Gastrointestinal imaging: endoscopic ultrasound

Diagnostic Endoscopic Ultrasound (EUS) of the Luminal Gastrointestinal Tract

The purpose of this review is to focus on the diagnostic endoscopic ultrasound of the gastrointestinal tract. In the last decades, EUS has gained a central role in the staging of epithelial and sub-epithelial lesions of the gastrointestinal tract. With the evolution of imaging, the position of EUS in the diagnostic work-up and the staging flow-chart has continuously changed with two extreme positions: some gastroenterologists think that EUS is absolutely indispensable, and some think it is utterly useless. The truth is, as always, somewhere in between the two extremes. Analyzing the most up-to-date and strong evidence, we will try to give EUS the correct position in our daily practice.

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.

Circular array transducer based-photoacoustic/ultrasonic endoscopic imaging with tunable ring-beam excitation

Photoacoustic/ultrasound endoscopic imaging is regarded as an effective method to achieve accurate detection of intestinal disease by offering both the functional and structural information, simultaneously. Compared to the conventional endoscopy with single transducer and laser spot for signal detection and optical excitation, photoacoustic/ultrasound endoscopic probe using circular array transducer and ring-shaped laser beam avoids the instability brought by the mechanical scanning point-to-point, offering the dual-modality imaging with high accuracy and efficiency. Meanwhile, considering the complex morphological environments of intestinal tracts in clinics, developing the probe having sufficient wide imaging distance range is especially important. In this work, we develop a compact circular photoacoustic/ultrasonic endoscopic probe, using the group of fiber, lens and home-made axicon, to generate relatively concentrated ring-shaped laser beam for 360° excitation with high efficiency. Furthermore, the laser ring size can be tuned conveniently by changing the fiber-lens distance to ensure the potential applicability of the probe in various and complex morphological environments of intestines. Phantom experimental results demonstrate imaging distance range wide enough to cover from 12 mm to 30 mm. In addition, the accessibility of the photoacoustic signals of molecular probes in ex vivo experiments at the tissue depth of 7 mm using excitation energy of 5 mJ has also been demonstrated, showing a high optical excitation efficiency of the probe.

Endoscopic ultrasonography: Enhancing diagnostic accuracy

Endoscopic ultrasound (EUS) is an essential technique for the management of several diseases. Over the years, new technologies have been developed because to improve and overcome certain limitations related to EUS guided tissue acquisition. Among these new methods, EUS guided elastography and contrast enhanced EUS has arisen as the most widely recognized and available. We will review in this manuscript the different techniques of elastography and contrast enhancement. Nowadays, there are well establish indications for advance imaging, mainly for supporting the management of pancreatic diseases (diagnosis of chronic pancreatitis and differential diagnosis of solid and cystic pancreatic tumors) and characterization of lymph nodes. However, there are more data on new potential indications for the near future.

Ex vivo ultrasonographic and histological morphometry of small intestinal wall layers in horses

Ultrasonographic morphometry of wall layers is commonly used in veterinary patients with suspected small intestinal disease, however published studies comparing this method with histopathology in horses are limited. This prospective, methods comparison study compared the qualitative and quantitative characteristics of small intestinal wall layers using ex vivo high‐frequency ultrasound versus histopathology in a sample of 16 horses. Transverse section images of duodenum, distal jejunum, and ileum were acquired with a high‐frequency linear transducer (7–15 MHz). Transverse histological cryosections were obtained at the same level. Appearance and measurements of the intestinal wall layers were assessed on the ultrasonographic and histological images. High‐frequency scanning with the probe in close contact with the serosal surface of the equine intestinal wall allowed a clear and detailed definition of wall layers. A hyperechoic line was consistently detected within the tunica muscularis in all the intestinal tracts, corresponding histologically to the interface between its longitudinal and circular muscle layers. The overall trend of the values for wall layers thickness was comparable between ex vivo ultrasonography and histology. However, a poor agreement was found between the two methods for all layers. The ultrasonographic measurements were thicker compared to histological measurements, with the exception of the total wall and the muscular layer thicknesses. These layers were thinner on ultrasonography in the duodenum and in all the intestinal segments, respectively. Findings from the current study can be used as background for future ultrasonographic investigations of small intestinal diseases in horses.

Comparison of the Diagnostic Efficiency of Radial- and Convex-Arrayed Echoendoscopes for Indirect Findings of Pancreatic Cancer: A Retrospective Comparative Study Using Propensity Score Method

Simple Summary

Pancreatic cancer (PC) has a poor prognosis; however, diagnosing PC at an earlier stage could improve long-term patient outcomes. Endoscopic ultrasonography (EUS) plays an important role in PC detection, and the indirect findings (caliber change, retention cysts, and dilatation of the branch duct) that are detected by EUS are especially important for the early detection of PC. The aim of this retrospective study was to compare the diagnostic efficacy of radial- and convex-arrayed echoendoscope for the detection rate of indirect findings. As a result, the radial-arrayed echoendoscope was found to be an independent detection factor of indirect findings by multivariate analysis. The radial-arrayed echoendoscope is useful for the detection of indirect findings.

Abstract

Endoscopic ultrasonography (EUS) is useful for detecting early-stage pancreatic cancer. Because the detection of small lesions is difficult, it is important to detect indirect findings, namely caliber change, retention cysts, and dilatation of the branch duct, during the procedure. Although two types of EUS endoscopes are frequently used, there is no comparative study on their efficacy for detecting indirect findings. Therefore, we aimed to compare the diagnostic efficacy of these two types for indirect findings. We retrospectively analyzed 316 consecutive patients who had undergone EUS for pancreaticobiliary disease at a single center between January 2017 and December 2018. The main outcome was the detection rate of indirect findings and its comparison between the two echoendoscope types. This outcome was achieved using the inverse probability of treatment weighting (IPTW) analysis. The detection rate of indirect findings was higher for the radial-arrayed endoscope than for the convex-arrayed echoendoscope (9.2% vs. 2.3% (p = 0.02)). The univariate analysis also revealed that the radial-arrayed echoendoscope was significantly superior to the convex-arrayed echoendoscope in terms of the detection of indirect findings (odds ratio, 5.94; 95% confidence interval, 1.68–21.10; p = 0.01) after IPTW. After adjustment for magnetic resonance imaging (MRI) and computed tomography (CT), radial-arrayed echoendoscope remained an independent factor for indirect finding detection (odds ratio, 6.04; 95% confidence interval, 1.74–21.00; p = 0.01). Finally, five patients who had indirect EUS findings were diagnosed with pancreatic cancer. Our results indicate that the radial-arrayed echoendoscope is useful for the detection of indirect findings.

