Dynamic analysis of EUS used for the differentiation of benign and malignant lymph nodes

A quantitative sonoelastography evaluation of ocular and periocular elasticity after intravitreal ranibizumab injection

PURPOSE

We evaluated changes in ocular and periocular elasticity by ultrasound (US) elastography in intravitreal ranibizumab-treated eyes and the healthy fellow eyes of patients with neovascular AMD.

METHODS

The study was performed on 52 eyes of 26 volunteers who ranged in age from 59 to 89 (mean 72±7.78) years old. The study group consisted of the patients with neovascular AMD treated with intravitreal ranibizumab. The fellow eyes (without choroidal neovascularization) of the study group were selected as the control group. All patients were examined with sonoelastography before intravitreal injection and at 1day, 1week, and 1month after intravitreal injection. All images were acquired with a Toshiba Aplio 500 ultrasound system (Tokyo, Japan) including software with a combined autocorrelation method and a multifrequency linear probe. The elastography values of the anterior vitreous (AV), posterior vitreous (PV), retina-choroid-sclera complex (RCS), retrobulbar fat tissue (RF), optic nerve head (ONH) and retrobulbar optic nerve (RON) were measured in each eye.

RESULTS

There were 13 male (50%) and 13 female (50%) participants in our study. Anterior vitreous, posterior vitreous, RCS, retrobulbar fat tissue, ONH, and RON US elastography values were similar in both groups (P˃0.05 for all). On the other hand, there was a positive correlation between the difference between baseline and 1-month PV sonoelastography values and age (r=0.47, P=0.035).

CONCLUSION

A single dose intravitreal Ranibizumab (Lucentis®, Genentech, USA) injection does not alter the elasticity of ocular and periocular structures.

Endoscopic Ultrasound (EUS) Guided Elastography

Endoscopic ultrasound (EUS) is an essential technique for the management of several diseases. Over the years, new technologies have been developed to improve and overcome certain limitations related to EUS-guided tissue acquisition. Among these new methods, EUS-guided elastography, which is a real-time method for the evaluation of tissue stiffness, has arisen as one of the most widely recognized and available. At present, there are available two different systems to perform an elastographic evaluation: strain elastography and shear wave elastography. Strain elastography is based on the knowledge that certain diseases lead to a change in tissue hardness while shear wave elastography monitored shear-wave propagation and measures its velocity. EUS-guided elastography has shown in several studies high accuracy in differentiating benign from malignant lesions from many different locations, mostly in the pancreas and lymph nodes. Therefore, nowadays, there are well-established indications for this technology, mainly for supporting the management of pancreatic diseases (diagnosis of chronic pancreatitis and differential diagnosis of solid pancreatic tumors) and characterization of different diseases. However, there are more data on new potential indications for the near future. In this review, we will present the theoretical bases of this technology and we will discuss the scientific evidence to support its use.

Endoscopic Ultrasound Advanced Techniques for Diagnosis of Gastrointestinal Stromal Tumours

Gastrointestinal Stromal Tumors (GISTs) are subepithelial lesions (SELs) that commonly develop in the gastrointestinal tract. GISTs, unlike other SELs, can exhibit malignant behavior, so differential diagnosis is critical to the decision-making process. Endoscopic ultrasound (EUS) is considered the most accurate imaging method for diagnosing and differentiating SELs in the gastrointestinal tract by assessing the lesions precisely and evaluating their malignant risk. Due to their overlapping imaging characteristics, endosonographers may have difficulty distinguishing GISTs from other SELs using conventional EUS alone, and the collection of tissue samples from these lesions may be technically challenging. Even though it appears to be less effective in the case of smaller lesions, histology is now the gold standard for achieving a final diagnosis and avoiding unnecessary and invasive treatment for benign SELs. The use of enhanced EUS modalities and elastography has improved the diagnostic ability of EUS. Furthermore, recent advancements in artificial intelligence systems that use EUS images have allowed them to distinguish GISTs from other SELs, thereby improving their diagnostic accuracy.

The expanding role of endoscopic ultrasound elastography

Endoscopic ultrasound (EUS) is an invaluable tool for assessing various GI diseases. However, using just the conventional B-mode EUS imaging may not be sufficient to accurately delineate the lesion's character. Using the principle of stress-induced tissue strain, EUS elastography (EUS-E) can help in the real-time sonographic assessment of the level of tissue stiffness or hardness of any organ of interest during a routine EUS procedure. Thus, EUS-E can better characterize the lesion's nature and highlight the more suspicious areas within an individual lesion. The most commonly studied lesions with EUS-E are the pancreatic lesions, namely, chronic pancreatitis, pancreatic cancer, and lymph nodes. However, EUS-E is gradually expanding its use for lesion characterization of the liver, bile duct, adrenals, gastrointestinal tract, and even therapy response. Moreover, the use of EUS-E along with other image enhancement techniques such as harmonic EUS and contrast-enhanced EUS can improve the accuracy of the diagnosis. However, several technical aspects need to be standardized before EUS-E can be truly used as a tool for "virtual biopsy". This review focuses on the various technical aspects of the use of EUS-E, it is established and expanding indications and an extensive outline of the various studies on EUS-E. We also discuss the current pitfalls and future trends in EUS-E.

Accuracy of Ultrasound Diagnosis of Benign and Malignant Thyroid Nodules: A Systematic Review and Meta-Analysis

Background

Distinguishing between benign and malignant thyroid nodules remains difficult. Ultrasound has been established as a non-invasive and relatively simple imaging technique for thyroid nodules. This study aimed to assess the diagnostic accuracy of conventional ultrasound and ultrasound elastography for the differentiation between benign and malignant thyroid nodules by meta-analyzing published studies.

Methods

Literature was retrieved from the PubMed and Embase databases from inception to May 31, 2022. The literature was screened using inclusion and exclusion criteria. The Quality Assessment of Diagnostic Accuracy Studies (QUADAS2) scale was used to assess the quality of the included literature. Publication bias of the included studies was assessed by Deek's funnel plot. Heterogeneity tests were performed using Cochrane Q statistic and I2 statistic.

Results

Finally, 9 articles were included. The meta-analysis showed that the combined sensitivity and specificity of ultrasound for the diagnosis of thyroid nodules were 0.88 [95% CI (0.83-0.91)] and 0.86 [95% CI (0.79-0.90)], respectively. The area under the curve (AUC) of the summary receiver operating characteristic curve (SROC) was 0.92 [95% CI (0.90-0.94)]. There was no significant publication bias in this study. Discussion. Existing evidence shows that ultrasound has a certain accuracy in diagnosing benign and malignant thyroid nodules, providing a scientific basis for thyroid assessment and diagnosis.

