title: Proton relaxation enhancement associated with iodinated contrast agents in MR imaging of the CNS.
abstract: OBJECTIVE
  To study the effects of iodinated radiographic contrast agents on proton relaxation in MR imaging.
  
  
  METHODS
  Two patients were evaluated after the intrathecal administration of an iodinated nonionic contrast agent (Isovue) and five subjects with cranial tumors following the intravenous administration of an iodinated ionic contrast medium (Renografin).
  
  
  RESULTS
  Both patients with subarachnoid iodinated contrast media demonstrated a relative reduction in T1 and/or T2 times using a spin-echo sequence, while four of five of the subjects with intracranial tumors (one glioma, one dural metastasis, three meningiomas) and intravenous enhancement revealed a visible MR effect. Confirmation of these in vivo observations was obtained by in vitro measurement of T1 and T2 while varying the concentration of the contrast media in saline. All iodinated contrast media showed progressively reduced relaxation times (T1 and T2) as the concentration of the agent was increased. The largest contributing relaxation mechanism is probably due to the binding and exchange of the surrounding water with the contrast molecules.
  
  
  CONCLUSIONS
  The observed T1/T2 effects suggest that administration of iodinated contrast media in the period immediately prior to MR scanning may be contraindicated in selected cases due to the demonstrated alteration of MR signal intensity that may lead to diagnostic inaccuracies.
authors.affiliation: Department of Radiology, University of Texas Health Science Center, San Antonio 78284-7800.
authors.forename: J R
authors.initials: JR
authors.lastname: Jinkins
authors.forename: J W
authors.initials: JW
authors.lastname: Robinson
authors.forename: L
authors.initials: L
authors.lastname: Sisk
authors.forename: G D
authors.initials: GD
authors.lastname: Fullerton
authors.forename: R F
authors.initials: RF
authors.lastname: Williams
mesh_terms: D001932:Brain Neoplasms / Q000175:diagnosis / Q000000981:diagnostic imaging; D002490:Central Nervous System / Q000000981:diagnostic imaging / Q000473:pathology*; D000075202:Contraindications; D003287:Contrast Media; D003973:Diatrizoate; D003974:Diatrizoate Meglumine; D004338:Drug Combinations; D006801:Humans; D006849:Hydrocephalus / Q000175:diagnosis / Q000000981:diagnostic imaging; D007472:Iohexol; D007479:Iopamidol; D008279:Magnetic Resonance Imaging; D013997:Time Factors; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media; D004338:Drug Combinations; D003973:Diatrizoate; D003974:Diatrizoate Meglumine; D007472:Iohexol; C027278:urovision; D007479:Iopamidol