid ARFI measurements; and (3) confirmation of the diagnosis of an MM by histological examination and/or clinical and radiological follow-up. To examine the mean ARFI velocities (MAVs) for potential cut-off values between benign and malignant MMs, a receiver operating characteristics analysis was implemented. Results: In total, 37/69 of the MMs were benign (53.6%) and 32/69 malignant (46.4%). Benign MMs demonstrated significantly lower MAVs than mMMs (1.59 ± 0.93 vs. 2.76 ± 1.01 m/s; p < 0.001). Selecting 2.05 m/s as a cut-off value yielded a sensitivity and specificity of 75.0% and 70.3%, respectively, in diagnosing malignant MMs (area under the curve = 0.802, 95% confidence interval 0.699–0.904). Conclusion: ARFI elastography may represent an additional non-invasive tool for differentiating benign from malignant MMs. However, to validate the results of this study, further prospective randomized studies are required.

Ultrasound elastography

Physicians have used palpation as a diagnostic examination to understand the elastic properties of pathology for a long time since they realized that tissue stiffness is closely related to its biological characteristics. US elastography provided new diagnostic information about elasticity comparing with the morphological feathers of traditional US, and thus expanded the scope of the application in clinic. US elastography is now widely used in the field of diagnosis and differential diagnosis of abnormality, evaluating the degree of fibrosis and assessment of treatment response for a range of diseases. The World Federation of Ultrasound Medicine and Biology divided elastographic techniques into strain elastography (SE), transient elastography and acoustic radiation force impulse (ARFI). The ARFI techniques can be further classified into point shear wave elastography (SWE), 2D SWE, and 3D SWE techniques. The SE measures the strain, while the shear wave-based techniques (including TE and ARFI techniques) measure the speed of shear waves in tissues. In this review, we discuss the various techniques separately based on their basic principles, clinical applications in various organs, and advantages and limitations and which might be most appropriate given that the majority of doctors have access to only one kind of machine.

Pancreatic shear wave elastography in children with type 1 diabetes: relation to diabetes duration, glycemic indices, fasting C-peptide and diabetic complications

BACKGROUND

Little is known about changes in the pancreas as the course of type 1 diabetes progresses. Recently, shear wave elastography (SWE) emerged as a tool for assessing pancreatic stiffness in chronic pancreatitis and pancreatic cancer with a few studies assessing it in diabetes.

OBJECTIVE

To compare pancreatic SWE in children with recent-onset and long-standing type 1 diabetes to healthy controls and to correlate it with diabetes duration, glycated hemoglobin (HbA1C), functional B cell reserve (fasting C-peptide) and diabetic complications.

MATERIALS AND METHODS

Fifty children with type 1 diabetes (25 with recent-onset and 25 with long-standing type 1 diabetes) and 50 controls were enrolled. Diabetes duration, insulin therapy, fundoscopic examination of the eyes and the neuropathy disability score were assessed. Fasting C-peptide, lipids, HbA1C and urinary albumin-creatinine ratio were measured. Pancreatic SWE was measured using the General Electric Logiq P9 ultrasound system.

RESULTS

The mean SWE of the studied children with recent-onset type 1 diabetes was 4.81±0.62 kilopascals (Kpa), those with long-standing type 1 diabetes was 7.10±1.56Kpa and for controls was 5.57±0.27 Kpa (P&lt;0.001). SWE was positively correlated to diabetes duration (P&lt;0.001) and negatively correlated to fasting C-peptide (P&lt;0.001). Regarding diabetes complications, SWE was positively correlated to frequency of severe hypoglycemia (P=0.005), HbA1C (P=0.03), low-density lipoproteins (P&lt;0.001) and cholesterol (P&lt;0.001) and significantly related to diabetic neuropathy (P=0.04) and nephropathy (P=0.05). Diabetes duration, fasting C-peptide, HbA1C and frequency of severe hypoglycemia were the significant independent variables related to SWE increase by multivariable regression analysis.