Recent Advances in Endosonography-Elastography: Literature Review

Ultrasonographic elastography is a modality used to visualize the elastic properties of tissues. Technological advances in ultrasound equipment have supported the evaluation of elastography (EG) in endosonography (EUS). Currently, the usefulness of not only EUS-strain elastography (EUS-SE) but also EUS-shear wave elastography (EUS-SWE) has been reported. We reviewed the literature on the usefulness of EUS-EG for various diseases such as chronic pancreatitis, pancreatic solid lesion, autoimmune pancreatitis, lymph node, and gastrointestinal and subepithelial lesions. The importance of this new diagnostic parameter, "tissue elasticity" in clinical practice might be applied not only to the diagnosis of liver fibrosis but also to the elucidation of the pathogeneses of various gastrointestinal diseases, including pancreatic diseases, and to the evaluation of therapeutic effects. The most important feature of EUS-EG is that it is a non-invasive modality. This is an advantage not found in EUS-guided fine needle aspiration (EUS-FNA), which has made remarkable progress in the field of diagnostics in recent years. Further development of artificial intelligence (AI) is expected to improve the diagnostic performance of EUS-EG. Future research on EUS-EG is anticipated.

Ultrasound Elastography for the Evaluation of Lymph Nodes

The differential diagnosis of lymphadenopathy is important for predicting prognosis, staging, and monitoring the treatment, especially for cancer patients. Conventional computed tomography and magnetic resonance imaging characterize lymph node (LN) with disappointing sensitivity and specificity. Conventional ultrasound with the advantage of high resolution has been widely used for the LN evaluation. Ultrasound elastography (UE) using color map or shear wave velocity can non-invasively demonstrate the stiffness and homogeneity of both the cortex and medulla of LNs and can detect early circumscribed malignant infiltration. There is a need of a review to comprehensively discuss the current knowledge of the applications of various UE techniques in the evaluation of LNs. In this review, we discussed the principles of strain elastography and shear wave-based elastography, and their advantages and limitations in the evaluation of LNs. In addition, we comprehensively introduced the applications of various UE techniques in the differential diagnosis of reactive LNs, lymphoma, metastatic LNs, and other lymphadenopathy. Moreover, the applications of endoscopic UE and endobronchial UE are also discussed, including their use for improving the positive rate of diagnosis of fine-needle aspiration biopsy.

Automatic Image Selection Model Based on Machine Learning for Endobronchial Ultrasound Strain Elastography Videos

Background

Endoscopic ultrasound (EBUS) strain elastography can diagnose intrathoracic benign and malignant lymph nodes (LNs) by reflecting the relative stiffness of tissues. Due to strong subjectivity, it is difficult to give full play to the diagnostic efficiency of strain elastography. This study aims to use machine learning to automatically select high-quality and stable representative images from EBUS strain elastography videos.

Methods

LNs with qualified strain elastography videos from June 2019 to November 2019 were enrolled in the training and validation sets randomly at a quantity ratio of 3:1 to train an automatic image selection model using machine learning algorithm. The strain elastography videos in December 2019 were used as the test set, from which three representative images were selected for each LN by the model. Meanwhile, three experts and three trainees selected one representative image severally for each LN on the test set. Qualitative grading score and four quantitative methods were used to evaluate images above to assess the performance of the automatic image selection model.

Results

A total of 415 LNs were included in the training and validation sets and 91 LNs in the test set. Result of the qualitative grading score showed that there was no statistical difference between the three images selected by the machine learning model. Coefficient of variation (CV) values of the four quantitative methods in the machine learning group were all lower than the corresponding CV values in the expert and trainee groups, which demonstrated great stability of the machine learning model. Diagnostic performance analysis on the four quantitative methods showed that the diagnostic accuracies were range from 70.33% to 73.63% in the trainee group, 78.02% to 83.52% in the machine learning group, and 80.22% to 82.42% in the expert group. Moreover, there were no statistical differences in corresponding mean values of the four quantitative methods between the machine learning and expert groups (p >0.05).

Conclusion

The automatic image selection model established in this study can help select stable and high-quality representative images from EBUS strain elastography videos, which has great potential in the diagnosis of intrathoracic LNs.

Efficacy of Endoscopic Ultrasound Elastography in Differential Diagnosis of Gastrointestinal Stromal Tumor Versus Gastrointestinal Leiomyoma

BACKGROUND The diagnostic efficacy of endoscopic ultrasound (EUS) elastography for alimentary tract diseases remains uncertain. The aim of this study was to evaluate the utility of EUS elastography in differential diagnosis between the 2 most common subepithelium tumors of the digestive tract - gastrointestinal stromal tumors (GISTs) and gastrointestinal leiomyomas (GILs) - which cannot be differentiated by conventional EUS imaging. MATERIAL AND METHODS Electronic records were retrospectively reviewed from Jan 2015 to Jul 2019. Patients accepting EUS elastography with histopathological diagnosis of GISTs or GILs were included. The images of EUS elastography were analyzed by hue histogram in Photoshop. Hue values of RGB, R, G, and B channels of each group were acquired. We used the t test, ROC curve analysis, and binary logistic regression analysis for data post-processing. RESULTS We included 47 patients with GISTs and 14 with GILs. The mean±standard deviations (SD) of hue values were 20.25±0.72, -0.79±0.78, 20.79±1.68, 39.72±1.30 for GISTs and 20.80±0.46, 1.80±1.05, 28.39±2.15, and 31.95±2.60 for GILs of RGB, R, G, and B channels, respectively. The t test showed statistically significant differences in mean hue values between GISTs and GILs in B and G channels, but not in RGB and R channels. The area under the ROC curve combining B and G values was 0.723. Binary logistic regression analysis suggested no statistically significant difference in ability to differentiate between GISTs and GILs with B and G values (P>0.05). CONCLUSIONS There was insufficient evidence to support the application of quantitative EUS elastography for differential diagnosis of GISTs and GILs in this study.

Enhanced EUS imaging (with videos)

BACKGROUND AND AIMS

EUS remains a primary diagnostic tool for the evaluation of pancreaticobiliary disease. Although EUS combined with FNA or biopsy sampling is highly sensitive for the diagnosis of neoplasia within the pancreaticobiliary tract, limitations exist in specific clinical settings such as chronic pancreatitis. Enhanced EUS imaging technologies aim to aid in the detection and diagnosis of lesions that are commonly evaluated with EUS.

METHODS

We reviewed technologies and methods for enhanced imaging during EUS and applications of these methods. Available data regarding efficacy, safety, and financial considerations are summarized.

RESULTS

Enhanced EUS imaging methods include elastography and contrast-enhanced EUS (CE-EUS). Both technologies have been best studied in the setting of pancreatic mass lesions. Robust data indicate that neither technology has adequate specificity to serve as a stand-alone test for pancreatic malignancy. However, there may be a role for improving the targeting of sampling and in the evaluation of peritumoral lymph nodes, inflammatory pancreatic masses, and masses with nondiagnostic FNA or fine-needle biopsy sampling. Further, novel applications of these technologies have been reported in the evaluation of liver fibrosis, pancreatic cysts, and angiogenesis within neoplastic lesions.

CONCLUSIONS

Elastography and CE-EUS may improve the real-time evaluation of intra- and extraluminal lesions as an adjunct to standard B-mode and Doppler imaging. They are not a replacement for EUS-guided tissue sampling but provide adjunctive diagnostic information in specific clinical situations. The optimal clinical use of these technologies continues to be a focus of ongoing research.

Diagnostic value of endobronchial ultrasound image features: A specialized review

Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) technology is important in the diagnosis of intrathoracic benign and malignant lymph nodes (LNs). With the development of EBUS imaging technology, its role in noninvasive diagnosis, as a supplement to pathology diagnosis, has been given increasing attention in recent years. Many studies have explored qualitative and quantitative methods for the three EBUS modes, as well as a variety of multimodal analysis methods, to find the optimal method for the noninvasive diagnosis using EBUS for LNs. Here, we review and comment on the research methods and predictive diagnostic value, discuss the existing problems, and look ahead to the future application of EBUS imaging.

