title: Comparison between two separate injections and a single injection of double-dose contrast medium for contrast-enhanced MR imaging of metastatic brain tumors.
abstract: OBJECTIVE
  As stereotactic radiotherapy (SRT) becomes widespread, precise information including number, location, and margin of lesions is required when magnetic resonance (MR) imaging of brain metastasis is performed. We compare methods using 2 separate injections and a single injection for the administration of a double dose of contrast medium for contrastenhanced MR imaging.
  
  
  METHODS
  We divided 40 patients with brain metastasis into 2 groups of 20 patients. Group A received 2 separate injections (0.2 + 0.2 mL/kg) of contrast medium (gadoteridol); Group B received a single injection of the same total dose (0.4 mL/kg). Group A underwent spin echo (SE) T1-weighted imaging (T1WI) and magnetization prepared rapid acquisition with gradient echo sequence (MPRAGE) after each injection, and Group B underwent the same MR studies at the same timing as Group A. We evaluated the number, signal-to-noise ratio (SNR), diameter, margin delineation, and volume of lesions and compared them between early and delayed studies by the 2 methods.
  
  
  RESULTS
  The number of detected lesions was largest in delayed studies of MPRAGE in both groups. The SNR of the lesions was statistically lower in early studies of Group A than other studies. Delayed studies of Group B showed statistically better margin delineation than other studies on both SE-T1WI and MPRAGE studies. Diameter and enhanced volume were statistically significantly larger on delayed phase than early phase in both groups.
  
  
  CONCLUSIONS
  Use of a single injection of double-dose contrast medium and longer delay time may improve margin delineation of lesions for the study of brain metastasis. Enhanced volume was larger on delayed phase, and it may influence selection of therapeutic strategy.
authors.affiliation: Department of Radiology, Nara Medical University; Department of Radiology, Nara Prefectural Mimuro Hospital 1-14-16 Mimuro, Sangouchou, Ikoma, Nara 636-0802, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Ochi
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Taoka
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Matsuda
authors.forename: Masahiko
authors.initials: M
authors.lastname: Sakamoto
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Akashi
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Tamamoto
authors.forename: Tadashi
authors.initials: T
authors.lastname: Sugimoto
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sakaguchi
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Hasegawa
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nakase
authors.forename: Kimihiko
authors.initials: K
authors.lastname: Kichikawa
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000473:pathology; D001931:Brain Mapping / Q000379:methods; D001932:Brain Neoplasms / Q000473:pathology*; D003287:Contrast Media / Q000008:administration & dosage; D004305:Dose-Response Relationship, Drug; D005260:Female; D005682:Gadolinium / Q000008:administration & dosage; D006571:Heterocyclic Compounds / Q000008:administration & dosage; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007267:Injections; D007564:Japan; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009942:Organometallic Compounds / Q000008:administration & dosage; D011446:Prospective Studies; D059629:Signal-To-Noise Ratio
chemical_list: D003287:Contrast Media; D006571:Heterocyclic Compounds; D009942:Organometallic Compounds; C062402:gadoteridol; D005682:Gadolinium