The future of endoscopy

Quantitative evaluation of comb-structure correction methods for multispectral fibrescopic imaging

Removing the comb artifact introduced by imaging fibre bundles, or 'fibrescopes', for example in medical endoscopy, is essential to provide high quality images to the observer. Multispectral imaging (MSI) is an emerging method that combines morphological (spatial) and chemical (spectral) information in a single data 'cube'. When a fibrescope is coupled to a spectrally resolved detector array (SRDA) to perform MSI, comb removal is complicated by the demosaicking step required to reconstruct the multispectral data cube. To understand the potential for using SRDAs as multispectral imaging sensors in medical endoscopy, we assessed five comb correction methods with respect to five performance metrics relevant to biomedical imaging applications: processing time, resolution, smoothness, signal and the accuracy of spectral reconstruction. By assigning weights to each metric, which are determined by the particular imaging application, our results can be used to select the correction method to achieve best overall performance. In most cases, interpolation gave the best compromise between the different performance metrics when imaging using an SRDA.

Predictive Factors of Portal Hypertensive Enteropathy Exacerbation in Patients with Liver Cirrhosis: A Capsule Endoscopy Study

BACKGROUND/AIMS

The clinical course and exacerbation of portal hypertensive enteropathy (PHE) are yet to be fully clarified. This study aimed to identify factors related to PHE exacerbation in patients with liver cirrhosis (LC).

METHODS

Fifty patients with LC (33 male; mean age, 67 years), who underwent capsule endoscopy (CE) at the Hiroshima University Hospital between February 2009 and September 2015, were followed up for >6 months. Exacerbation is defined as the appearance of new lesions or worsening of existing lesions. The association between PHE exacerbation and the clinical factors was evaluated.

RESULTS

PHE exacerbation was identified in 24 out of 50 (48%) of cases: erythema (14 cases); angioectasia (11 cases); erosions (9 cases); villous edema (8 cases); and esophageal varices (EVs; 6 cases). The following factors were significantly associated with PHE exacerbation: portosystemic shunts, EVs and portal hypertensive gastropathy (PHG) exacerbation. After therapy, CE findings among the 24 cases were as follows: villous edema (19 cases); erythema (17 cases); angioectasia (16 cases); erosions (12 cases); and EVs (9 cases), and no observable abnormalities in 2 cases. On multivariate analysis, exacerbation of EVs and PHG were independent predictors of PHE exacerbation.

CONCLUSION

EVs and PHG exacerbation may predict PHE exacerbation in patients with LC.

Advanced Endoscopic Navigation: Surgical Big Data, Methodology, and Applications

Interventional endoscopy (e.g., bronchoscopy, colonoscopy, laparoscopy, cystoscopy) is a widely performed procedure that involves either diagnosis of suspicious lesions or guidance for minimally invasive surgery in a variety of organs within the body cavity. Endoscopy may also be used to guide the introduction of certain items (e.g., stents) into the body. Endoscopic navigation systems seek to integrate big data with multimodal information (e.g., computed tomography, magnetic resonance images, endoscopic video sequences, ultrasound images, external trackers) relative to the patient's anatomy, control the movement of medical endoscopes and surgical tools, and guide the surgeon's actions during endoscopic interventions. Nevertheless, it remains challenging to realize the next generation of context-aware navigated endoscopy. This review presents a broad survey of various aspects of endoscopic navigation, particularly with respect to the development of endoscopic navigation techniques. First, we investigate big data with multimodal information involved in endoscopic navigation. Next, we focus on numerous methodologies used for endoscopic navigation. We then review different endoscopic procedures in clinical applications. Finally, we discuss novel techniques and promising directions for the development of endoscopic navigation.

Capsule endoscopy: The road ahead

Since its introduction into clinical practice 15 years ago, capsule endoscopy (CE) has become the first-line investigation procedure in some small bowel pathologies, and more recently, dedicated esophageal and colon CE have expanded the fields of application to include the upper and lower gastrointestinal disorders. During this time, CE has become increasingly popular among gastroenterologists, with more than 2 million capsule examinations performed worldwide, and nearly 3000 PubMed-listed studies on its different aspects published. This huge interest in CE may be explained by its non-invasive nature, patient comfort, safety, and access to anatomical regions unattainable via conventional endoscopy. However, CE has several limitations which impede its wider clinical applications, including the lack of therapeutic capabilities, inability to obtain biopsies and control its locomotion. Several research groups are currently working to overcome these limitations, while novel devices able to control capsule movement, obtain high quality images, insufflate the gut lumen, perform chromoendoscopy, biopsy of suspect lesions, or even deliver targeted drugs directly to specific sites are under development. Overlooking current limitations, especially as some of them have already been successfully surmounted, and based on the tremendous progress in technology, it is expected that, by the end of next 15 years, CE able to perform both diagnostic and therapeutic procedures will remain the major form of digestive endoscopy. This review summarizes the literature that prognosticates about the future developments of CE.

Major predictors of portal hypertensive enteropathy in patients with liver cirrhosis

BACKGROUND AND AIM

Portal hypertensive enteropathy (PHE) is acknowledged as a source of bleeding, and predicting its presence has become more important. We assessed PHE using capsule endoscopy (CE) and investigated factors that may predict its presence, including portosystemic shunts (PSs).