Evaluating the use of elastography in endobronchial ultrasound technique as a diagnostic approach for mesothorax lymphadenopathy

Introduction: Non-small cell lung cancer is still diagnosed at a late stage although we have new diagnostic equipment such the radial endobronchial ultrasound, convex probe endobronchial ultrasound, and electromagnetic navigation. The diagnostic techniques have been upgraded with rapid on-site evaluation (ROSE) and currently from 2014 real-time elastography is being evaluated as a ROSE technique.Areas covered: A thorough search was performed on PubMed and Scopus with the following key words: elastography, strain ratio, convex probe EBUS, endoscopic ultrasound (EUS), elastography. In the current mini review, we will focus on published data regarding elastography with the convex probe endobronchial ultrasound in two different systems and comment on this future ROSE technique. Elastography, strain ratio, and factors such as(I) margin (indistinct or distinct); (II) shape (oval or round); (III) short-axis size less or more than 1 cm; (IV) presence or absence of central hilar structure (CHS); (V) echogenicity (homogeneous or heterogeneous); and (VI) presence or absence of coagulation necrosis sign are presented in our review based on published literature.Expert opinion: Current data indicate that we can have up to 93% sensitivity and specificity of real-time elastography and strain ratio for the evaluation of benignancy and malignancy; however, sample biopsy is still necessary. For now, we can only reduce the number of punctures.

Contribution of endobronchial ultrasound elastography to the characterization of mediastinal lymphadenopathy: A single-center, prospective, observational study

BACKGROUND

Endobronchial ultrasound transbronchial needle aspiration (EBUS-TBNA) is a reliable technique providing high diagnostic yield in mediastinal lymphadenopathy. However, mediastinoscopy is sometimes necessary to eliminate false-negative results. Elastography is a recent technique that can be combined with EBUS to evaluate the elasticity and consequently the nature of a tissue. The primary objective was to evaluate the diagnostic performance of EBUS-TBNA combined with elastography for the assessment of mediastinal lymph nodes.

METHODS

Single-center, prospective study in patients with mediastinal lymphadenopathy. EBUS-TBNA combined with elastography was performed in each patient. Several elastographic parameters were studied: colorimetric score, average elasticity, elasticity ratio, percentage of hard areas. The final diagnosis was that obtained by TBNA cytology, histology of a surgical biopsy, when performed, or follow-up CT and PET-CT at 6 months.

RESULTS

Overall, 110 lymph nodes were examined in 87 patients: 44 were malignant according to TBNA. These nodes had significantly higher elasticity ratio, percentage of hard areas and colorimetric score and significantly lower average elasticity compared to benign nodes (P<0.001). With a negative predictive value of 100%, the cut-offs defined by receiver operating characteristic curves were 1.4 for elasticity ratio, 84.8 for average elasticity, 32.6 for percentage of hard areas and 3 for colorimetric score. No adverse events were observed.

CONCLUSION

Endobronchial ultrasound elastography is a non-invasive technique that can contribute to prediction of the nature of lymph nodes by distinguishing malignant from benign nodes. Although EBUS cannot replace histological examination, elastography can provide reliable complementary information when combined with EBUS.

Performance of Molecular Lymphosonography for Detection and Quantification of Metastatic Involvement in Sentinel Lymph Nodes

OBJECTIVES

To assess the performance of molecular lymphosonography with dual-targeted microbubbles in detecting and quantifying the metastatic involvement in sentinel lymph nodes (SLNs) using a swine melanoma model.

METHODS

Targeted microbubbles were labeled with P-selectin and αV β3 -integrin antibodies. Control microbubbles were labeled with immunoglobulin G antibodies. First lymphosonography with Sonazoid (GE Healthcare, Oslo, Norway) was used to identify SLNs. Then dual-targeted and control microbubbles were injected intravenously to detect and quantify metastatic disease in the SLNs. Distant non-SLNs were imaged as benign controls. All evaluated lymph nodes (LNs) were surgically removed, and metastatic involvement was characterized by a histopathologic analysis. Two radiologists blinded to histopathologic results assessed the baseline B-mode images of LNs, and the results were compared to the histologic reference standard. The mean intensities of targeted and control microbubbles within the examined LNs were measured and compared to the LN histologic results.

RESULTS

Thirty-five SLNs and 34 non-SLNs from 13 Sinclair swine were included in this study. Twenty-one SLNs (62%) were malignant, whereas 100% of non-SLNs were benign. The sensitivity of B-mode imaging for metastatic LN diagnosis for both readers was relatively high (90% and 71%), but the specificity was very poor (50% and 58%). The sensitivity and specificity of molecular lymphosonography for metastatic LN detection were 91% and 67%, respectively. The mean intensities from dual-targeted microbubbles correlated well with the degree of metastatic LN involvement (r = 0.6; P < 0.001).

CONCLUSIONS

Molecular lymphosonography can increase the specificity of metastatic LN detection and provide a measure to quantify the degree of metastatic involvement.

Gastroenterology and pancreatic adenocarcinoma: what the radiologist needs to know

In this article, we review the information that radiologists need to know regarding the endoscopic approach to the diagnosis and management of pancreatic cancer. This includes a review of the indications, techniques, and complications of endoscopic ultrasound. We also review information regarding endoscopic retrograde cholangiopancreatography, including the various biliary drainage techniques and the use of endoscopic palliation for patients with pancreatic cancer.

New Imaging Techniques: Endoscopic Ultrasound-Guided Elastography

Endoscopic ultrasound (EUS) is a major imaging method in the management of several diseases of the gastrointestinal tract and surrounding structures. Elastography is a novel technique providing additional information to standard B-mode imaging on the tissue stiffness. Elastography can be performed under EUS guidance. This method has proven to be an accurate and additional tool in the evaluation of pancreatic diseases and lymph nodes analysis. Possible uses include the study of liver lesions, subepithelial masses, and many more. This article reviews current knowledge and future perspectives.

Maximizing the endosonography: The role of contrast harmonics, elastography and confocal endomicroscopy

New technologies in endoscopic ultrasound (EUS) evaluation have been developed because of the need to improve the EUS and EUS-fine needle aspiration (EUS-FNA) diagnostic rate. This paper reviews the principle, indications, main literature results, limitations and future expectations for each of the methods presented. Contrast-enhanced harmonic EUS uses a low mechanical index and highlights slow-flow vascularization. This technique is useful for differentiating solid and cystic pancreatic lesions and assessing biliary neoplasms, submucosal neoplasms and lymph nodes. It is also useful for the discrimination of pancreatic masses based on their qualitative patterns; however, the quantitative assessment needs to be improved. The detection of small solid lesions is better, and the EUS-FNA guidance needs further research. The differentiation of cystic lesions of the pancreas and the identification of the associated malignancy features represent the main indications. Elastography is used to assess tissue hardness based on the measurement of elasticity. Despite its low negative predictive value, elastography might rule out the diagnosis of malignancy for pancreatic masses. Needle confocal laser endomicroscopy offers useful information about cystic lesions of the pancreas and is still under evaluation for use with solid pancreatic lesions of lymph nodes.

