Forward-viewing radial-array echoendoscope for staging of colon cancer beyond the rectum

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.

Evaluation of appendiceal mucinous neoplasms by curved linear-array echoendoscope: A preliminary study

BACKGROUND

Preoperative diagnosis of appendiceal mucinous neoplasms is challenging, and there are few reports regarding the endosonographic characteristics of these neoplasms.

AIM

To provide a retrospective assessment of the imaging features of appendiceal mucinous neoplasms using endoscopic ultrasound (EUS) by curved linear-array echoendoscope.

METHODS

A database of all patients with appendiceal mucinous neoplasms who had received EUS examination at our hospital between January 2018 and July 2023 was retrospectively analyzed. The EUS characteristics and patients’ clinical data were reviewed.

RESULTS

Twenty-two patients were included in the study. The linear-array echoendoscope successfully reached the ileocecal region in every patient. In the endoscopic view, we could observe the protrusion in the appendiceal orifice in all patients. A volcano sign was observed in two patients, and an atypical volcano sign was seen in two patients. EUS showed that all 22 lesions were submucosal cystic hypoechoic lesions with clear boundaries. No wall nodules were observed, but an onion-peeling sign was observed in 17 cases.

CONCLUSION

Linear-array echoendoscope is safe to reach the ileocecal region under the guidance of EUS. Image features on endoscopic and echoendosonograhic views could be used to diagnose appendiceal mucinous neoplasms.

Colonoscopic Ultrasound-Guided Fine-Needle Aspiration Using a Curvilinear Array Transducer: A Single-Center Retrospective Cohort Study

BACKGROUND

Curvilinear array ultrasound transducers enable tissue sampling and have therapeutic capabilities. Nevertheless, colonic intubation and maneuvering with these transducers is technically challenging and is therefore typically limited to the rectosigmoid area. This retrospective cohort study aimed to evaluate the safety, feasibility, and diagnostic yield of colonoscopic ultrasound-guided fine-needle aspiration in deep colonic intubation.

IMPACT OF INNOVATION

The impact of this innovation is to enable tissue sampling of colonic and extracolonic lesions guided by endoscopic ultrasound.

TECHNOLOGY, MATERIALS, AND METHODS

Curvilinear array ultrasound is used in the evaluation of luminal and extraluminal colonic diseases. Thirteen patients underwent colonoscopic ultrasound with a curvilinear array ultrasound endoscope in a single center for subepithelial lesions, cancer staging, and extracolonic lesions from July 2015 to February 2021. Endosonography was performed using an Olympus EU-ME1 and GF-UCT 180 with a 5-12MHz curvilinear array transducer. The primary outcome was the percentage of patients who were successfully scanned with the endoscopic ultrasound. The secondary outcomes included the success rate of fine-needle aspiration, the diagnostic yield of the tissue samples, and the adverse events related to the procedure.

PRELIMINARY RESULTS

A total of 13 female patients underwent colonoscopic ultrasound. All patients (100%, 13/13) were successfully scanned. Fine-needle aspiration was deemed necessary and successfully performed in 100% (5/5) of the patients. Tissue samples collected by fine-needle aspiration resulted in a diagnostic yield of 60%, and no adverse events resulted from this intervention.

CONCLUSIONS

This study demonstrates the feasibility of performing colonoscopic ultrasound with a curvilinear array transducer. Fine-needle aspiration for subepithelial, colonic, and extracolonic lesions is feasible and safe in this setting with no adverse events reported in our study.

FUTURE DIRECTIONS

Future research should be directed toward validating colonoscopic ultrasound with a curvilinear array transducer technique in prospective randomized trials. Studies evaluating the feasibility and safety of endoscopic ultrasound-guided interventions in the colon, such as abscess drainage and enteral anastomosis, should be considered.

Colorectal Endoscopic Submucosal Dissection: An Update on Best Practice

Endoscopic submucosal dissection (ESD) is a method of en-bloc resection of neoplastic colorectal lesions which is less invasive compared to surgical resection. Lesion stratification, architecture recognition and estimation of depth of invasion are crucial for patient selection. Expert endoscopists have integrated a variety of classification systems including Paris, lateral spreading tumor (LST), narrow band imaging (NBI), international colorectal endoscopic (NICE) and Japanese NBI expert team (JNET) in their day-to-day practice to enhance lesion detection accuracy. Major societies recommend ESD for LST-non granular (NG), Kudo-VI type, large depressed and protruded colonic lesions with shallow submucosal invasion. Chance of submucosal invasion enhances with increased depth as well as tumor location and size. In comparison to endoscopic mucosal resection (EMR), ESD has a lowerl recurrence rate and higher curative resection rate, making it superior for larger colonic lesions management. Major complications such as bleeding and perforation could be seen in up to 11% and 16% of patients, respectively. In major Western countries, performing ESD is challenging due to limited number of expert providers, lack of insurance coverage, and unique patient characteristics such as higher BMI and higher percentage of previously manipulated lesions.