Staging esophageal cancer: low EUS accuracy in t2n0 patients

Background and study aims  Esophageal cancer (EC) is one of the most lethal malignancies worldwide. Staging of EC is performed with computed tomography (CT), positron-emission tomography (PET), and endoscopic ultrasonography (EUS). Patient management mostly depends on lymph node status. Compared to histopathology, the accuracy of EUS for T and N parameters is about 85 % and 75 %, respectively. Errors in staging may change prognosis. The aim of this study was to assess the role of EUS in T2-N0 EC considering the experience of two high-volume digestive endoscopic centers. Methods  Two prospectively collected databases were queried to identify all patients with EC, staged as cT2N0 by EUS, with no distant metastases at CT/PET scan and who underwent transthoracic esophagectomy. Preoperative EUS staging (cTNM) was compared to histopathology of the surgical specimen (pTNM) to evaluate accuracy. Results  Of 729 consecutive patients with EC between January 2011 and September 2018, 72 (49 men) had cT2N0 disease. CT and PET scans confirmed the absence of distant metastasis. In 43 of 72 patients (60 %), the evaluation was correct, 23 of 72 (31,7 %) were understaged, and six of 72 patients (8,3 %) were overstaged. Among the understaged patients, eight were understaged by tumor depth (35 %), seven by nodal involvement (30 %), and eight by both (35 %). All six patients who were overstaged had T1b-N0 disease. EUS accuracy was 77 % in staging for tumor depth and 82 % in staging for nodal metastases. The positive predictive value (PPV) for cT2N0 EC was 60 % (43 pT2N0 /72 cT2N). Conclusions  The accuracy of EUS staging of T2N0 EC is low, with only 60 % of patients undergoing appropriate therapy based on histopathology.

Factors Affecting the Accuracy of Endoscopic Ultrasonography in the Diagnosis of Early Gastric Cancer Invasion Depth: A Meta-analysis

Background

Endoscopic ultrasonography (EUS) is the first imaging modality for investigating the depth of invasion in early gastric cancer (EGC). However, there is presently no consensus on the accuracy of EUS in diagnosing the invasion depth of EGC.

Aim

This study is aimed at systematically evaluating the accuracy of EUS in diagnosing the invasion depth of EGC and its affecting factors.

Methods

The literatures were identified by searching PubMed, SpringerLink, Cochrane Library, Web of Science, Nature, and Karger knowledge databases. Two researchers extracted the data from the literature and reconstructed these in 2 × 2 tables. The Meta-DiSc software was used to evaluate the overall sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic advantage ratio, and 95% confidence interval (CI). The SROC was drawn, and the area under the curve (AUC) was calculated to evaluate the diagnostic value.

Results

A total of 17 articles were selected, which included 4525 cases of lesions. The sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic dominance ratio, and 95% CI of EUS for diagnosing EGC was 0.87 (95% CI: 0.86-0.88), 0.67 (95% CI: 0.65-0.70), 2.90 (95% CI: 2.25-3.75), 0.17 (95% CI: 0.13-0.23), and 18.25 (95% CI: 12.61-26.39), respectively. The overall overstaging rate of mucosa/submucosa 1 (M/SM1) and SM by EUS was 13.31% and 32.8%, respectively, while the overall understaging rate of SM was 29.7%. The total misdiagnosis rates for EUS were as follows: 30.4% for lesions ≥ 2 cm and 20.9% for lesions < 2 cm, 27.7% for ulcerative lesions and 21.4% for nonulcerative lesions, and 22% for differentiated lesions and 26.9% for undifferentiated lesions.

Conclusion

EUS has a moderate diagnostic value for the depth of invasion of EGC. The shape, size, and differentiation of lesions might be the main factors that affect the accuracy of EUS in diagnosing EGC.

Quantitative Elastography Versus Fine-needle Aspiration by Endoscopic Ultrasound for the Assessment of Pancreatic Solid Masses

BACKGROUND AND AIMS

Pancreatic solid masses (PSM) are difficult to assess; endoscopic ultrasound with fine-needle aspiration (FNA) enables tissue acquisition, but has high false-negative rates. Quantitative elastography (QE) predicts diagnosis on the basis of the strain ratio (SR). We aimed to compare both methods to evaluate PSM.

MATERIALS AND METHODS

This prospective study, carried out between January and December 2016, included suspected PSM cases; those with advanced disease and cystic components were excluded. Both procedures were performed; histologic information was obtained for the final diagnoses. Diagnostic tests and receiver-operating characteristic curve were calculated. P<0.05 was considered statistically significant.

RESULTS

We included 134 patients (53% women; mean, 53±16.2 y). The median tumor size was 30 (10 to 78) mm, with 69.4% and 30.6% malignant and benign tumors (median SR: 19.5 vs. 7.5; P=0.000), respectively, and 87% were pancreatic adenocarcinoma. QE with SR cutoff ≥10 showed similar parameters to FNA in both PSM types: sensitivity, 94% in both; specificity, 85% versus 87%; positive predictive value, 93% versus 94%; negative predictive value, 87% in both; and accuracy, 92% for malignant and sensitivity, 85% versus 87%; specificity, 94% in both; positive predictive value, 87% in both; negative predictive value, 93% versus 94%; and accuracy, 92% for benign. The area under the curve was 0.96 (P<0.000; 95% confidence interval, 0.940-0.995). New classifications on the basis of positive likelihood ratio were grouped as follows: A ≤8.7 (benign tumor); B >8.7 to <15.5 (indeterminate); and C ≥15.5 (malignant).

CONCLUSIONS

QE has similar capacity to FNA in PSM evaluation. However, the former can be used potentially as a substitute of the latter in certain cases on the basis of these new SR cutoff-based classifications.

Effects of premedication with Pronase for endoscopic ultrasound of the stomach: A randomized controlled trial

AIM

To analyze the effects of premedication with Pronase for endoscopic ultrasound (EUS) examination of the stomach.

METHODS

This was a prospective, randomized and controlled clinical study. All patients were randomly assigned to either the Pronase group or placebo group. The pretreatment solution was a mixed solution of 20000 U of Pronase and 60 mL sodium bicarbonate solution in the Pronase group, while an equal amount of sodium bicarbonate solution was administered to the placebo group. All operators, image evaluators and experimental recorders in EUS did not participate in the preparation and allocation of pretreatment solution. Two blinded investigators assessed the obscurity scores for the EUS images according to the size of artifacts (including ultrasound images of the gastric cavity and the gastric wall). Differences in imaging quality, the duration of examination and the usage of physiological saline during the examination process between the Pronase group and the control group were compared.

RESULTS

No differences existed in patient demographics between the two groups. For the gastric cavity, the Pronase group had significantly lower mean obscurity scores than the placebo group (1.0476 ± 0.77 vs 1.6129 ± 0.96, respectively, P = 0.000). The mean obscurity scores for the gastric mucosal surface were significantly lower in the Pronase group than the placebo group (1.2063 ± 0.90 vs 1.7581 ± 0.84, respectively, P = 0.001). The average EUS procedure duration for the Pronase group was 11.60 ± 3.32 min, which was significantly shorter than that of the placebo group (13.13 ± 3.81 min, P = 0.007). Less saline was used in the Pronase group than the placebo group, and the difference was significant (417.94 ± 121.38 mL vs 467.42 ± 104.52 mL, respectively, P = 0.016).

CONCLUSION

The group that had Pronase premedication prior to the EUS examination had clearer images than the placebo group. With Pronase premedication, the examination time was shorter, and the amount of saline used during the EUS examination was less.

Acute Pancreatitis Etiology Investigation: A Workup Algorithm Proposal

BACKGROUND

Acute pancreatitis represents a significant number of hospital admissions. Most of the patients are admitted in an acute setting. Early identification of its etiology is an essential step toward the rational approach, both for its implications in the immediate therapy and the prevention of recurrence. Although often obvious, the etiological workup of acute pancreatitis can be challenging.