The impact of electrode resistance on the biogalvanic characterisation technique

Measurement of a tissue-specific electrical resistance may offer a discriminatory metric for evaluation of tissue health during cancer surgery. With a move toward minimally-invasive procedures, applicable contact sensing modalities must be scalable, fast and robust. A passive resistance characterisation method utilising a biogalvanic cell as an intrinsic power source has been proposed as a potentially suitable solution. Previous work has evaluated this system with results showing effective discrimination of tissue type and damage (through electroporation). However, aspects of the biogalvanic cell have been found to influence the characterisation performance, and are not currently accounted for within the system model. In particular, the electrode and salt-bridge resistance are not independently determined, leading to over-predictions of tissue resistivity.

This paper describes a more comprehensive model and characterisation scheme, with electrode parameters and salt-bridge resistivity being evaluated independently. In a generalised form, the presented model illustrates how the relative resistive contributions from the electrodes and medium relate to the existing characterisation method efficacy. We also describe experiments with physiologically relevant salt solutions (1.71, 17.1, 154 mM), used for validation and comparison. The presented model shows improved performance over the current biogalvanic measurement technique at the median conductivity. Both the proposed and extant system models become unable to predict conductivity accurately at high conductivity due to the dominance of the electrodes. The characterisation techniques have also been applied to data collected on freshly excised human colon tissue (healthy and cancerous). The findings suggest that the resistance of the cell under the test conditions is electrode dominated, leading to erroneous tissue resistance determination. Measurement optimisation strategies and the surgical applicability of the biogalvanic technique are discussed in light of these findings.

Endoscopic Ultrasound Elastography: Current Clinical Use in Pancreas

Elastography is a newer technique for the assessment of tissue elasticity using ultrasound. Cancerous tissue is known to be stiffer (hence, less elastic) than corresponding healthy tissue, and as a result, could be identified in an elasticity-based imaging. Ultrasound elastography has been used in the breast, thyroid, and cervix to differentiate malignant from benign neoplasms and to guide or avoid unnecessary biopsies. In the liver, elastography has enabled a noninvasive and reliable estimate of fibrosis. Endoscopic ultrasound has become a robust diagnostic and therapeutic tool for the management of pancreatic diseases. The addition of elastography to endoscopic ultrasound enabled further characterization of pancreas lesions, and several European and Asian studies have reported encouraging results. The current clinical role of endoscopic ultrasound elastography in the management of pancreas disorders and related literature are reviewed.

Endobronchial ultrasound elastography

Elastographic techniques have recently become available as advanced diagnostic tools for tissue characterization. Strain elastography is a real-time technique used with transcutaneous ultrasound (US) and endoscopic US. Convincing evidence is available demonstrating a significant value of strain elastography for the discrimination of benign and malignant lymph nodes (LNs). This paper reviews preliminary data demonstrating the feasibility of performing real-time elastography during endobronchial US (EBUS) and a potential application of this technique for selection of LNs for EBUS-guided transbronchial needle aspiration in patients with lung cancer and extrathoracic malignancies.

Diagnostic potential of endoscopic ultrasonography-elastography for gastric submucosal tumors: A pilot study

BACKGROUND AND AIM

Qualitative diagnosis for gastric submucosal tumors (SMT) is not easy. Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) in combination with EUS-elastography (EUS-EG) is reported useful for qualitatively diagnosing pancreatic tissues. We prospectively studied whether EUS-EG could be useful in qualitative diagnosis of gastric SMT.

METHODS

We prospectively registered 25 consecutive patients with gastric SMT diagnosed by esophagogastroduodenoscopy and carried out qualitative evaluations using EUS-EG (May 2013 to March 2015) followed by histopathological diagnosis using EUS-FNA or endoscopic mucosal cutting biopsy. Elastic scores of gastric SMT were compared to the cytological diagnosis.

RESULTS

Of 25 patients, 22 had a confirmed cytological diagnosis. Regarding the Giovannini elastic score, of three patients with aberrant pancreas, one was score 1 and two were score 2; of eight patients with leiomyoma, seven were score 2 and one was score 3. Both of two patients with schwannoma were score 4. Of nine patients with gastrointestinal stromal tumor, six were score 4 and three were score 5. Gastrointestinal stromal tumor (GIST) is harder than other types of gastric SMT, and our study's findings suggested the usefulness of EUS-EG, which can also assess tumor hardness of gastric SMT.

CONCLUSION

EUS-EG might be helpful for the differential diagnosis of gastric SMT, especially to differentiate GIST from other SMT.

A novel multiple electrode direct current technique for characterisation of tissue resistance during surgery

Electrochemical and electrical characteristics have the potential to help differentiate between, and assess the health state of, different biological tissues. However, measurement and interpretation of these characteristics is non-trivial. We propose a new DC galvanostatic sensing method for application to laparoscopic cancer surgery. This presents a simple and cost-effective measurement coupled with straightforward data interpretation. This paper describes the electrochemical and electrical theory underpinning the technique. Additionally, we describe a measurement system employing this technique and present an investigation into the feasibility of using it for measuring the resistance of different tissue types. Measurements were performed on ex vivo porcine liver, colon and rectum tissues. Outputs were consistent with theory and showed a significant difference between the resistance of the different tissue types, (one-way ANOVA, F(2, 28) = 1369, p <; 0.01). These findings indicate that this novel technique may be viable as a low cost method for the discrimination and health assessment of tissues in clinical scenarios.

Transcutaneous Ultrasound: Elastographic Lymph Node Evaluation. Current Clinical Applications and Literature Review

Distinguishing malignant versus benign lymphadenopathies is a major diagnostic dilemma in clinical medicine. Metastatic deposits in normal-sized lymph nodes (LNs) can be smaller than a millimeter, thus presenting a diagnostic challenge. In most clinical settings, however, enlarged LNs detected on imaging need to be classified as malignant or benign. Ultrasound seems to be a very reliable method for LN characterization because of the high resolution, especially in the subcutaneous areas. However, B-mode and Doppler-ultrasound criteria for characterization of a lymphadenopathy as benign or malignant are lacking specificity. Newer methods such as elastography seem to be valuable for identifying metastatic deposits within LNs and may help discriminate malignant and benign LNs. This review summarizes the different elastographic methods available and provides an overview of the relevant publications. According to the literature, elastography can be used for identifying metastatic deposits, to guide fine needle aspiration and to non-invasively choose the most suspicious LN of a group of enlarged LNs for targeted biopsy.

