title: Two-pass dual-energy CT imaging for simultaneous detection, characterization, and volume measurement of urinary stones with excretory-phase CT urography alone: a phantom study.
abstract: OBJECTIVE
  To evaluate if two-pass dual-energy CT imaging--i.e., simultaneous three-material and two-material decomposition analysis--can depict and characterize urinary stones in various concentrations of iodine solution in vitro.
  
  
  METHODS
  Twelve urinary stones were scanned with a dual-source CT scanner. First, each stone (in a saline-filled tube) underwent single- and dual-energy mode CT scans in order to measure the volume of the stone. Each stone was then placed in various concentrations of contrast medium and scanned in dual-energy mode to calculate its volume via three-material decomposition analysis. Two-pass dual-energy CT imaging analysis software for the Matlab environment, which was developed specifically to process simultaneous three-material and two-material decomposition, was applied to characterize and calculate the volume of each stone.
  
  
  RESULTS
  Although the virtual non-contrast images from three-material decomposition analysis clearly visualized all of the stones in contrast medium with up to 80 mgI/mL, the volumes of the uric acid stones were overestimated. Two-pass dual-energy CT imaging was able to depict and characterize non-uric-acid stones in diluted contrast medium with up to 80 mgI/mL, whereas uric acid stones were correctly evaluated in diluted contrast medium with 40 mgI/mL or less.
  
  
  CONCLUSIONS
  Two-pass dual-energy CT imaging is able to depict and characterize urinary stones in contrast medium.
authors: Department of Radiology, Sumitomo Hospital, 4-3-20 Nakanoshima, Kita-ku, Osaka, Osaka 530-0041, Japan. staka@med.kobe-u.ac.jp
authors: Satoru
authors: S
authors: Takahashi
authors: Toshihide
authors: T
authors: Itoh
authors: Hidekazu
authors: H
authors: Niikawa
authors: Atsushi
authors: A
authors: Shikata
authors: Emi
authors: E
authors: Murakami
authors: Hiroshi
authors: H
authors: Tsunoda
authors: Toshiaki
authors: T
authors: Yoshioka
authors: Masao
authors: M
authors: Tsujihata
authors: Hiroshi
authors: H
authors: Yamamoto
mesh_terms: D003287:Contrast Media; D006801:Humans; D019047:Phantoms, Imaging; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014545:Urinary Calculi / Q000000981:diagnostic imaging*; D014567:Urography
chemical_list: D003287:Contrast Media
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