CONCLUSION

There are several studies emphasizing the multiple etiologies underlying acute pancreatitis but lacking structured diagnostic workups to allow a rational and organized study. The main goal of this work is to develop an algorithm proposal, which aims to serve as a guide for the investigation of the etiology of acute pancreatitis based on a review of already published literature, adjusted to the reality of our hospital and the available resources.

Endoscopic ultrasound-guided fine needle aspiration: The wet suction technique

Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) has become a fundamental tool in obtaining cytopathological diagnosis of pancreatic tumors. When sampling solid lesions of the pancreas, the endosonographer can use two suction techniques to enhance tissue acquisition; the dry and the wet suction techniques. The standard dry suction technique relies on applying negative pressure suction on the proximal end of the needle after the stylet is removed with a pre-vacuum syringe. The wet suction technique relies on pre-flushing the needle with saline to replace the column of air with fluid followed by aspiration the proximal end by using a prefilled syringe with saline. A new modified wet suction technique (hybrid suction technique) relies on preloading the needle with saline, but having continuous negative pressure with a pre-vacuum syringe to avoid manual intermittent suction. Tissue acquisition can be enhanced by applying fluid dynamic principles to the current aspiration techniques, such as the column of water used in the needle of the wet technique. In this review, we will focus on EUS-FNA using the wet suction technique for sampling of pancreatic solid lesions.

Correlation between preoperative endoscopic ultrasound and surgical pathology staging of gastric adenocarcinoma: A single institution retrospective review

BACKGROUND

Recent evidence validates the effectiveness of neoadjuvant chemotherapy in the treatment of gastric adenocarcinoma. Endoscopic ultrasonographic (EUS) staging has been proposed as a useful adjunct in this setting.

METHODS

We performed a retrospective review of patients treated at our institution for gastric adenocarcinoma between July 2005 and January 2014. We identified patients referred for EUS before surgery as part of a prospective treatment plan. Histopathologic staging was compared to EUS staging, with a focus on T- and N-stage. Agreement between the two modalities was examined using kappa-statistics.

RESULTS

We identified 614 patients with biopsy-proven gastric adenocarcinoma; 145 underwent curative-intent surgery. Surgical pathology and EUS results were available from 69 patients. The accuracy of EUS for the evaluation of T- and N-stage was 44.9% and 56.5%, respectively. EUS demonstrated greater concordance with histopathology at evaluating T-stage (κ = 0.3469) than N-stage (κ = 0.1316). EUS underestimated T- and N-stage in 40.8% and 30.4% of patients, respectively.

CONCLUSION

EUS seems to correlate poorly with pathology in the preoperative staging of gastric adenocarcinoma. In the majority of inaccurate cases, EUS underestimates T-stage and N-stage, limiting its utility in the neoadjuvant setting.

Performance of novel tissue harmonic echo imaging using endoscopic ultrasound for pancreatic diseases

BACKGROUND AND STUDY AIMS

Recently, tissue harmonic echo (THE) imaging has advanced with the development of a new endoscopic ultrasound (EUS) monitor/processing unit. With this new technology, penetration (THE-P) and resolution (THE-R) images can be obtained. The aim of this study was to investigate the performance of this novel THE imaging using a new processing unit for pancreatic diseases.

PATIENTS AND METHODS

Fifty patients with pancreatic lesions (38 cystic, 12 solid) were retrospectively analyzed. At each examination, 3 EUS images of the same pancreatic lesion were obtained using B-mode, THE-P mode, and THE-R mode imaging. Each set of EUS images was randomly arranged and evaluated independently by 4 physicians blinded to the imaging technique. Images were compared using a Likert scale 5-point grading system for each parameter.

RESULTS

For cystic lesions, THE-P mode images were significantly superior to conventional B-mode images for visualizing the boundary, septum, nodules, and total image quality (P < 0.05). THE-R mode images were significantly superior to conventional B-mode images for visualizing the boundary, septum, and total image quality (P < 0.05). However, for solid lesions, there was no significant difference in all the evaluation points between THE-P and conventional B-mode images. THE-R mode images were inferior to conventional B-mode images for visualizing the boundary, internal structure, and total image quality (P < 0.05).

CONCLUSIONS

For pancreatic cystic lesions, THE mode images provided better lesion characterization than conventional B-mode images. Further research is required to determine if this improvement will result in improved EUS diagnostics.

Endoscopic ultrasonography for staging depth of invasion in early gastric cancer: A meta-analysis

BACKGROUND AND AIM

Endoscopic ultrasonography (EUS) is a widely used imaging modality for detecting the depth of early gastric cancer (EGC) invasion. However, the studies pertaining to EUS for staging early gastric cancer have reported widely varied sensitivities and specificities. This study was conducted to estimate the overall diagnostic accuracy of EUS for staging the depth in EGCs.

METHODS

The literatures were identified by searching in PubMed, Embase, and Web of Knowledge 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 also was constructed. Meta-regression and subgroup analysis were used to explore the sources of heterogeneity.

RESULTS

The pooled sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio of EUS for M staging were 76% (95% confidence interval [CI], 74-78%), 72% (95% CI, 69-75%), 3.67 (95% CI, 2.48-5.44), and 0.31 (95% CI, 0.24-0.40), respectively. For SM staging, these results were 62% (95% CI, 59-66%), 78% (95% CI, 76-80%), 2.99 (95% CI, 2.26-3.96), and 0.43 (95% CI, 0.32-0.57), respectively. For M/SM1 staging, they were 90% (95% CI, 88-92%), 67% (95% CI, 61-72%), 3.14 (95% CI, 2.08-4.73), and 0.12 (95% CI, 0.07-0.22), respectively. The area under the curve for mucosal, submucosal, and mucosal/minimal submucosal invasion staging were 0.85, 0.82, and 0.81, respectively.

CONCLUSIONS

Endoscopic ultrasonography only has a relatively low accuracy for staging the depth of invasion in EGCs. Accordingly, EUS may be not indispensable in the staging of EGCs.

Linear-array EUS improves detection of pancreatic lesions in high-risk individuals: a randomized tandem study

BACKGROUND

Studies comparing linear and radial EUS for the detection of pancreatic lesions in an asymptomatic population with increased risk for pancreatic cancer are lacking.

OBJECTIVES

To compare pancreatic lesion detection rates between radial and linear EUS and to determine the incremental diagnostic yield of a second EUS examination.

DESIGN

Randomized controlled tandem study.

SETTING

Five academic centers in the United States.

PATIENTS

Asymptomatic high-risk individuals (HRIs) for pancreatic cancer undergoing screening EUS.

INTERVENTIONS

Linear and radial EUS performed in randomized order.

MAIN OUTCOME MEASUREMENTS

Pancreatic lesion detection rate by type of EUS, miss rate of 1 EUS examination, and incremental diagnostic yield of a second EUS examination (second-pass effect).