CONCLUSION

Pancreatic SWE changes significantly with duration of type 1 diabetes, being lowest in those with recent-onset type 1 diabetes and highest in those with long-standing type 1 diabetes, particularly those with diabetic nephropathy and neuropathy.

Controversies in ERCP: Indications and preparation

The aim of the series of papers on controversies of biliopancreatic drainage procedures is to discuss the pros and cons of the varying clinical practices and techniques in ERCP and EUS for drainage of biliary and pancreatic ducts. The first part focuses on indications, clinical and imaging prerequisites before ERCP, sedation options, post-ERCP pancreatitis (PEP) prophylaxis, and other related technical topics. In the second part, specific procedural ERCP-techniques including precut techniques and its timing as well as management algorithms are discussed. In addition, controversies in EUS-guided bile duct and pancreatic drainage procedures are under preparation.

Diagnostic Accuracy of Transabdominal Ultrasound and Computed Tomography in Chronic Pancreatitis: A Head-to-Head Comparison

Purpose Computed tomography (CT) is the most used imaging modality for diagnosing chronic pancreatitis (CP), but advances in transabdominal ultrasound (US) technology have given US a position as a viable alternative. We aimed to evaluate the diagnostic accuracy of abdominal CT and pancreatic US compared to the reference standard, a modified Mayo score. Materials and Methods CT, US, and endoscopic ultrasound (EUS) were performed in patients referred due to suspected CP. The modified Mayo score included EUS results, clinical presentation, and results from exocrine and endocrine pancreatic function tests. We scored CT findings according to the modified Cambridge classification and US findings according to the Rosemont classification. Results In total, 73 patients were included. 53 patients (73%) were categorized as CP and 20 (27%) as non-CP. CT and US yielded similar sensitivities (68% and 64%, respectively) and specificities (75 and 85%, respectively) and similar areas under the receiver operating characteristic curves for diagnosing CP. We found no significant differences between the areas under the receiver operating characteristic curves (AUROCs) for CT (AUROC 0.75, 95% CI 0.63-0.87) and US (AUROC 0.81, 95% CI 0.71-0.91). Conclusion We conclude that CT and US had comparable, moderate accuracy in diagnosing CP. Neither modality had high enough sensitivity to exclude the diagnosis as a standalone method.

Pancreatic Fibrosis (Early Chronic Pancreatitis) as Emerging Diagnosis in Structural Causes of Dyspepsia: Evidence from Endoscopic Ultrasonography and Shear Wave Elastography

A new concept for the diagnosis and management of non-functional dyspepsia in guidelines was lacking in the past decade. Medical advancement has proven pancreatic fibrosis (essential image evidence of early chronic pancreatitis) to be a cause of dyspepsia and related to pancreatic exocrine dysfunction. This study aimed to analyze the clinical picture, biomarker, and percentage of pancreatic fibrosis in the dyspeptic population. A total of 141 consecutive patients were retrospectively enrolled. They were diagnosed with peptic ulcer disease, 9.2% (n = 13); pancreatic fibrosis, 17% (n = 24); pure Helicobacter pylori infection, 19.9% (n = 28); functional dyspepsia, 53.2% (n = 75); and chronic pancreatitis, 0.7% (n = 1). Among those with pancreatic fibrosis, (n = 24), 11 were diagnosed on the basis of a pancreatic acoustic radiation force impulse exceeding 1.4 m/s, and the remaining 13 were diagnosed with early chronic pancreatitis with at least three of the Japanese endoscopic ultrasonography criteria. The anatomic distribution of parenchymal criteria of early chronic pancreatitis was head, 53%; body, 38%; and tail, 9%. There were 17 cases (71%, 17/24) without Helicobacter pylori and whose dyspepsia improved after pancreatic enzyme replacement with a ratio of 82.3% (14/17). Of the 141 cases, 19 received gastric emptying scintigraphy and Western blot analysis of chromogranin-A in duodenal mucosa. Delayed gastric emptying was more common in functional dyspepsia and chromogranin-A was expressed more in pancreatic fibrosis. In conclusion, pancreatic fibrosis (including early chronic pancreatitis) outnumbered peptic ulcer disease in the dyspeptic population and pancreatic enzyme therapy was effective for 82% of cases. In early chronic pancreatitis, pancreatic fibrosis is dominant in the head location, and duodenum mucosa chromogranin-A is a potential biomarker with increased expression in an age-matched manner.

