Computer-aided Lung Nodule Detection in CT: Results of Large-Scale Observer Test 1

Early detection of pulmonary nodules is crucial for improving prognosis of patients with lung cancer. Computer-aided detection of lung nodules in thoracic computed tomography (CT) scans has a great potential to enhance the performance of the radiologist in detecting nodules. In this paper we present a computer-aided lung nodule detection system for computed tomography (CT) scans that works in three steps. The system first segments the lung using thresholding and hole filling. From this segmentation the system extracts candidate nodules using Laplacian of Gaussian. To reject false positives among the detected candidate nodules, multiple established features are calculated. We propose a novel feature based on a spherical shell filter, which is specifically designed to distinguish between vascular structures and nodular structures. The performance of the proposed CAD system was evaluated by partaking in the ANODE09 challenge, which presents a platform for comparing automatic nodule detection programs. The results from the challenge show that our CAD system ranks third among the submitted works, demonstrating the efficacy of our proposed CAD system. The results also show that our proposed spherical shell filter in combination with conventional features can significantly reduce the number of false positives from the detected candidate nodules.

Automated Computer-Aided Detection of Lung Nodules in Metastatic Colorectal Cancer Patients for the Identification of Pulmonary Oligometastatic Disease

Diminution index: A novel 3D feature for pulmonary nodule detection

To compare the features of patients with peptic ulcer between Han and Uyghur ethnicity from 2013 to 2018 in Xinjiang and to provide the evidence of prevention and treatment for the different ethnicity. Data of 3 586 patients with peptic ulcer (3 293 Han and 293 Uyghur) in the Karamay Central Hospital of Xinjiang, including the detection rate of peptic ulcer, helicobacter pylori (Hp) detection rate of population, season, gender, lesion location and complication, were collected from January 2013 to December 2018 and compared between 2 nationalities. There were significant difference in the detection rate of peptic ulcer and population's Hp between Han and Uyghur (P<0.01). The detection rates for peptic ulcer of Han were sustainable declined from 15.20% to 10.23%, while Uyghur's detective rates for peptic ulcer were raised again from 17.49% to 8.38%. The Hp detection rate of Uyghur's population was higher than that of Han (P<0.01). There were significant difference in the season's detection rate for peptic ulcer between Han and Uyghur (P<0.01). The detection rate for peptic ulcer of Han was the highest in the winter, while that of Uyghur was the highest in the spring. The detective rate of Uyghur's peptic ulcer was significant higher than that of Han in the spring (P<0.01). The detection rates for peptic ulcer of 2 nationality were the highest at ≤25 age groups, the detection rate for Uyghur's peptic ulcer was higher than that of Han at ≤35 age groups (P<0.05). There were more men than women in peptic ulcer in the 2 nationalities. The approximate proportion was 2꞉1. The rates of multiple gastric ulcer and compound duodenal ulcer of Han were more than those of Uyghur (P<0.05), but the rate for pyloric obstruction of Uyghur patient was higher than that of Han (P<0.05). There are statistical difference in detection rate of PU, Hp detection rate of population, morbidity season, age, complication and the rate of complex ulcer between Han and Uyghur, However, there aren't statistical difference in Hp detection rate of peptic ulcer patient, the gender, lesion location between the 2 nationalities during last 6 years.

