Oral Contrast-Enhanced Gastric Ultrasonography in the Assessment of Gastric Lesions: A Large-Scale Multicenter Study

Clinical value of oral contrast-enhanced ultrasonography in diagnosis of gastric tumors

BACKGROUND

The incidence of gastric cancer remains high, and it is the sixth most common cancer and the fourth leading cause of cancer deaths worldwide. Oral contrast-enhanced ultrasonography is a simple, non-invasive, and painless method for the diagnosis of gastric tumors.

AIM

To explore the diagnostic value of oral contrast-enhanced ultrasonography for the detection of gastric tumors.

METHODS

The screening results based on oral contrast-enhanced ultrasonography and electronic gastroscopy were compared with those of the postoperative pathological examination.

RESULTS

Among 42 patients with gastric tumors enrolled in the study, the diagnostic accordance rate was 95.2% for oral contrast-enhanced ultrasonography (n = 40) and 90.5% for electronic gastroscopy (n = 38) compared with postoperative pathological examination. The Kappa value of consistency test with pathological findings was 0.812 for oral contrast-enhanced ultrasonography and 0.718 for electronic gastroscopy, and there was no significant difference between them (P = 0.397). For the TNM staging of gastric tumors, the accuracy rate of oral contrast-enhanced ultrasonography was 81.9% for the overall T staging and 50%, 77.8%, 100%, and 100% for T1, T2, T3, and T4 staging, respectively. The sensitivity and specificity were both 100% for stages T3 and T4. The diagnostic accuracy rate of oral contrast-enhanced ultrasonography was 93.8%, 80%, 100%, and 100% for stages N0, N1-N3, M0, and M1, respectively.

CONCLUSION

The accordance rate of qualitative diagnosis by oral contrast-enhanced ultrasonography is comparable to that of gastroscopy, and it could be used as the preferred method for the early screening of gastric tumors.

Risk stratification of gastric cancer screening in community population based on oral contrast-enhanced ultrasonography examination: A 3-year follow-up analysis report

Objective

This study aimed to retrospectively investigate the use of oral contrast-enhanced ultrasonography (O-CEUS) in assessing the thickness of the gastric wall for gastric cancer (GC) screening and to establish screening strategies for GC with different risk stratifications based on the gastric wall thickness.

Methods

From January 2015 to March 2020, people who underwent O-CEUS at the Physical Examination Center of our hospital with at least three years of follow-up were included in this study. The thickness of the gastric wall measured by O-CEUS was divided into three groups using 6 mm and 9 mm as cutoff values. The occurrence of GC in each group was observed. The imaging and clinical information of these populations were recorded and analyzed. Kaplan-Meier survival analysis and Cox's proportional hazards regression were performed to calculate the risk of GC occurrence.

Results

A total of 4,047 people were finally included in this study. During the follow-up period, GC occurred in 7 individuals (incidence rate 0.17%). Among them, according to the thickness of the gastric wall, one case occurred in Group A (< 6 mm), two cases occurred in Group B (6-9 mm), and four cases occurred in Group C (>9mm). Based on Kaplan-Meier survival analysis, the curves of the three groups were significantly different (P < 0.01). The risk of GC occurrence in Group C and Group B were higher than that in Group A (4.76E+2-fold and 1.50E+2-fold).

Conclusion

O-CEUS is a convenient, economical, safe, and noninvasive screening method for GC. Measuring the thickness of the gastric wall is helpful to predict the risk of GC occurrence according to our stratification screening system.

Utility of Transabdominal Ultrasonography Enhanced by Oral Cellulose-Based Contrast Agent in Depicting Varices at Cardia and Fundus

