title: Iodine quantification with dual-energy CT: phantom study and preliminary experience with renal masses.
abstract: OBJECTIVE
  The purpose of this study was to validate the utility of dual-source dual-energy MDCT in quantifying iodine concentration in a phantom and in renal masses.
  
  
  METHODS
  A series of tubes containing solutions of varying iodine concentration were imaged with dual-source dual-energy MDCT. Iodine concentration was calculated and compared with known iodine concentration. Single-phase contrast-enhanced dual-source dual-energy MDCT data on 15 patients with renal lesions then were assessed independently by two readers. Dual-energy postprocessing was used to generate iodine-only images. Regions of interest were placed on the iodine image over the lesion and, as a reference, over the aorta, for recording of iodine concentration in the lesion and in the aorta. Another radiologist determined lesion enhancement by comparing truly unenhanced with contrast-enhanced images. Mixed-model analysis of variance based on ranks was used to compare lesion types (simple cyst, hemorrhagic cyst, enhancing mass) in terms of lesion iodine concentration and lesion-to-aorta iodine ratio.
  
  
  RESULTS
  In the phantom study, there was excellent correlation between calculated and true iodine concentration (R(2) = 0.998, p < 0.0001). In the patient study, 13 nonenhancing (10 simple and three hyperdense cysts) and eight enhancing renal masses were evaluated in 15 patients. The lesion iodine concentration and lesion-to-aorta iodine ratio in enhancing masses were significantly higher than in hyperdense and simple cysts (p < 0.0001).
  
  
  CONCLUSIONS
  Iodine quantification with dual-source dual-energy MDCT is accurate in a phantom and can be used to determine the presence and concentration of iodine in a renal lesion. Characterization of renal masses may be possible with a single dual-source dual-energy MDCT acquisition without unenhanced images or reliance on a change in attenuation measurements.
authors: Department of Radiology, New York University Langone Medical Center, 550 First Ave, HW 202, New York, NY 10016, USA. hersh.chandarana@nyumc.org
authors: Hersh
authors: H
authors: Chandarana
authors: Alec J
authors: AJ
authors: Megibow
authors: Benjamin A
authors: BA
authors: Cohen
authors: Ramya
authors: R
authors: Srinivasan
authors: Danny
authors: D
authors: Kim
authors: Christianne
authors: C
authors: Leidecker
authors: Michael
authors: M
authors: Macari