Technology Insight: current status of endoscopic ultrasonography

Quadruple ultrasound, photoacoustic, optical coherence, and fluorescence fusion imaging with a transparent ultrasound transducer

Ultrasound and optical imagers are used widely in a variety of biological and medical applications. In particular, multimodal implementations combining light and sound have been actively investigated to improve imaging quality. However, the integration of optical sensors with opaque ultrasound transducers suffers from low signal-to-noise ratios, high complexity, and bulky form factors, significantly limiting its applications. Here, we demonstrate a quadruple fusion imaging system using a spherically focused transparent ultrasound transducer that enables seamless integration of ultrasound imaging with photoacoustic imaging, optical coherence tomography, and fluorescence imaging. As a first application, we comprehensively monitored multiparametric responses to chemical and suture injuries in rats' eyes in vivo, such as corneal neovascularization, structural changes, cataracts, and inflammation. As a second application, we successfully performed multimodal imaging of tumors in vivo, visualizing melanomas without using labels and visualizing 4T1 mammary carcinomas using PEGylated gold nanorods. We strongly believe that the seamlessly integrated multimodal system can be used not only in ophthalmology and oncology but also in other healthcare applications with broad impact and interest.

Training in Endoscopy: Endoscopic Ultrasound

Endoscopic ultrasound (EUS) has been recently established as an indispensable modality for the diagnosis and management of pancreatobiliary and gastrointestinal (GI) disorders. EUS proficiency requires both cognitive and technical abilities, including an understanding of the appropriate indications, the performance of appropriate evaluations before and after the procedure, and the management of procedure-related complications. An increasing demand for skills to handle a growing range of interventional EUS procedures and a continual shortage of EUS training programs are two major obstacles for EUS training. Acquiring the skills necessary to comprehend and conduct EUS often requires training beyond the scope of a standard GI fellowship program. In addition to traditional formal EUS training and preceptorships, regular short-term intensive EUS training programs that provide training at various levels may help EUS practitioners improve and maintain EUS-related knowledges and skills. Theoretical knowledge can be acquired from lectures, textbooks, atlases, slides, videotapes, digital video discs, interactive compact discs, and websites. Informal EUS training is generally based on 1- or 2-day intensive seminars, including didactic lectures, skills demonstrated by expert practitioners through live video-streaming of procedures, and hands-on learning using animal or phantom models.

Training in endoscopic ultrasonography: An Asian perspective

Training of endoscopic ultrasonography (EUS) in Asia faces two major challenges: (i) the ever-increasing demand for skills to handle a growing range of interventional EUS procedures; and (ii) a continual shortage of EUS training programs. As the therapeutic application of EUS continues to expand, the need to train more new endosonographers and upgrade skills of existing ones has become more critical than ever before. A formal fellowship to acquire EUS knowledge and skills in an advanced endoscopy center has always been perceived as the best way of training novices, but such opportunities remain limited in most Asian countries. To keep up with the pace of development in EUS, more short-term EUS programs have been conducted across Asia in recent years. Such programs are generally intensive and may combine didactic lectures, live-case demonstrations, and hands-on training on phantoms, or live animal models for teaching. Although not as rigorous as conventional full-time EUS fellowships, such short-term programs are not necessarily inferior in quality. With courses offered from basic to advanced levels, and at regular intervals, busy practising endoscopists have the flexibility to attend the course that best matches their individual levels of experience, learn at their own pace and acquire EUS knowledge and skills over as many courses as desired. This open-ended progressive learning model is more agile than established fixed-term learning models and is expected to adapt better to future needs.

Contrast-enhanced harmonic endoscopic ultrasound is able to discriminate benign submucosal lesions from gastrointestinal stromal tumors

BACKGROUND

Although endoscopic ultrasound (EUS) has improved the diagnostic of potential malignancies, gastric lesions with suspicion of gastrointestinal stromal tumors (GIST) or benign lesions like lipoma or leiomyoma can often not be accurately differentiated by EUS, therefore, requiring tissue sampling with the risk of bleeding complications especially in GIST. As with the newest generation of EUS machines, contrast-enhanced harmonic endoscopic ultrasound (CEH-EUS) has become a new option to determine perfusion characteristics. The aim of this analysis was to evaluate whether CEH-EUS may help to discriminate various submucosal lesions.

METHODS

Data sets of 17 patients with suspicious gastric or esophageal lesions, who were investigated with CEH-EUS were analyzed. Perfusion characteristics were classified by the investigator immediately and statistically analyzed after investigation. Samples from EUS-fine needle aspirates, biopsy samples after needle cut or surgical specimen served as gold standard.

RESULTS

CEH-EUS showed nine lesions with reduced contrast enhancement (maximum intensity 6.2 ± 1.9 db) and eight lesions with hyperenhancement (47.3 ± 11.6 db). The latter eight lesions were all histologically identified as GIST, while the nine hypoenhanced lesions emerged to be four lipoma and five leiomyoma. Statistical analysis corresponded with initial perfusion classification in all cases.

