Mucosal Changes in the Small Intestines in Portal Hypertension: First Study Using the Pillcam SB3 Capsule Endoscopy System

Diagnosis and management of ectopic varices in portal hypertension

Ectopic variceal bleeding is a rare cause of gastrointestinal bleeding that can occur in settings of cirrhotic and non-cirrhotic portal hypertension and is characterised by its development at locations remote from the oesophagus and stomach. Ectopic varices can be difficult to identify and access, and, although a relatively uncommon cause of portal hypertensive bleeding, can represent a difficult diagnostic and therapeutic challenge associated with considerable mortality. Low incidence and variance in variceal anatomy preclude large randomised controlled trials, and clinical practice is based on experience from case reports, case series, and specialist centre expertise. Optimisation of survival outcomes relies on understanding a patient's portal venous anatomy and functional hepatic reserve to guide timely and targeted endoscopic and endovascular interventions to facilitate the rapid control of ectopic variceal bleeding.

Artificial intelligence and capsule endoscopy: automatic detection of vascular lesions using a convolutional neural network

Background

Capsule endoscopy (CE) is the first line for evaluation of patients with obscure gastrointestinal bleeding. A wide range of small intestinal vascular lesions with different hemorrhagic potential are frequently found in these patients. Nevertheless, reading CE exams is time-consuming and prone to errors. Convolutional neural networks (CNN) are artificial intelligence tools with high performance levels in image analysis. This study aimed to develop a CNN-based model for identification and differentiation of vascular lesions with distinct hemorrhagic potential in CE images.

Methods

The development of the CNN was based on a database of CE images. This database included images of normal small intestinal mucosa, red spots, and angiectasia/varices. The hemorrhagic risk was assessed by Saurin's classification. For CNN development, 11,588 images (9525 normal mucosa, 1026 red spots, and 1037 angiectasia/varices) were ultimately extracted. Two image datasets were created for CNN training and testing.

Results

The network was 91.8% sensitive and 95.9% specific for detection of vascular lesions, providing accurate predictions in 94.4% of cases. In particular, the CNN had a sensitivity and specificity of 97.1% and 95.3%, respectively, for detection of red spots. Detection of angiectasia/varices occurred with a sensitivity of 94.1% and a specificity of 95.1%. The CNN had a frame reading rate of 145 frames/sec.

Conclusions

The developed algorithm is the first CNN-based model to accurately detect and distinguish enteric vascular lesions with different hemorrhagic risk. CNN-assisted CE reading may improve the diagnosis of these lesions and overall CE efficiency.

Role of Video Capsule in Small Bowel Bleeding

Video capsule endoscopy has an essential role in the diagnosis and management of small bowel bleeding and is the first-line study recommended for this purpose. This article reviews the risk factors for small bowel bleeding, optimal timing for video capsule endoscopy testing, and algorithms recommended for evaluation. Used primarily for the assessment of nonacute gastrointestinal blood loss, video capsule endoscopy has an emerging role for more urgent use in emergency settings and in special populations. Future software incorporation of neural networks to enhance lesion detection will likely result in an augmented role of video capsule endoscopy in small bowel bleeding.

The Role of Video Capsule Endoscopy in Liver Disease

In the setting of chronic liver disease, capsule endoscopy is safe and well tolerated, making it an appealing diagnostic procedure. It is used mainly for the surveillance of esophageal varices, investigation of anemia, and exploration of the small bowel for complications of portal hypertension. Capsule endoscopy is recognized as a viable alternative in patients unable or unwilling to undergo upper gastrointestinal endoscopy for investigations of esophageal varices. In evaluating the small bowel of patients with liver disease and unexplained anemia, capsule endoscopy increases recognition of mucosal abnormalities, although their clinical significance is often unclear.