RESULTS

Two hundred seventy-eight HRIs were enrolled, mean age 56 years (43.2%), and 90% were familial pancreatic cancer relatives. Two hundred twenty-four HRIs underwent tandem radial and linear EUS. When we used per-patient analysis, the overall prevalence of any pancreatic lesion was 45%. Overall, 16 of 224 HRIs (7.1%) had lesions missed during the initial EUS that were detected by the second EUS examination. The per-patient lesion miss rate was significantly greater for radial followed by linear EUS (9.8%) than for linear followed by radial EUS (4.5%) (P = .03). When we used per-lesion analysis, 73 of 109 lesions (67%) were detected by radial EUS and 99 of 120 lesions (82%) were detected by linear EUS (P < .001) during the first examination. The overall miss rate for a pancreatic lesion after 1 EUS examination was 47 of 229 (25%). The miss rate was significantly lower for linear EUS compared with radial EUS (17.5% vs 33.0%, P = .007).

LIMITATIONS

Most detected pancreatic lesions were not confirmed by pathology.

CONCLUSION

Linear EUS detects more pancreatic lesions than radial EUS. There was a "second-pass effect" with additional lesions detected with a second EUS examination. This effect was significantly greater when linear EUS was used after an initial radial EUS examination.

High-resolution MR imaging of gastrointestinal tissue by intracavitary RF coil with remote tuning and matching technique for integrated MR-endoscope system

The goal of this study is to establish novel medical technologies by combining magnetic resonance imaging (MRI) with endoscopy to improve diagnostic precision and the safety of endoscopic surgeries. One of the key components of the integrated magnetic resonance (MR) endoscope system is a radio-frequency (RF) coil; this detects the MR signal from tissue and should be placed inside the body. Resonance characteristics such as the resonant frequency and the impedance of the RF coil, which affect the quality of MR images, change depending on the electric properties of the surrounding tissue and the coil deformation. Therefore, the technique of remote tuning and matching of the RF coil was developed, and its feasibility was investigated using a developed intracavitary RF coil, 1.5 tesla MR scanner, and models of phantom and resected porcine stomach. As a result, the frequency tuning and impedance matching was remotely adjusted in both models. In addition, the signal-to-noise ratio (SNR) of MR images was improved up to 134%. The developed remote tuning and matching technique was able to adjust the resonant characteristics of RF coil and can contribute the improvement of MR image quality, which would facilitate safe and precise endoscopy and endoscopic surgeries.

Accuracy of endoscopic ultrasound in the diagnosis of T2N0 esophageal cancer

BACKGROUND

Accurate staging of esophageal carcinoma (EC) is important since it directs further management. Endoscopic ultrasound (EUS) is the best tool available in the locoregional staging of EC; however, differentiating depth of tumor invasion (T) and nodal involvement (N) can be challenging. Accurate staging is particularly important to differentiate T1-2 N0 cancers, which can proceed directly to surgical resection versus TXN1 or T3N0/1 cancers, which benefit from induction chemoradiation prior to surgery. We report the accuracy of EUS staging for cT2N0 lesions.

PATIENTS AND INTERVENTIONS

Six hundred six patients underwent EUS for staging of EC between October 2003 and February 2013 by a single interventional endoscopist specially trained in endoscopic ultrasound. Thirty-eight patients were diagnosed with T2N0 tumors and underwent surgical resection without preoperative chemoradiation. EUS staging was compared to surgical pathology to evaluate accuracy. Patient follow-up was obtained from a retrospective chart review.

RESULTS

Thirty-eight patients (34 men, mean age 65.8 ± 10.5 years) with cT2N0 tumors by EUS underwent surgical resection of EC without chemoradiation after a mean of 22.4 ± 13.7 days post-EUS. When compared with final pathologic outcomes, 12 (32%) were understaged by EUS and 18 (47%) were overstaged. Understaging occurred due to tumor depth (T) in two patients (17%), nodal disease (N) in six (50%), and both in four (33%). Overstaging occurred due to pathology consistent with pT1b tumors instead of T2 tumors in all 17 cases. Based on EUS, 74% were referred for appropriate therapy.

CONCLUSION

While EUS is highly accurate in staging EC, it is less accurate in staging tumors which are not on either ends of the spectrum (mucosally based or clearly transmural). In this challenging group of patients, EUS understaged EC in 32% of cases resulting in surgical resection when neoadjuvant chemoradiation may have been beneficial. We suspect that newer generation EUS systems, which provide better imaging, will result in improved accuracy in staging this group of patients.

Diagnostic accuracy of endoscopic ultrasonography (EUS) for the preoperative locoregional staging of primary gastric cancer

BACKGROUND

Endoscopic ultrasound (EUS) is proposed as an accurate diagnostic device for the locoregional staging of gastric cancer, which is crucial to developing a correct therapeutic strategy and ultimately to providing patients with the best chance of cure. However, despite a number of studies addressing this issue, there is no consensus on the role of EUS in routine clinical practice.

OBJECTIVES

To provide both a comprehensive overview and a quantitative analysis of the published data regarding the ability of EUS to preoperatively define the locoregional disease spread (i.e., primary tumor depth (T-stage) and regional lymph node status (N-stage)) in people with primary gastric carcinoma.

SEARCH METHODS

We performed a systematic search to identify articles that examined the diagnostic accuracy of EUS (the index test) in the evaluation of primary gastric cancer depth of invasion (T-stage, according to the AJCC/UICC TNM staging system categories T1, T2, T3 and T4) and regional lymph node status (N-stage, disease-free (N0) versus metastatic (N+)) using histopathology as the reference standard. To this end, we searched the following databases: the Cochrane Library (the Cochrane Central Register of Controlled Trials (CENTRAL)), MEDLINE, EMBASE, NIHR Prospero Register, MEDION, Aggressive Research Intelligence Facility (ARIF), ClinicalTrials.gov, Current Controlled Trials MetaRegister, and World Health Organization International Clinical Trials Registry Platform (WHO ICTRP), from 1988 to January 2015.

SELECTION CRITERIA

We included studies that met the following main inclusion criteria: 1) a minimum sample size of 10 patients with histologically-proven primary carcinoma of the stomach (target condition); 2) comparison of EUS (index test) with pathology evaluation (reference standard) in terms of primary tumor (T-stage) and regional lymph nodes (N-stage). We excluded reports with possible overlap with the selected studies.

DATA COLLECTION AND ANALYSIS

For each study, two review authors extracted a standard set of data, using a dedicated data extraction form. We assessed data quality using a standard procedure according to the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) criteria. We performed diagnostic accuracy meta-analysis using the hierarchical bivariate method.