Objective: To compare the 10 years risk for ischemic cardiovascular disease among Han, Uygur, Kazak nationality residents of Xinjiang Uygur Autonomous Region. Methods: From October 2007 to October 2010,14 618 adult (aged ≥35 years) Han (n=5 757),Uygur (n=4 767) and Kazak (n=4 094) residents were selected to join this study through the four-stage stratified cluster sampling method from 7 cities and regions of Xinjiang Uygur Autonomous Region. The 10 years risk for ischemic cardiovascular disease was calculated according to the 10 years ischemic cardiovascular disease risk assessment form modified with Chinese characteristics and compared among the residents of 3 nationalities. Results: (1) There were significant differences in age, body mass index, systolic blood pressure, diastolic blood pressure,fasting blood glucose,triglycerides,total cholesterol,low-density lipoprotein,high-density lipoprotein cholesterol, smoking history, and drinking history among Han, Uygur, Kazak nationality population (all P< 0.001). (2) There were significant differences in 10 years risk for ischemic cardiovascular disease between different gender and age group including 35-39, 40-44, 45-49, 50-54, 55-59, and ≥60 years old between Han, Uygur, Kazak nationality population (all P<0.001). (3) There were significant differences in rates of 10%-20% and>20% of 10 years risk for ischemic cardiovascular disease between different gender in Han, Uygur, Kazak nationality population (P values were 0.013 and <0.001, respectively). There were no significant differences in rates of <5% and 5%-9% of 10 years risk for ischemic cardiovascular disease between different gender in Han,Uygur,Kazak nationality population (all P>0.05).(4) There were significant differences in detection rates of diabetes,hypertension,smoking,hypertriglyceridemia,and obesity in male and female Han,Uygur,Kazak nationality population with 10 years risk for ischemic cardiovascular disease ≥10% (P<0.01 or 0.05). Meanwhile,there was significant difference in detection rates of hypercholesteremia in male Han, Uygur, Kazak nationality adults(P<0.001). There were no significant differences in detection rates of elevated low density lipoprotein cholesterol and reduced high density lipoprotein cholesterol in male and female Han,Uygur,Kazak nationality adults (all P>0.05). Conclusion: There are gender and age differences in the 10 years risk for ischemic cardiovascular disease in ≥35 years old Han,Uygur,Kazak nationality adults from Xinjiang Uygur Autonomous Region.

We are developing a computer-aided detection system to assist radiologists in the detection of lung nodules on thoracic computed tomography (CT) images. The purpose of this study was to improve the false-positive (FP) reduction stage of our algorithm by developing features that extract three-dimensional (3D) shape information from volumes of interest identified in the prescreening stage. We formulated 3D gradient field descriptors, and derived 19 gradient field features from their statistics. Six ellipsoid features were obtained by computing the lengths and the length ratios of the principal axes of an ellipsoid fitted to a segmented object. Both the gradient field features and the ellipsoid features were designed to distinguish spherical objects such as lung nodules from elongated objects such as vessels. The FP reduction performance in this new 25-dimensional feature space was compared to the performance in a 19-dimensional space that consisted of features extracted using previously developed methods. The performance in the 44-dimensional combined feature space was also evaluated. Linear discriminant analysis with stepwise feature selection was used for classification. The parameters used for feature selection were optimized using the simplex algorithm. Training and testing were performed using a leave-one-patient-out scheme. The FP reduction performances in different feature spaces were evaluated by using the area Az under the receiver operating characteristic curve and the number of FPs per CT section at a given sensitivity as accuracy measures. Our data set consisted of 82 CT scans (3551 axial sections) from 56 patients with section thickness ranging from 1.0 to 2.5 mm. Our prescreening algorithm detected 111 of the 116 solid nodules (nodule size: 3.0-30.6 mm) marked by experienced thoracic radiologists. The test Az values were 0.95 +/- 0.01, 0.88 +/- 0.02, and 0.94 +/- 0.01 in the new, previous, and combined feature spaces, respectively. The number of FPs per section at 80% sensitivity in these three feature spaces were 0.37, 1.61, and 0.34, respectively. The improvement in the test Az with the 25 new features was statistically significant (p<0.0001) compared to that with the previous 19 features alone.