Comparison of point and two-dimensional shear wave elastography of the spleen in healthy subjects

BACKGROUND

Few systematic comparative studies of the different methods of physical elastography of the spleen are currently available.

AIM

To compare point shear wave and two-dimensional elastography of the spleen considering the anatomical location (upper, hilar, and lower pole).

METHODS

As part of a prospective clinical study, healthy volunteers were examined for splenic elasticity using four different ultrasound devices between May 2015 and April 2017. The devices used for point shear wave elastography were from Siemens (S 3000) and Philips (Epiq 7), and those used for two-dimensional shear wave elastography were from GE (Logiq E9) and Toshiba (Aplio 500). In addition, two different software versions (5.0 and 6.0) were evaluated for the Toshiba ultrasound device (Aplio 500). The study consisted of three arms: A, B, and C.

RESULTS

In study arm A, 200 subjects were evaluated (78 males and 122 females, mean age 27.9 ± 8.1 years). In study arm B, 113 subjects were evaluated (38 men and 75 women, mean age 26.0 ± 6.3 years). In study arm C, 44 subjects were enrolled. A significant correlation of the shear wave velocities at the upper third of the spleen (r = 0.33088, P < 0.0001) was demonstrated only for the Philips Epiq 7 device compared to the Siemens Acuson S 3000. In comparisons of the other ultrasound devices (GE, Siemens, Toshiba), no comparable results could be obtained for any anatomical position of the spleen. The influencing factors age, gender, and body mass index did not show a clear correlation with the measured shear wave velocities.

CONCLUSION

The absolute values of the shear wave elastography measurements of the spleen and the two different elastography methods are not comparable between different manufacturers or models.

Endoscopic ultrasound ablation in a patient with multiple metastatic pancreatic tumors from adrenocorticotropic hormone-producing thymic neuroendocrine neoplasm

Adrenocorticotropic hormone (ACTH)-producing neuroendocrine neoplasm (NEN) of the thymus is rare. Lymph nodes and bones are the most common metastatic sites. Most cases present with florid Cushing's syndrome (CS). Here, we reported a 58-year-old woman, who presented with intermittent flush and weight loss. Imaging studies revealed tumors in the mediastinum, pancreas, and bones. Contrast-enhanced harmonic endoscopic ultrasound (EUS) of the pancreatic tumors showed heterogeneous and hyperenhancing characteristics. EUS elastography revealed a heterogeneous stiff pattern. EUS-fine needle biopsy to the pancreatic lesion confirmed the NEN nature. Serum ACTH and cortisol levels were abnormally high. Immunohistochemical staining of the thymic and pancreatic specimens was positive for ACTH. However, the patient did not have obvious CS appearance. The patient underwent surgery, radiation, EUS-guided ethanol injection, and anti-cancer medications, but the disease still progressed. The patient died from infection 16 months after NEN was diagnosed. In conclusion, the pancreas can be a metastatic site for ACTH-producing thymic NEN. EUS-associated procedures can help in the diagnosis and treatment of pancreatic metastatic NEN.

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).