MAIN RESULTS

We identified 66 articles (published between 1988 and 2012) that were eligible according to the inclusion criteria. We collected the data on 7747 patients with gastric cancer who were staged with EUS. Overall the quality of the included studies was good: in particular, only five studies presented a high risk of index test interpretation bias and two studies presented a high risk of selection bias.For primary tumor (T) stage, results were stratified according to the depth of invasion of the gastric wall. The meta-analysis of 50 studies (n = 4397) showed that the summary sensitivity and specificity of EUS in discriminating T1 to T2 (superficial) versus T3 to T4 (advanced) gastric carcinomas were 0.86 (95% confidence interval (CI) 0.81 to 0.90) and 0.90 (95% CI 0.87 to 0.93) respectively. For the diagnostic capacity of EUS to distinguish T1 (early gastric cancer, EGC) versus T2 (muscle-infiltrating) tumors, the meta-analysis of 46 studies (n = 2742) showed that the summary sensitivity and specificity were 0.85 (95% CI 0.78 to 0.91) and 0.90 (95% CI 0.85 to 0.93) respectively. When we addressed the capacity of EUS to distinguish between T1a (mucosal) versus T1b (submucosal) cancers the meta-analysis of 20 studies (n = 3321) showed that the summary sensitivity and specificity were 0.87 (95% CI 0.81 to 0.92) and 0.75 (95% CI 0.62 to 0.84) respectively. Finally, for the metastatic involvement of lymph nodes (N-stage), the meta-analysis of 44 studies (n = 3573) showed that the summary sensitivity and specificity were 0.83 (95% CI 0.79 to 0.87) and 0.67 (95% CI 0.61 to 0.72), respectively.Overall, as demonstrated also by the Bayesian nomograms, which enable readers to calculate post-test probabilities for any target condition prevalence, the EUS accuracy can be considered clinically useful to guide physicians in the locoregional staging of people with gastric cancer. However, it should be noted that between-study heterogeneity was not negligible: unfortunately, we could not identify any consistent source of the observed heterogeneity. Therefore, all accuracy measures reported in the present work and summarizing the available evidence should be interpreted cautiously. Moreover, we must emphasize that the analysis of positive and negative likelihood values revealed that EUS diagnostic performance cannot be considered optimal either for disease confirmation or for exclusion, especially for the ability of EUS to distinguish T1a (mucosal) versus T1b (submucosal) cancers and positive versus negative lymph node status.

AUTHORS' CONCLUSIONS

By analyzing the data from the largest series ever considered, we found that the diagnostic accuracy of EUS might be considered clinically useful to guide physicians in the locoregional staging of people with gastric carcinoma. However, the heterogeneity of the results warrants special caution, as well as further investigation for the identification of factors influencing the outcome of this diagnostic tool. Moreover, physicians should be warned that EUS performance is lower in diagnosing superficial tumors (T1a versus T1b) and lymph node status (positive versus negative). Overall, we observed large heterogeneity and its source needs to be understood before any definitive conclusion can be drawn about the use of EUS can be proposed in routine clinical settings.

Role of endoscopic ultrasound in the diagnosis of pancreatic cancer

Endoscopic ultrasonography (EUS) with or without fine needle aspiration has become the main technique for evaluating pancreatobiliary disorders and has proved to have a higher diagnostic yield than positron emission tomography, computed tomography (CT) and transabdominal ultrasound for recognising early pancreatic tumors. As a diagnostic modality for pancreatic cancer, EUS has proved rates higher than 90%, especially for lesions less than 2-3 cm in size in which it reaches a sensitivity rate of 99% vs 55% for CT. Besides, EUS has a very high negative predictive value and thus EUS can reliably exclude pancreatic cancer. The complication rate of EUS is as low as 1.1%-3.0%. New technical developments such as elastography and the use of contrast agents have recently been applied to EUS, improving its diagnostic capability. EUS has been found to be superior to the recent multidetector CT for T staging with less risk of overstaying in comparison to both CT and magnetic resonance imaging, so that patients are not being ruled out of a potentially beneficial resection. The accuracy for N staging with EUS is 64%-82%. In unresectable cancers, EUS also plays a therapeutic role by means of treating oncological pain through celiac plexus block, biliary drainage in obstructive jaundice in patients where endoscopic retrograde cholangiopancreatography is not affordable and aiding radiotherapy and chemotherapy.

Endoscopic ultrasound in gastroenterology: From diagnosis to therapeutic implications

Since its advent in 1980, the scope of endoscopic ultrasound (EUS) has grown to include a wide range of indications, and it is now being incorporated as an integral part of everyday practice in the field of gastroenterology. Its use is extending from an adjuvant imaging aid to utilization as a therapeutic tool for various gastrointestinal disorders. EUS was first used to visualize remote organs, such as the pancreas and abdominal lymph nodes. When fine needle aspiration was introduced, the indications for EUS expanded to include tissue sampling for diagnostic purposes. At the same time, the needle can be used to convey a potential therapy to the internal organs, allowing access to remote sites. In this review, we aim to highlight the expanding spectrum of EUS indications and uses in the field of gastroenterology.

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.

Micromachining techniques in developing high-frequency piezoelectric composite ultrasonic array transducers

Several micromachining techniques for the fabrication of high-frequency piezoelectric composite ultrasonic array transducers are described in this paper. A variety of different techniques are used in patterning the active piezoelectric material, attaching backing material to the transducer, and assembling an electronic interconnection board for transmission and reception from the array. To establish the feasibility of the process flow, a hybrid test ultrasound array transducer consisting of a 2-D array having an 8 × 8 element pattern and a 5-element annular array was designed, fabricated, and assessed. The arrays are designed for a center frequency of ~60 MHz. The 2-D array elements are 105 × 105 μm in size with 5-μm kerfs between elements. The annular array surrounds the square 2-D array and provides the option of transmitting from the annular array and receiving with the 2-D array. Each annular array element has an area of 0.71 mm(2) with a 16-μm kerf between elements. The active piezoelectric material is (1 - x) Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT)/epoxy 1-3 composite with a PMN-PT pillar lateral dimension of 8 μm and an average gap width of ~4 μm, which was produced by deep reactive ion etching (DRIE) dry etching techniques. A novel electric interconnection strategy for high-density, small-size array elements was proposed. After assembly, the array transducer was tested and characterized. The capacitance, pulse-echo responses, and crosstalk were measured for each array element. The desired center frequency of ~60 MHz was achieved and the -6-dB bandwidth of the received signal was ~50%. At the center frequency, the crosstalk between adjacent 2-D array elements was about -33 dB. The techniques described herein can be used to build larger arrays containing smaller elements.

Prognostic assessment and treatment of primary gastric lymphomas: how endoscopic ultrasonography can help in tailoring patient management

Endoscopic ultrasonography (EUS) has recently gained a pivotal role in the management of gastric lymphomas, especially in the diagnostic workup. Its accuracy and reliability have overcome those of other imaging techniques, such that it represents an invaluable tool for the management of gastric lymphomas. Although this technique is operator dependent, its application in large series has proved its reliability. Thus, it has generally been considered a useful tool for providing information crucial in deciding the treatment program, especially for mucosa-associated lymphoid tissue (MALT) lymphomas, for which EUS can provide an accurate evaluation of disease extension and treatment response probability. Limited-stage disease, confined to the submucosa, has a greater probability to respond to sole Helicobacter pylori eradication. In contrast, the value of EUS in response assessment and follow-up monitoring is still debated, with discordant opinions about its reliability and clinical advantages, because normalization of the EUS findings occurs with a considerable delay compared to the histologic evaluation. In the follow-up setting, preliminary data have indicated that persistently positive EUS findings in low-grade gastric lymphoma could represent a warning for a possible relapse. However, in high-grade gastric lymphoma, such findings do not have any clinical implications.

Clinical controversies in endoscopic ultrasound

The field of diagnostic and therapeutic endoscopic ultrasound (EUS) is growing rapidly. Although EUS has enhanced our ability to diagnose and treat a wide variety of GI conditions, there are many controversial issues regarding the appropriate application of EUS techniques. In this review we discuss five controversial topics in EUS: the utility of EUS in staging of esophageal and gastric cancer; selection of appropriate needle gauge for fine needle aspiration (FNA); use of the stylet in FNA; and the emerging role of contrast agents in endoscopic ultrasound.