Endoscopic ultrasound elastography: Current status and future perspectives

Elastography is a new ultrasound modality that provides images and measurements related to tissue stiffness. Endoscopic ultrasound (EUS) has played an important role in the diagnosis and management of numerous abdominal and mediastinal diseases. Elastography by means of EUS examination can assess the elasticity of tumors in the proximity of the digestive tract that are hard to reach with conventional transcutaneous ultrasound probes, such as pancreatic masses and mediastinal or abdominal lymph nodes, thus improving the diagnostic yield of the procedure. Results from previous studies have promised benefits for EUS elastography in the differential diagnosis of lymph nodes, as well as for assessing masses with pancreatic or gastrointestinal (GI) tract locations. It is important to mention that EUS elastography is not considered a modality that can replace biopsy. However, it may be a useful adjunct, improving the accuracy of EUS-fine needle aspiration biopsy (EUS-FNAB) by selecting the most suspicious area to be targeted. Even more, it may be useful for guiding further clinical management when EUS-FNAB is negative or inconclusive. In the present paper we will discuss the current knowledge of EUS elastography, including the technical aspects, along with its applications in the differential diagnosis between benign and malignant solid pancreatic masses and lymph nodes, as well as its aid in the differentiation between normal pancreatic tissues and chronic pancreatitis. Moreover, the emergent indication and future perspectives are summarized, such as the benefit of EUS elastography in EUS-guided fine needle aspiration biopsy, and its uses for characterization of lesions in liver, biliary tract, adrenal glands and GI tract.

Endobronchial ultrasound elastography strain ratio for mediastinal lymph node diagnosis

Background

Ultrasound elastography is an imaging procedure that can assess the biomechanical characteristics of different tissues. The aim of this study was to define the diagnostic value of the endobronchial ultrasound (EBUS) elastography strain ratio of mediastinal lymph nodes in patients with a suspicion of lung cancer. The diagnostic values of the strain ratios were compared with the EBUS brightness mode (B-mode) features of selected mediastinal lymph nodes and with their cytological diagnoses.

Patients and methods

This prospective, single-centre study enrolled patients with an indication for biopsy and mediastinal staging after a non-invasive diagnostic workup of a lung tumour. EBUS with standard B-mode evaluation and elastography with strain ratio measurement were performed before endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA).

Results

Thirty-three patients with 80 suspicious mediastinal lymph nodes were included. Malignant infiltration was confirmed in 34 (42.5%) lymph nodes. The area under the receiver operating characteristic curve for the strain ratio was 0.87 (p < 0.0001). At a strain ratio ≥ 8, the accuracy for malignancy prediction was 86.25% (sensitivity 88.24%, specificity 84.78%, positive predictive value [PPV] 81.08%, negative predictive value [NPV] 90.70%). The strain ratio is more accurate than conventional B-mode EBUS modalities for differentiating between malignant and benign lymph nodes.

Conclusions

EBUS-guided elastography with strain ratio assessment can distinguish malignant from benign mediastinal lymph nodes with greater accuracy than conventional EBUS modalities. This new method may reduce the number of mediastinal EBUS-TBNAs and thus reduce the invasiveness and expense of mediastinal staging in patients with non-small lung cancer (NSCLC).

Ultrasound Elastography for Differentiating Benign from Malignant Thickened Greater Omentum

OBJECTIVES

To investigate whether ultrasound elastography (UE) is an effective non-invasive diagnostic procedure for evaluating benign and malignant thickened greater omentum.

METHODS

Ultrasound elastographic images from 118 patients who underwent ultrasound-guided biopsy for thickened greater omentum from May 2012 to October 2013 were retrospectively analysed. The results were compared with the pathological findings from the biopsies, and evaluated by ROC curve analysis.

RESULTS

A total of 93.6% of the benign thickened greater omentum had elasticity scoring of 1 or 2, whereas 93.0% of the malignant thickened greater omentum had elasticity scoring of 3 or 4. The elasticity strain ratios for malignant thickened greater omenta were higher than for benign thickened greater omenta using muscle or fat yielded as reference tissue (P < 0.01). The optimal cut-off point for elasticity strain ratios using fat as reference was 2.6. The sensitivity, specificity, accuracy, and positive and negative predictive values for determining elasticity strain ratios using fat as reference were 83.3%, 90.6%, 86.5%, 92.1%, and 80.6%, respectively, and for elasticity scoring were 95.2%, 96.9%, 95.9%, 97.6%, and 93.9%, respectively.

CONCLUSIONS

UE using elasticity scoring or elasticity strain ratios is an effective new non-invasive method for differentiating benign from malignant thickened greater omentum.

KEY POINTS

• Elasticity score is an objective method for differentiating greater omentum lesions. • Elasticity strain ratio is another method for differentiating greater omentum lesions. • Fat tissue is better than abdominal wall muscle as reference in elasticity imaging. • UE is a new effective, non-invasive method for diagnosing omental diseases.

A time-dependent model for improved biogalvanic tissue characterisation

Measurement of the passive electrical resistance of biological tissues through biogalvanic characterisation has been proposed as a simple means of distinguishing healthy from diseased tissue. This method has the potential to provide valuable real-time information when integrated into surgical tools. Characterised tissue resistance values have been shown to be particularly sensitive to external load switching direction and rate, bringing into question the stability and efficacy of the technique. These errors are due to transient variations observed in measurement data that are not accounted for in current electrical models. The presented research proposes the addition of a time-dependent element to the characterisation model to account for losses associated with this transient behaviour. Influence of switching rate has been examined, with the inclusion of transient elements improving the repeatability of the characterised tissue resistance. Application of this model to repeat biogalvanic measurements on a single ex vivo human colon tissue sample with healthy and cancerous (adenocarcinoma) regions showed a statistically significant difference (p < 0.05) between tissue types. In contrast, an insignificant difference (p > 0.05) between tissue types was found when measurements were subjected to the current model, suggesting that the proposed model may allow for improved biogalvanic tissue characterisation.

Endoscopic Ultrasound in the Diagnosis and Staging of Pancreatic Cancer

Pancreatic cancer is one of the digestive cancers with the poorest prognosis, so an early and correct diagnosis is of utmost importance. With the development of new therapeutic options an accurate staging is essential. Endoscopic ultrasonography (EUS) has a major role in all stages of the management of these patients. EUS has a high accuracy in the diagnosis of pancreatic adenocarcinoma and the possibility to perform fine-needle aspiration/biopsy (FNA/FNB) increases the diagnostic yield of EUS. There is still no consensus on the several technical aspects of FNA, namely on the rapid on-site evaluation (ROSE), the diameter and type of needle, the number of passes and the use of stylet and suction. Contrast-enhanced EUS (CE-EUS) and EUS elastography (EUS-E) have been used in recent years as an adjunct to EUS-FNA. Given the higher sensitivity of these techniques a negative cytology by EUS-FNA should not exclude malignancy when CE-EUS and/or EUS-E are suggestive of pancreatic neoplasia. EUS remains one of the main methods in the staging of pancreatic adenocarcinoma, namely to further evaluate patients with non-metastatic disease that appears resectable on initial imaging. EUS is crucial for an accurate preoperative evaluation of pancreatic cancer which is essential to choose the correct management strategy. The possibility to obtain samples from suspicious lesions or lymph nodes, by means of EUS-guided fine-needle aspiration as well as the use of contrast-enhanced and elastography, makes EUS an ideal modality for the diagnosis and staging of pancreatic cancer.

Endoscopic ultrasound: Elastographic lymph node evaluation

Different imaging techniques can bring different information which will contribute to the final diagnosis and further management of the patients. Even from the time of Hippocrates, palpation has been used in order to detect and characterize a body mass. The so-called virtual palpation has now become a reality due to elastography, which is a recently developed technique. Elastography has already been proving its added value as a complementary imaging method, helpful to better characterize and differentiate between benign and malignant masses. The current applications of elastography in lymph nodes (LNs) assessment by endoscopic ultrasonography will be further discussed in this paper, with a review of the literature and future perspectives.

