title: MR arthrography: impact of steroids, local anesthetics, and iodinated contrast material on gadolinium signal intensity in phantoms at 1.5 and 3.0 T.
abstract: OBJECTIVE
  To determine if gadolinium signal intensity at direct magnetic resonance (MR) arthrography is affected by the addition of steroids, anesthetics, or iodinated contrast material.
  
  
  METHODS
  This study did not require approval by the institutional review board because no patients or patient data were involved. An in vitro study was performed to evaluate various concentrations of three gadolinium contrast agents (gadopentetate dimeglumine, gadobenate dimeglumine, and gadofosveset trisodium) diluted in either saline or iodinated contrast material (50% and full-strength iohexol 300). Three steroids (betamethasone, triamcinolone, and methylprednisolone) and three local anesthetics (lidocaine, ropivacaine, and bupivacaine) were added to solutions in clinical doses. T1-weighted fat-suppressed MR imaging sequences were performed in phantoms at 1.5 and 3.0 T. Signal intensities were measured. All experiments were repeated in full for a total of three replications each. The data were analyzed by using two-way factorial analysis of variance.
  
  
  RESULTS
  Dilution of gadolinium into iohexol reduced the signal intensity in all samples compared with dilution in saline alone. Peak signal intensities were at 0.625 and 1.25 mmol/L of gadolinium in iohexol at both magnet strengths. At 1.5 T, the addition of steroids and anesthetics to the saline solutions had no impact on the signal intensity curves, with the peak signal intensity at gadolinium concentrations of 2.5 and 1.25 mmol/L. At 3.0 T, the addition of steroids and anesthetics had minimal effect on signal intensity curves, with the peak signal intensity at 1.25 mmol/L of gadolinium.
  
  
  CONCLUSIONS
  The addition of steroids and/or anesthetics to gadolinium solutions for MR arthrography does not substantially impact signal intensity. When gadolinium is diluted into a 50% or greater strength of iohexol, the signal intensity curve shifts so that the maximum signal intensity is obtained with lower gadolinium concentrations (0.625-1.25 mmol/L).
authors.affiliation: From the Department of Radiology and Medical Imaging (M.A.U., B.H.H., M.G.F., C.M.G.) and Department of Public Health Sciences (J.T.P.), University of Virginia Health System, PO Box 800170, Charlottesville, VA 22908.
authors.forename: Marco A
authors.initials: MA
authors.lastname: Ugas
authors.forename: Bang H
authors.initials: BH
authors.lastname: Huynh
authors.forename: Michael G
authors.initials: MG
authors.lastname: Fox
authors.forename: James T
authors.initials: JT
authors.lastname: Patrie
authors.forename: Cree M
authors.initials: CM
authors.lastname: Gaskin
mesh_terms: D000779:Anesthetics, Local / Q000737:chemistry*; D003287:Contrast Media / Q000737:chemistry*; D005682:Gadolinium / Q000737:chemistry; D019786:Gadolinium DTPA / Q000737:chemistry; D007270:Injections, Intra-Articular; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008536:Meglumine / Q000031:analogs & derivatives / Q000737:chemistry; D009942:Organometallic Compounds / Q000737:chemistry; D019047:Phantoms, Imaging; D059629:Signal-To-Noise Ratio; D012996:Solutions; D013256:Steroids / Q000737:chemistry*
chemical_list: D000779:Anesthetics, Local; D003287:Contrast Media; D009942:Organometallic Compounds; D012996:Solutions; D013256:Steroids; C064572:gadobenic acid; D008536:Meglumine; D005682:Gadolinium; D019786:Gadolinium DTPA; C109932:gadofosveset trisodium