title: Enhancement effects of test injection with a small amount of MR contrast medium in the oral and maxillofacial region.
abstract: OBJECTIVE
  To examine whether the signal intensity of dynamic contrast-enhanced MRI (DCE-MRI) is altered by test injection of 1 ml of contrast medium, and if so, whether this change affects the DCE-MRI analysis.
  
  
  METHODS
  Six healthy volunteers were examined by DCE-MRI using a Magnevist syringe and/or an Omniscan syringe for the injection of contrast medium. Each scan was performed 10 times using steady-state free precession (3D-FISP), a sequence for DCE-MRI, before and after intravenous injection of 1 ml of the contrast medium. The internal pterygoid muscle, masseter muscle, tongue, parotid gland, submandibular gland, bone marrow of the mandible, subcutaneous adipose tissue, and common carotid artery were determined to be regions of interest (ROI), and the ROI internal average signal intensity was measured. The 10 data sets obtained before or after contrast medium administration for each ROI were evaluated using the paired t-test.
  
  
  RESULTS
  The test injection increased the signal intensities of six of eight ROIs, with all 20 experiments in the submandibular gland showing significant differences. There was no significant difference in the two ROIs corresponding to the carotid artery and subcutaneous adipose tissue of the cheek.
  
  
  CONCLUSIONS
  The enhanced signal intensity in the tissue might have been caused by the small amount of contrast medium in the test injection. To eliminate this discrepancy caused by the test injection, a pre-contrast scan should be performed when the average signal intensity of an ROI is measured. We therefore believe that the data obtained before a test injection may be important in the analysis of DCE-MRI.
authors.affiliation: Department of Oral Diagnosis and Dentomaxillofacial Radiology, Okayama University Hospital of Medicine and Dentistry, 5-1 Shikata-cho, 2-chome, Okayama 700-8525, Japan.
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Yanagi
authors.forename: Jun-ichi
authors.initials: J
authors.lastname: Asaumi
authors.forename: Hironobu
authors.initials: H
authors.lastname: Konouchi
authors.forename: Miki
authors.initials: M
authors.lastname: Hisatomi
authors.forename: Hidenobu
authors.initials: H
authors.lastname: Matsuzaki
authors.forename: Jun
authors.initials: J
authors.lastname: Murakami
authors.forename: Yuu
authors.initials: Y
authors.lastname: Maki
authors.forename: Teruhisa
authors.initials: T
authors.lastname: Unetsubo
authors.forename: Kanji
authors.initials: K
authors.lastname: Kishi
mesh_terms: D000328:Adult; D017536:Carotid Artery, Common; D002610:Cheek; D003287:Contrast Media / Q000008:administration & dosage*; D004333:Drug Administration Routes; D019786:Gadolinium DTPA / Q000008:administration & dosage*; D006801:Humans; D007267:Injections; D008279:Magnetic Resonance Imaging; D008297:Male; D008334:Mandible; D008406:Masseter Muscle; D010306:Parotid Gland; D011626:Pterygoid Muscles; D013363:Submandibular Gland; D014059:Tongue
chemical_list: D003287:Contrast Media; C064925:gadodiamide; D019786:Gadolinium DTPA