A forward-viewing radial-array echoendoscope is useful for diagnosing the depth of colorectal neoplasia invasion

BACKGROUND

It is important to accurately diagnose the depth of colorectal neoplasia invasion. We aimed to evaluate the usefulness of a new forward-viewing radial-array echoendoscope (FRE), relative to the pit pattern method.

METHODS

In this prospective study, the invasion depth of suspected early-stage carcinoma was diagnosed using the pit pattern and FRE methods. The diagnoses were classified as T1a (submucosal invasion distance < 1,000 μm) or shallower and T1b (≥ 1,000 μm) or deeper. Pathological diagnoses were used to compare the diagnostic capabilities of the two methods.

RESULTS

The final analyses included 110 lesions. The FRE was successfully inserted to the lesion in all cases. There were no significant differences between the two methods regarding the correct prediction rate (79.1% vs. 75.5%, P = 0.57), accuracy (81.3% vs. 79.0%, P = 0.68), specificity (81.3% vs. 70.8%, P = 0.135), positive predictive value (65.0% vs. 60.4%, P = 0.649), negative predictive value (91.0% vs. 98.1%, P = 0.108), or frequency of unevaluable cases (2.7% vs. 4.5%, P = 0.471). The correct prediction rate was calculated by adding the number of unevaluable cases to the denominator of accuracy. Relative to the pit pattern method, the FRE method offered significantly higher sensitivity for predicting T1b or deeper invasion (81.3% vs. 97.0%, P = 0.048). The pit pattern method had significantly poorer accuracy for large lesions (> 36 mm) than for smaller lesions (≤ 36 mm). In contrast, the accuracy of the FRE method did not differ significantly with lesion size. When using the FRE method, no cases were unevaluable because of attenuation. The FRE method provided correct diagnoses in 2 of 3 cases that were unevaluable using the pit pattern method.

CONCLUSIONS

The pit pattern and FRE methods offered similar diagnostic performance for invasion depth. Furthermore, the FRE method may be used to correctly diagnose cases that are unevaluable using the pit pattern method.

New modality for the quantitative evaluation of tissue elasticity using a forward-viewing radial-array echoendoscope for colorectal neoplasms

PURPOSE

Sound speed correction (SSC) is a non-invasive modality that quantifies the hardness of neoplasms. The aim of our study was to evaluate the usefulness of SSC for the diagnostic accuracy of colorectal neoplasms and to differentiate the depth of invasion.

METHODS

Forty colorectal neoplasms, contributed by 40 patients, were included in the analysis. The primary outcome was the diagnostic ability of SSC for the depth of invasion of colorectal neoplasms, with the secondary endpoint being the clinical efficacy of SSC to distinguish between a neoplasm and normal mucosa.

RESULTS

The median sound speeds for colorectal neoplasms and normal mucosa were 1580 m/s and 1515 m/s, respectively (p < 0.001), with a median sound speed of 1583 m/s for lesions with a depth shallower than that of the muscularis propria and 1610 m/s for depths deeper than that of the muscularis propria (p = 0.002). The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 80.0%, 100%, 100%, 83.3%, 90.0%, and 100%, respectively, for the diagnosis of neoplasms (using a cut-off sound speed of 1557 m/s) and 100%, 77.8%, 33.3%, 100%, 80.0%, respectively, for the diagnosis of the depth of invasion (using a cut-off of 1590 m/s).

CONCLUSION

We identified absolute sound speeds for colorectal neoplasms and the depth of invasion of neoplasms which yielded a good diagnostic performance. SSC provides an objective evaluation of colorectal neoplasms and the depth of invasion of neoplasms and, thus, might be a useful modality in practice.

TRIAL REGISTRATION

UMIN000038235 , Date of registration; October 8, 2019.

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.

