title: Low-dose contrast-enhanced magnetic resonance imaging of brain metastases at 3.0 T using high-relaxivity contrast agents.
abstract: BACKGROUND
  Lesion-to-brain contrast after gadolinium administration is significantly higher at 3.0 Tesla (T) compared to 1.5 T. The high in vivo relaxivity of gadobenate dimeglumine (Gd-BOPTA) may permit the use of lower-dose contrast agents.
  
  
  OBJECTIVE
  To investigate whether low-dose contrast-enhanced MRI at 3.0 T using a high-relaxivity contrast agent (Gd-BOPTA) can achieve a comparable or improved contrast-to-noise ratio (CNR) for the detection of brain metastases compared with examination of the same patient at 1.5 T using a standard dose of gadopentetate dimeglumine (Gd-DTPA).
  
  
  METHODS
  A total of 18 patients with known brain metastases were first imaged at 1.5 T with 0.1 mmol/kg Gd-DTPA. Patients returned at least 24 hours later for imaging at 3.0 T with Gd-BOPTA at cumulative doses of 0.025 mmol/kg, 0.05 mmol/kg, 0.075 mmol/kg, and 0.1 mmol/kg (0.1 mmol/kg body weight overall). The CNR of enhancing brain lesions compared to the normal contralateral white matter was calculated. For the 3.0 T study using different cumulative doses of Gd-BOPTA, the CNR of lesions was compared with CNR of the same lesions imaged at 1.5 T using 0.1 mmol/kg Gd-DTPA, by using the Wilcoxon matched-pairs signed-rank test.
  
  
  RESULTS
  At 1.5 T with 0.1 mmol/kg Gd-DTPA, the mean CNR between enhanced lesions and cerebral white matter was 12.01 +/- 2.53. With 3.0 T imaging using different cumulative doses of Gd-BOPTA, the mean CNRs were 7.19 +/- 4.06, 15.31 +/- 6.37, 25.44 +/- 11.02, and 31.88 +/- 13.21. At 3.0 T with 0.05 mmol/kg Gd-BOPTA, CNR was 1.34-fold higher compared to CNR at 1.5 T with 0.1 mmol/kg Gd-DTPA (P <0.01).
  
  
  CONCLUSIONS
  Comparable contrast enhancement of brain metastases can be achieved with a 0.05-mmol/kg dose of Gd-BOPTA at 3.0 T compared to imaging at 1.5 T using 0.1 mmol/kg Gd-DTPA.
authors.affiliation: Department of Radiology, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, China. cjr.huangbiao@vip.163.com
authors.forename: Biao
authors.initials: B
authors.lastname: Huang
authors.forename: Chang-Hong
authors.initials: CH
authors.lastname: Liang
authors.forename: Hong-Jun
authors.initials: HJ
authors.lastname: Liu
authors.forename: Guang-Yi
authors.initials: GY
authors.lastname: Wang
authors.forename: Shui-Xing
authors.initials: SX
authors.lastname: Zhang
mesh_terms: D000368:Aged; D001932:Brain Neoplasms / Q000556:secondary*; D003287:Contrast Media / Q000008:administration & dosage*; D005260:Female; D019786:Gadolinium DTPA / Q000008:administration & dosage*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008536:Meglumine / Q000008:administration & dosage / Q000031:analogs & derivatives*; D008875:Middle Aged; D009942:Organometallic Compounds / Q000008:administration & dosage*; D018709:Statistics, Nonparametric
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; C064572:gadobenic acid; D008536:Meglumine; D019786:Gadolinium DTPA