title: MR imaging in recurrent pain after back surgery. A comparative study using standard and high doses of gadolinium contrast agents.
abstract: OBJECTIVE
  To compare the diagnostic results following injection of (a) a high dose (0.3 mmol/kg b.w.) of gadodiamide injection and (b) the standard dose (0.1 mmol/kg b.w.) of Gd-DTPA, in patients with recurrent symptoms after surgery for lumbar disc herniation.
  
  
  METHODS
  Twenty patients with recurrent or sustained symptoms after surgery for lumbar disc herniations were examined. MR imaging (0.3 T) was first performed before and after Gd-DTPA at 0.1 mmol/kg b.w., and then within one month (17 patients) or within 3 months (3 patients) before and after gadodiamide injection at 0.3 mmol/kg b.w. The examinations were first evaluated by 2 neuroradiologists blinded to dose but not to patient as the images were presented in pairs. Six months later the same investigators evaluated the examinations again, this time blinded to both dose and patient.
  
  
  RESULTS
  At the evaluation in pairs (with the investigators blinded to dose only) the high-dose examinations were considered the most informative (p=0.05). However, at the later evaluation (with the investigators blinded both to dose and patient) no significant difference between high and standard dose was found regarding diagnosis or diagnostic certainty.
  
  
  CONCLUSIONS
  In this study the high-dose contrast enhancement of MR imaging at 0.3 T did not increase the diagnostic information for differentiating between scar and recurrent hernia. The high-dose images were considered more informative when evaluated in pairs, but gave no additional or different information when evaluated separately. The study also indicated that comparisons in pairs should be interpreted with caution.
authors.affiliation: Department of Radiology, University Hospital, Lund, Sweden.
authors.forename: P
authors.initials: P
authors.lastname: Akeson
authors.forename: M
authors.initials: M
authors.lastname: Annertz
authors.forename: D T
authors.initials: DT
authors.lastname: Kristoffersen
authors.forename: E
authors.initials: E
authors.lastname: Jonsson
authors.forename: S
authors.initials: S
authors.lastname: Holtas
mesh_terms: D000328:Adult; D000368:Aged; D001416:Back Pain / Q000209:etiology*; D003287:Contrast Media / Q000008:administration & dosage*; D005260:Female; D005682:Gadolinium / Q000008:administration & dosage; D019786:Gadolinium DTPA; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000175:diagnosis* / Q000601:surgery; D008159:Lumbar Vertebrae / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009942:Organometallic Compounds / Q000008:administration & dosage; D004369:Pentetic Acid / Q000008:administration & dosage / Q000031:analogs & derivatives; D011183:Postoperative Complications / Q000175:diagnosis*; D012008:Recurrence
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; D004369:Pentetic Acid; C064925:gadodiamide; D005682:Gadolinium; D019786:Gadolinium DTPA