A clinically interpretable convolutional neural network for the real-time prediction of early squamous cell cancer of the esophagus: comparing diagnostic performance with a panel of expert European and Asian endoscopists

BACKGROUND AND AIMS

Intrapapillary capillary loops (IPCLs) are microvascular structures that correlate with the invasion depth of early squamous cell neoplasia and allow accurate prediction of histology. Artificial intelligence may improve human recognition of IPCL patterns and prediction of histology to allow prompt access to endoscopic therapy for early squamous cell neoplasia where appropriate.

METHODS

One hundred fifteen patients were recruited at 2 academic Taiwanese hospitals. Magnification endoscopy narrow-band imaging videos of squamous mucosa were labeled as dysplastic or normal according to their histology, and IPCL patterns were classified by consensus of 3 experienced clinicians. A convolutional neural network (CNN) was trained to classify IPCLs, using 67,742 high-quality magnification endoscopy narrow-band images by 5-fold cross validation. Performance measures were calculated to give an average F1 score, accuracy, sensitivity, and specificity. A panel of 5 Asian and 4 European experts predicted the histology of a random selection of 158 images using the Japanese Endoscopic Society IPCL classification; accuracy, sensitivity, specificity, positive and negative predictive values were calculated.

RESULTS

Expert European Union (EU) and Asian endoscopists attained F1 scores (a measure of binary classification accuracy) of 97.0% and 98%, respectively. Sensitivity and accuracy of the EU and Asian clinicians were 97%, 98% and 96.9%, 97.1%, respectively. The CNN average F1 score was 94%, sensitivity 93.7%, and accuracy 91.7%. Our CNN operates at video rate and generates class activation maps that can be used to visually validate CNN predictions.

CONCLUSIONS

We report a clinically interpretable CNN developed to predict histology based on IPCL patterns, in real time, using the largest reported dataset of images for this purpose. Our CNN achieved diagnostic performance comparable with an expert panel of endoscopists.

Real-world effectiveness of direct-acting antiviral agents for chronic hepatitis C patients with genotype-2 infection after completed treatment

Chronic hepatitis C (CHC) is a major cause of cirrhosis, hepatocellular carcinoma (HCC), and mortality. Eliminating hepatitis C virus (HCV) can greatly improve long-term outcomes. Several direct-acting antiviral agents (DAAs), including sofosbuvir (SOF) plus different NS5A inhibitors, as well as non-SOF-based DAAs, including glecaprevir/pibrentasvir (GLE/PIB), have been approved for treating CHC genotype-2 (GT-2) patients in Taiwan. However, there is limited real-world effectiveness data regarding these different regimens. Thus, we aimed to evaluate the real-world efficacy in CHC GT-2 patients who underwent these DAA regimens. We retrospectively enrolled CHC GT-2 patients who were treated with SOF-based DAAs or GLE/PIB at a single medical center. A total of 704 enrolled patients were treated with either SOF + ribavirin (RBV), SOF/daclatasvir (DCV) ± RBV, SOF/ledipasvir (LDV) ± RBV, SOF/velpatasvir (VEL) ± RBV, or with GLE/PIB. The overall sustained virological response (SVR) rate was 97.9%. The SVR rate was significantly lower in the SOF + RBV group (95.6%) than in the non-SOF + RBV (98.9%) group, especially compared to the SOF/DCV (100%) and GLE/PIB groups (99.5%). Among patients treated with SOF + RBV, cirrhotic patients had significantly lower SVR rates than noncirrhotic patients (89.4% vs 98.2%). Multivariate analysis showed that patients with a younger age, hepatitis B virus coinfection, baseline cirrhosis, or those who received SOF + RBV were less likely to achieve SVR. In conclusion, for CHC GT-2 patients, SOF in combination with DCV, LDV, or VEL, as well as GLE/PIB, achieved similar high efficacies, regardless of cirrhosis, treatment experience, or chronic kidney disease status. Therefore, the use of DAA therapy to eradicate HCV should not be delayed in these populations.

