title: Prospective comparison of catheter-based endoscopic sonography versus standard endoscopic sonography: evaluation of gastrointestinal-wall abnormalities and staging of gastrointestinal malignancies.
abstract: OBJECTIVE
  Endoscopic sonography (EUS) is an important imaging modality for evaluating benign and malignant luminal gastrointestinal-tract abnormalities. The objectives of this study were to evaluate the feasibility of catheter-based EUS (C-EUS) during standard upper and lower endoscopy in patients with malignancies and other abnormalities of the gastrointestinal-tract lumen, to assess the image quality obtained with the 12.5-MHz catheter-based ultrasound transducer, and to prospectively compare the interpretations of C-EUS images with those of the standard EUS (S-EUS) images.
  
  
  METHODS
  One hundred thirty-seven consecutive patients referred for EUS were evaluated with C-EUS followed by S-EUS. The patients were assigned to 1 of 2 groups: group A, patients with intramural masses or intestinal wall thickening, with biopsies negative for malignancy; and group B, patients with esophageal, gastric, duodenal, or rectal cancer referred for staging. The results of C-EUS and S-EUS were compared for each group.
  
  
  RESULTS
  C-EUS was completed in 134 patients: 81 patients with 83 lesions in group A and 53 patients in group B. For group A, C-EUS image interpretation concurred with that of S-EUS in 74 (89%) of 83 lesions. For group B, C-EUS concurred with S-EUS for tumor depth (T) and nodal (N) classifications in 19 cases (36%) and 26 cases (49%), respectively. The depth of invasion was underestimated by C-EUS in all 34 cases in which the T classifications by C-EUS and S-EUS were discordant. In 1 of 6 patients with stenotic cancer that was nontraversable by S-EUS, C-EUS identified lymphadenopathy (incorrectly classified as N0 by S-EUS).
  
  
  CONCLUSIONS
  C-EUS was easily performed, and the C-EUS images were comparable to the S-EUS images in assessing mucosal and intramural lesions. The limited depth of penetration of the catheter-based transducer resulted in understaging the extent of tumor invasion and underestimating the nodal spread.
authors.affiliation: Division of Gastroenterology, Department of Medicine, San Francisco General Hospital, University of California, San Francisco, 1001 Potrero Avenue, San Francisco, California 94110, USA.
authors.forename: J
authors.initials: J
authors.lastname: Koch
authors.forename: R A
authors.initials: RA
authors.lastname: Halvorsen
authors.forename: S D
authors.initials: SD
authors.lastname: Levenson
authors.forename: J P
authors.initials: JP
authors.lastname: Cello
mesh_terms: D000328:Adult; D000368:Aged; D002404:Catheterization; D004064:Digestive System / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D019160:Endosonography / Q000379:methods*; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000000981:diagnostic imaging*; D006801:Humans; D007413:Intestinal Mucosa / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012680:Sensitivity and Specificity