title: Small-bowel obstruction in a phantom model of ex vivo porcine intestine: comparison of PACS stack and tile modes for CT interpretation.
abstract: OBJECTIVE
  To compare computed tomographic (CT) image interpretation with picture archiving and communication systems (PACS) stack and tile modes for speed and accuracy of transition zone localization in small-bowel obstruction by using ex vivo porcine specimens.
  
  
  METHODS
  Twenty-five small-bowel obstruction phantom models made of ex vivo porcine intestines from a slaughterhouse were imaged at CT. One was used for observer training, and 24 were used for experimentation. At 20-cm intervals throughout the intestines, metallic markers were placed in the mesenteries immediately adjacent to bowel. One obstruction was made in each intestine, midway between markers, by ligating intestine with a 3-0 silk suture to simulate mechanical small-bowel obstruction. The lumen proximal to the ligation site was distended with air and a soybean oil-iodized oil mixture until at least two-thirds of the proximal intestine exceeded 2.0 cm in transverse diameter. Dilated segments were 310-550 cm in length. Soybean oil and a mixture of soybean and iodized oil were used to simulate differences in attenuation among bowel wall, intraluminal fluid, and extraluminal abdominal fat. Four experienced abdominal radiologists independently determined the transition zone by using stack mode (cine viewing of stacked images) and, at least 2 weeks later, tile mode (side-by-side image display). Accuracy and degree of error in counting markers were evaluated, and speed of interpretation was recorded. Statistical analysis was performed with the McNemar and Wilcoxon signed rank tests.
  
  
  RESULTS
  For all observers, accuracy of transition zone localization tended to be better with stack mode (63%-83% [15-20 phantoms]) than with tile mode (50%-63% [12-15 phantoms]), but the differences were not significant. For each observer, mean counting error was lower in stack mode (range, 0.96-2.48) than in tile mode (range, 1.74-3.22), with significance for three observers (P < .01, P < .01, and P = .04). Interpretation was significantly faster with stack mode by a factor of two to three for all observers (P < .01).
  
  
  CONCLUSIONS
  Stack mode evaluation for identification of the transition zone in obstructed small bowel is faster than evaluation with tile mode. Accuracy is not significantly different between modes, although there is a tendency toward better results with stack mode.
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, Institute of Radiation Medicine at Seoul National University Medical Research Center, Chongno-gu, Seoul, 110-744, Korea.
authors.forename: Young Jun
authors.initials: YJ
authors.lastname: Kim
authors.forename: Joon Koo
authors.initials: JK
authors.lastname: Han
authors.forename: Se Hyung
authors.initials: SH
authors.lastname: Kim
authors.forename: Jun Yong
authors.initials: JY
authors.lastname: Jeong
authors.forename: Su Kyung
authors.initials: SK
authors.lastname: An
authors.forename: Chang Jin
authors.initials: CJ
authors.lastname: Han
authors.forename: Kyu-Ri
authors.initials: KR
authors.lastname: Son
authors.forename: Kyoung Ho
authors.initials: KH
authors.lastname: Lee
authors.forename: Jeong Min
authors.initials: JM
authors.lastname: Lee
authors.forename: Byung Ihn
authors.initials: BI
authors.lastname: Choi
mesh_terms: D000818:Animals; D066298:In Vitro Techniques; D007415:Intestinal Obstruction / Q000000981:diagnostic imaging*; D007421:Intestine, Small; D019047:Phantoms, Imaging; D011857:Radiographic Image Interpretation, Computer-Assisted; D011873:Radiology Information Systems; D018709:Statistics, Nonparametric; D013552:Swine; D014057:Tomography, X-Ray Computed