Forward-Looking Multimodal Endoscopic System Based on Optical Multispectral and High-Frequency Ultrasound Imaging Techniques for Tumor Detection

We developed a forward-looking (FL) multimodal endoscopic system that offers color, spectral classified, high-frequency ultrasound (HFUS) B-mode, and integrated backscattering coefficient (IBC) images for tumor detection in situ. Examination of tumor distributions from the surface of the colon to deeper inside is essential for determining a treatment plan of cancer. For example, the submucosal invasion depth of tumors in addition to the tumor distributions on the colon surface is used as an indicator of whether the endoscopic dissection would be operated. Thus, we devised the FL multimodal endoscopic system to offer information on the tumor distribution from the surface to deep tissue with high accuracy. This system was evaluated with bilayer gelatin phantoms which have different properties at each layer of the phantom in a lateral direction. After evaluating the system with phantoms, it was employed to characterize forty human colon tissues excised from cancer patients. The proposed system could allow us to obtain highly resolved chemical, anatomical, and macro-molecular information on excised colon tissues including tumors, thus enhancing the detection of tumor distributions from the surface to deep tissue. These results suggest that the FL multimodal endoscopic system could be an innovative screening instrument for quantitative tumor characterization.

Endoscopic Ultrasound Elastography as a Novel Diagnostic Method for the Assessment of Hardness and Depth of Invasion in Colorectal Neoplasms

INTRODUCTION

We aimed to compare the efficacy of endoscopic ultrasound elastography (EUS-EG) with that of magnifying chromoendoscopy (MCE) and endoscopic ultrasonography (EUS) for the diagnosis of the depth of invasion in colorectal neoplasms. This is an important clinical issue as the depth of invasion is associated with the risk of metastasis.

METHODS

Consecutive patients with suspected superficial colorectal neoplasms, evaluated by MCE, EUS, and EUS-EG, for whom endoscopic submucosal dissection was considered, were enrolled in 2018 (derivation study) and in 2019-2020 (validation study). The primary clinical endpoint was the diagnostic yield differentiating intramucosal and shallow submucosal neoplasms from deep submucosal (dSM) and advanced colorectal cancers. In addition, inter- and intra-observer agreements of the elastic score of colorectal neoplasm (ES-CRN) were evaluated by 2 expert and 2 non-expert endoscopists.

RESULTS

Thirty-one (33 lesions) and 50 (55 lesions) patients were enrolled in the derivation and validation studies, respectively. Sensitivity, specificity, positive, and negative predictive values, and accuracy of assessment of the depth of submucosal or deeper invasion in the derivation and validation groups were as follows: EUS-EG, 100/88.2/86.7/100/93.3% and 77.8/86.1/73.7/88.6/83.3%; MCE, 66.7/94.4/90.9/77.3/81.8% and 84.2/91.4/84.2/91.4/88.9%; and EUS, 93.3/77.8/77.8/93.3/84.8% and 89.5/65.7/58.6/92.0/74.1%, respectively. For the 2 expert endoscopists, interobserver agreement for the ES-CRN (first and second assessments) in the derivation group was 0.84 and 0.78, respectively; these values were 0.73 and 0.49, respectively, for the 2 non-expert endoscopists.

DISCUSSION/CONCLUSION

All 3 modalities presented similar diagnostic yield. Inter- and intra-observer agreements of the ES-CRN were substantial, even for non-expert endoscopists. Therefore, EUS-EG may be a useful modality in determining the depth of invasion in colorectal neoplasms.

Rectal Endoscopic Ultrasound in Clinical Practice

PURPOSE OF REVIEW

Endoscopic ultrasound (EUS) is routinely utilized for evaluation of disorders of the lower gastrointestinal tract. In this review, we summarize the current status of rectal EUS in clinical practice and describe recent developments in diagnostic and therapeutic rectal EUS.

RECENT FINDINGS

Recent guidelines recommend rectal EUS for rectal cancer staging as a second line modality in cases where MRI is contraindicated. Forward-viewing echoendoscopes and through the scope EUS miniprobes allow for EUS imaging of lesions through the entire colon and for evaluation beyond stenoses or luminal narrowings. EUS can be used to assess perianal disease and drain pelvic abscess associated with IBD, along with newer applications currently under investigation. For rectal varices, EUS can confirm the diagnosis, assess the optimal site for banding, guide therapy placement with sclerotherapy and/or coils, and assess response to treatment by confirming absence of flow. Therapeutic rectal EUS is emerging as a promising modality for drainage of pelvic fluid collection drainage and fiducial placement for rectal or prostatic cancer. Drug delivery mechanisms and substances that may increase the scope of therapy with rectal EUS are in varying stages of development. Rectal EUS continues to be an important modality for evaluation of benign and malignant disorders of the lower gastrointestinal tract, although its use as a cancer staging modality has declined due to improvements in MRI technology. Various technologies to enhance ultrasound imaging and for therapeutics have been developed that have or may contribute to expanded indications for rectal EUS.