Can elastography replace fine needle aspiration?

Endoscopic ultrasound (EUS) is one of the best diagnostic methods for diseases of the digestive tract and surrounding organs. Whereas EUS-guided fine needle aspiration (FNA) has been very useful for providing histological confirmation for previously hard to reach lesions, elastography is aiming to obtain a “virtual biopsy” by assessing differences in elasticity between the normal and pathological – usually malignant – tissue. A question that arises is whether EUS-elastography has reached a stage where it might successfully supplant the use of EUS-FNA in some of its clinical indications. The main indications of EUS-guided FNA are listed in this article and published data on the usage of elastography in these settings is reviewed for each one. In some of the indications, a plethora of studies have been published, notably for the evaluation of solid pancreatic masses and lymph nodes, while in others there is little relevant data (submucosal masses, left liver lesions, left adrenal masses), or elastography simply is not suitable as a diagnostic means (cystic lesions). Our conclusion is that elastography is not yet ready to replace EUS-FNA in its indications, but should complement it in various settings, especially for the assessment of lymph nodes. It can only be considered an alternative on a case-by-case basis, in situations where FNA is regarded as a contraindication. Furthermore, it could be used in conjunction with other imaging techniques, such as contrast-enhanced EUS, in order to further improve the accuracy of non-invasive EUS assessment, possibly making the case for a more limited or targeted use of EUS-FNA in selected cases.

Yield of Contrast-Enhanced Power Doppler Endoscopic Ultrasonography and Strain Ratio Obtained by EUS-Elastography in the Diagnosis of Focal Pancreatic Solid Lesions

OBJECTIVE

Although endoscopic ultrasonography-guided fine needle aspiration (EUS-FNA) is the gold standard for diagnosing pancreatic lesions, its negative predictive value is suboptimal. Our aim was to evaluate the yield of contrast-enhanced EUS (CED-EUS) and of strain ratio EUS-elastography (SR-E-EUS) for differentiating pancreatic solid lesions.

METHODS

Forty-seven patients (27 men, 20 women, 70 ± 11 years) were consecutively involved in this single-center, prospective study. They were submitted to EUS, SR-E-EUS, CED-EUS with Sonovue(®), and EUS-FNA. The final diagnosis was based on the histological assessment of EUS-FNA and/or surgical specimens when available, and on follow-up of at least 6 months.

RESULTS

From the 47 focal pancreatic lesions included, 13 (28%) were benign and 34 (72%) malignant. Patients with malignancy were older (70 ± 11 vs. 61 ± 8, P = 0.003), and had larger lesions (34 ± 12 mm vs. 22 ± 11 mm, P = 0.03). Malignant lesions had higher SR-E-EUS (31 ± 32 vs. 8 ± 9, P = 0.001) and more hypovascular pattern (93% vs. 33%, P < 0.001). Logistic regression determined that only hypovascularity (OR = 2.6, 95%CI: 1.5-130, P = 0.02) was independently predictive of malignancy. ROC analysis for SR-E-EUS yielded an optimal cutoff of 8 (AUC 0.91, 95%CI: 0.74-0.98) for the best power distinction for malignancy. There was no significant difference concerning sensitivity (79%, 90%, 93%) and specificity rates (85%, 75%, 67%) of EUS-FNA, SR-E-EUS, and CED-EUS, respectively. By analysis of the inconclusive EUS-FNA subset (9 patients, 19%), SR-E-EUS > 8 and hypovascularity showed sensitivity of 80% and 100%, and specificity of 67% and 67%, respectively.

CONCLUSION

The clinical utility of CED-EUS and SR-E-EUS remains questionable. The accuracies of CED-EUS and SR-E-EUS are similar to EUS-FNA. Hypovascularity was independently predictive of malignancy. Patients with inconclusive EUS-FNA could benefit from CED-EUS due to the high sensitivity of hypovascularity for diagnosing malignancy.

Distant lymph node metastases in gastroesophageal junction adenocarcinoma: impact of endoscopic ultrasound-guided fine-needle aspiration

OBJECTIVE

Endoscopic ultrasound (EUS) is established as the most accurate technique for pre-operative locoregional staging of gastroesophageal junction (GEJ) adenocarcinoma, the purpose of the present study was to evaluate the distant lymph nodes (LNs) EUS-fine-needle aspiration (FNA) impact in therapeutic decision for patients with GEJ adenocarcinoma.

MATERIALS AND METHODS

Retrospective study was made, with cross-sectional, non-probabilistic analysis from prospectively collected database for all GEJ adenocarcinoma staging patients referred between January 2009 and August 2012 in Paoli-Calmette Institute in Marseille-France.

RESULTS

A total of 154 patients with GEJ adenocarcinoma were managed in our institution, of whom 113 (73.3%) had non-distant metastatic disease at computed tomography (CT) scan and underwent EUS for initial tumor staging prior to a treatment decision. On A total of 113 patients undergoing EUS, 8 (7%) patients underwent endoscopic resection and 6 (5.3%) underwent direct surgical resection. Of the remaining 99 patients (87.6%), 24 (21.2%) distant LN EUS-FNA were made. Seventeen LN had EUS malignant features, including 9 (52.9%) that were confirmed as malignant and underwent palliative treatment with chemotherapy. Ninety (79.6%) patients were treated with pre-operative neoadjuvant therapy and were revaluated after. 4 (4.4%) had metastatic disease at CT scan (underwent palliative treatment) and 65 (72.2%) underwent EUS restaging to treatment decision revaluation. Of these, twelve (18.4%) distant LN EUS-FNA were performed. Seven had LN EUS malignancy features, including 4 (57.1%) that were confirmed as malignant and underwent palliative treatment. The remaining 61 patients underwent surgery. As stated above, 21 patients (23.3%) did not undergo EUS restaging, including 10 (47.6%) that did not go to surgery because patient's age, poor general status and comorbidities, 6 (28.5%) had a loss of follow-up, 1 (4.7%) underwent to surgery due to chemotherapy collateral effects, 3 (14.2%) were still on pre-operative chemotherapy and 1 (4.7%) died for sepsis after mediastinal EUS-FNA, this was the only complication event evidenced. EUS-FNA changed clinical management in 54.2% of patients who met the criteria inclusion (distant LN with malignancies EUS features), which corresponds to 11.5% of patients with GEJ adenocarcinoma.

CONCLUSION

EUS-FNA was able to provide a different tumor staging and these differences were associated with treatment received. EUS-FNA had a significant impact on treatment decision.

Accuracy of visual scoring and semi-quantification of ultrasound strain elastography--a phantom study

Purpose

The aim of this study was to evaluate the performance of strain elastography in an elasticity phantom and to assess which factors influenced visual scoring, strain histograms and strain ratios. Furthermore this study aimed to evaluate the effect of observer experience on visual scorings.

Materials and Methods

Two operators examined 20 targets of various stiffness and size (16.7 to 2.5 mm) in an elasticity phantom at a depth of 3.5 cm with a 5–18 MHz transducer. Two pre-settings were used yielding 80 scans. Eight evaluators, four experienced, four inexperienced, performed visual scorings. Cut-offs for semi-quantitative methods were established for prediction of target stiffness. Data was pooled in two categories allowing calculations of sensitivity and specificity. Statistical tests chi-square test and linear regression as relevant.

