Image-based discriminating morphological features for gastric atrophy assessment: A step to go further

Interobserver variation in assessment of gastric premalignant lesions: higher agreement for intestinal metaplasia than for atrophy

BACKGROUND

Either atrophy or intestinal metaplasia of the gastric mucosa are considered premalignant lesions. The new operative link for gastritis assessment staging system is based on the detection of atrophy, and the operative link for assessment of intestinal metaplasia staging system is based on the detection of intestinal metaplasia. Good interobserver agreement is necessary for identification of any premalignant condition.

AIMS

The aim of this study was to compare the agreement between findings of gastric atrophy and intestinal metaplasia by expert and general pathologists and to analyze the possible reasons behind any possible disagreement.

METHODS

Patients with dyspeptic symptoms, aged 55 years and above, without previous Helicobacter pylori eradication were enrolled and analyzed according to the updated Sydney Classification by two expert pathologists and an experienced general pathologist; the results were compared with the consensus driven by the two experts.

RESULTS

Gastric biopsy specimens from 121 patients (91 women) were included in the analysis; the mean age of the patients was 67.4 years. H. pylori infection was present in 61.2% of patients. The level of agreement between the general pathologist and the two experts (κ-value) was 0.12, 0.46, and 0.87, respectively, for detecting atrophy in the corpus; 0.77, 0.77, and 0.65, respectively, for detecting intestinal metaplasia in the corpus; 0.06, 0.51, and 0.54, respectively, for detecting atrophy in the antrum; and 0.69, 0.85, and 0.79, respectively, for detecting metaplasia in the antrum.

CONCLUSION

The agreement was substantially higher for intestinal metaplasia than for atrophy. This could result in discrepancies when the operative link for gastritis assessment and operative link for assessment of intestinal metaplasia staging systems are applied and can be caused by differences in the criteria used to define atrophy.

An intelligent decision support system for quantitative assessment of gastric atrophy

Aims

To build an automated decision support system to assist pathologists in grading gastric atrophy according to the updated Sydney system.

Methods

A database of 143 biopsies was used to train and examine the proposed system. A panel of three experienced pathologists reached a consensus regarding the grading of the studied biopsies using the visual scale of the updated Sydney system. Digital imaging techniques were utilised to extract a set of discriminating morphological features that describe each atrophy grade sufficiently and uniquely. A probabilistic neural networks structure was used to build a grading system. To evaluate the performance of the proposed system, 66% of the biopsies (94 biopsy images) were used for training purposes and 34% (49 biopsy images) were used for testing and validation purposes.

Results

During the training phase, a 98.9% precision was achieved, whereas during testing, a precision of 95.9% was achieved. The overall precision achieved was 97.9%.

Conclusions

A fully automated decision support system to grade gastric atrophy according to the updated Sydney system is proposed. The system utilises advanced image processing techniques and probabilistic neural networks in conducting the assessment. The proposed system eliminates inter- and intra-observer variations with high reproducibility.

Helicobacter pylori and gastric cancer in the Middle East: A new enigma?

The Middle East is the home of ethnic groups from three main backgrounds: Semitic (Arabs and Jews), Indo-European (Persians and Kurdish) and Turkic (Turkish and Turkmens). Its geographic location, which has been under continuous influences from Asia, Europe and Africa, has made it an ideal site for epidemiological studies on Helicobacter pylori (H. pylori) infection and genotyping. The gastric cancer rate differs in this region from very high in Iran (26.1/10⁵) to low in Israel (12.5/10⁵) and very low in Egypt (3.4/10⁵). Epidemiological studies showed that the prevalence of H. pylori is almost similar in those countries with a high level of infection in childhood. Importantly, the frequency of vacA s1 and m1 regions and cagA+ genotypes were higher in non Semitic populations who inhabit the North than Semitic populations, the inhabitants of Southern parts of the Middle East. H. pylori infection prevalence, distribution pattern of virulence factors, diet and smoking could not have explained the difference in cancer rate. This reflects the multifactorial aetiology of gastric cancer and suggests that H. pylori infection does not always directly correlate with the risk for gastrointestinal disease, such as gastric cancer. Further detailed investigations and international comparative studies of each risk factor need to be performed to investigate whether this represents a true enigma.