title: Contrast enhancement in bladder tumors examined with CT urography using traditional scan phases.
abstract: BACKGROUND
  Bladder assessment in an early contrast-enhancing computed tomography urography (CTU) phase requires that bladder tumors be enhanced using contrast material.
  
  
  OBJECTIVE
  To investigate the enhancement pattern in bladder tumors using a CTU protocol where the scan is enhancement triggered.
  
  
  METHODS
  Fifty patients diagnosed with bladder cancer were examined during the unenhanced (UP), corticomedullary (CMP), and excretory phases (EP). Twenty-one patients, all aged 50 years or older, were also examined during the nephrographic phase (NP). A ROI placed in the aorta was used to start the scan during the CMP when the attenuation reached 200 Hounsfield units (HU). The NP and EP were started with a 40 s and 300 s delay, respectively, after the CMP was finished. Attenuation and size measurements were made in the axial plane.
  
  
  RESULTS
  Mean contrast enhancement of bladder tumors was 37, 25, and 17 HU in the CMP, NP, and EP, respectively. The differences in contrast enhancement were significant across all three phases. Eighty-eight percent of patients showed the highest contrast enhancement in the CMP. In 96% of the cases, contrast enhancement >20 HU was seen. The mean value of the shortest dimension of the bladder tumors was 22 ± 12 mm.
  
  
  CONCLUSIONS
  The contrast enhancement is significantly higher in the CMP than in the NP and EP, suggesting that the CMP is preferable when assessing the bladder in the early contrast enhancing phase.
authors.affiliation: Uppsala University, Radiology Department Uppsala Akademiska Hospital, Uppsala, Sweden malin.helenius@akademiska.se.
authors.forename: Malin
authors.initials: M
authors.lastname: Helenius
authors.affiliation: Uppsala University, Radiology Department Uppsala Akademiska Hospital, Uppsala, Sweden.
authors.forename: Pär
authors.initials: P
authors.lastname: Dahlman
authors.affiliation: Pharmetheus AB Uppsala, Uppsala, Sweden.
authors.forename: Mats
authors.initials: M
authors.lastname: Magnusson
authors.affiliation: Uppsala University, Radiology Department Uppsala Akademiska Hospital, Uppsala, Sweden.
authors.forename: Maria
authors.initials: M
authors.lastname: Lönnemark
authors.affiliation: Uppsala University, Radiology Department Uppsala Akademiska Hospital, Uppsala, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Magnusson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D005260:Female; D006801:Humans; D007472:Iohexol; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed / Q000379:methods*; D001749:Urinary Bladder Neoplasms / Q000000981:diagnostic imaging*
chemical_list: D003287:Contrast Media; D007472:Iohexol
keywords: CT; bladder; neoplasms; tissue characterization