Comparison of underwater and conventional endoscopic mucosal resection for removing sessile colorectal polyps: a propensity-score matched cohort study

Background and study aims  Endoscopic mucosal resection (EMR) is a standard method for removing sessile colorectal polyps ≥ 10 mm. Recently, underwater EMR (UEMR) has been introduced as a potential alternative. However, the effectiveness and safety of UEMR compared with conventional EMR is un clear. Patients and methods  In this 1:1 propensity score (PS) matched retrospective cohort study, we compared the en bloc resection rates, procedure time, intraprocedural and delayed bleeding rates, and incidence of muscle layer injury. We also performed subgroup analyses by sizes of polyps (< 20 mm and ≥ 20 mm). Results  Among 350 polyps in 315 patients from August 2012 to November 2017, we identified 121 PS-matched pairs. Mean polyp size was 16.8 mm. With similar en bloc resection rates (EMR: 82.6 % vs. UEMR: 87.6 %, rate difference: 5.0, 95 % confidence interval [95 % CI]: - 4 to 13.9 %), UEMR demonstrated a shorter resection time (10.8 min vs. 8.6 min, difference: - 2.2 min, 95 % CI: - 4.1 to - 0.3 min) and a lower intraprocedural bleeding rate (15.7 % vs. 5.8 %, rate difference: - 9.9 %, 95 % CI: - 17.6 to - 2.2 %). Incidence of delayed bleeding and muscle layer injury were low in both groups. For polyps < 20 mm, effectiveness and safety outcomes were similar in both groups. For polyps ≥ 20 mm (42 PS-matched pairs), the UEMR group has a comparable en bloc resection rate with shorter procedure time and superior safety outcomes Conclusions  UEMR achieved an en bloc resection rate comparable to conventional EMR with less intraprocedural bleeding and a shorter procedure time.

Elevated interleukin-4 levels predicted advanced fibrosis in chronic hepatitis C

BACKGROUND

Cytokine imbalance has been associated with chronic hepatitis C virus (HCV) infection. We hypothesized that cytokines have an important role in fibrosis development in HCV infection.

METHODS

Data of 92 patients were analyzed retrospectively. Fluorescent Bead immunoassay was used to measure the following serum cytokine levels: Interferon γ, tumor necrosis factor α, interleukin (IL)-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, and IL-12. Various statistical analyses were used as appropriate.

RESULTS

Of the 92 HCV-infected patients, 49 (53.3%) were male, 23 (25%) patients had advanced (fibrosis grades 3-4) fibrosis, and the mean age of the study population was 51.9 ± 9.4 years. Elevation of baseline IL-4 level (>490 pg/mL) was associated with liver fibrosis grade by χ test (odds ratio [OR] = 2.99; 95%, CI = 1.02-8.78; p = 0.042) and multivariate logistic regression (OR = 4.26; 95% CI = 1.13-16.02; p = 0.032). Also, IL-4 had strong diagnostic value in advanced liver fibrosis by using area under receiver operating characteristics curve analysis. Assessment of fibrosis score was consequently developed from our findings and compared with other noninvasive serum markers to assess liver fibrosis.

CONCLUSION

This study provides evidence that increased IL-4 expression predicted advanced liver fibrosis in treatment of naive HCV-infected patients. The newly developed "FIL4" score had good predictive value for advanced fibrosis before treatment and this value was even strong in HCV-genotype 1b patients.

A training program of a new simplified classification of magnified narrow band imaging for superficial esophageal squamous cell carcinoma

BACKGROUND AND AIM

Optimal staging of the invasion depth of superficial esophageal squamous cell carcinoma is vital before endoscopic treatment. A new simplified magnified narrow-band imaging (M-NBI) classification system based on vascular architecture has recently been developed by the Japan Esophageal Society; however, its validity remains uncertain.

METHODS

A total of 11 experienced and 11 inexperienced endoscopists were invited to join an endoscopic training program, which was composed of pretest, educational section, and post-test. The pretest and post-test sections included a set of endoscopic photos from 40 subjects with superficial esophageal squamous cell carcinoma with various invasion depths. Each subject appeared twice in the test, one with white-light imaging (WLI) only and the other with both WLI and M-NBI. The educational section included lectures and video demonstrations.

RESULTS

The accuracy of WLI alone and combined with M-NBI at baseline were 0.53, 0.57 and 0.43, 0.41 for the experienced and inexperienced endoscopists, respectively, which then improved to 0.57, 0.63 and 0.49, 0.52 after training. Inter-observer agreement (k-value) of WLI alone and combined WLI and M-NBI for the experienced and inexperienced endoscopists also improved from 0.61, 0.61, and 0.61, 0.53 to 0.68, 0.71, and 0.71, 0.59, respectively. Multivariate analysis revealed that the educational course but not experience in endoscopy, NBI, or magnification significantly improved the diagnostic accuracy. M-NBI had a significant additional benefit to WLI, with an improvement in accuracy from 36% to 56% for the cases with m3/sm1 cancers (P < 0.05).

CONCLUSIONS

A well-designed training program can improve the diagnostic accuracy in evaluating cancer invasion depth, with substantial agreement.

Association of type 2 diabetes with liver cirrhosis: a nationwide cohort study

Background

The link between the subcategories of liver cirrhosis and type 2 diabetes is not well known. We investigated the association of type 2 diabetes mellitus with alcoholic cirrhosis and cirrhosis without alcohol.

Methods

This nationwide cohort study used the Taiwan National Health Insurance Research Database. Cirrhotic individuals and their matched controls were identified from 2001-2008. In all, 9 313 cirrhotic patients aged 20 years or older were matched by age, sex, and index date with the non-cirrhotic individuals (n = 37 252). Cirrhosis was categorized into alcoholic cirrhosis and cirrhosis without alcohol. Type 2 diabetes mellitus was identified from January 2001- December 2011.

Results

The incidence densities (per 1 000 person-months) of type 2 diabetes were as follows: 1.14 (95% CI: 1.09-1.20) in the non-cirrhotic group, 1.88 (CI 1.76-2.01) in patients with cirrhosis, 1.62 (CI 1.48-1.78) in patients with cirrhosis without alcohol, and 2.92 (CI 2.64-3.23) in patients with alcoholic cirrhosis. The adjusted hazards ratio (aHR) for type 2 diabetes mellitus among cirrhotic individuals was 0.774 (CI: 0.715-0.8934). Alcoholic cirrhotic men had a significantly higher risk of type 2 diabetes (aHR 1.182, CI: 1.046-1.335) compared with non-cirrhotic individuals. Increased risks were seen in men (aHR 1.690; CI: 1.455-1.963) and women (aHR 1.715; CI: 1.113-2.645) with alcoholic cirrhosis compared to those with cirrhosis without alcohol.

Conclusions

This study indicates that alcoholic cirrhosis is a significant risk factor for type 2 diabetes mellitus compared with cirrhosis without alcohol.

Predictors for postoperative esophageal stricture after balloon-based radiofrequency ablation for early esophageal squamous neoplasia: a multicenter validation study

BACKGROUND

Endoscopic radiofrequency ablation (RFA) is a rapidly evolving therapeutic modality for early flat esophageal squamous cell neoplasms (ESCNs), but the risk factors for postoperative stricture have not been elucidated. The objective of this study was to identify and validate a predictor for post-RFA stenosis.

METHODS

We consecutively enrolled patients with flat-type 'large' (length no less than 3 cm extending no less than half the circumference of the esophagus), early ESCNs, treated with balloon-based RFA (12 J/cm(2)-clean-12 J/cm(2) regimen). The tumor and technical factors for postoperative stricture were investigated and we validated the results externally with a society-based multicenter cohort using the same ablation regimen.

RESULTS

A total of 51 patients were enrolled (30 in the development set and 21 in the validation set). The complete remission rate at 12 months was 93%, and the rates of perforation and postoperative stenosis were 0% and 17%, respectively. Patients with post-RFA stenosis had a significantly larger longitudinal tumor size (mean 115 versus 61 mm, p = 0.003). There were no significant differences in age, body mass index, tumor circumferential extension, pretreatment histological grade, treatment efficacy or size of balloon catheter between the groups with or without stenosis. The optimal cut-off value was set as 9 cm to predict post-RFA stenosis by receiver operating characteristic curve [area under curve (AUC) = 0.881], which was then confirmed to be a reliable predictor by multivariate analysis (odds ratio, 12.7, 95% confidence interval, 1.18-136.28, p = 0.03) and have a good predictive performance in the validation set (AUC = 0.876).

CONCLUSIONS

The most frequent adverse event of RFA was esophageal stenosis, for which the longitudinal tumor size was a significant predictive factor. Early intervention or prevention for stricture should be applied for those with long segment (⩾9 cm) ESCNs.

Basic principles and practice of gastric cancer screening using high-definition white-light gastroscopy: Eyes can only see what the brain knows

Endoscopic diagnosis of gastrointestinal tumors consists of the following processes: (i) detection; (ii) differential diagnosis; and (iii) quantitative diagnosis (size and depth) of a lesion. Although detection is the first step to make a diagnosis of the tumor, the lesion can be overlooked if an endoscopist has no knowledge of what an early-stage 'superficial lesion' looks like. In recent years, image-enhanced endoscopy has become common, but white-light endoscopy (WLI) is still the first step for detection and characterization of lesions in general clinical practice. Settings and practice of routine esophagogastroduodenoscopy (EGD) such as use of antispasmodics, number of endoscopic images taken, and observational procedure are customarily decided in each facility in each country and are not well standardized. Therefore, in the present article, we attempted to outline currently available evidence and actual Japanese practice on gastric cancer screening using WLI, and provide tips for detecting EGC during routine EGD which could become the basis of future research.

Differences in routine esophagogastroduodenoscopy between Japanese and international facilities: A questionnaire survey

BACKGROUND AND AIM

The mortality rate of gastric cancer (GC) is close to the incidence rate worldwide. However, in Korea and Japan, the mortality rate of GC is less than half of the incidence rate. We hypothesized that good-quality routine esophagogastroduodenoscopy (EGD) contributes to a high detection rate for early GC (EGC) and improves mortality in these countries.

METHODS

To clarify the differences in routine EGD, a questionnaire survey was conducted in 98 Japanese and 53 international institutions.

RESULTS

Prevalence of screening examination among routine EGD was higher in Japanese than in international institutions. Japanese endoscopists noted that endoscopic mucosal atrophy was the most significant risk factor for GC, whereas international endoscopists paid more attention to clinical information such as age, symptoms and family history. Antispasmodics, mucolytics and defoaming agents were used more frequently in Japanese institutions. The examination time was similar (mostly 5-10 min) between Japanese and international institutions. Japanese endoscopists took more pictures (>20 in almost all institutions) than international endoscopists (≤20 in two-thirds of institutions). In Japanese institutions, biopsy specimens were more frequently taken from areas of mucosal discoloration, unevenness or spontaneous bleeding rather than from obvious endoscopic lesions such as ulceration or polyps. In most Japanese institutions, one or two biopsy specimens were taken per lesion, compared with ≥three in international institutions.

CONCLUSION

There were some discrepancies between Japanese and international institutions for routine EGD. Thus, standardization is required for adequate risk assessment, proper techniques, and knowledge of endoscopic diagnosis of EGC.

Liquid antibiotics in bone cement: an effective way to improve the efficiency of antibiotic release in antibiotic loaded bone cement

Objectives

The objective of this study was to compare the elution characteristics, antimicrobial activity and mechanical properties of antibiotic-loaded bone cement (ALBC) loaded with powdered antibiotic, powdered antibiotic with inert filler (xylitol), or liquid antibiotic, particularly focusing on vancomycin and amphotericin B.

Methods

Cement specimens loaded with 2 g of vancomycin or amphotericin B powder (powder group), 2 g of antibiotic powder and 2 g of xylitol (xylitol group) or 12 ml of antibiotic solution containing 2 g of antibiotic (liquid group) were tested.

Results

Vancomycin elution was enhanced by 234% in the liquid group and by 12% in the xylitol group compared with the powder group. Amphotericin B elution was enhanced by 265% in the liquid group and by 65% in the xylitol group compared with the powder group. Based on the disk-diffusion assay, the eluate samples of vancomycin-loaded ALBC of the liquid group exhibited a significantly larger inhibitory zone than samples of the powder or the xylitol group. Regarding the ALBCs loaded with amphotericin B, only the eluate samples of the liquid group exhibited a clear inhibitory zone, which was not observed in either the xylitol or the powder groups. The ultimate compressive strength was significantly reduced in specimens containing liquid antibiotics.

Conclusions

Adding vancomycin or amphotericin B antibiotic powder in distilled water before mixing with bone cement can significantly improve the efficiency of antibiotic release than can loading ALBC with the same dose of antibiotic powder. This simple and effective method for preparation of ALBCs can significantly improve the efficiency of antibiotic release in ALBCs.

Cite this article: Bone Joint Res 2014;3:246–51.

Potential clinical role of 18F FDG-PET/CT in detecting hip prosthesis infection: a study in patients undergoing two-stage revision arthroplasty with an interim spacer

AIM

We evaluated the potential role of [18F]fluorodeoxyglucose-positron emission tomography/computed tomography ([18F]FDG-PET/CT) to identify latent infections at the site of an interim hip spacer after resection arthroplasty for hip prosthesis infection.

METHODS

Twelve patients with an interim hip spacer following resection arthroplasty (Group A) were investigated. Twelve patients with painful primary hip prostheses served as controls (Group B). All underwent PET/CT before surgery. Both non-attenuation-corrected (NAC) and attenuation-corrected (AC) images were analyzed. Serum C-reactive protein (CRP) levels were measured in 22 patients. Elevated CRP level was defined as >/=10 mg/L. The diagnosis of infection was based on the results of intraoperative tissue cultures, intraoperative pathology, and clinical follow-up.

RESULTS

FDG-PET/CT had 100% sensitivity and 100% negative predictive value for detection of latent infection in both groups. However, there were 4 and 3 false positive cases in Group A and Group B, respectively. Specificity improved from 50% to 62.5% in Group A, and from 62.5% to 87.5% in Group B when using NAC instead of AC. Seventeen patients had CRP values >/=10 mg/L, but only 8 were true positive for infection. FDG-PET/CT ruled out infection in 77.8% (7/9) of false-positive cases identified by CRP levels.

CONCLUSION

FDG-PET/CT is highly sensitive to detect latent infections in prosthetic hips and in interim hip spacers. The high negative predictive value of PET/CT scans is useful to rule out infections in patients with persistently elevated CRP levels. PET/CT might serve as an auxiliary tool to exclude latent infections in patients posing a clinical diagnostic dilemma.

Effects of pulse voltage on inkjet printing of a silver nanopowder suspension

Inkjet printing of a liquid suspension prepared by dispersing silver powders of size around 4 nm in deionized (DI) water at 30 wt% was investigated in this study. By comparing with the results of pure DI water, the effects of nanoparticles on droplet formation between the nozzle and the substrate were also studied. A bipolar pulse waveform was employed in driving the piezoelectric printhead with pulse voltage set as the primary variable of this study. Observations showed that a higher driving pulse voltage was required for the silver suspension to form droplets than DI water. The liquid column broke up at the nozzle orifice for DI water while the silver suspension broke up further away below the nozzle office. It was also observed that the droplet size of the silver suspension was smaller than that of DI water. For the silver suspension the liquid column formed was thinner and longer and the pinch-off time of the liquid column to form droplets was also longer. However, the characteristic adjustment time for droplet recombination was shorter for the silver suspension than for DI water.

Effects of glucose, fructose and 5-hydroxymethyl-2-furaldehyde on the presystemic metabolism and absorption of glycyrrhizin in rabbits

Our previous study reported that co-administration of honey significantly increased the serum levels of glycyrrhetic acid (GA) after oral administration of glycyrrhizin (GZ) in rabbits. The components of honey are sucrose, glucose, fructose and 5-hydroxymethyl-furaldehyde (HMF). To clarify the causative component(s) in honey that altered the metabolic pharmacokinetics of GZ, rabbits were given GZ (150 mg kg(-1)) with and without glucose (5 g/rabbit), fructose (5 g/rabbit) and HMF (1 mg kg(-1)), respectively, in crossover designs. An HPLC method was used to determine concentrations of GZ and GA in serum as well as GA and 3-dehydroglycyrrhetic acid (3-dehydroGA) in faeces suspension. A noncompartment model was used to calculate the pharmacokinetic parameters and analysis of variance was used for statistical comparison. Our results indicated that the area under curve (AUC) of GA was significantly increased by 29% when HMF was coadministered, whereas the pharmacokinetics of GZ and GA were not significantly altered by coadministration of glucose or fructose. An in-vitro study, using faeces to incubate GZ and GA individually, indicated that HMF significantly inhibited the oxidation of GA to 3-dehydroGA and this may explain the enhanced GA absorption in-vivo. It was concluded that HMF is the causative component in honey that affects the presystemic metabolism and pharmacokinetics of GZ in-vivo.

Hip arthroplasty in patients with cirrhosis of the liver

We retrospectively reviewed 45 hip arthroplasties which were performed over a period of 20 years in 38 patients with cirrhosis of the liver. There was a high perioperative 30-day complication rate (26.7%). Advanced cirrhosis was associated with a higher risk of complications (p = 0.004) as also was increased age, a high level of creatinine, a low level of albumin, a low platelet count, ascites, encephalopathy and an increased operative blood loss. The survival of the prosthesis at five years was 77.8% and infection was a major cause of failure. In view of the high rate of early complications and the limited longevity of the prosthesis, surgeons who perform hip arthroplasty on such patients should counsel them appropriately preoperatively.

Robustness of conditional moments: an application to premium calculation of reinsurance treaties

In this study, the tail probability of a class of distributions commonly used in assessing the severity of insurance losses was examined. Without specifying any particular distribution, the use of an algebraic functional form Cx(-alpha) to approximate the tail behavior of the distributions in the class was demonstrated. Norwegian fire insurance data were examined, and the algebraic functional form was applied to derive the expected loss of a reinsurance treaty that covers all losses exceeding a retention limit. It was shown that (1) the expected loss is insensitive to the parameter alpha for a high retention limit (e.g., a catastrophe treaty), and (2) with a low retention limit (e.g., a largest claim treaty), a reliable estimate of the parameter alpha and a sound judgment on the maximum potential loss of the treaty could provide useful and defensible summary statistics for pricing the treaty. Thus, when dealing with the losses of certain reinsurance treaties, it was concluded that knowledge of a specific probability distribution is not critical, and the summary statistics derived from the model are robust with respect to a large class of loss distributions.