title: Effect of intravenous gadolinium-DTPA on diffusion-weighted images: evaluation of normal brain and infarcts.
abstract: OBJECTIVE
  Diffusion-weighted imaging (DWI) is usually done before administration of intravenous contrast agents. Repetition of DWI is occasionally necessary after administration, but the effects of contrast material on DWI and apparent diffusion coefficient (ADC) values have not yet been fully examined. The present study assesses whether administration of gadolinium-based contrast material significantly affects DWI and ADC values.
  
  
  METHODS
  We examined DWI data from 39 patients (mean age, 67.9 years; range, 34 to 87 years) who were evaluated with a stroke protocol at our institute. All patients were scanned at the acute or subacute stages of infarct from 3 hours to 5 days after symptom onset. We obtained DWI images using single-shot echo-planar imaging with a b value of 1000 s/mm2. Patients were injected with 0.1 mmol gadopentetate dimeglumine per 1 kg body weight. We examined the signal-to-noise ratio of the normal brain and the infarct and evaluated the contrast-to-noise ratio of each lesion. In addition, we compared the ADC values calculated from the DWI images before and after administration of contrast. The statistical significance of differences between precontrast and postcontrast administration was determined by use of a paired t test.
  
  
  RESULTS
  The signal-to-noise and contrast-to-noise ratios of the DW images were not significantly different before and after administration of contrast agent. The ADC values were slightly lower after administration of contrast agent for both normal brain (P=0.0011) and infarcts (P=0.038). The estimated differences in the ADC values were approximately 1.3% and 3.5% for normal brain and infarcts, respectively.
  
  
  CONCLUSIONS
  The lack of a significant difference between the signal-to-noise and contrast-to-noise ratios of DW images before and after administration of contrast agent indicates the feasibility of postcontrast DWI.
authors.affiliation: Department of Radiology, Kyoto Prefectural University of Medicine, Kyoto City, Japan. kyamada@koto.kpu-m.ac.jp
authors.forename: Kei
authors.initials: K
authors.lastname: Yamada
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kubota
authors.forename: Osamu
authors.initials: O
authors.lastname: Kizu
authors.forename: Hisao
authors.initials: H
authors.lastname: Nakamura
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Ito
authors.forename: Sachiko
authors.initials: S
authors.lastname: Yuen
authors.forename: Osamu
authors.initials: O
authors.lastname: Tanaka
authors.forename: Takao
authors.initials: T
authors.lastname: Kubota
authors.forename: Masahiro
authors.initials: M
authors.lastname: Makino
authors.forename: Marc
authors.initials: M
authors.lastname: Van Cauteren
authors.forename: Tsunehiko
authors.initials: T
authors.lastname: Nishimura
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000033:anatomy & histology / Q000473:pathology; D002544:Cerebral Infarction / Q000175:diagnosis*; D003287:Contrast Media / Q000008:administration & dosage; D004058:Diffusion; D017352:Echo-Planar Imaging / Q000379:methods; D005240:Feasibility Studies; D019786:Gadolinium DTPA; D006801:Humans; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D020244:Infarction, Middle Cerebral Artery / Q000175:diagnosis; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA