Gastrointestinal imaging: endoscopic ultrasound

Accuracy of endoscopic ultrasound staging of gastric cancer in routine clinical practice in Singapore

OBJECTIVE

Endoscopic ultrasound has emerged as the leading modality to assess the T and N stage in gastric cancer. This study aimed to assess the accuracy of TN staging by endoscopic ultrasound in routine clinical practice in Singapore.

METHODS

Over a period of 7 years, 77 patients (male: 70%; median age 62.8 years) with gastric cancer underwent preoperative staging with endoscopic ultrasound. Fifty-seven patients eventually underwent surgery with tissues available for histopathological staging and comparison.

RESULTS

The tumor locations were: cardia: 13; corpus: 20; incisura: 19; antrum: 25. The majority was poorly differentiated (57.1%); 26% were moderately differentiated and 16.9% were well differentiated adenocarcinoma. Compared to pathological staging, the overall accuracy of T staging by endoscopic ultrasound was 77.2% (17.5% under-staged: 5.3% over-staged). The staging accuracy of T1 (92.9%) and T3 (81.8%) was higher than T2 (57.1%) and T4. For N staging, the accuracy of endoscopic ultrasound was 59.6% (26.3% under-staged; 14% over-staged); this was significantly superior to computer tomography (43.9%).

CONCLUSION

Endoscopic ultrasound is useful for the T staging of gastric cancer, with an overall accuracy rate of 77%, and up to 93% for T1 lesions. Under-staging may occur due to microscopic tumor infiltration, while over-staging may arise due to inflammatory reactions. The accuracy of N staging is lower at 60%, but could be further improved with the use of fine needle aspiration.

The importance of PET in the diagnosis and response evaluation of esophageal cancer

The major aims of imaging in esophageal cancer are to distinguish between locoregional and systemic disease (M-stage), to determine local tumor extension (T- and N-stage), to assess response to chemo- or chemoradiotherapy and to identify recurrence of cancer. The sensitivity of computed tomography (CT) for detection of distant metastases ranges between < 50% and > 90%. In esophageal cancer, F-18-fluorodeoxyglucose positron emission tomography (FDG-PET) has been shown to detect metastatic disease in approximately 20% of patients who are considered as having only locoregional disease on CT. In locoregional pretherapeutic tumor staging, FDG-PET specificity of 80% is sufficient, but FDG-PET sensitivity of 50% is rather low. However, the initial staging of regional lymph nodes is less important because at the moment there is no pretherapeutic therapy stratification based on lymph node category. The accuracy for correct identification of recurrence in esophageal cancer is higher for FDG-PET than for CT scan. Unfortunately until today no reliable essays for prediction of response or prognosis exist for esophageal cancer in clinical practice for patients with neoadjuvant treatment. Thus the identification of parameters predicting response and/or prognosis is crucial for the future. Post-therapeutic assessment of tumor response by FDG-PET has been shown to correlate with histopathologic tumor regression and patient survival. Furthermore, quantitative measurements of tumor FDG-uptake may allow an early metabolic response evaluation after only 2 weeks of therapy. An association of metabolic response with histopathologic tumor regression and patient outcome 2 weeks after initiation of preoperative chemotherapy may be shown for esophageal cancer.

Colonic muco-submucosal elongated polyp: diagnosis with endoscopic ultrasound

Colonic muco-submucosal elongated polyp is a new clinical entity first reported in 1998. The purpose of this report is to determine the value of endoscopic ultrasound in the diagnosis of this condition. We reviewed the endosonographic and histological findings of seven colonic muco-submucosal elongated polyps that were removed completely by endoscopic resection or surgery. The lesions appeared as pedunculated submucosal tumours, measuring 1-4 cm in maximal diameter. Endosonographically, all lesions consisted of mucosal and submucosal layers, and microcystic components were found in the submucosal layer. There were no echogenic masses or muscularis propria within the polyps. These endosonographic features corresponded to histological findings of this type of polyp which was covered with normal mucosa and composed of submucosal layer alone. The submucosal layer consisted of oedematous, loose, connective tissue and/or fibrous tissue, accompanied by dilated blood vessels and lymphatics. Endoscopic ultrasound enabled differentiation of colonic muco-submucosal elongated polyp from other submucosal lesions.

Assessment of the impact of an educational course on knowledge of appropriate EUS indications

BACKGROUND

The knowledge level of EUS among gastroenterologists likely influences the appropriateness of requested indications for EUS. It remains unknown what the impact is of a short EUS course, involving didactic teaching, on knowledge levels of EUS indications for EUS. The aim of this study was to assess the impact of a 3-day educational course on knowledge levels of attending gastroenterologists regarding the appropriateness of indications for EUS.

METHODS

A questionnaire was designed that tested knowledge of indications for EUS in 4 anatomic sites: esophagus, gastroduodenum, hepatopancreatobiliary system, and colorectum. This questionnaire was distributed to all attendees of a 3-day EUS educational course. All attendees completed the survey before and immediately after the course.

RESULTS

A total of 24 gastroenterologists completed the pre- and post-course survey. Before the course, respondents scored highest in questions on EUS applications in the gastroduodenum (94%) and the hepatopancreatobiliary system (88%) compared with the esophagus (72%) and the colorectum (74%). Statistically significant improvements in knowledge were recorded in all organ categories: gastroduodenum (100%, p = 0.002 vs. pretest score), hepatopancreatobiliary system (99%, p < 0.0001), esophagus (92%, p < 0.0001), and colorectum (93%, p = 0.0004). The biggest improvement was observed in knowledge levels for the esophagus (20%) and the colorectum (18%).

CONCLUSIONS

There was a consistent improvement in the gastroenterologists' knowledge levels of EUS indications among all organ categories after an educational course. Our findings suggest that education enhances gastroenterologists' understanding of EUS. Future studies should seek to assess the impact of these improved knowledge levels on the appropriateness of EUS referral patterns.

Interventional endoscopy

PURPOSE OF REVIEW

This review provides an updated summary of gastric interventional endoscopy. Relevant original articles and topic reviews are highlighted in the areas of infection control, light sedation, hemostasis, endoscopic mucosal resection, and endoscopic placement of enteric devices.

RECENT FINDINGS

Several key findings are worth noting: the increased use of propofol by nonanesthesiologists for deep sedation with minimal adverse side effects, the adaptation of tissue adhesive agents for the treatment of bleeding gastric varices, the successful treatment of early gastric cancer by endoscopic mucosal resection, and the development of direct percutaneous endoscopic jejunostomy tubes for patients at high risk of aspiration.

SUMMARY

These recent developments in the field of interventional endoscopy have already made a great impact on clinical care. More advanced procedures can be performed safely while the patient is under deep sedation. Yet, these developments have not slowed down the need for improvement in interventional endoscopy. Researchers continue to look for smaller instruments, better optics, and more advanced accessories. This constant state of flux marks the field of interventional endoscopy and ensures its progress.