To the Editor: Fecal immunochemical tests (FITs) are immunoassays that are designed to detect human hemoglobin to indicate the occurrence of colonic neoplasia, which have been widely used in global colorectal cancer (CRC) screening programs. Previous diagnostic studies demonstrated that strong gradient in site-specific sensitivity existed with typically higher rate for advanced adenoma located in distal colon/rectum than that in the proximal parts, which may be explained by the colonic transition time affecting the degradation of hemoglobin, and the shape of adenoma (pedunculated, flat, and sessile) in different anatomic regions.[1] In addition, questionnaire-based risk assessment (QRA) using the established CRC-related risk factors has been proposed to identify high-risk populations for CRC screening.[2] However, previous studies demonstrated that site-specific differences existed for several risk factors.[3,4] In a CRC screening setting, whether and to what extent the FIT and QRA would affect the site-specific detection rate of colorectal neoplasia have not been evaluated. Therefore, we aimed to empirically evaluate the site-specific variations of the detection rates of adenomas for the FIT- and QRA-based screening based on a population-based CRC screening trial (TARGET-C). The study was conducted in the context of an ongoing TARGET-C trial consisted of 19,546 participants, aiming to evaluate the effectiveness of colonoscopy, FIT, and risk-adapted screening approaches in CRC screening in China, and the detailed study protocol has been previously published.[5,6] For the present study, we included 3825 subjects aged 40 to 74 years undertaking colonoscopy in the baseline screening in 2018–2019, of which 1665 were for screening purpose (colonoscopy arm), 1436 were for diagnostic purpose following positive-FIT (FIT arm or risk-adapted screening arm), and 724 were for diagnostic purpose following positive-QRA (risk-adapted screening arm). This study was approved by the Ethics Committee of the National Cancer Center/Cancer Hospital, the Chinese Academy of Medical Sciences and Peking Union Medical College (No. 18-013/1615). All participants provided written informed consent. For the QRA use in the present study, the modified Asian-Pacific colorectal screening (APCS) score was used for risk stratification, including five risk factors of CRC (age, sex, family history of CRC among first-degree relatives, smoking, and body mass index [BMI]). Each factor is allocated a score, as followed described: age (0 point: 50–54 years; 1 point: 55–65 years; 2 points: 65–74 years); sex (0 point: female; 1 point: male); family history of CRC among first-degree relatives (0 point: absent; 1 point: present); smoking (0 point: non-smoker; 1 point: current or past smoker); and BMI (0 point: <23; 1 point: ≥23). The cumulative score was calculated. Subjects with scores ≥4 were defined as high-risk and were referred for colonoscopy; those with scores <4 were defined as low-risk and were referred for FIT screening. A self-administered qualitative FIT for hemoglobin (Pupu Tube, New Horizon Health Technology, Hangzhou, China) was used in this trial. The FIT enabled visual interpretation of the test results as positive or negative by eye if the fecal hemoglobin concentration exceeded the threshold specified by the manufacturer (100 ng Hb/mL, equivalent to 4 μg Hb/g feces). Participants with confirmed positive-FIT results were scheduled for subsequent diagnostic colonoscopy. Additional information regarding the study design is provided in the Supplementary File, https://links.lww.com/CM9/A447. The primary outcome of interest was the detection rate for advanced adenoma or non-advanced adenoma, which was calculated by numbers of the carriers with disease divided by the total number included participants. Advanced adenoma was defined as high-grade dysplasia, villous or tubular-villous histologic features, measuring 1 cm or more in diameter. Regarding the location of the neoplasm, the proximal colon was considered to include the splenic flexure and all segments proximal to it, and the rest was considered distal colon/rectum. For subjects having multiple adenomas, the outcome and anatomic location were defined according to the most advanced one. Site-specific detection rate was therefore calculated and compared between the three groups of subjects undertaking colonoscopy, that is, screening purpose, diagnostic purpose either of positive-FIT or positive-QRA. For the 3825 included subjects, the mean (standard deviation) age was 60.5 (6.3) years and slightly more men (n = 1977, 51.7%) were included. Overall, among the subjects undertaking screening colonoscopy and diagnostic colonoscopy after positive-FIT, no significant differences regarding the distribution of sociodemographic factors were observed. For subjects undertaking diagnostic colonoscopy after positive-QRA, the distribution of these factors was significantly different than the other two groups, because factors of age, sex, BMI, cigarette smoking, and history of CRC among the first-degree relatives were included in the risk assessment [Supplementary Table 1, https://links.lww.com/CM9/A447]. For subjects undertaking screening colonoscopy, the detection rates of advanced adenoma located in the distal colon/rectum and proximal colon were 3.12% (95% CI: 2.39–4.07%) and 2.52% (95% CI: 1.87–3.39%), the rate ratio distal vs. proximal was 1.24 (95% CI: 0.83–1.85), and the rate difference distal vs. proximal was 0.60% (95% CI: −0.52 to 1.73%). As expected, the detection rates of advanced adenoma increased for subjects with either positive-FIT (proximal vs. distal: 8.64% [95% CI: 