General principles of image optimization in EUS

With the development of modern EUS, multiple imaging functions, transducer settings, and examination modes have become available for clinical settings. While the major determinants of the ultrasound beam are still comprised of the signal wavelength, its frequency range, and its amplitude, other modifications and calculations have gained more interest for advanced users, such as tissue harmonic imaging (THI), spatial and frequency compounding, certain versions of speckle reduction, and various Doppler/duplex settings. The goal of such techniques is a better, perhaps more realistic image, with reduced artifacts (such as speckle), better image contrast, and an improved signal-to-noise ratio. In addition, “add-ons” such as THI, which is based on the phenomenon of nonlinear distortion of acoustic signals as they travel through tissues, provide greater contrast and an enhanced spatial resolution than conventional EUS. Finally, optimization of spectral and color Doppler imaging in EUS requires experience and knowledge about the basic principles of Doppler/duplex phenomena. For these purposes, factors such as adjustment of Doppler controls, Doppler angle, color gain, spectral wall filters, and others require special attention during EUS examinations. Incorporating these advanced techniques in EUS examinations may be time-consuming and cumbersome. Hence, practical guidelines enabling endosonographers to steer safely through the large quantity of technological properties and settings (knobology) are appreciated. This review provides an overview of the role of important imaging features to be adjusted before, during, and after EUS procedures.

What does liver elastography measure? Technical aspects and methodology

Elastography can be thought as an extension of the ancient technique of palpation. After giving a short introduction to the history of elastography, the different technologies that are nowadays available and the physics behind them, the article focuses on the assessment of liver stiffness in patients with diffuse liver disease using shear wave elastography (SWE). Practical advices on how to perform the SWE techniques and on the factors that should be considered for a correct interpretation of the results are given. This paper aimed to provide a practical guide for beginners and advanced clinical users to better understand technical aspects, methodologies and terminology.

Is Ultrasound Elastography Useful in Predicting Clinically Relevant Pancreatic Fistula After Pancreatic Resection?: A Systematic Review and Meta-analysis

OBJECTIVES

Ultrasound (US) elastography has been proposed for the non-invasive prediction of clinically relevant pancreatic fistula (CR-POPF) in patients undergoing pancreatic resection. We aimed to perform a systematic review with meta-analysis to assess the diagnostic value of US elastography in predicting CR-POPF.

METHODS

MEDLINE via PubMed, Ovid Embase, Scopus, and Cochrane Library databases, and abstracts of international conference proceedings were searched up to April 20, 2020. Studies assessing the performance of abdominal US elastography in predicting CR-POPF in patients undergoing pancreatic resection were included. The quality of the studies was assessed using Quality Assessment of Diagnostic Accuracy Studies.

RESULTS

Five studies, including 247 patients who underwent partial pancreatic resection of whom 72 patients experiencing CR-POPF, were selected. All studies performed US elastography in different pancreatic sites. The pooled mean strain value was lower in pancreatic segments of patients experiencing CR-POPF than in those without, with a pooled weighted mean difference of -0.187 (95% confidence intervals, -0.303 to -0.071; P = 0.002). There was low heterogeneity between studies (I = 7.6%), and all studies were at "high risk" or "unclear risk" of bias.

CONCLUSIONS

This study provides evidence that US elastography values are statistically significantly lower in patients experiencing CR-POPF.

Comparison of Supersonic Shear Wave Imaging-Derived Renal Parenchyma Stiffness Between Diabetes Mellitus Patients With and Without Diabetic Kidney Disease