The use of transabdominal color Doppler ultrasound after oral administration of an oral cellulose-based contrast agent (TUS-OCCA) in depicting varices at the cardia and fundus was explored. Both gastroscopy and transabdominal color Doppler ultrasound (TUS) were performed for this purpose, with gastroscopy serving as the gold standard. Patients were assigned by TUS protocol to one of three groups: TUS + empty stomach (TUS-ES); TUS + oral water intake (TUS-OW); and TUS-OCCA. TUS-based grading of varices reflected venous diameters and blood flow velocities, designated as follows: Ux = difficulty discerning gastric fundus and cardia or delineating varices; U0 = no detectable varices; U1 = diameter <5 mm, flow rate <10 cm/s; U2 = diameter <5 mm, flow rate ≥10 cm/s; U3 = diameter 5-10 mm, flow rate <10 cm/s; U4 = diameter 5-10 mm, flow rate ≥10 cm/s; and U5 = diameter >10 mm, any flow rate. Between August 2016 and August 2019, 239 patients with cirrhosis were enrolled prospectively, including bleeding (n = 71) and non-bleeding (n = 168) groups. Varices were directly observed in 10.5% (25/239) of TUS-ES group members, compared with 59.2% (58/98) of the TUS-OW group and 89.6% (104/116) of the TUS-OCCA group; all detection rates differed significantly (TUS-OCCA > TUS-OW > TUS-ES, p < 0.05). TUS-based grading (as defined) revealed the following patient distribution: Ux, n = 34; U0, n = 18; U1, n = 50; U2, n = 41; U3, n = 16; U4, n = 46; U5, n = 34. In grading by variceal diameter, overall correspondence between TUS and gastroscopy was 93% (174/187). TUS-OCCA greatly improved rates of detection of varices at the cardia and fundus, offering a new method by which diagnosis and quantitative grading may be achieved and affording an excellent, non-invasive approach to dynamic follow-up.

Pitfalls in ultrasound imaging of the stomach and the intestines

The gastrointestinal tract is an extraordinary human organ in terms of its morphology and function. Its complex structure and enormous length as well as frequent presence of gas discourage many doctors performing ultrasound examination from its exploration. Moreover, there are anatomical structures in multiple locations which can mimic certain abnormalities. It is difficult to present an exhaustive account of the problem of gastrointestinal tract ultrasound imaging errors in a single work; therefore, this study focuses mainly on false positive errors which usually result from a lack of knowledge of anatomical variants of the gastrointestinal tract structure. In the case of the stomach, rugae and muscle layer thickening towards the pylorus have been mentioned, which constitute variants of the structure of this organ examined when empty. Diagnostic pitfalls in the small intestine may include the dudenojejunal flexure (ligament of Treitz), the horizontal part of the duodenum and the ileocaecal valve. The status of the apparent lesions in all of the cases mentioned will be resolved following fluid intake by the patient. In the colon, the varied structure of semilunar folds should be taken note of. Their large thickness can warrant suspicion of wall invasion or a polyp. In addition, the study emphasises the importance of appropriate preparation of a patient for gastrointestinal tract examination since it determines the accuracy of the diagnosis. The authors also take note of common ‘sins’ of physicians such as hasty examination and failure to comply with the stomach and appendix examination protocol.

Preliminary opinion on assessment categories of stomach ultrasound report and data system (Su-RADS)

OBJECTIVE

Transabdominal ultrasound after oral administration of an echoic cellulose-based gastric ultrasound contrast agent (TUS-OCCA) has recently been suggested as a valuable mass-screening tool for gastric cancer. The aim of this study was to propose a producible stomach ultrasound reporting and data system (Su-RADS) using TUS-OCCA for gastric cancer screening.

PATIENTS

The study includes information of 2738 patients who underwent both gastroscopy and TUS-OCCA examinations recorded in software system. Gastroscopy examination with pathological diagnosis was considered as gold standard. Various gastric lesions were classified into category 1-5 based on gastric wall thicknesses of them (especially the mucosa layer).

RESULTS

The total malignant ratios of patients enrolled in this study were 17.1% (469/2738). The malignant ratios for category 1-5 were, respectively, 1.1, 1.7, 12.2, 34.2 and 78.1%. Category 2 indicated mild thickening of gastric wall at low risk for malignancy (1.7%); category 3 indicated moderate thickening at moderate risk for malignancy (12.2%); category 4 indicated severe thickening at high risk for malignancy (34.2%); category 5 indicated extremely severe thickening at extremely high risk for malignancy (78.1%). If category 2 was identified as cut-off point distinguishing between benign and malignant, the sensitivity and specificity by Su-RADS are 95.1 and 78.6%, respectively.

CONCLUSION

The Su-RADS system could inform the physicians about key findings, indicating the risk for malignancy and necessity of additional gastroscopy examination. Prospectively randomly controlled study design with larger clinical trial is needed for further investigations.