7.29–10.20%] vs. 3.90% [95% CI: 3.01–5.03%]) or positive-QRA (proximal vs. distal: 6.91% [95% CI: 5.28–8.99%] vs. 4.70% [95% CI: 3.38–6.49%]), however, the rate ratiodistal vs. proximal increased to 2.21 (95% CI: 1.63–3.00; PFIT vs. colonoscopy = 0.025) and 1.47 (0.96–2.24; PQRA vs. colonoscopy = 0.567), respectively; and the rate differencedistal vs. proximal increased to 4.74% and 2.21%, respectively. Regarding detection for non-advanced adenoma and any adenoma, there were no significant differences in detection rates among the subjects of either positive-FIT or positive-QRA compared with the subjects undertaking screening colonoscopy. Detailed results are shown in Table 1. Table 1 - Differences in detection rate of colorectal adenoma among subjects performing colonoscopy with different indications (n=3825) Outcome Site Detected cases (n) Detection rate (%, 95%CI) Rate ratio P value ∗ Rate difference (%, 95% CI) Advanced adenoma Colonoscopy (n = 1665) Distal 52 3.12 (2.39–4.07) 1.24 (0.83–1.85) Reference 0.60 (–0.52–1.73) Proximal 42 2.52 (1.87–3.39) Reference Reference FIT (n = 1436) Distal 124 8.64 (7.29–10.20) 2.21 (1.63–3.00) 0.025 4.74 (2.97–6.50) Proximal 56 3.90 (3.01–5.03) Reference Reference QRA (n = 724) Distal 50 6.91 (5.28–8.99) 1.47 (0.96–2.24) 0.567 2.21 (–0.20–4.62) Proximal 34 4.70 (3.38-6.49) Reference Reference Non-advanced adenoma Colonoscopy (n = 1665) Distal 207 12.43 (10.93–14.10) 1.35 (1.11–1.64) Reference 3.24 (1.14–5.35) Proximal 153 9.19 (7.89–10.67) Reference Reference FIT (n = 1436) Distal 228 15.88 (14.08–17.86) 1.37 (1.14–1.65) 0.915 4.32 (1.81–6.83) Proximal 166 11.56 (10.00–13.32) Reference Reference QRA (n = 724) Distal 105 14.50 (12.13–17.26) 1.21 (0.93–1.58) 0.514 2.49 (–1.01–5.98) Proximal 87 12.02 (9.85–14.59) Reference Reference Any adenoma Colonoscopy (n = 1665) Distal 259 15.56 (13.89–17.38) 1.33 (1.12–1.58) Reference 3.84 (1.52–6.17) Proximal 195 11.71 (10.25–13.35) Reference Reference FIT (n = 1436) Distal 352 24.51 (22.36–26.80) 1.59 (1.37–1.85) 0.125 9.05 (6.15–11.96) Proximal 222 15.46 (13.68–17.42) Reference Reference QRA (n = 724) Distal 155 21.41 (18.58–24.54) 1.28 (1.03–1.59) 0.786 4.70 (0.66–8.74) Proximal 121 16.71 (14.17–19.60) Reference Reference FIT: Fecal immunochemical test; QRA: Questionnaire-based risk assessment. ∗P values were calculated comparing the differences of rate ratios between the examined group and the colonoscopy group using the Z-test proposed by Douglas G Altman and J Matrtin Bland (BMJ 2003;326: 219). In this retrospective analysis based on a population-based CRC screening trial, by setting the yield of screening colonoscopy as a reference reflecting the real-world prevalence of adenoma in different anatomic locations, we found that FIT- and QRA-based screening had large variations in terms of detection rates for proximal and distal located advanced adenoma, although the difference was only statistically significant for the FIT-based approach. There were several reasons that might explain the variations of the detection rates for advanced neoplasia located in the proximal and distal colon/rectum. First, most of the distal adenomas are pedunculated, which may therefore be more prone to be bleeding than the flat and sessile adenomas that are more likely to be detected in the proximal colon. Second, the degradation time for fecal hemoglobin is longer for proximal lesions than distal ones, which may therefore lead to the variation of the detection rate, although data to support this are sparse. Previous studies have suggested that lowering the positivity threshold of FIT may help to increase the sensitivity for detecting proximal neoplasm. The positivity threshold of FIT used in the present study was 4 μg Hb/g feces, which was lower than other FIT-based CRC screening programs.[8] Based on our results, such a strategy of lowering the positivity threshold of FIT may not aid such an issue. Another important finding of our study was that QRA also lead to divergent detection rates for proximal and distal neoplasms, although the differences were not statistically significant. Although the reasons behind this cannot be fully understood, we inferred that a series of factors such as smoking and BMI had different magnitudes of attributable risk in proximal and distal CRC, as demonstrated in a recently published study.[3,4] Further attention should be paid to this issue, since combining environmental and polygenic factors has been suggested in tailored risk-adapted CRC screening. Our study has limitations. First, the analysis was derived from a single round of screening, however, the current finding indicated that the differences between the detection rate for proximal and distal advanced adenoma may be even larger over multiple rounds of screening. Second, despite the overall large sample size of the trial, numbers of the advanced adenomas were still rather limited leading to rather wide confidence intervals, which should be addressed in further larger studies.[7] To sum up, we empirically demonstrated the divergent detection rates of proximal and distal advanced adenomas existed in FIT-based but not in the QRA-based CRC screening. Further efforts should be made to optimize the effectiveness of CRC screening by improving the lower detection rate of proximal advanced adenomas. Funding This work was supported by grants from the CAMS Innovation Fund for Medical Sciences (No. 2017-I2M-1-006), the National Natural Science Foundation of China (No. 81703309), Beijing Nova Program of Science and Technology (No. Z191100001119065), and the Natural Science Foundation of Beijing Municipality (No. 7202169). Conflicts of interest None.

