Endoscopic ultrasonography: imaging and beyond

Advances in Endoscopic Photoacoustic Imaging

Photoacoustic (PA) imaging is able to provide extremely high molecular contrast while maintaining the superior imaging depth of ultrasound (US) imaging. Conventional microscopic PA imaging has limited access to deeper tissue due to strong light scattering and attenuation. Endoscopic PA technology enables direct delivery of excitation light into the interior of a hollow organ or cavity of the body for functional and molecular PA imaging of target tissue. Various endoscopic PA probes have been developed for different applications, including the intravascular imaging of lipids in atherosclerotic plaque and endoscopic imaging of colon cancer. In this paper, the authors review representative probe configurations and corresponding preclinical applications. In addition, the potential challenges and future directions of endoscopic PA imaging are discussed.

Forward-Looking Multimodal Endoscopic System Based on Optical Multispectral and High-Frequency Ultrasound Imaging Techniques for Tumor Detection

We developed a forward-looking (FL) multimodal endoscopic system that offers color, spectral classified, high-frequency ultrasound (HFUS) B-mode, and integrated backscattering coefficient (IBC) images for tumor detection in situ. Examination of tumor distributions from the surface of the colon to deeper inside is essential for determining a treatment plan of cancer. For example, the submucosal invasion depth of tumors in addition to the tumor distributions on the colon surface is used as an indicator of whether the endoscopic dissection would be operated. Thus, we devised the FL multimodal endoscopic system to offer information on the tumor distribution from the surface to deep tissue with high accuracy. This system was evaluated with bilayer gelatin phantoms which have different properties at each layer of the phantom in a lateral direction. After evaluating the system with phantoms, it was employed to characterize forty human colon tissues excised from cancer patients. The proposed system could allow us to obtain highly resolved chemical, anatomical, and macro-molecular information on excised colon tissues including tumors, thus enhancing the detection of tumor distributions from the surface to deep tissue. These results suggest that the FL multimodal endoscopic system could be an innovative screening instrument for quantitative tumor characterization.

Endoscopic tumor length is an independent prognostic factor in esophageal squamous cell carcinoma

PURPOSE

To investigate the impact of endoscopic esophageal tumor length on survival for patients with resected esophageal squamous cell carcinoma (ESCC).

METHODS

We retrospectively reviewed the clinicopathologic characteristics of 244 ESCC patients who underwent curative resection as the primary treatment at Taipei Veterans General Hospital between January 2000 and November 2010. The endoscopic tumor length was defined as a uniform measurement before completion of the esophagectomy. The impact of endoscopic tumor length on a patient's overall survival (OS) and disease-free survival (DFS) were assessed. A Cox regression model was used to identify prognostic factors.

RESULTS

The 1-, 3-, and 5-year OS rates were 81.2, 48.2, and 39.6%, respectively, with a median survival time of 18.0 months. The 1-, 3-, and 5-year DFS rates were 66.2, 34.7, and 32.4%, respectively, with a median DFS of 15.0 months. Endoscopic tumor length correlated with pathologic tumor length [Pearson correction (r)=0.621; P<0.001] Regression trees analyses suggested an optimum cutoff point of >4 cm to identify patients with decreased long-term survival. In multivariate survival analysis, endoscopic tumor length (more or less than 4 cm) remained an independent prognostic factor for both OS (P=0.006) and DFS (P=0.002).

CONCLUSIONS

Endoscopic tumor length could have a significant impact on both the OS and DFS of patients with resected ESCC and may provide additional prognostic value to the current tumor, node, and metastasis staging system before patients receive any cancer-specific treatment.

Role of endoscopic ultrasound in the diagnosis and staging of pancreatic cancer

Early diagnosis of pancreatic cancer remains a difficult task, and multiple imaging tests have been proposed over the years. The aim of this review is to describe the current role of endoscopic ultrasound (EUS) for the diagnosis and staging of patients with pancreatic cancer. A detailed search of MEDLINE between 1980 and 2007 was performed using the following keywords: pancreatic cancer, endoscopic ultrasound, diagnosis, and staging. References of the selected articles were also browsed and consulted. Despite progress made with other imaging methods, EUS is still considered to be superior for the detection of clinically suspected lesions, especially if the results of other cross-sectional imaging modalities are equivocal. The major advantage of EUS is the high negative predictive value that approaches 100%, indicating that the absence of a focal mass reliably excludes pancreatic cancer. The introduction of EUS-guided fine needle aspiration allows a preoperative diagnosis in patients with resectable cancer, as well as a confirmation of diagnosis before chemoradiotherapy for those that are not. This comprehensive review highlighted the diagnostic capabilities of EUS including the newest refinements such as contrast-enhanced EUS, EUS elastography, and 3-dimensional EUS. The place of EUS-guided biopsy is also emphasized, including the addition of molecular marker techniques.

Values of endoscopic ultrasonography for diagnosis and treatment of duodenal protruding lesions

OBJECTIVE

The diagnoses of patients with duodenal protruding lesions are difficult when using conventional examinations such as computed tomography (CT) and conventional endoscope etc. Thus, we investigated the clinical value of endoscopic ultrasonography (EUS) with miniature ultrasonic probes on the diagnosis and treatment of duodenal protruding lesions.

