Endoscopic Ultrasound (EUS) of the Entire Small Intestine: Normal Anatomy and Pathologic Lesions

Objective: The aim of this study is to evaluate the feasibility, variability of normal anatomy and initial clinical role of intra-small intestinal ultrasonography (ISUS) during complete small bowel evaluation using the double balloon enteroscope system. Methods: 11 patients with obscure GI bleeding, chronic diarrhea and unknown abdominal pain were enrolled into the study. All patients suspected with small intestinal diseases underwent double-balloon enteroscopy (DBE). In addition ISUS was performed in all DBE positive subjects during the same procedure to characterize the lesions found. Ultrasonic system SP-702 and prototype catheter probe were used in these procedures. Results: Of the 11 patients in the study, 9 had clinically significant lesions diagnosed by DBE and subsequently evaluated successfully by ISUS in 8 cases. In an additional in vitro study, we defined normal anatomy in various regions of the small intestine including jejunum and ileum and found: there were six layer structures which correlated with histology. Amongst the 9 lesions evaluated, ISUS revealed 2 cases of small intestinal carcinoma; 1 case of GIST; 1 case of polyp; 1 case of lymph-vessel tumor; 2 cases of early acute stage Crohn's disease. However, the intra-luminal ultrasonic image is not clear enough to detect mucosal vascular deformity. One failure case occurred because the catheter probe could not be pushed out of the accessory channel of DBE. The ISIU assessments were in accordance with surgical interventions and histological biopsy results with a diagnostic accuracy of 77.8% (7/9) while it was 100% in combined with DBE. Conclusions: ISUS is feasible and safe as an adjunct to DBE in evaluating lesions in the entire small intestine. This study defines some of the normal small bowel anatomic variations encountered on ISUS examinations and describes its role in the evaluation of small bowel lesions.