The potential of an artificial intelligence for diagnosing MRI images in rectal cancer: multicenter collaborative trial

The version of record of this article, first published in Journal of Gastroenterology, is available online at Publisher’s website: https://doi.org/10.1007/s00535-024-02133-8.Background: An artificial intelligence-based algorithm we developed, mrAI, satisfactorily segmented the rectal tumor, rectum, and mesorectum from MRI data of rectal cancer patients in an initial study. Herein, we aimed to validate mrAI using an independent dataset. Methods: We utilized MRI images collected in another nationwide research project, "Open versus Laparoscopic Surgery for Advanced Low Rectal Cancer Patients". MRIs from 467 cases with upfront surgery were utilized; six radiologists centralized the MRI evaluations. The diagnostic accuracies of mrAI and the radiologists for tumor depth were compared using pathologic diagnosis as a reference. Results: For all cases, centralized diagnosis demonstrated 84.2% sensitivity, 37.7% specificity, and 73.7% accuracy; mrAI exhibited 70.6% sensitivity, 61.3% specificity, and 68.5% accuracy. After limiting MRIs to those acquired by a Philips scanner, with an inter-slice spacing of ≤ 6 mm—both conditions similar to those used in the development of mrAI—the performance of mrAI improved to 76.8% sensitivity, 76.7% specificity, and 76.7% accuracy, while the centralized diagnosis showed 81.8% sensitivity, 36.7% specificity, and 71.3% accuracy. Regarding relapse-free survival, the prognosis for tumors staged ≥ T3 was significantly worse than for tumors staged ≤ T2 (P = 0.0484) in the pathologic diagnosis. While no significant difference was observed between ≥ T3 and ≤ T2 tumors in the centralized diagnosis (P = 0.1510), the prognosis for ≥ T3 was significantly worse in the mrAI diagnosis (P = 0.0318). Conclusion: Proper imaging conditions for MRI can enhance the accuracy of mrAI, which has the potential to provide feedback to radiologists without overestimating tumor stage

Antral Somatostatin Contents and Acidity of Gastric Juice in Normal Subjects and Patients with Duodenal Ulcer

The antral somatostatin contents were investigated in biopsy specimens of the antrum from normal subjects and patients with duodenal ulcer. There was good correlation (r=0.77044) between antral somatostatin contents and maximal acidity in normal subjects, but the correlation between antral somatostatin contents and maximal acid output was not significant (r=0.254367). This result may indicate that antral somatostatin content is regulated by intragastric pH in normal subjects. On the other hands, no correlation was observed between antral somatostatin contents and acidity or acid output in patients with duodenal ulcer. Therefore the impaired regulation of acid on antral somatostatin contents could be one of the important factors in the pathogenesis of duodenal ulcer disease

Helicobacter pylori Infection and Gastroduodenal Disease : a Comparison of Endoscopic Findings, Histology, and Urease Test Data

To determine the prevalence and significance of Helicobacter pylori (H. pylori) infection, biopsies of the antral mucosa were obtained from 139 patients and 43 asymptomatic volunteers. The specimens were examined by hematoxylin-eosin staining and the urease test. The detection rate of H. pylori by histologic examination was 91.3% in patients with duodenal ulcer, 75.0% in those with combined duodenal and gastric ulcer, 63.6% in those with gastric ulcer, 22.9% in those with gastric carcinoma, 36.4% in those with gastric adenoma, 14.3% in those with gastric hyperplastic polyp, and 51.7% in those with gastritis, and the respective percentages detected by the urease test were 91.3%, 75.0%, 54.5%, 28.6%, 27.3%, 14.3%, and 44.8%. H. pylori was also detected in 10/43 (23.3%) asymptomatic healthy volunteers by histology and the urease test. The prevalence of H. pylori was significantly higher in the patients than in the asymptomatic healthy volunteers (p < 0.05). H. pylori was detected in 62.9% of patients with endoscopic erosive gastritis and in 97.9% of those with histologically proven chronic active gastritis. The urease test was positive in 77/82 patients who were histologically positive for the organism (sensitivity: 93.9%), and it was negative in 98/100 patients who were negative by histology (specificity: 98.0%). Thus, there was over 90% agreement between the urease test and histology. Our investigations showed that H. pylori was closely related to peptic ulcers and antral gastritis, and that the urease test provides a simple, rapid and accurate diagnosis of H. pylori infection

The Usefulness of Gastric Mass Screening Using Serum Pepsinogen Levels Compared with Photofluorography

Chronic atrophic gastritis, which is thought to be a high risk for gastric cancer, can be diagnosed by serum pepsinogen levels. We compared the usefulness of the measurement of pepsinogen levels and indirect photofluorography as indicators of gastric cancer in a mass screening involving 5,620 Japanese subjects (mean age: 60.1 years old; male : female = 2,268 : 3,352) in 1991 and 1992. Subjects with a serum pepsinogen I level below 30 μg/liter or a pepsinogen I/II ratio below 2.0 were considered to be at high risk of gastric cancer. The incidence of gastric cancer and the ratio of early cancers detected by pepsinogen levels (0.12%, 4/7) were similar to those detected by photofluorography (0.11 %, 4/6). Our results showed that mass screening using pepsinogen levels was as useful as indirect photofluorography for the detection of gastric cancer in Japan. In addition, our results showed that the sensitivity of gastric mass screening was increased when the measurement of serum pepsinogen levels was combined with photofluorography

The Relationship between Gastric Secretion and Type of Early Gastric Carcinoma

To determine the relationship between gastric secretion and gastric carcinoma, we investigated gastric acid secretion and the fasting serum levels of pepsinogen I and gastrin in 50 Japanese patients with early gastric carcinoma. After the histological and macroscopic type of carcinoma had been determined, results were compared with findings in 50 Japanese control subjects whose gastric mucosa was endoscopically normal. The maximum gastric acid secretion and fasting levels of serum pepsinogen I were significantly lower in intestinal type gastric carcinoma than in diffuse type carcinoma and in the controls. They were also significantly lower in the non-ulcerative (elevated or flat) type than in the ulcerative (depressed) type of carcinoma. The serum gastrin levels in patients with early gastric carcinoma of either the intestinal or diffuse type were higher than those in the control subjects, though the difference was not significant. Gastric acid secretion and serum pepsinogen I levels were related with both the histological and macroscopic types of gastric carcinoma. These findings suggest that the serum pepsinogen I level might be useful as a maker for early gastric carcinoma of the intestinal type