title: Optimization of the contrast mixture ratio for simultaneous direct MR and CT arthrography: an in vitro study.
abstract: OBJECTIVE
  This study was designed to determine the optimal mixture ratio of gadolinium and iodinated contrast agent for simultaneous direct MR arthrography and CT arthrography.
  
  
  METHODS
  An in vitro study was performed utilizing mixtures of gadolinium at six different concentrations (0.625, 1.25, 2.5, 5.0, 10 and 20 mmol/L) and iodinated contrast agent at seven different concentrations (0, 12.5, 25, 37.5, 50, 75 and 92-99.9%). These mixtures were placed in tissue culture plates, and were then imaged with CT and MR (with T1-weighted sequences, proton-density sequences and T2-weighted sequences). CT numbers and signal intensities were measured. Pearson's correlation coefficients were used to assess the correlations between the gadolinium/iodinated contrast agent mixtures and the CT numbers/MR signal intensities. Scatter diagrams were plotted for all gadolinium/iodinated contrast agent combinations and two radiologists in consensus identified the mixtures that yielded the optimal CT numbers and MR signal intensities.
  
  
  RESULTS
  The CT numbers showed significant correlation with iodinated contrast concentrations (r = 0.976, p < 0.001), whereas the signal intensities as measured on MR images showed a significant correlation with both gadolinium and iodinated contrast agent concentrations (r = -484 to -0.719, p < 0.001). A review of the CT and MR images, graphs, and scatter diagram of 42 combinations of the contrast agent showed that a concentration of 1.25 mmol/L gadolinium and 25% iodinated contrast agent was the best combination for simultaneous CT and MR imaging.
  
  
  CONCLUSIONS
  A mixture of 1.25 mmol/L gadolinium and 25% iodinated contrast agent was found to be optimal for simultaneous direct MR arthrography and CT arthrography.
authors.affiliation: Department of Radiology and Institute of Radiation Medicine, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Ja Young
authors.initials: JY
authors.lastname: Choi
authors.forename: Heung Sik
authors.initials: HS
authors.lastname: Kang
authors.forename: Sung Hwan
authors.initials: SH
authors.lastname: Hong
authors.forename: Joon Woo
authors.initials: JW
authors.lastname: Lee
authors.forename: Na Ra
authors.initials: NR
authors.lastname: Kim
authors.forename: Woo Sun
authors.initials: WS
authors.lastname: Jun
authors.forename: Sung Gyu
authors.initials: SG
authors.lastname: Moon
authors.forename: Jung Ah
authors.initials: JA
authors.lastname: Choi
mesh_terms: D001175:Arthrography; D003287:Contrast Media / Q000008:administration & dosage*; D005682:Gadolinium / Q000008:administration & dosage; D066298:In Vitro Techniques; D007472:Iohexol / Q000008:administration & dosage / Q000031:analogs & derivatives*; D008279:Magnetic Resonance Imaging; D008536:Meglumine / Q000008:administration & dosage; D009942:Organometallic Compounds / Q000008:administration & dosage; D019047:Phantoms, Imaging; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; D007472:Iohexol; D008536:Meglumine; C038192:iopromide; D005682:Gadolinium; C072417:gadoterate meglumine