The main cause of gastric cancer is Helicobacter pylori infection. Therefore, measures against this infection are critical for both screening and prevention of gastric cancer. Serum H. pylori antibody test and related ABC classification are among the most common methods for diagnosing H. pylori infection. However, serological analysis may lead to false-negative results.

Ever since the recommendation of the Ministry of Health, Labour and Welfare, the endoscopic screening for gastric cancer has been increasingly used across the country. Besides its diagnostic value in gastric cancer, the endoscopic examination also allows for gastric cancer-risk stratification by applying both the endoscopic ABC classification and the Kyoto classification of gastritis. In this context, it is anticipated that a hybrid-type method, combining H. pylori testing and endoscopic examination, may be ideal for screening gastric cancer, representing an achievable countermeasure against the disease.

Considering this, since 2017, Takasaki City has implemented such a combined method including the serum ABC classification as well as endoscopy. Overall, it has become widely accepted and is being used in Japan. Hence, in this study, we described the value of the hybrid-type screening method in gastric cancer management.

The Japanese Society of Gastrointestinal Cancer Screening's Criteria of X-ray image interpretation for population-based screening of gastric cancer was used to investigate its accuracy at assisting image interpretation by radiological technologists. The overall proper diagnosis rate by technologists was 62.3%, sensitivity 60.5% (early stage cancer sensitivity: 67.0%, advanced cancer sensitivity 61.0%, and esophageal cancer sensitivity 34.3%), and specificity 63.5%. Meanwhile, the proper diagnosis rate by specialists was 75.0%, sensitivity 77.5% (early stage cancer sensitivity: 89.5%, advanced cancer sensitivity: 71.4%, and esophageal cancer sensitivity: 50.0%), and specificity 70.0%. In an analysis adjusted for the years of experience or types of certifications obtained by the technologists, there was no difference in accuracy by whether radiological technologists were certified or by the type of certification. The accuracy of technologists was almost same as that of specialists, with the proper diagnosis rate of 71.6%, sensitivity 83.9% (early stage cancer sensitivity: 85.7%, advanced cancer sensitivity: 80.6%, and esophageal cancer sensitivity: 71.4%), and specificity 55.7%.

Aims: Evaluating the accuracy of hybrid ABC (Hyb ABC) combined with the serum ABC classification and the endoscopic ABC classification in gastric cancer risk assessment

Methods: A total of 462 patients were enrolled in the study. All persons underwent endoscopic examination and several H. pylori tests at the Inui Clinic of Internal Medicine, between May 2016 and January 2018. They were stratified into five groups (A to E) based on serum ABC classification using L-type Wako H. pylori antibody J. Furthermore, they were stratified into five groups (A to E) based on the grades of endoscopic findings (endoscopic ABC classification). Hyb ABC was defined as consistent results of serum ABC classification and endoscopic ABC classification.

Results: Hyb A had 100% accuracy at diagnosing naïve H. pylori-infected status. The accuracy of Hyb B and Hyb C at diagnosing current H. pylori-infected status were 96.4% and 94.4%, respectively. The accuracy of both Hyb D and Hyb E at diagnosing previous H. pylori-infected status was 100%.

Conclusion: This study showed that the hybrid ABC enables to accurate gastric cancer risk assessment reflected by H. pylori-infected status.

Since only the 8-film double-contrast method is applied in the population-based screening with the new stomach x-ray radiography, images with better adherence of barium to mucosa need to be obtained to ensure a constant accuracy of examinations. However, we often encounter subjects who have difficulty in undergoing x-ray examination due to reasons such as (1) difficulties in postural changes, (2) severe hearing loss, (3) gastric remnant, and (4) food residue in the actual screening. In this article, we have reported the measures taken to handle the above cases (1 to 4) at our center. In case 1, we gave instructions on how to change body postures during a radiography and place an order for the next examination. In case 2, we let subjects watch a video explaining how to undergo radiography beforehand and gave them a signal by using dedicated cards during a radiography. In case 3, we proposed new methodologies for barium swallowing and postural changes to prevent early runoff of barium to the small intestine. In case 4, we performed radiography by moving the food residue in the target region with barium and once again explained the restrictions on meals and water prior to the next examination to the subjects. If x-ray radiography is considered impossible despite the above measures, we recommend that subjects should undergo endoscopy after being given a thorough explanation and the reports on those cases be sent including the measures to be taken for the next examination to a person-in-charge in the local government.

We studied the image quality improved by the nonlinear noise reduction filter mounted on the CT apparatus for images with increased noise due to low-dose imaging and analyzed, whether the image quality was equivalent to that of the SD 20 image performed by the conventional large intestine CT examination and whether the image would not hinder diagnosis. We studied these using a water phantom and a phantom for large intestine CT.

In the examination of the water phantom, the shooting SD value and the type of the filter to be used were examined. In the shooting SD 25, 3D-Q 03 was performed once. In SD 30, 3D-Q 09 was performed once. In SD 34, 3D-Q 03 was performed twice. In SD 38, 3D-Q09 was performed twice and was subjected to filtering, which was almost equivalent to SD 20.

Next, the image quality was examined using a large intestine CT phantom, but in images taken with SD 34 and SD 38, an increase in the SD value, seemingly due to dose deficiency in the area surrounded by the bone, was observed. Thus an excessively low-dose imaging may interfere with diagnosis, and the SD value taken up to 30 was reasonable.

Based on the average absorbed dose when photographing a CT phantom, it was suggested that SD 30 imaging was 35% less than radiation exposure compared to SD 20 imaging.