A novel 3-dimensional EUS technique for real-time visualization of the volume data reconstruction process

A novel three-dimensional endoscopic ultrasound technique for the freehand examination of the oesophagus

This study details the development and evaluation of a freehand radial three-dimensional endoscopic ultrasound (3D-EUS) technique for use in the upper gastro-intestinal tract. It comprised of a commercial EUS system, a custom acquisition system to simultaneous acquire radial B-mode images and corresponding incremental changes in position of the scope as it was withdrawn and a custom 3D-EUS package written in Matlab™, to reconstruct and analyse the volume. This technique was evaluated using an EUS phantom with embedded objects of known dimensions and volumes and with clinical images acquired during routine cancer staging. For the phantom measurements, average Z-dimensional error was <1% and volume errors were 1.4% (volume(1) = 48930 mm(3)) and 4.5% (volume(2) = 5100 mm(3)). Application of this technique to EUS acquired clinical images produced excellent characterisation of oesophageal structures and accurate dimension and volume measurements. It also enabled the endoscopist to review "off-line" the EUS examination in case important information was missed.

Diagnostic procedures for submucosal tumors in the gastrointestinal tract

This review is part one of three, which will present an update on diagnostic procedures for gastrointestinal (GI) submucosal tumors (SMTs). Part two identifies the classification and part three the therapeutic methods regarding GI SMTs. Submucosal tumors are typically asymptomatic and therefore encountered incidentally. Advances in diagnostic tools for gastrointestinal submucosal tumors have emerged over the past decade. The aim of this paper is to provide the readers with guidelines for the use of diagnostic procedures, when a submucosal tumor is suspected. Literature searches were performed to find information on diagnostics for gastrointestinal submucosal tumors. Based on the searches, the optimal diagnostic procedures and specific features of the submucosal tumors could be outlined. Standard endoscppy, capsule endoscopy and push-and-pull enteroscopy (PPE) together with barium contrast X-ray do not alone provide sufficient information, when examining submucosal tumors. Endoscopic ultrasound (EUS), computed tomography (CT), magnetic resonance imaging (MRI) and fluorodeoxyglucose-labeled positron emission tomography (FDG-PET) are recommended as supplementary tools.

Anorectal ultrasound for neoplastic and inflammatory lesions

Accurate staging of rectal and anal carcinoma is crucial for planning surgery and indicating adjuvant therapy. Although, computed tomography and magnetic resonance imaging are very sensitive in detecting metastatic disease, the local staging of rectal cancer with these techniques has been disappointing. Endorectal ultrasound (ERUS) and anal endosonography (AE) remain the most accurate methods for staging rectal and anal cancer. Anal endosonography is also of value in evaluating perianal sepsis: it can assist the surgeon in planning the surgical strategy by delineating the anatomy of fistula tracts, and can aid in puncturing abscesses in the operating room. Continued research and development has made the instrumentation for ERUS and AE more accurate and user-friendly. New techniques that have contributed significantly to the evolution of ERUS include three-dimensional ERUS, high-frequency miniprobes, transrectal ultrasound-guided biopsy techniques and hydrogen peroxide-enhanced endosonography. Further improvements can be expected from contrast enhancement with microbubbles and colour Doppler imaging. In this new millennium, new developments in ERUS and anal endosonography, such as tri-dimensional ERUS and anal endosonography and radial electronic probing, widen the role of ERUS in the staging of rectal and anal carcinoma, as well as for perianal inflammatory conditions.

Role of endoscopic ultrasonography in the staging of esophageal cancer: a review

PURPOSE OF REVIEW

This review summarizes the important studies, published since April 2002, on the role of endoscopic ultrasonography for staging of esophageal cancer.

RECENT FINDINGS

The loco-regional staging accuracy for esophageal cancer by endoscopic ultrasonography is superior to other currently available imaging modalities such as helical computed tomography. Endoscopic ultrasonographic staging accuracy is further enhanced by the ability to obtain guided fine needle aspiration specimens for cytology from any suspicious celiac lymph nodes. In addition to the initial staging of esophageal cancer, endoscopic ultrasonography-based measurement of reduction of tumor cross-sectional area appears to be a reliable predictor of pathologic response to initial neoadjuvant therapy. Recently published studies on the outcomes of endoscopic ultrasonography support its utility in the staging of esophageal cancer, particularly in guiding different treatment options for different stages of loco-regional involvement.

SUMMARY

Overall, endoscopic ultrasonography for staging of patients with esophageal cancer seems to be a cost-effective intervention.

A linear-array freehand 3-D endoscopic ultrasound

Recognition of the clinical importance of linear-array endoscopic ultrasound (EUS) has increased. In this study, we developed a linear-array 3-D EUS, a miniature position sensor attached to the tip of the echoendoscope used in freehand scanning. To evaluate the geometrical accuracy of the 3-D reconstruction of the system, the diameter of a sphere-shaped phantom (38 mm) was determined by five examiners and five measurers. Measured size of the sphere was 39.03 +/- 1.29 mm, with variance between examiners and measurers, and interaction of examiners with measurers was not significant. In animal and clinical studies, the system facilitated anatomical interpretation of the EUS images, especially in the pancreatobiliary area and vascular images. We concluded that this system is both accurate and reproducible, and may resolve difficulties in linear-array EUS.

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