METHODS

We analyzed data from 134 consecutive patients with liver cirrhosis, from February 2009 to September 2013. All patients had undergone dynamic computed tomography and esophagogastroduodenoscopy before CE examination. The frequencies and types of PHE lesions, and the relationships between the presence of PHE and patients' clinical characteristics were evaluated. The distribution of the lesions was also determined.

RESULTS

PHE was found in 91 (68%), erythema in 70 (52%), erosions in 25 (19%), angioectasia in 24 (18%), villous edema in 18 (13%), and varices in 10 (7%) patients. Most lesions were located in the jejunum. The clinical characteristics associated with the presence of PHE were a Child-Pugh grade of B or C (P = 0.0058), and the presence of PSs (P < 0.0001), ascites (P = 0.0017), portal thrombosis (P = 0.016), esophageal varices (P = 0.0017), and portal hypertensive gastropathy (P = 0.0029). The presence of PSs was an independent predictor of PHE (odds ratio [OR]: 3.15; 95% confidence interval [CI]: 1.27-7.95). Among the shunt types, left gastric vein (OR: 5.31; 95% CI: 1.97-17.0) and splenorenal shunts (OR: 4.26; 95% CI: 1.29-19.4) were independent predictors of PHE.

CONCLUSION

PSs, especially left gastric vein and splenorenal shunts, appear to reliably predict the presence of PHE.

The role of fluorescence diagnosis in clinical practice

Fluorescence diagnosis is a fast, easy, noninvasive, selective, and sensitive diagnostic tool for estimation of treatment results in oncology. In clinical practice the use of photodynamic diagnosis is focused on five targets: detection for prevention of malignant transformation precancerous changes, detection of neoplasmatic tissue in the early stages for fast removal, prevention of expansion and detection of recurrence of the cancer, monitoring therapy, and the possibility of excluding neoplasmatic disease. In this article, selected applications of fluorescence diagnosis at the Center for Laser Diagnostics and Therapy in Bytom, Poland, for each of these targets are presented.

Modernization of an anatomy class: From conceptualization to implementation. A case for integrated multimodal-multidisciplinary teaching

It has become increasingly apparent that no single method for teaching anatomy is able to provide supremacy over another. In an effort to consolidate and enhance learning, a modernized anatomy curriculum was devised by attempting to take advantage of and maximize the benefits from different teaching methods. Both the more traditional approaches to anatomy teaching, as well as modern, innovative educational programs were embraced in a multimodal system implemented over a decade. In this effort, traditional teaching with lectures and dissection was supplemented with models, imaging, computer-assisted learning, problem-based learning through clinical cases, surface anatomy, clinical correlation lectures, peer teaching and team-based learning. Here, we review current thinking in medical education and present our transition from a passive, didactic, highly detailed anatomy course of the past, to a more interactive, as well as functionally and clinically relevant anatomy curriculum over the course of a decade.

Autofluorescence endoscopy with "real-time" digital image processing in differential diagnostics of selected benign and malignant lesions in the oesophagus

BACKGROUND

Oesophageal papilloma and Barrett's oesophagus are benign lesions known as risk factors of carcinoma in the oesophagus. Therefore, it is important to diagnose these early changes before neoplastic transformation.

METHOD

Autofluorescence endoscopy is a fast and non-invasive method of imaging of tissues based on the natural fluorescence of endogenous fluorophores. The aim of this study was to prove the diagnostic utility of autofluorescence endoscopy with digital image processing in histological diagnosis of endoscopic findings in the upper digestive tract, primarily in the imaging of oesophageal papilloma.

RESULTS

During the retrospective analysis of about 200 endoscopic procedures in the upper digestive tract, 67 cases of benign, precancerous or cancerous changes were found. White light endoscopy (WLE) image, single-channel (red or green) autofluorescence images, as well as green and red fluorescence intensities in two modal fluorescence image and red-to-green (R/G) ratio (Numerical Colour Value, NCV) were correlated with histopathologic results. The NCV analysis in autofluorescence imaging (AFI) showed increased R/G ratio in cancerous changes in 96% vs. 85% in WLE. Simultaneous analysis with digital image processing allowed us to diagnose suspicious tissue as cancerous in all of cases. Barrett's metaplasia was confirmed in 90% vs. 79% (AFI vs. WLE), and 98% in imaging with digital image processing. In benign lesions, WLE allowed us to exclude tissue as malignant in 85%. Using autofluorescence endoscopy R/G ratio was increased in only 10% of benign changes causing the picture to be interpreted as suspicious, but when both methods were used together, 97.5% were cases excluded as malignancies. Mean R/G ratios were estimated to be 2.5 in cancers, 1.25 in Barrett's metaplasia and 0.75 in benign changes and were statistically significant (p=0.04).

CONCLUSION

Autofluorescence imaging is a sensitive method to diagnose precancerous and cancerous early stages of the diseases located in oesophagus. Especially in two-modal imaging including white light endoscopy, autofluorescence imaging with digital image processing seems to be a useful modality of early diagnostics. Also in observation of papilloma changes, it facilitates differentiation between neoplastic and benign lesions and more accurate estimation of the risk of potential malignancy.