CONCLUSION

This is the first study showing that CEH-EUS can discriminate GIST from benign lesions with good accuracy. In the future, CEH-EUS-guided discrimination may lead to individualized diagnostic and therapeutic strategies in handling submucosal lesions.

Digestive cancer management in Asia: position statements: a report on GI Oncology Summit in 2011

BACKGROUND AND AIM

With the rising incidence of digestive cancers in the Asia Pacific region and the advancement in diagnosis, management and palliation in these conditions, the clinical burden on oncologists is ever increasing. This Summit meeting was called to discuss the optimal management of digestive cancers and the role of Gastroenterologists.

METHOD

Experts from Asia Pacific countries in the fields of medical, oncologic, surgical and endoscopic management of cancers in the esophagus, stomach, colon/rectum and the liver reviewed the literature and their practice. 18 position statements were drafted, debated and voted.

RESULTS

It was agreed that the burden on GI cancer is increasing. More research will be warranted on chemotherapy, chemoprevention, cost-effectiveness of treatment and nutrition. Cancer management guidelines should be developed in this region when more clinical data are available. In order to improve care to patients, a multi-disciplinary team coordinated by a "cancer therapist" is proposed. This cancer therapist can be a gastroenterologist, a surgeon or any related discipline who have acquired core competence training. This training should include an attachment in a center-of-excellence in cancer management for no less than 12 months.

CONCLUSION

The management of GI cancer should be an integrated multi-disciplinary approach and training for GI cancer therapists should be provided for.

EUS-guided submucosal implantation of a radiopaque marker: a simple and effective procedure to facilitate subsequent surgical and radiation therapy

BACKGROUND

Endosonography (EUS) is widely used for locoregional staging of malignant GI tumors. Delineation of a tumor's margins with a long-lasting fluoroscopically visible material will facilitate subsequent surgical and radiation therapy.

OBJECTIVE

To assess the feasibility of EUS-guided submucosal implantation of a radiopaque marker in a porcine model.

SETTING

Survival experiments on four 50-kg pigs.

METHODS

A linear array echoendoscope was introduced into the esophagus and advanced to the stomach. With a 19-gauge FNA needle, a submucosal bleb was created by injecting 3 mL of normal saline solution into the gastric and esophageal wall followed by injection of 1 mL of tantalum suspension under fluoroscopic observation. Fluoroscopy was repeated after 1, 2, and 4 weeks followed by euthanasia and necropsy.

MAIN OUTCOME MEASUREMENTS

Long-term depositions of the marker in the injection sites.

RESULTS

Submucosal injections of tantalum were easily performed through the 19-gauge FNA needle, resulting in good fluoroscopic opacification of injected material. Follow-up fluoroscopy in 1, 2, and 4 weeks demonstrated stable deposition of the tantalum at the sites of injection. There were no complications during and after the tantalum implantation. Histologic examination of the injection sites demonstrated submucosal tantalum depositions without signs of infection, inflammation, tissue damage, or necrosis.

LIMITATIONS

Animal experiments with 4 weeks' follow-up.

CONCLUSIONS

EUS-guided implantation of tantalum as a radiopaque marker into the submucosal layer of the GI tract in a porcine model is technically feasible and safe. Long-lasting fluoroscopically visible tantalum markings could facilitate subsequent surgical and radiation therapy.

Endoscopic ultrasonography in pediatric patients with gastrointestinal disorders

BACKGROUND

Endoscopic ultrasound is a diagnostic tool for evaluation of gastrointestinal diseases in adults, but in children the use of endoscopic ultrasound is limited. This study retrospectively evaluates endoscopic ultrasound indications in, safety in, and impact on children.

PATIENTS AND METHODS

We reviewed the data of all of the pediatric patients (<18 years old) that underwent endoscopic ultrasound in our institution. The main goal was to evaluate the impact of endoscopic ultrasound in this patient population. Significant impact was defined as a new diagnosis or treatment attributed to the endoscopic ultrasound examination.

RESULTS

Thirty-two children (21 boys, 11 girls) at mean age 12 +/- 5 years; (range = 1.5-18 years) underwent endoscopic ultrasound during a period of 6 years. The pancreas and biliary tract were examined in 19 children, esophagus in 8, and the stomach and rectum in 2 children each. Only 1 child had endoscopic ultrasound for duodenal indication. The indications in the pancreas and biliary tract group were recurrent pancreatitis in 9 children, cyst or mass in 6 children, and obstructive jaundice in 4 children. Indications in the esophagus group were stenosis in 4 children, and suspected duplication and esophageal mass in 2 children each. We used conscious sedation in 18 children and unconscious sedation in 12. Two children underwent endoscopic ultrasound with no anesthesia at all. In 7 cases, endoscopic ultrasound-guided fine-needle aspiration was performed. The procedure was successful in all of the patients with no complications. Endoscopic ultrasound changed the diagnosis or therapy in 14 cases.

CONCLUSIONS

Endoscopic ultrasound is an effective tool in the evaluation of pediatric gastrointestinal patients, mostly with pancreatobiliary or esophageal disorders. Endoscopic ultrasound is a safe procedure with a significant impact in almost half of the children examined.