Endoscopic submucosal dissection for treatment of gastric submucosal tumors originating from the muscularis propria layer

BACKGROUND AND AIMS

We aimed to study the feasibility of endoscopic submucosal dissection (ESD) for the removal of gastric muscularis propria tumors and to evaluate the efficacy and safety of ESD for this treatment.

METHODS

Eighteen patients with gastric SMTs originating from the muscularis propria were treated by ESD between July 2008 and July 2011. Tumor characteristics, complications, en bloc resection rate, and local recurrence rate were evaluated.

RESULTS

Among the 18 patients, 11 were women (61.1 %). The median age was 65.3 ± 6.3 years old (range 30-71 years old). Seventeen tumors were resected completely by ESD (success rate 94.4 %). The mean tumor size as determined by endoscopic ultrasound was 2.6 ± 1.2 cm (range 1.0-3.5 cm). The histological diagnosis was gastrointestinal stromal tumor for 13 lesions and leiomyoma for four tumors. The mean operation time was 90 ± 38 min (range 50-120 min), and the average blood loss was 20 ml. Two patients developed perforation, which was closed by endoscopic methods with metallic clips. The tumor was closely adhered to the muscularis propria and was convex to the enterocoelia in one case. No single case had severe complications, such as GI bleeding, peritonitis, or abdominal abscess, and there were no other immediate post-procedure complications.

CONCLUSIONS

ESD is a safe, effective, well-tolerated, and minimally invasive therapy for the intraluminal SMTs originating from gastric muscularis propria with relatively few complications. Although there is a risk of perforation which has become manageable endoscopically.

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.

Gastric cancer: imaging and staging with MDCT based on the 7th AJCC guidelines

Gastric cancer is a common deadly cancer worldwide. The tumor-node-metastasis (TNM) staging system is one of the most commonly used staging systems, and is accepted and maintained by the International Union against Cancer (UICC) and the American Joint Committee on Cancer (AJCC). The TNM system is well known to effectively predict the prognosis of gastric cancer patients. The latest revision of TNM staging was presented in the 7th edition of the AJCC in 2009. Multi-detector row CT (MDCT) is a powerful test for non-invasive evaluation and can assess metastatic and locoregional staging simultaneously. Current MDCT with isotropic imaging and 3D images has increased the accuracy of T and N staging in patients with gastric cancer. Multi-planar reformatted images permit the radiologist to select the optimal imaging plane to accurately evaluate tumor invasion depth of the gastric wall and perigastric infiltration to identify a fat plane between a tumor and adjacent organs, to avoid partial volume averaging effects, and to differentiate lymph nodes from small perigastric vessels. Thus, MDCT provides a useful all-in-one diagnostic method for the pre-operative evaluation of patients with known, or strongly suspected, gastric cancer according to the 7th AJCC TNM staging system.

EUS elastography: advances in diagnostic EUS of the pancreas

Elastography is an imaging modality for the evaluation of tissue stiffness, which has been used for the analysis of superficial organs, such as those of the breast and prostate. The measurement of tissue elasticity has been reported to be useful for the diagnosis and differentiation of tumors, which are stiffer than normal tissues. Endoscopic ultrasonography elastography (EUS-EG) is a promising imaging technique with a high degree of accuracy for the differential diagnosis of solid pancreatic tumors. Recent introduction of second generation EUS-EG allows for the quantitative analysis of tissue stiffness. Here, we review our knowledge and preliminary experience with the use of EUS-elastography for the diagnosis of pancreatic disease.

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.

Gastric adenocarcinoma surgery and adjuvant therapy

Gastric adenocarcinoma is one of the most common causes of death worldwide. Surgical resection remains the mainstay of therapy, offering the only chance for complete cure. Resection is based on the principles of obtaining adequate margins, with the extent of lymphadenectomy remaining controversial. Neoadjuvant and adjuvant therapies are used to reduce local recurrence and improve long-term survival. This article reviews the literature and provides a summary of surgical management options and neoadjuvant/adjuvant therapies for gastric adenocarcinoma.

EUS for the staging of gastric cancer: a meta-analysis

BACKGROUND

The role of EUS in the locoregional staging of gastric carcinoma is undefined.

OBJECTIVE

We aimed to comprehensively review and quantitatively summarize the available evidence on the staging performance of EUS.

DESIGN

We systematically searched the MEDLINE, Cochrane, CANCERLIT, and EMBASE databases for relevant studies published until July 2010.

SETTING

Formal meta-analysis of diagnostic accuracy parameters was performed by using a bivariate random-effects model.

PATIENTS

Fifty-four studies enrolling 5601 patients with gastric cancer undergoing disease staging with EUS were eligible for the meta-analysis.

MAIN OUTCOME MEASUREMENTS

EUS staging accuracy across eligible studies was measured by computing overall sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR).

RESULTS

EUS can differentiate T1-2 from T3-4 gastric cancer with high accuracy, with overall sensitivity, specificity, PLR, NLR, and DOR of 0.86 (95% CI, 0.81-0.90), 0.91 (95% CI, 0.89-0.93), 9.8 (95% CI, 7.5-12.8), 0.15 (95% CI, 0.11-0.21), and 65 (95% CI, 41-105), respectively. In contrast, the diagnostic performance of EUS for lymph node status is less reliable, with overall sensitivity, specificity, PLR, NLR, and DOR of 0.69 (95% CI, 0.63-0.74), 0.84 (95% CI, 0.81-0.88), 4.4 (95% CI, 3.6-5.4), 0.37 (95% CI, 0.32-0.44), and 12 (95% CI, 9-16), respectively. Results regarding single T categories (including T1 substages) and Bayesian nomograms to calculate posttest probabilities for any target condition prevalence are also provided.

LIMITATIONS

Statistical heterogeneity was generally high; unfortunately, subgroup analysis did not identify a consistent source of the heterogeneity.

CONCLUSIONS

Our results support the use of EUS for the locoregional staging of gastric cancer, which can affect the therapeutic management of these patients. However, clinicians must be aware of the performance limits of this staging tool.

Factors Associated with Inadequate Tissue Yield in EUS-FNA for Gastric SMT

Aims. Our aim was to identify the factors that made the specimens inadequate and nondiagnostic in endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) biopsy of suspected submucosal tumors (SMTs). Methods. From August 2001 to October 2009, 47 consecutive patients with subepithelial hypoechoic tumors originating in the fourth sonographic layer of the gastric wall suspected as GIST by standard EUS in Chiba University hospital underwent EUS-FNA for histologic diagnosis. We evaluated patient age, sex, location of lesion, size, pattern of growth in a stomach, and pattern of echography retrospectively. We defined a case of gaining no material or an insufficient material for immunohistological diagnosis as nondiagnostic. Results. The diagnostic yield of EUS-FNA for the diagnosis of gastric SMTs was 74.5%. Multivariate logistic regression analysis identified that age of under 60 years (compared with patients older than 60 years: odds ratio [OR] = 11.91, 95% confidence interval [CI] = 1.761-80.48) and location of SMT at lower third area (compared with upper or middle third area: OR = 10.62, 95% CI = 1.290-87.42) were the predictive factors for inadequate tissue yield in EUS-FNA. Conclusions. The factors associated with inadequate tissue yield in EUS-FNA were younger age and the location of lesion at lower third area in stomach.