Computer-vision techniques based on wavelets are presented with applications to computer-aided diagnosis (CAD) in medical images. CAD is a method for assisting radiologists’ interpretation of medical images. CAD schemes act as a second reader and alert radiologists to suspicious lesions. Development of CAD schemes is an active area of research, motivated by the fact that radiologists tend to misdiagnose cancerous lesions in medical images. In the past several years, we have been extensively developing wavelet-based techniques for CAD schemes. Development of these techniques has led to a new CAD scheme and has yielded significant improvements in the performance of the existing CAD schemes. This chapter describes two wavelet-based, low-level computer vision techniques: simultaneous segmentation and registration, and matching pursuit with optimally weighted wavelet packets. We present their application to the computer-aided detection of lung nodules in chest radiographs and microcalcifications in mammograms.

We are developing a computer-aided detection system to aid radiologists in diagnosing lung cancer in thoracic computed tomographic (CT) images. The purpose of this study was to improve the false-positive (FP) reduction stage of our algorithm by developing and incorporating a gradient field technique. This technique extracts 3D shape information from the gray-scale values within a volume of interest. The gradient field feature values are higher for spherical objects, and lower for elongated and irregularly-shaped objects. A data set of 55 thin CT scans from 40 patients was used to evaluate the usefulness of the gradient field technique. After initial nodule candidate detection and rule-based first stage FP reduction, there were 3487 FP and 65 true positive (TP) objects in our data set. Linear discriminant classifiers with and without the gradient field feature were designed for the second stage FP reduction. The accuracy of these classifiers was evaluated using the area Az under the receiver operating characteristic (ROC) curve. The Az values were 0.93 and 0.91 with and without the gradient field feature, respectively. The improvement with the gradient field feature was statistically significant (p=0.01).

