title: In vitro comparison of plain radiography, double-contrast cystography, ultrasonography, and computed tomography for estimation of cystolith size.
abstract: OBJECTIVE
  To compare accuracy of estimates of cystolith size obtained by means of plain radiography, double-contrast cystography, ultrasonography, and computed tomography.
  
  
  METHODS
  30 canine cystoliths ranging from 1 to 11 mm in diameter with various mineral compositions.
  
  
  METHODS
  A bladder phantom model was created by filling a rubber balloon with saline (1% NaCl) solution and positioning it on top of a 2% gelatin cushion at the bottom of a water-filled 4-quart container. Cystoliths were individually placed in the bladder phantom and imaged by each of the 4 techniques. For each image, cystolith size was measured by 2 radiologists with computerized calipers, and size estimates were compared with actual cystolith size.
  
  
  RESULTS
  Mean cystolith size estimates obtained by means of radiography, cystography, and computed tomography did not differ significantly from each other. However, for ultrasonographic images, mean +/- SD difference between actual and estimated cystolith size (2.95 +/- 0.73 mm) was significantly higher than mean difference for radiographic, cystographic, and computed tomographic images. For ultrasonography, mean +/- SD percentage overestimation in cystolith size was 68.4 +/- 51.5%.
  
  
  CONCLUSIONS
  Results indicated that measurements of cystolith size obtained by means of ultrasonography may overestimate the true size. This suggests that cystolith size estimates obtained by means of ultrasonography should be interpreted with caution whenever cystolith size may influence patient management.
authors.affiliation: Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA.
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Byl
authors.forename: John M
authors.initials: JM
authors.lastname: Kruger
authors.forename: Jennifer
authors.initials: J
authors.lastname: Kinns
authors.forename: Nathan C
authors.initials: NC
authors.lastname: Nelson
authors.forename: Joe G
authors.initials: JG
authors.lastname: Hauptman
authors.forename: Cheri A
authors.initials: CA
authors.lastname: Johnson
mesh_terms: D000818:Animals; D004283:Dog Diseases / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D004285:Dogs; D019047:Phantoms, Imaging; D011859:Radiography / Q000662:veterinary; D014057:Tomography, X-Ray Computed / Q000662:veterinary; D014463:Ultrasonography / Q000662:veterinary; D001744:Urinary Bladder Calculi / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery / Q000662:veterinary*