Quantitative endoscopic ultrasound elastography: an accurate method for the differentiation of solid pancreatic masses

BACKGROUND & AIMS

Qualitative endoscopic ultrasound (EUS) elastography is an accurate but subjective tool for the differential diagnosis of solid pancreatic masses. Second-generation EUS elastography allows quantitative analysis of tissue stiffness. We evaluated the accuracy of quantitative, second-generation EUS elastography in the differential diagnosis of solid pancreatic masses.

METHODS

The study included 86 consecutive patients who underwent EUS for the evaluation of solid pancreatic masses. EUS elastography was performed with the linear Pentax EUS and the Hitachi EUB900. Representative areas from the mass (A) and soft reference areas (B) were analyzed. The result of the elastographic evaluation was defined by the quotient B/A (strain ratio). Final diagnosis was based on histology of surgical specimens and cytology of EUS-fine-needle aspiration samples. The diagnostic accuracy of EUS elastography in detecting malignancy was calculated using receiver operating curve analysis.

RESULTS

The mean size of the pancreatic masses was 31.4 ± 12.3 mm. The final diagnoses were pancreatic adenocarcinoma (n = 49), inflammatory mass (n = 27), malignant neuroendocrine tumor (n = 6), metastatic oat-cell lung cancer (n = 2), pancreatic lymphoma (n = 1), and pancreatic solid pseudopapillary tumor (n = 1). The strain ratio was significantly higher among patients with pancreatic malignant tumors compared with those with inflammatory masses. The sensitivity and specificity of strain ratio for detecting pancreatic malignancies were 100% and 92.9%, respectively (area under the receiver operating curve, 0.983).

CONCLUSIONS

Quantitative, second-generation EUS elastography is useful for differential diagnosis of solid pancreatic masses. It allows for a quantitative and objective evaluation of tissue stiffness, which indicates the malignant or benign nature of the pancreatic lesion.

Associated factors for a hyperechogenic pancreas on endoscopic ultrasound

AIM: To identify the associated risk factors for hyperechogenic pancreas (HP) which may be observed on endoscopic ultrasound (EUS) and to assess the relationship between HP and obesity.

METHODS: From January 2007 to December 2007, we prospectively enrolled 524 consecutive adults who were scheduled to undergo EUS. Patients with a history of pancreatic disease or with hepatobiliary or advanced gastrointestinal cancer were excluded. Finally, 284 patients were included in the analyses. We further analyzed the risk of HP according to the categories of visceral adipose tissue (VAT) and subcutaneous adipose tissue in 132 patients who underwent abdominal computed tomography scans.

RESULTS: On univariate analysis, age older than 60 years, obesity (body mass index > 25 kg/m²), fatty liver, diabetes mellitus, hypertension and hypercholesterolemia were identified as risk factors associated with HP (P < 0.05). On multivariate analysis, fatty liver [P = 0.008, odds ratio (OR) = 2.219], male gender (P = 0.013, OR = 2.636), age older than 60 years (P = 0.001, OR = 2.874) and hypertension (P = 0.044, OR = 2.037) were significantly associated with HP. In the subgroup analysis, VAT was a statistically significant risk factor for HP (P = 0.010, OR = 5.665, lowest quartile vs highest quartile).

CONCLUSION: HP observed on EUS was associated with fatty liver, male gender, age older than 60 years, hypertension and VAT.

Endoluminal MR imaging of porcine gastric structure in vivo

BACKGROUND AND AIMS

Recently, several new endoscopic instruments have been developed. However, even with the full use of current modalities, the safety of endoscopic surgery is not guaranteed. Information regarding factors such as fibrosis and the blood vessels under the mucosa is very important for avoiding procedure-related complications. The aim of this study was to define the detailed anatomy of the gastric wall structure in vivo using original endoluminal radiofrequency coils for safer endoscopic therapy.

METHODS

Swine were used as the subjects and controlled with general anesthesia. Anatomical images were obtained with T1-weighted fast spin echo (T1FSE) and T2-weighted fast spin echo (T2FSE). Dynamic magnetic resonance (MR) angiography was also obtained with three-dimensional T1-weighted fast spoiled gradient recalled acquisition in the steady state (3D-DMRA) following the injection of hyaluronic acid sodium into the submucosal layer.

RESULTS

Porcine gastric wall structure was visualized, and four layers were discriminated in the T1FSE and T2FSE images. The vascular structure was clearly recognized in the submucosa on 3D-DMRA.

CONCLUSION

Endoluminal MR imaging was able to visualize the porcine stomach with similar quality to endoscopic ultrasonography imaging. Additionally, it was possible to visualize the vascular structures in the submucosal layer. This is the first report to show that blood vessels under the gastric mucosa can be depicted in vivo.

Clinical staging of adenocarcinoma of the esophagogastric junction

Tumors of the esophagogastric junction are among the most frequent and cause lethal cancers. Patients often do not present until late in the disease when the tumor is sufficiently large to cause obstruction or invasion of the adjacent structures, and thus becomes symptomatic. Preoperative staging is critical to select those patients whose disease is still locally confined for curative surgery. Ideally, clinical staging should accurately predict tumor invasion, lymph node involvement, and distant metastases. Upper endoscopy establishes the tumor diagnosis by multiple biopsies and defines the tumor type (Siewert I-III), based on tumor localization in relation to the endoscopic cardia. Preoperative TNM staging has a strong impact on treatment strategy. Endoscopic Ultrasound (EUS) determines the T category, and to a lesser extent, the presence of lymph node metastases. Multislice Computed Tomography (CT) and 18Fluorode-ocx-glucose Positron Emission Computed Tomography (18FDG-PET-CT) provide further information, especially about systemic metastases. Diagnostic laparascopy is suggested in advanced (CT3/4) Siewert type II-III tumors to exclude peritoneal carcinomatosis. This chapter summarizes current staging modalities and their accuracy in clinical practice.

EUS elastography for the characterization of solid pancreatic masses

BACKGROUND

Differential diagnosis of solid pancreatic masses remains a challenge. EUS elastography, by analyzing tissue stiffness of the mass, may be of help in this setting.

OBJECTIVE

To evaluate the different elastographic patterns of solid pancreatic masses and the diagnostic accuracy of EUS elastography for malignancy.

DESIGN

Prospective, consecutive, descriptive study with a second blind evaluation of elastographic patterns for concordance analysis and use of a well-defined reference method for calculation of diagnostic accuracy.

PATIENTS

This study involved 130 consecutive patients with solid pancreatic masses and 20 controls with normal pancreases.

INTERVENTION

EUS elastography was performed by using a linear Pentax echoendoscope and Hitachi EUB-8500 US.

MAIN OUTCOME MEASUREMENTS

Elastographic patterns of solid pancreatic masses and accuracy of the technique for malignancy.

RESULTS

Mean (SD) size of the masses was 30.9 (12.5) mm. The final diagnosis was malignant tumor in 78 patients, inflammatory mass in 42 patients, and neuroendocrine tumor in 10 patients. Four elastographic patterns were described, with a high concordance among 2 blinded investigators. A green-predominant pattern, either homogeneous or heterogeneous, excluded malignancy with a high accuracy. On the contrary, a blue-predominant pattern, either homogeneous or heterogeneous, supported the diagnosis of malignant tumor. Sensitivity, specificity, positive and negative predictive values, and overall accuracy of EUS elastography for diagnosis of malignancy were 100%, 85.5%, 90.7%, 100%, and 94.0%, respectively.

