Current endosonographic possibilities in the upper gastrointestinal tract

A deep learning-based system to identify originating mural layer of upper gastrointestinal submucosal tumors under EUS

Background and Objective

EUS is the most accurate procedure to determine the originating mural layer and subsequently select the treatment of submucosal tumors (SMTs). However, it requires superb technical and cognitive skills. In this study, we propose a system named SMT Master to determine the originating mural layer of SMTs under EUS.

Materials and Methods

We developed 3 models: deep convolutional neural network (DCNN) 1 for lesion segmentation, DCNN2 for mural layer segmentation, and DCNN3 for the originating mural layer classification. A total of 2721 EUS images from 201 patients were used to train the 3 models. We validated our model internally and externally using 283 images from 26 patients and 172 images from 26 patients, respectively. We applied 368 images from 30 patients for the man-machine contest and used 30 video clips to test the originating mural layer classification.

Results

In the originating mural layer classification task, DCNN3 achieved a classification accuracy of 84.43% and 80.68% at internal and external validations, respectively. In the video test, the accuracy was 80.00%. DCNN1 achieved Dice coefficients of 0.956 and 0.776 for lesion segmentation at internal and external validations, respectively, whereas DCNN2 achieved Dice coefficients of 0.820 and 0.740 at internal and external validations, respectively. The system achieved 90.00% accuracy in classification, which is comparable with that of EUS experts.

Conclusions

Our proposed system has the potential to solve difficulties in determining the originating mural layer of SMTs in EUS procedures, which relieves the EUS learning pressure of physicians.

Diagnosis of subepithelial tumors in the upper gastrointestinal tract by endoscopic ultrasonography

Endoscopic ultrasonography (EUS) is the most accurate procedure for detecting and diagnosing subepithelial tumors, due to its higher sensitivity and specificity than other imaging modalities. EUS can characterize lesions by providing information on echogenic origin, size, borders, homogeneity, and the presence of echogenic or anechoic foci. Linear echoendoscopes, and recently also electronic radial echoendoscopes, can be used with color Doppler or power Doppler to assess the vascular signals from subepithelial masses, and thus permit the differentiation of vascular structures from cysts, as well as the assessment of the tumor blood supply. However, the diagnostic accuracy of EUS imaging alone has been shown to be low in subepithelial lesions with 3rd and 4th layers. It is also difficult to differentiate exactly between benign and malignant tumors and to gain an accurate picture of histology using EUS. On the other hands, EUS guided fine needle aspiration (EUS-FNA) can provide samples for cytologic or histologic analysis. Hypoechoic lesions of the 3rd and the 4th EUS layers, more than in 1 cm diameter are recommended, and histologic confirmation using endoscopic submucosal resection or EUS-FNA should be obtained when possible. Therefore, EUS-FNA plays an important role in the clinical management of subepithelial tumors. Furthermore improvements in endoscopic technology are expected to be more useful modalities in differential diagnosis and discrimination between benign and malignant subepithelial tumors.

Classification of submucosal tumors in the gastrointestinal tract

This review is part two of three, which will present an update on the classification of gastrointestinal submucosal tumors. Part one treats of the diagnosis and part three of the therapeutic methods regarding gastrointestinal submucosal tumors. In the past there has been some confusion as to the classification of gastrointestinal submucosal tumors. Changes in classifications have emerged due to recent advances in mainly immunohistochemistry and electron microscopy. The aim of this paper is to update the reader on the current classification. Literature searches were performed to find information related to classification of gastrointestinal submucosal tumors. Based on these searches the twelve most frequent submucosal tumor types were chosen for description of their classification. The factors that indicate whether tumors are benign or malignant are mainly size and number of mitotic counts. Gastrointestinal stromal tumors are defined mainly by their CD117 positivity. In the future, there should be no more confusion between gastrointestinal stromal tumors and other types of submucosal tumors.

Therapeutic procedures for submucosal tumors in the gastrointestinal tract

This review is part three of three and will present an update on the therapeutic options and procedures concerning gastrointestinal (GI) submucosal tumors (SMTs). The aim of this paper is to investigate the treatments of GI SMTs and to present a case of a gastrointestinal stromal tumor (GIST). Literature searches were performed to find information on therapy for GI SMTs. Based on these searches, the optimal therapeutic procedures could be outlined. The choice of treatment of localized tumors is endoscopic resection if possible or, alternatively, laparoscopic resection or surgical resection by an open procedure. However, benign SMTs should only be excised if symptoms are present, and GISTs should be treated with particular precautions. Irresectable or recurrent GISTs may be successfully treated with the tyrosine kinase inhibitor, imatinib.

Diagnostic procedures for submucosal tumors in the gastrointestinal tract

This review is part one of three, which will present an update on diagnostic procedures for gastrointestinal (GI) submucosal tumors (SMTs). Part two identifies the classification and part three the therapeutic methods regarding GI SMTs. Submucosal tumors are typically asymptomatic and therefore encountered incidentally. Advances in diagnostic tools for gastrointestinal submucosal tumors have emerged over the past decade. The aim of this paper is to provide the readers with guidelines for the use of diagnostic procedures, when a submucosal tumor is suspected. Literature searches were performed to find information on diagnostics for gastrointestinal submucosal tumors. Based on the searches, the optimal diagnostic procedures and specific features of the submucosal tumors could be outlined. Standard endoscppy, capsule endoscopy and push-and-pull enteroscopy (PPE) together with barium contrast X-ray do not alone provide sufficient information, when examining submucosal tumors. Endoscopic ultrasound (EUS), computed tomography (CT), magnetic resonance imaging (MRI) and fluorodeoxyglucose-labeled positron emission tomography (FDG-PET) are recommended as supplementary tools.

Dieulafoy's disease: endosonographic detection and endosonography-guided treatment

BACKGROUND

To investigate whether endosonography can help in the detection and treatment of Dieulafoy's disease, we examined eight patients with suspicion of Dieulafoy's disease.

METHODS

Between December 1992 and April 1995, eight patients were referred because of suspicion of Dieulafoy's disease. Seven presented with upper gastrointestinal bleeding and one with a tiny ulcer. In all eight patients the stomach was examined with an Olympus GF-UM20 echoendoscope. The stomach was filled with 200 to 400 ml of water after which the body, fundus, and cardia were carefully visualized.

RESULTS

In all eight patients a clearly visible, relatively large caliber (2 to 3 mm) vessel was seen to penetrate the muscularis propria and could be followed running through the submucosa for 2 to 4 cm. Subsequently four patients received sclerotherapy, three under endosonographic guidance. Follow-up of all patients (median 10 months), showed recurrent bleeding in two patients, 3 and 5 months after sclerotherapy. One was then diagnosed with a duodenal ulcer and one with recurrent bleeding from the Dieulafoy's lesion.

CONCLUSIONS

Endosonography is useful in the detection of Dieulafoy's disease in patients with unexplained upper gastrointestinal bleeding. Sclerotherapy can be performed during the same procedure, with endosonography-guided injection of the sclerosing agent near the abnormal vessel.

Primary tumour staging of gastric and colorectal cancer

Almost 15 years after its introduction, endosonography or endoscopic ultrasonography is an important technique in a wide range of gastrointestinal diseases. Other imaging techniques are CT, MRI and barium examination. There is a general consensus that the most important prognostic factor in gastric and colorectal carcinoma is the presence or absence of lymph node invasion, but malignant fixation of tumour through direct invasion of adjacent tissues also appears to be very important. Non-invasive preoperative assessment of tumour stage based on one or a combination of the above imaging modalities should allow appropriate treatment to be planned in each case.