title: Efficacy of high-frequency ultrasound probes for the preoperative staging of invasion depth in flat and depressed colorectal tumors.
abstract: BACKGROUND
  Flat and depressed nonpolypoid types of colorectal tumors have drawn much attention. Since endoscopic mucosal resection technique is available, it is of great importance to distinguish intramucosal carcinoma from invasive carcinoma because determination of the invasion depth is essential for choosing this therapy. The usefulness of high-frequency (20 MHz) ultrasound probes for preoperative staging of invasion depth in this type of colorectal tumor was evaluated.
  
  
  METHODS
  Forty-nine cases of flat and depressed tumors were examined with the ultrasound probe and diagnostic accuracy was confirmed by comparing ultrasonic images with the pathologic findings of the specimens resected either by endoscopic mucosal resection or surgical operation.
  
  
  RESULTS
  The normal colonic wall was visualized as a nine-layered structure and the muscularis mucosae was depicted in 37 (76%) of 49 cases. Flat and depressed tumors were visualized as hypoechoic lesions and the invasion depth was accurately diagnosed in 43 (88%) of 49 lesions.
  
  
  CONCLUSIONS
  High-frequency ultrasound probes proved to be useful in determining the invasion depth and therapeutic strategy in flat and depressed colorectal tumors.
authors.affiliation: Third Department of Internal Medicine, Asahikawa Medical College, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Saitoh
authors.forename: T
authors.initials: T
authors.lastname: Obara
authors.forename: K
authors.initials: K
authors.lastname: Einami
authors.forename: M
authors.initials: M
authors.lastname: Nomura
authors.forename: M
authors.initials: M
authors.lastname: Taruishi
authors.forename: T
authors.initials: T
authors.lastname: Ayabe
authors.forename: T
authors.initials: T
authors.lastname: Ashida
authors.forename: Y
authors.initials: Y
authors.lastname: Shibata
authors.forename: Y
authors.initials: Y
authors.lastname: Kohgo
mesh_terms: D000236:Adenoma / Q000000981:diagnostic imaging / Q000473:pathology; D002277:Carcinoma / Q000000981:diagnostic imaging / Q000473:pathology; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D019160:Endosonography; D006801:Humans; D009367:Neoplasm Staging / Q000379:methods*; D011300:Preoperative Care