LIMITATION

Single-center study.

CONCLUSION

EUS elastography is a useful tool for differential diagnosis of solid pancreatic masses. It provides specific patterns supporting the benign or malignant nature of the disease.

Tumour length measured on PET-CT predicts the most appropriate stage-dependent therapeutic approach in oesophageal cancer

To compare the accuracy of determining the most appropriate treatment approach based on a visual analysis on combined PET-CT, based on a visual analysis on PET (reviewed side-by-side with CT) and based on tumour length measurements (on PET and PET-CT). Tumour length, SUV, and the length-SUV index (length x SUV) were assessed (on PET and PET-CT) in benign oesophageal lesions (reflux oesophagitis; n = 29), in potentially curable stages of oesophageal cancer (Tis; T1-T3NxM0; curable group; n = 52), and in stages of oesophageal cancer best treated with palliative therapy (T4NxMx; TxNxM1; palliative group; n = 30). All lesions were histopathologically proven. Based on a visual analysis, PET-CT (sensitivity: 77%;specificity: 96%) was more accurate than PET (sensitivity: 67%; specificity: 89%) in assessing the appropriate treatment (curative vs. palliative). The length-SUV index was the most accurate quantitative parameter to distinguish palliative from curable stages (sensitivity: 93%; specificity: 90%) and to predict survival. The highest overall accuracy was reached when combining the results of the quantitative (length-SUV index) analysis with those of the qualitative (visual) analysis (sensitivity: 93%; specificity: 96%). Moreover, neither tumour length nor SUV can be used to distinguish reflux oesophagitis from early malignant lesions (T1 stage). Tumour length measured with PET-CT or PET is associated with stage and overall survival of oesophageal cancer and helps to guide the appropriate treatment approach.

Endoscopic ultrasound of the upper gastrointestinal tract and mediastinum: diagnosis and therapy

Endoscopic ultrasound (EUS) has developed significantly over the last two decades and has had a considerable impact on the imaging and staging of mass lesions within or in close proximity to the gastrointestinal (GI) tract. In conjunction with conventional imaging such as helical computed tomography and magnetic resonance imaging, the indications for EUS include (1) differentiating between benign and malignant lesions of the mediastinum and upper GI tract, (2) staging malignant tumors of the lung, esophagus, stomach, and pancreas prior to surgery or oncological treatment, (3) excluding common bile duct stones before laparoscopic cholecystectomy, thereby avoiding the need for endoscopic retrograde cholangiopancreatography (ERCP) in some patients, and (4) assessing suspected lesions that are either equivocal or not seen on conventional imaging. In recent years, EUS has charted a course similar to that taken by ERCP, evolving from a purely diagnostic modality to one that is interventional and therapeutic. These indications include (5) obtaining a tissue diagnosis by EUS-guided fine-needle aspiration or trucut-type needle biopsy and (6) providing therapy such as coeliac plexus neurolysis and pancreatic pseudocyst drainage--in many cases, more accurately and safely than conventional techniques. Emerging investigational techniques include EUS-guided enteric anastomosis formation and fine-needle injection therapy for malignant disease.

Preoperative diagnosis of gastrointestinal stromal tumor by endoscopic ultrasound-guided fine needle aspiration

AIM: To evaluate the role of endoscopic ultrasonography-guided fine needle aspiration (EUS-FNA) in the preoperative diagnosis of gastrointestinal stromal tumor (GIST).

METHODS: From September 2002 to June 2006, Fifty-three consecutive EUS-FNAs of GI tract subepithelial hypoechoic tumors with continuity to proper muscle layer suspected as GIST by standard EUS were evaluated prospectively. The reference standards for the final diagnosis were surgery (n = 31), or clinical follow-up (n = 22). Additionally, immunophenotyping of specimens obtained by EUS-FNA and surgical resection specimens were compared.

RESULTS: In 2 cases puncture was not performed because of anatomical problems. The collection rate of adequate specimens from the GI tract subepithelial hypoechoic tumor with continuity to proper muscle layer was 82% (42/51). The diagnostic rate for the tumor less than 2 cm, 2 to 4 cm, and 4 cm or more were 71% (15/21), 86% (18/21), and 100% (9/9), respectively. In 29 surgically resected cases, the sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of EUS-FNA using immunohistochemical analysis of GIST were 100% (24/24), 80% (4/5), 96% (24/25), 100% (4/4), and 97% (28/29), respectively. No major complications were encountered.

CONCLUSION: EUS-FNA with immunohistochemical analysis is a safe and accurate method in the prethera-peutic diagnosis of GIST. It should be taken into consideration in decision making, especially in early diagnosis following minimal invasive surgery for GIST.

ROLE OF ENDOSCOPIC ULTRASOUND IN STAGING UPPER GASTROINTESTINAL CANCERS

The key clinical management points in this article are that (i) endoscopic ultrasound is the most accurate imaging method for local staging of oesophageal, gastric and pancreatic neoplasms; (ii) addition of fine-needle aspiration biopsy to the technique is safe and well tolerated and increases diagnostic accuracy for nodal staging purposes; and (iii) endoscopic ultrasound +/- fine-needle aspiration has the capacity to influence significantly, the management of patients with malignancies of the upper gastrointestinal tract, particularly with respect to selection for surgery. The learning objectives were that at the end of this paper the reader should be able to (i) understand the usefulness and limitations of various imaging methods in the staging of upper gastrointestinal cancers; and (ii) incorporate the various imaging methods, particularly endoscopic ultrasound, into management algorithms for oesophageal cancer, gastric cancer, mucosa-associated lymphoid tissue lymphomas, gastrointestinal stromal tumours, pancreatic cystic lesions and pancreatic cancer.

Endoscopic ultrasonography in the diagnosis and management of cancer

Since its development and introduction to clinical practice, endoscopic ultrasonography (EUS) has progressed rapidly from being a purely imaging modality with limited use in the detection of small pancreatic cancers to one that can provide a tissue diagnosis by fine-needle aspiration (FNA) and deliver therapy. EUS has now firmly established a place as the investigation of choice in the diagnosis, locoregional staging and management of a wide range of gastrointestinal cancers. With the increasing use of FNA, the accuracy of EUS has substantially improved and may become a stand-alone investigation in some situations. However, it is recommended that a combination of information obtained from other imaging modalities and EUS is needed to maximize the accuracy, in particular to complete staging beyond locoregional stage. In addition to well-established indications, newer applications of EUS are emerging and are no longer limited to the gastrointestinal system. In lung cancer, EUS combined with endobronchial ultrasonography is emerging as an accurate, minimally invasive, nonsurgical alternative to staging of the mediastinum. Furthermore, the ability of EUS to acquire tissue safely and conveniently results in a potential role of the molecular diagnostics to enhance the performance of EUS-guided FNA. Besides a diagnostic role of EUS, there continues to be technological advances in the field of interventional EUS, with many potential applications under investigation. This review focuses on the current and future roles of EUS in the diagnosis and management of cancers.