METHODS

Patients with duodenal protruding lesions who were indicated for EUS were examined by EUS with 12 approximately 15 MHz miniature ultrasonic probes and double-cavity electronic endoscope. According to diagnosis of EUS, those patients were indicated for biopsy and treatment received biopsy, endoscopic resection or surgical excision. The postoperative histological results were compared with the preoperative diagnosis of EUS. Those patients without endoscopic resection or surgical excision were periodically followed up with EUS.

RESULTS

A total of 169 patients with duodenal protruding lesions were examined by EUS, of which 40 were diagnosed with cysts, 36 with inflammatory protruding or polyp, 25 with Brunner's gland adenoma, 19 with ectopic pancreas, 17 with gastrointestinal stromal tumor, 12 with extrinsic compression, 12 with minor papilla, 6 with lipoma, 1 with adenocarcinoma and 1 with lymphoma. After EUS examinations, 75 patients received biopsy, endoscopic resection or surgical excision respectively. The postoperative histological results of 70 patients were completely consistent with the preoperative diagnosis of EUS, with 93.33% diagnostic accuracy. The results of follow-up with EUS indicated that duodenal cyst, Brunner's gland adenoma, ectopic pancreas, gastrointestinal stromal tumor and lipoma remained unchanged within 1 approximately 3 years. No related complications occurred among all patients that received EUS examinations.

CONCLUSION

EUS is an effective and reliable diagnostic method for duodenal protruding lesions.

Endoscopic ultrasound of the upper gastrointestinal tract and mediastinum: diagnosis and therapy

Endoscopic ultrasound (EUS) has developed significantly over the last two decades and has had a considerable impact on the imaging and staging of mass lesions within or in close proximity to the gastrointestinal (GI) tract. In conjunction with conventional imaging such as helical computed tomography and magnetic resonance imaging, the indications for EUS include (1) differentiating between benign and malignant lesions of the mediastinum and upper GI tract, (2) staging malignant tumors of the lung, esophagus, stomach, and pancreas prior to surgery or oncological treatment, (3) excluding common bile duct stones before laparoscopic cholecystectomy, thereby avoiding the need for endoscopic retrograde cholangiopancreatography (ERCP) in some patients, and (4) assessing suspected lesions that are either equivocal or not seen on conventional imaging. In recent years, EUS has charted a course similar to that taken by ERCP, evolving from a purely diagnostic modality to one that is interventional and therapeutic. These indications include (5) obtaining a tissue diagnosis by EUS-guided fine-needle aspiration or trucut-type needle biopsy and (6) providing therapy such as coeliac plexus neurolysis and pancreatic pseudocyst drainage--in many cases, more accurately and safely than conventional techniques. Emerging investigational techniques include EUS-guided enteric anastomosis formation and fine-needle injection therapy for malignant disease.

Application of endoscopic ultrasonography in the diagnosis and interventional treatment of pancreatic diseases

Pancreas is located behind the peritoneum without bone tissues, and general body examination and imaging detection have some limitations in the diagnosis of pancreatic diseases, which leads to the failure of early diagnosis. Endoscopic ultrasonography can provide us with high-resolution images of the pancreas the nearby structures, and it is an effective imaging modality for the diagnosis of pancreatic diseases with a high specificity and sensitivity. In this article, we reviewed the value of endoscopic ultrasonography in the diagnosis and interventional therapy for panceatic diseases.

What are the useful biological and functional markers of early-stage chronic pancreatitis?

Early-stage chronic pancreatitis may be undetected as a clinical entity. However, it may carry a definite risk for subsequent secondary damage, depending on the etiology of the disease. Therefore, the most important question is whether indeed the patient in question does have early-stage chronic pancreatitis rather than oligosymptomatic advanced-stage chronic pancreatitis. This can be easily determined by appropriate imaging such as abdominal computed tomography. For early changes, endoscopic ultrasound is superior to any other technique. Endosonography may also tell about anatomical obstacles (e.g., papillary stenosis, pancreas divisum) that may be treated to prevent progression of the disease. Treatment options at this stage are endoscopic for the most part. Depending on the etiology and familiar/hereditary background of the given patient, one must look further into molecular markers. Such markers may give an estimate on the progression or dynamics of the disease in the future and include mutations in the cationic (PRSS1) and anionic (PRSS2) trypsinogen genes as well as mutations in the serine protease (SPINK1) or cystic fibrosis (CFTR) genes. Admitted ly, these are not markers of early-stage chronic pancreatitis but must be investigated if and when such pathogenesis is suspected. Further, rare forms of chronic pancreatitis, such as autoimmune pancreatitis, which can be cured by appropriate medical treatment with steroids, must be excluded. Markers for autoimmune pancreatitis are elevated serum IgG, especially IgG4, and autoantibodies to carbonic anhydrase (type II) and lactoferrin. It is noteworthy that these markers, present in almost every Asian patient with autoimmune pancreatitis, are mostly lacking in Caucasian populations of patients with autoimmune pancreatitis.