Results

Strain ratios and strain histograms were superior to visual scorings of both experienced and inexperienced observers (p = 0.025, strain histograms vs. experienced observers, p<0.001, strain histograms vs. inexperienced observers, p = 0.044 strain ratios vs. experienced observers and p = 0.002 strain ratios vs. inexperienced observers). No significant difference in predicting target stiffness between strain ratios and strain histograms (p = 0.83) nor between experienced and inexperienced observers (p = 0.054) was shown when using four categories. When pooling data in two groups (80 kPa/45 kPa vs. 14/8 kPa) the difference between the observers became significant (p<0.001). Target size had a significant influence on strain ratios measurements (p = 0.017) and on visual scorings (p<0.001) but not on the strain histograms(p = 0.358). Observer experience had significant effect on visual scorings(p = 0.003).

Conclusion

Strain ratios and strain histograms are superior to visual scoring in assessing target stiffness in a phantom. Target size had a significant impact on strain ratios and visual scoring, but not on strain histograms. Experience influenced visual scorings but the difference between experienced and inexperienced observers was only significant when looking at two classes of target stiffness.

Technical Advances in Endoscopic Ultrasound (EUS)-Guided Tissue Acquisition for Pancreatic Cancers: How Can We Get the Best Results with EUS-Guided Fine Needle Aspiration?

Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is one of the least invasive and most effective modality in diagnosing pancreatic adenocarcinoma in solid pancreatic lesions, with a higher diagnostic accuracy than cystic tumors. EUS-FNA has been shown to detect tumors less than 3 mm, due to high spatial resolution allowing the detection of very small lesions and vascular invasion, particularly in the pancreatic head and neck, which may not be detected on transverse computed tomography. Furthermore, this minimally invasive procedure is often ideal in the endoscopic procurement of tissue in patients with unresectable tumors. While EUS-FNA has been increasingly used as a diagnostic tool, most studies have collectively looked at all primary pancreatic solid lesions, including lymphomas and pancreatic neuroendocrine neoplasms, whereas very few studies have examined the diagnostic utility of EUS-FNA of pancreatic ductal carcinoma only. As with any novel and advanced endoscopic procedure that may incorporate several practices and approaches, endoscopists have adopted diverse techniques to improve the tissue procurement practice and increase diagnostic accuracy. In this article, we present a review of literature to date and discuss currently practiced EUS-FNA technique, including indications, technical details, equipment, patient selection, and diagnostic accuracy.

New ultrasound techniques for lymph node evaluation

Conventional ultrasound (US) is the recommended imaging method for lymph node (LN) diseases with the advantages of high resolution, real time evaluation and relative low costs. Current indications of transcutaneous ultrasound and endoscopic ultrasound include the detection and characterization of lymph nodes and the guidance for LN biopsy. Recent advances in US technology, such as contrast enhanced ultrasound (CEUS), contrast enhanced endoscopic ultrasound (CE-EUS), and real time elastography show potential to improve the accuracy of US for the differential diagnosis of benign and malignant lymph nodes. In addition, CEUS and CE-EUS have been also used for the guidance of fine needle aspiration and assessment of treatment response. Complementary to size criteria, CEUS could also be used to evaluate response of tumor angiogenesis to anti-angiogenic therapies. In this paper we review current literature regarding evaluation of lymphadenopathy by new and innovative US techniques.

Distant lymph node metastases in gastroesophageal junction adenocarcinoma: impact of endoscopic ultrasound-guided fine-needle aspiration

OBJECTIVE

Endoscopic ultrasound (EUS) is established as the most accurate technique for pre-operative locoregional staging of gastroesophageal junction (GEJ) adenocarcinoma, the purpose of the present study was to evaluate the distant lymph nodes (LNs) EUS-fine-needle aspiration (FNA) impact in therapeutic decision for patients with GEJ adenocarcinoma.

MATERIALS AND METHODS

Retrospective study was made, with cross-sectional, non-probabilistic analysis from prospectively collected database for all GEJ adenocarcinoma staging patients referred between January 2009 and August 2012 in Paoli-Calmette Institute in Marseille-France.

RESULTS

A total of 154 patients with GEJ adenocarcinoma were managed in our institution, of whom 113 (73.3%) had non-distant metastatic disease at computed tomography (CT) scan and underwent EUS for initial tumor staging prior to a treatment decision. On A total of 113 patients undergoing EUS, 8 (7%) patients underwent endoscopic resection and 6 (5.3%) underwent direct surgical resection. Of the remaining 99 patients (87.6%), 24 (21.2%) distant LN EUS-FNA were made. Seventeen LN had EUS malignant features, including 9 (52.9%) that were confirmed as malignant and underwent palliative treatment with chemotherapy. Ninety (79.6%) patients were treated with pre-operative neoadjuvant therapy and were revaluated after. 4 (4.4%) had metastatic disease at CT scan (underwent palliative treatment) and 65 (72.2%) underwent EUS restaging to treatment decision revaluation. Of these, twelve (18.4%) distant LN EUS-FNA were performed. Seven had LN EUS malignancy features, including 4 (57.1%) that were confirmed as malignant and underwent palliative treatment. The remaining 61 patients underwent surgery. As stated above, 21 patients (23.3%) did not undergo EUS restaging, including 10 (47.6%) that did not go to surgery because patient's age, poor general status and comorbidities, 6 (28.5%) had a loss of follow-up, 1 (4.7%) underwent to surgery due to chemotherapy collateral effects, 3 (14.2%) were still on pre-operative chemotherapy and 1 (4.7%) died for sepsis after mediastinal EUS-FNA, this was the only complication event evidenced. EUS-FNA changed clinical management in 54.2% of patients who met the criteria inclusion (distant LN with malignancies EUS features), which corresponds to 11.5% of patients with GEJ adenocarcinoma.

CONCLUSION

EUS-FNA was able to provide a different tumor staging and these differences were associated with treatment received. EUS-FNA had a significant impact on treatment decision.

EUS elastography for diagnosis of solid pancreatic masses: a meta-analysis

BACKGROUND

The differential diagnosis of solid pancreatic masses has been a significant challenge up until now. EUS elastography is now used as a new technique to distinguish benign from malignant pancreatic masses. However, the sensitivity, specificity, and accuracy are still questionable.

OBJECTIVE

To evaluate the accuracy of EUS elastography for diagnosis of solid pancreatic masses.

DESIGN

Thirteen articles for EUS elastography diagnosing solid pancreatic masses were selected. The Mantel-Haenszel and DerSimonian Laird methods were used to analyze pooled results.

PATIENTS

This study involved 1044 patients.

INTERVENTION

EUS elastography.

MAIN OUTCOME MEASUREMENTS

The pooled sensitivity, specificity, likelihood ratios, diagnostic odds ratio, and summary receiver operating characteristic (sROC) curve.