Computer-aided diagnoses programs are developed for alerting the radiologist by indicating potential sites of lesions. One of the important tasks in the development of a computational system for detecting lung nodules is to diminish the number of false positives keeping on high sensitivities. In this work we describe a system for automatic lung nodule detection. The detection is carried out in several stages. First, a knowledge-based segmentation process delimits the lung boundaries. Then, a progressive thresholding of an image in which the conspicuity of nodules has been enhanced by means of filter matching and a set of growth and circularity tests fix the areas suspicious of being nodules into region previously labelled as lungs. Finally, these suspicious regions are confirmed as nodules in a new feature (curvature) space, which gives us an important help in the task of distinguishing true and false nodules from previously extracted suspicious regions. Preliminary results are very promising, achieving high sensitivities with a little ratio of false positives.

ObjectiveSimultaneous PET/MRI combines soft-tissue contrast of MRI with high molecular sensitivity of PET in one session. The aim of this prospective study was to evaluate detection rates of recurrent prostate cancer by 18F-fluciclovine PET/MRI.MethodsPatients with biochemical recurrence (BCR) or persistently detectable prostate specific antigen (PSA), were examined with simultaneous 18F-fluciclovine PET/MRI. Multiparametric MRI (mpMRI) and PET/MRI were scored on a 3-point scale (1-negative, 2-equivocal, 3-recurrence/metastasis) and detection rates (number of patients with suspicious findings divided by total number of patients) were reported. Detection rates were further stratified based on PSA level, PSA doubling time (PSAdt), primary treatment and inclusion criteria (PSA persistence, European Association of Urology (EAU) Low-Risk BCR and EAU High-Risk BCR). A detailed investigation of lesions with discrepancy between mpMRI and PET/MRI scores was performed to evaluate the incremental value of PET/MRI to mpMRI. The impact of the added PET acquisition on further follow-up and treatment was evaluated retrospectively.ResultsAmong patients eligible for analysis (n=84), 54 lesions were detected in 38 patients by either mpMRI or PET/MRI. Detection rates were 41.7% for mpMRI and 39.3% for PET/MRI (score 2 and 3 considered positive). There were no significant differences in detection rates for mpMRI versus PET/MRI. Disease detection rates were higher in patients with PSA≥1ng/mL than in patients with lower PSA levels but did not differ between patients with PSAdt above versus below 6 months. Detection rates in patients with primary radiation therapy were higher than in patients with primary surgery. Patients categorized as EAU Low-Risk BCR had a detection rate of 0% both for mpMRI and PET/MRI. For 15 lesions (27.8% of all lesions) there was a discrepancy between mpMRI score and PET/MRI score. Of these, 10 lesions scored as 2-equivocal by mpMRI were changed to a more definite score (n=4 score 1 and n=6 score 3) based on the added PET acquisition. Furthermore, for 4 of 10 patients with discrepancy between mpMRI and PET/MRI scores, the added PET acquisition had affected the treatment choice.ConclusionCombined 18F-fluciclovine PET/MRI can detect lesions suspicious for recurrent prostate cancer in patients with a range of PSA levels. Combined PET/MRI may be useful to select patients for appropriate treatment, but is of limited use at low PSA values or in patients classified as EAU Low-Risk BCR, and the clinical value of 18F-fluciclovine PET/MRI in this study was too low to justify routine clinical use.

Background: To investigate the influence of the reduced image quality of transnasal esophagogastroduodenoscopy (EGD) with the ultrathin endoscope (transnasal EGD) on endoscopic diagnoses, we compared the detection rate (DR) of early gastric cancer and gastric adenoma by transnasal EGD with that of transoral EGD using a standard endoscope.Methods: Transnasal EGD was carried out in 2791 examinations for the purposes of screening or other reasons. Controls were examined by transoral EGD and numbered 3591 examinations. The transnasal endoscope used was an EG530N. Lesions graded C‐3 or higher by Kimura‐Takemoto's classification were regarded as endoscopic atrophy.Results: (i) DR in all subjects and those with atrophy were not different between transnasal and transoral EGD. (ii) Multivariate analysis of DR in subjects with atrophy was carried out using five variables: gender, age, purposes of endoscopy, endoscopic insertion route and the four endoscopists. DR was significantly higher in males or subjects ≥60 years. No difference was noted between the endoscopic insertion routes (transnasal vs transoral). (iii) The subjects analyzed in (ii) were divided into the transnasal and transoral groups, and multivariate analysis of DR was carried out using four variables. DR was not different among the endoscopists in the transoral group. However, in the transnasal group, DR increased as the years of endoscopic experience was prolonged.Conclusions: Multivariate analysis detected no significant difference in DR between transnasal and transoral EGD. However, a significant difference in DR by transnasal EGD among the endoscopists is detected. Transnasal EGD should be carefully carried out by experienced endoscopists.