Assessing tumor angiogenesis in colorectal cancer by quantitative contrast-enhanced endoscopic ultrasound and molecular and immunohistochemical analysis

BACKGROUND AND OBJECTIVES

Data on contrast-enhanced endoscopic ultrasound (CE-EUS) for colorectal cancer (CRC) evaluation are scarce. Therefore, we aimed to assess the vascular perfusion pattern in CRC by quantitative CE-EUS and compare it to immunohistochemical and genetic markers of angiogenesis.

PATIENTS AND METHODS

We performed a retrospective analysis of CE-EUS examinations of 42 CRC patients, before any therapy. CE-EUS movies were processed using a dedicated software. Ten parameters were automatically generated from the time-intensity curve (TIC) analysis: peak enhancement (PE), rise time (RT), mean transit time, time to peak (TTP), wash-in area under the curve (WiAUC), wash-in rate (WiR), wash-in perfusion index (WiPI), wash-out AUC (WoAUC), and wash-in and wash-out AUC (WiWoAUC). The expression levels of the vascular endothelial growth factor receptor 1 (VEGFR1) and VEGFR2 genes were assessed from biopsy samples harvested during colonoscopy. Microvascular density and vascular area were calculated after CD31 and CD105 immunostaining.

RESULTS

Forty-two CE-EUS video sequences were analyzed. We found positive correlations between the parameters PE, WiAUC, WiR, WiPI, WoAUC, WiWoAUC, and N staging (Spearman r = 0.437, r = 0.336, r = 0.462, r = 0.437, r = 0.358, and r = 0.378, respectively, P < 0.05), and also between RT and TTP and CD31 vascular area (r = 0.415, and r = 0.421, respectively, P < 0.05). VEGFR1 and VEGFR2 expression did not correlate with any of the TIC parameters.

CONCLUSIONS

CE-EUS with TIC analysis enables minimally invasive assessment of CRC angiogenesis and may provide information regarding the lymph nodes invasion. However, further studies are needed for defining its role in the evaluation of CRC patients.

Endoscopic ultrasound in oncology: An update of clinical applications in the gastrointestinal tract

An accurate staging is necessary to select the best treatment and evaluate prognosis in oncology. Staging usually begins with noninvasive imaging such as computed tomography, magnetic resonance imaging or positron emission tomography. In the absence of distant metastases, endoscopic ultrasound plays an important role in the diagnosis and staging of gastrointestinal tumors, being the most accurate modality for local-regional staging. Its use for tumor and nodal involvement in pre-surgical evaluation has proven to reduce unnecessary surgeries. The aim of this article is to review the current role of endoscopic ultrasound in the diagnosis and staging of esophageal, gastric and colorectal cancer.

Endoscopic ultrasonography and computed tomography scanning for preoperative staging of colonic cancer

PURPOSE

With an increasing demand for more accurate preoperative staging methods for colon cancer, we aimed to compare preoperative tumour (T)- and nodal (N)-stage in patients with left-sided colon cancer by endoscopic ultrasonography (EUS) and computed tomography (CT) with post-operative histology as gold standard.

METHODS

A total of 44 patients were prospectively recruited at Herlev and Roskilde University Hospitals during November 2014-January 2016. Thirty-five patients were included in the final analysis and underwent EUS, CT and surgery within 2 weeks. Diagnostic values were evaluated for "low risk" (T1+T2+T3 with ≤5 mm extramural invasion) and "high risk" (T3 with >5 mm of extramural spread + T4) colonic cancer.

RESULTS

Sensitivity and specificity in "low risk" colonic cancer evaluated with EUS was 0.90 [0.74;0.98] and 0.75 [0.19;0.99] and with CT 0.96 [0.80;0.99] and 0.25 [<0.01;0.81]. EUS and CT were poor in predicting N0 or N+ disease.

CONCLUSIONS

The sensitivity of EUS and CT were good and comparable regarding T-stage evaluation, while EUS had a significantly higher specificity in the evaluation of "low risk" tumours. The results obtained for "high risk" colonic cancer were difficult to evaluate due to small patient numbers. EUS could be considered as a supplement to CT scans in selecting patients for neoadjuvant therapies, or local transmural treatment, in the future.