RESULTS

The pooled sensitivity, specificity, and diagnostic odds ratio of EUS elastography distinguishing benign from malignant solid pancreatic masses were 0.95 (95% confidence interval [CI], 0.94-0.97), 0.67 (95% CI, 0.61-0.73), and 42.28 (95% CI, 26.90-66.46), respectively. The sROC area under the curve was 0.9046. The subgroup analysis based on excluding the outliers showed that the heterogeneity was eliminated, and the pooled sensitivity and specificity were 0.95 (95% CI, 0.93-0.97) and 0.7 (95% CI, 0.63-0.76), respectively. The sROC area under the curve was 0.8872.

LIMITATIONS

Varied diagnostic standards for EUS elastography were used in the enrolled studies.

CONCLUSION

EUS elastography is a reliable technique for the characterization of solid pancreatic masses and may be a useful complementary tool for EUS-guided FNA. However, a more accurate computer-aided diagnosis method for EUS elastography is in demand to reduce various biases and improve the accuracy of EUS elastography for diagnosis of solid pancreatic masses.

Intra-operative tumour detection and staging in colorectal cancer surgery

AIM

Surgical resection for colorectal cancer involves segmental resection and regional lymphadenectomy. The appropriateness of this 'one-size-fits-all' strategy is questioned as bowel cancer screening programmes result in a shift to earlier stage disease. Currently, the nodal status of a colorectal cancer can only be reliably determined by histopathological examination of the resected specimen. New methods of intra-operative staging are required to allow surgical resection to be tailored to the stage of the disease.

METHOD

A literature search was performed of PubMed and Embase databases using the terms 'colon' OR 'colorectal' AND 'intra-operative detection' OR 'intra-operative staging' OR 'intra-operative detection' OR 'radioimmunoguided surgery'. Articles published between January 1980 and January 2012 were included. Technologies that have the potential to allow intra-operative staging and treatment stratification were identified and further searches performed.

RESULTS

Established techniques such as sentinel lymph node mapping and radioimmunoguided surgery have benefited from combination with other technologies to allow real-time intra-operative staging. Intra-operative fluorescence, using naturally fluorescent biomarkers or fluorescent tumour probes, probably offers the most practical means of intra-operative lymph node staging and may be facilitated using nanotechnology. Optical coherence tomography and real-time elastography have the potential to provide an in vivo'virtual biopsy'.

CONCLUSION

Technological advances may allow accurate intra-operative lymph node staging to facilitate tailored surgical resection. This may become the next paradigm shift in colorectal cancer surgery.

Diagnostic value of EUS elastography in differentiation of benign and malignant solid pancreatic masses: a meta-analysis

BACKGROUND/AIMS

EUS elastography is a novel technique that can be used for distinguishing benign from malignant lymph nodes and focal pancreatic masses. However, the studies pertaining to EUS elastography for differential diagnosis of solid pancreatic masses have reported widely varied sensitivities and specificities. A meta-analysis of all relevant articles was performed to estimate the overall diagnostic accuracy of EUS elastography for differentiating benign and malignant solid pancreatic masses.

METHODS

The literatures were identified by searching in PubMed and Embase databases. Two reviewers independently extracted the information from the literatures for constructing 2 × 2 table. A random-effect model or a fixed-effect model was used to estimate the sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio. A summary receiver operating characteristic curve (SROC) also was constructed. Meta-regression and subgroup analysis were used to explore the sources of heterogeneity.

RESULTS

13 studies including a total of 1042 patients with solid pancreatic masses were selected for meta-analysis. The pooled sensitivity and specificity of EUS elastography for differentiating benign and malignant solid pancreatic masses were 95% (95% confidence interval [CI], 93%-96%), 69% (95% CI, 63%-75%), respectively. The area under SROC (AUC) was 0.8695. Two significant variables were associated with heterogeneity: color pattern and blinding.

CONCLUSION

As a less invasive modality, EUS elastography is a promising method for differentiating benign and malignant solid pancreatic masses with a high sensitivity, and it can prove to be a valuable supplement to EUS-FNA.

Real-time elastography for diagnosis of liver fibrosis in chronic hepatitis B

OBJECTIVES

The purpose of this study was to prospectively investigate the value of real-time ultrasound elastography for diagnosis of liver fibrosis in patients with chronic hepatitis B and to correlate the elastographic findings with histologic stages of liver fibrosis and blood parameters.

METHODS

Liver biopsies, blood testing, and real-time elastography were performed in 71 patients with chronic viral hepatitis B and liver cirrhosis. The ratio of the elastic strain of liver tissue to that of muscle tissue was determined and correlated with the histologic fibrosis stages and laboratory examination results.

RESULTS

There was a highly negative correlation between the elastic strain ratio and the histologic fibrosis stage (Spearman r = -0.702; P < .001). There was a high correlation observed between a decreasing elastic strain ratio and an increasing fibrosis stage. With substantial liver fibrosis (Scheuer score ≥ S2) and cirrhosis (S4) as diagnostic criteria, the areas under the receiver operating characteristic curves (AUCs) of the elastic strain ratios were 0.863 and 0.797, respectively. The AUC for substantial fibrosis was higher than the AUC for the blood parameters used to diagnose substantial liver fibrosis. Elastic strain ratio cutoff values of 1.10 and 0.60 were identified as diagnostic of substantial fibrosis and cirrhosis, respectively, with sensitivities of 77.8% and 50.0%, respectively, and specificities of 80.0% and 96.7%.

CONCLUSIONS

Real-time elastography is a new clinically promising and noninvasive method for quantitative assessment of liver fibrosis.

Endoscopic ultrasound elastography

Endoscopic ultrasound (EUS) is a reference technique for diagnosing and staging several different diseases. EUS-guided biopsies and fine needle aspirations are used to improve diagnostic performance of cases where a definitive diagnosis cannot be obtained through conventional EUS. However, EUS-guided tissue sampling requires experience and is associated with a low but not negligible risk of complications. EUS elastography is a non-invasive method that can be used in combination with conventional EUS and has the potential for improving the diagnostic accuracy and reducing the need for EUS-guided tissue sampling in several situations. Elastography measures tissue stiffness by evaluating changes in the EUS image before and after the application of slight pressure to the target tissue by the ultrasonography probe. Pathologic processes such as cancerization and fibrosis alter tissue elasticity and therefore induce changes in elastographic appearance. Qualitative elastography depicts tissue stiffness using different colors, whereas quantitative elastography renders numerical results expressed as a strain ratio or hue histogram mean. EUS elastography has been proven to differentiate between benign and malignant solid pancreatic masses, as well as between benign and malignant lymph nodes with a high accuracy. Studies have also demonstrated that the early changes of chronic pancreatitis can be distinguished from normal pancreatic tissues under EUS elastography. In this article, we review the technical aspects and current clinical applications of qualitative and quantitative EUS elastography and emphasize the potential additional indications that need to be evaluated in future clinical studies.

Endoscopic ultrasound image enhancement elastography

Endoscopic ultrasound (EUS) represents an advance in the diagnosis and staging of several diseases. EUS-guided fine-needle aspiration is useful, but technically demanding, and can be associated with complications. Elastography emerges as a useful tool that is based on the knowledge that some diseases, like cancer, lead to a modification in tissue stiffness. Elastography evaluates the elastic properties of tissues and compares images obtained before and after compression to target tissues; differentiating benign from malignant lesions. This article reviews theoretical aspects and the methodology of EUS elastography. Clinical applications, mainly in pancreatic diseases and lymph nodes, are analyzed.