Three-dimensional esophageal varix model quantification of variceal volume by high-resolution endoluminal US

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.

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.

Collateral vessels around the esophageal wall in patients with portal hypertension: comparison of EUS imaging and microscopic findings at autopsy

BACKGROUND

In patients with portal hypertension, EUS reveals the presence of collateral vessels within and outside the esophageal wall such as esophageal varices, periesophageal collateral veins (peri-ECVs), paraesophageal collateral veins (para-ECVs), and perforating veins. This study retrospectively compared radial EUS images of these collateral vessels with histopathologic findings.

METHODS

Four patients with esophageal varices treated by endoscopic injection sclerotherapy were studied. EUS was performed to evaluate the effects of endoscopic injection sclerotherapy. After endoscopic injection sclerotherapy, the segment of the esophagus from the esophagogastric junction to a point 5 cm proximal to junction was imaged with a 20-MHz radial scanning catheter US probe. Esophageal collateral veins outside the esophageal wall were identified as peri-ECVs (veins lateral to muscularis propria or within adventitia) and para-ECVs (veins lateral and separate from muscularis propria) along with perforating veins (veins connecting extramural collateral veins to submucosal varices). At autopsy, the esophagus with surrounding tissue was removed and cross-sectioned at 1-cm intervals from the esophagogastric junction to a point 5 cm proximal to the junction. Radial EUS images were correlated with histopathologic findings.

RESULTS

Radial EUS after endoscopic injection sclerotherapy demonstrated peri-ECVs and perforating veins in all cases and para-ECVs in 3 cases. Based on histopathologic findings, veins associated with the esophageal wall were divided into 3 groups: those adjacent to the muscularis propria, veins separated from the wall without contact with the muscularis propria, and veins perforating the muscularis propria. All 3 groups of veins were observed in all cases. These 3 types of veins identified by histopathologic examination corresponded, respectively, to the peri-ECVs, para-ECVs, and perforating veins observed by EUS.

CONCLUSION

Collateral esophageal veins demonstrated by radial EUS in patients with portal hypertension correspond to collateral veins identified histopathologically. In patients with portal hypertension, EUS is useful for assessment of vascular anatomy around the esophageal wall.

Endoluminal sonography of the genitourinary and gastrointestinal tracts

OBJECTIVE

Endoluminal sonography with high-frequency catheter-based transducers is a technique well suited to imaging structures beyond the lumen of the hollow viscus. The purpose of this article was to review some aspects of endoluminal sonography, including instrumentation, clinical applications in the gastrointestinal and genitourinary tracts, and its three-dimensional reconstruction.

METHODS

The development of 6F to 10F catheter-based ultrasonic probes has made this technique available for use within a variety of lumina. Endoluminal sonography with frequencies of 9 to 20 MHz has been used for evaluation of a wide range of abnormalities in both the genitourinary and gastrointestinal tracts.

RESULTS

Uses in the gastrointestinal tract include quantification of esophageal varices, distinguishing between various submucosal lesions, and measuring the degree of fibrosis in scleroderma. In the genitourinary system, endoluminal sonography has been used to guide collagen injection, to diagnose urethral diverticula and upper tract neoplasms, to locate crossing vessels and septa for guiding endopyelotomy, and to identify submucosal calculi.

CONCLUSIONS

High-resolution endoluminal sonography is a new sonographic approach for evaluation of the genitourinary and gastrointestinal tracts. This should lead to the expansion of the diagnostic capabilities of sonography, providing important information for decision making relative to patient care and minimally invasive interventional procedures. Reconstructed three-dimensional endoluminal sonography has the potential to become a valuable tool in both the research and clinical areas.