TRIAL REGISTRATION

NCT02324023.

Advances in endoscopic ultrasound imaging of colorectal diseases

The development of endoscopic ultrasound (EUS) has had a significant impact for patients with digestive diseases, enabling enhanced diagnostic and therapeutic procedures, with most of the available evidence focusing on upper gastrointestinal (GI) and pancreatico-biliary diseases. For the lower GI tract the main application of EUS has been in staging rectal cancer, as a complementary technique to other cross-sectional imaging methods. EUS can provide highly accurate in-depth assessments of tumour infiltration, performing best in the diagnosis of early rectal tumours. In the light of recent developments other EUS applications for colorectal diseases have been also envisaged and are currently under investigation, including beyond-rectum tumour staging by means of the newly developed forward-viewing radial array echoendoscope. Due to its high resolution, EUS might be also regarded as an ideal method for the evaluation of subepithelial lesions. Their differential diagnosis is possible by imaging the originating wall layer and the associated echostructure, and cytological and histological confirmation can be obtained through EUS-guided fine needle aspiration or trucut biopsy. However, reports on the use of EUS in colorectal subepithelial lesions are currently limited. EUS allows detailed examination of perirectal and perianal complications in Crohn’s disease and, as a safe and less expensive investigation, can be used to monitor therapeutic response of fistulae, which seems to improve outcomes and reduce the need for additional surgery. Furthermore, EUS image enhancement techniques, such as the use of contrast agents or elastography, have recently been evaluated for colorectal indications as well. Possible applications of contrast enhancement include the assessment of tumour angiogenesis in colorectal cancer, the monitoring of disease activity in inflammatory bowel disease based on quantification of bowel wall vascularization, and differentiating between benign and malignant subepithelial tumours. Recent reports suggest that EUS elastography enables highly accurate discrimination of colorectal adenocarcinomas from adenomas, while inflammatory bowel disease phenotypes can be distinguished based on the strain ratio calculation. Among EUS-guided therapies, the drainage of abdominal and pelvic collections has been regarded as a safe and effective procedure to be used as an alternative for the transcutaneous route, while the placing of fiducial markers under EUS guidance for targeted radiotherapy in rectal cancer or the use of contrast microbubbles as drug-delivery vehicles represent experimental therapeutic applications that could greatly impact the forthcoming management of patients with colorectal diseases, pending on further investigations.

Endoscopic ultrasound for staging of colonic cancer proximal to the rectum: A systematic review and meta-analysis

Background and Objectives:

Treatment of colonic cancer patients is highly dependent on the depth of tumor invasion (T-stage) as well as the extension of lymph node involvement (N-stage). We aimed to systematically review the accuracy of endoscopic ultrasound (EUS) for staging of colonic cancer proximal to the rectum.

Patients and Methods:

Men and women with colonic adenocarcinomas were included in the study. EUS staging was compared to histopathology as the gold standard. Outcome measures were T- and N-staging accuracies. Articles were searched in PubMed, Web of Science, The Cochrane Library, and EMBASE.

Results:

Six studies were identified comparing EUS staging of colonic cancer to histopathology. The pooled-staging sensitivity and specificity were 0.90 and 0.98 for T1 tumors, 0.67 and 0.96 for T2 tumors, and 0.97 and 0.83 for T3/T4 tumors, respectively. Sensitivity and specificity for N + disease were 0.59 and 0.78, respectively.

Conclusions:

EUS is a feasible method for T-staging of cancers of the colon proximal to the rectum. The accuracy of lymph node staging needs to be verified by prospective multicenter studies including larger patient populations.

Current Role of Endoscopic Ultrasonography in Rectal Cancer Evaluation During Multidisciplinary Therapy

We report the case of a patient presenting in the Gastroenterology Department with intermittent rectal bleeding during the past year. A diagnosis of a low rectal adenocarcinoma was based on colonoscopy examination with biopsies, and staging procedures included transrectal endoscopic ultrasonography and magnetic resonance imaging of the abdomen and pelvis (cT2N0M0). Consequently the patient was referred for pre-operative chemoradiotherapy, achieving a complete clinical response as documented by repeated EUS and MRI examinations. Transanal endoscopic microsurgery with pathological assessment of the resected specimen revealed residual adenocarcinoma, highlighting the limitations of current imaging methods, and the constant need of technological improvements.