title: Dynamic contrast-enhanced MRI in mice at high field: estimation of the arterial input function can be achieved by phase imaging.
abstract: OBJECTIVE
  Quantitative dynamic contrast-enhanced MRI requires an accurate arterial input function (AIF). At high field, increased susceptibility effects and decreased longitudinal relaxivity of contrast agents lead to predominant T2* effects in blood vessels, producing a dip in signal during passage of the contrast agent bolus. This study determined phase-derived AIFs in mice at 11.7 T.
  
  
  METHODS
  AIFs were measured in aorta/vena cava for five FBV/N mice and in iliac arteries/veins for five NMRI mice with a fast low angle shot sequence, simultaneously with tumor imaging (temporal resolution: 1.19 s). Gadoterate was injected into the tail vein as a bolus (0.286 mmol Gd/kg). An in vitro study was also performed to calculate the relationship between ΔΦ and gadolinium concentration.
  
  
  RESULTS
  The phantom system confirmed the linear relationship between measured ΔΦ and gadolinium concentration. In vivo, a dip in arterial magnitude signal made it impossible to quantify the AIF. With phase imaging, a clear quantifiable bolus peak was obtained; peak measured concentration in plasma was 4.9 ± 0.9 mM for FBV/N mice and 8.0 ± 0.6 mM for NMRI mice, close to the expected concentration of 6.8 mM.
  
  
  CONCLUSIONS
  Phase imaging seems to be an appropriate means to measure the AIF of mice at high field.
authors: Biomedical Magnetic Resonance Group, Louvain Drug Research Institute, Université Catholique de Louvain, Brussels, Belgium.
authors: A-C
authors: AC
authors: Fruytier
authors: J
authors: J
authors: Magat
authors: F
authors: F
authors: Colliez
authors: B
authors: B
authors: Jordan
authors: G
authors: G
authors: Cron
authors: B
authors: B
authors: Gallez
mesh_terms: D000818:Animals; D001158:Arteries / Q000502:physiology*; D003287:Contrast Media / Q000494:pharmacology*; D005682:Gadolinium / Q000494:pharmacology; D066298:In Vitro Techniques; D008279:Magnetic Resonance Imaging / Q000379:methods*; D051379:Mice
chemical_list: D003287:Contrast Media; D005682:Gadolinium