843 COMPARISON OF PROSTATE CANCER DETECTION RATE BETWEEN PROSTATE BIOPSY PERFORMED WITH END-FIRE SINGLE-PLANE AND DUAL-PLANE TRANSRECTAL PROBE

Since capsule endoscopy (CE) is time consuming, one possible cost-effective strategy could be the use of an expert endoscopic assistant and available software to select images. Aims were to examine the clinical utility of RAPID(®) 5 Access software and find the optimum setting mode for reading. We also evaluated whether a nurse could preview the CE video and detect significant lesions accurately. The capsule images in 14 volunteers with known mucosal injury induced by low dose aspirin and in 30 patients who were known to have a variety of significant lesions were selected. Using three setting modes of RAPID(®) 5 Access software, the detection rate and reading time for CE images by two well-trained physicians and one expert nurse were compared. There was no significant difference in detection rate among the three readers. The detection rate using Quickview RAPID(®) 5 Access was significantly higher than that using RAPID(®) Reader version 4.1. Comparison among the three modes of RAPID(®) 5 Access showed that auto mode as well as displaying a single image at 12 fps was superior in the detection rate of denuded redness, while its reading time was longer compared to the other modes. Some significant lesions were not detected by using Quickview and Quadview modes. RAPID(®) 5 Access improves diagnostic yield, reducing reading time; however, it is still unacceptable because of the diagnostic miss rate and may be useful as an ancillary reading tool. Developing further improved software and training expert assistants for reading capsule images are necessary.

In real-world settings, many patients cannot or do not stop proton pump inhibitors (PPIs) due to symptoms, but guidelines do not address H. pylori testing in PPI users. We compared the rapid urease test (RUT) and histopathology (HPE) when H. pylori testing and endoscopy are indicated for patients with a recent history of PPI use. A prospective study of 164 patients who used PPIs within twoweeks of endoscopy was conducted. Gastric antrum and body biopsies were used for double-site RUT and polymerase chain reaction (PCR)analyses. The updated Sydney protocol was followed for HPE. Patients with at least two out of three positive tests were considered infected with H. pylori. Fifty patients, who underwent only PCR for H. pylori diagnosis after stopping PPIs for two weeks, were enrolled as controls to assess the effect on detection rates. Additionally, an analysis utilizing PCR as the gold standard was conducted. In patients on PPIs, there was no significant difference in detection rates (positivity rate) between HPE and RUT (31.7% vs. 27.4%, p = 0.3771 [McNemar]).The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV)and diagnostic accuracy of double-site RUT were 89.13%, 96.61%, 91.11%, 95.80% and 94.51%, respectively, whereas HPE was 82.61%, 88.14%, 73.08%, 92.86% and 86.59%. PCR had a much greater detection rate and there was no significant difference in detection rate by the PCR method in patients on and off PPI for at least twoweeks prior to testing for H. pylori (48% vs. 44%, p = 0.58). The sensitivity of double-site RUT and HPE was still comparable, albeit low, when only PCR was considered the gold standard (43.75% vs. 40%, respectively). Atrophic gastritis and intestinal metaplasia are found in approximately 9% and 5% of gastric body biopsies and 9% and 2.5% of gastric antrum biopsies, respectively. PPI use does not affect PCR-based testing for H. pylori. If PCR-based testing is unavailable, double-site RUT offers a cost-effective alternative for H. pylori testing in PPI users at the point of care, particularly in resource-limited settings, in comparison to HPE. The choice between biopsy using validated protocols or double RUT is also contingent upon the underlying risk factors for gastric cancer.