title: Impact of urinary stone volume on computed tomography stone attenuations measured in Hounsfield units in a large group of Austrian patients with urolithiasis.
abstract: BACKGROUND
  To investigate retrospectively the impact of urinary stone volume on computed tomography stone attenuations measured in Hounsfield units in 253 patients with urolithiasis.
  
  
  METHODS
  CT scans were performed in 253 patients with suspected urinary stone disease from 2008 to 2010 using CT-Scanner Siemens, SOMATOM, Sensation 64. One experienced radiologist (A.L) who was blinded to the chemical composition of the stones retrospectively reviewed images and analyzed data to determine the composition of the stones. The results were compared with the biochemical analysis results obtained by infrared spectroscopy (100 FTIR, PerkinElmer).
  
  
  RESULTS
  253 consecutive patients from 2008 to 2010 were included into analysis: 189 males, and 64 females. Mean age was 51.2. According to stone volume, stones were divided into 2 groups: 126 stones with volume of 4.3 mm or more, 127 stones with volume less than 4.3 mm. There was a significant relationship between stone volume and its CT attenuation only in stones with a volume 4.3 mm or more (p <0.05).
  
  
  CONCLUSIONS
  We failed to show a significant relationship between stone volume and its attenuations in Hounsfield units. We could not distinguish uric acid stones from non uric acid stones.
authors.affiliation: Department of Urology, Medical University Graz, Austria.
authors.forename: Badereddin Mohamad
authors.initials: BM
authors.lastname: Al-Ali
authors.affiliation: Department of Urology, Medical University Graz, Austria.
authors.forename: Johanna
authors.initials: J
authors.lastname: Patzak
authors.affiliation: Department of Radiology, Medical University Graz, Austria.
authors.forename: Andre
authors.initials: A
authors.lastname: Lutfi
authors.affiliation: Department of Urology, Medical University Graz, Austria.
authors.forename: Karl
authors.initials: K
authors.lastname: Pummer
authors.affiliation: Department of Urology, Medical University Graz, Austria.
authors.forename: Herbert
authors.initials: H
authors.lastname: Augustin
keywords: Hounsfield units; computed tomography; none uric acid stones; regions of interest; shock wave lithotripsy; uric acid stones