This study aims to evaluate the difference in renal parenchyma stiffness assessed by measuring Young's modulus (YM) using a supersonic shear wave imaging (SSI) technique among healthy patients and patients with type 2 diabetes mellitus (DM) with and without diabetic kidney disease (DKD). We analyzed the correlations of YM with clinical information and conventional ultrasound parameters. All patients (N = 124) were divided into three groups: (i) healthy patients (patients without kidney disease or type 2 DM, N = 31); (ii) patients with type 2 DM without kidney disease (N = 38); and (iii) patients with DKD (N = 55). Conventional and SSI ultrasound examinations were performed in all individuals for both kidneys. Then, we recorded renal length, width, parenchyma thickness, interlobar arterial resistive index (RI) and values of mean, mininum and maximum YM. The mean values of these parameters for the left and right kidneys were calculated for statistical analysis. Statistical significance was considered at p < 0.05. Among all ultrasound parameters, the mean YM demonstrated the largest area under the receiver operating characteristic (ROC) curve (0.860). The areas under the ROC curve (AUCs) for renal length, width, parenchyma thickness, interlobar arterial RI, minimum YM and maximum YM were 0.493, 0.616, 0.507, 0.733, 0.848 and 0.794, respectively. The corresponding cutoff value of mean YM was 31.73 kPa, with a sensitivity of 85.5% and a specificity of 71.0%. The mean YM in patients with type 2 DM without kidney disease (31.44 ± 3.83 kPa) was significantly higher than that in the healthy group (26.45 ± 4.32 kPa) and lower than that in the DKD group (37.60 ± 6.56 kPa). Patients with type 2 DM without kidney disease were considered as stage 0 of DKD. Thus, the mean YM in the control group was significantly lower than that in the stage 0, 2, 3, 4 and 5 subgroups. The mean YM in the stage 0-2 subgroups was lower than that in the stage 5 group, and the mean YM in the stage 0 group was lower than that in the stage 4 group. In the DKD group, the mean YM had a positive correlation with cystine-c (r = 0.634), urea (r = 0.596), creatine (r = 0.690), uric acid (r = 0.263), albumin/creatinine ratio (r = 0.428) and the presence or absence of diabetic retinopathy (r = 0.354). The mean YM also had a negative correlation with the estimated glomerular filtration rate (r = -0.657). SSI is a non-invasive method with which to diagnose DKD and has a performance superior to that of conventional ultrasound. In addition, SSI may provide a secondary index for the staging of DKD and the monitoring of renal damage in type 2 DM patients.

Pancreatic Fibrosis and Chronic Pancreatitis: Mini-Review of Non-Histologic Diagnosis for Clinical Applications

Pancreatic fibrosis is the dominant reversible pathological change and diagnostic factor in early chronic pancreatitis, defined by a mechanistic approach proposed in 2016. Main guidelines for chronic pancreatitis were published by the American Pancreas Association in 2014, the Japanese Society of Gastroenterology in 2015, and United European Gastroenterology in 2017. All three sets of guidelines mentioned that the staging of chronic pancreatitis is important but challenging. There are various image modalities for the non-histologic diagnosis of pancreatic fibrosis: (1) shear wave elastography, such as an acoustic radiation force impulse with a cut-off value of 1.4 m/s; (2) strain elastography using grades of strain; (3) endoscopic ultrasonography using the Rosemont criteria or endoscopic ultrasound criteria for early chronic pancreatitis proposed by the Japan Pancreas Society; (4) computed tomography using the Hounsfield scale or number of micro-calcifications; and (5) magnetic resonance imaging using the apparent diffusion coefficient and the T1w flash and T2w HASTE sequences. The clinical applications are to (1) evaluate pancreatic tumors and inflammatory disease; (2) monitor dyspepsia with early chronic pancreatitis; (3) monitor individuals with a high risk of pancreatic cancer; (4) analyze a fatty pancreas with fibrosis; (5) predict a fistula after pancreatic surgery; and (6) predict outcomes for chronic pancreatitis or pancreatic cancer. The selection of tools will be dependent on the clinical scenario. Conclusion: There are various modalities for the non-histologic diagnosis of pancreatic fibrosis. The selection of the optimal device will be dependent on the clinical scenario.

Do we need elastography for EUS?

We recently introduced a series of papers “What should be known prior to performing EUS exams.” In Part I, the authors discussed which clinical information and whether other imaging modalities are needed before embarking EUS examinations. In Part II, technical controversies on how EUS is performed were discussed from different points of view. In this article, important practical issues regarding EUS elastography will be raised and controversially discussed from very different points of view.