title: Optimization of the dynamic, Gd-EOB-DTPA-enhanced MRI of the liver: the effect of the injection rate.
abstract: BACKGROUND
  Tissue-specific gadolinium-based contrast agents such as Gd-BOPTA, Gd-EOB-DTPA are increasingly used for liver imaging. Despite the added value of the hepatobiliary phase a proper arterial phase is still critical, especially in patients with chronic liver diseases. So far, there are limited data in the literature about the effect of the injection speed of Gd-EOB-DTPA in liver and vessel enhancement.
  
  
  OBJECTIVE
  To evaluate the effect of injection rate on the enhancement of liver parenchyma and vasculature in Gd-EOB-DTPA-enhanced liver MRI.
  
  
  METHODS
  Eighty patients who underwent Gd-EOB-DTPA-enhanced liver MRI (1.5T multi-channel MR-system) were retrospectively evaluated. We used a Care Bolus technique with an injection rate of 2 mL/s in group 1 (n = 40) and a Care Bolus technique with an injection rate of 1 mL/s in group 2 (n = 40) to determine the start of the arterial-dominant phase. Signal intensities were measured in vascular structures and liver parenchyma. Signal-to-noise-ratio (SNR), SNR increase (SNRi), and percentage enhancement (PE) were calculated and compared by a students t-test.
  
  
  RESULTS
  The SNR, SNRi, and PE of the aorta in the arterial phase were significantly higher in group 2 in comparison to group 1 (P = 0.007, P = 0.0043, and P < 0.001, respectively). There were no significant differences concerning the SNR, SNRi, or PE of the portal vein and the normal liver parenchyma between both groups at all time points.
  
  
  CONCLUSIONS
  The study shows that a lower injection rate of 1 mL/s enables a higher enhancement in the aorta in the arterial phase compared with Gd-EOB-DTPA-enhanced MRI with the more commonly used injection rate of 2 mL/s.
authors.affiliation: Ludwig-Maximilian-University, Institute for Clinical Radiology, Munich, Germany. christine.schmid-tannwald@med.uni-muenchen.de
authors.forename: Christine
authors.initials: C
authors.lastname: Schmid-Tannwald
authors.forename: Karin
authors.initials: K
authors.lastname: Herrmann
authors.forename: Aytekin
authors.initials: A
authors.lastname: Oto
authors.forename: Alexandra
authors.initials: A
authors.lastname: Panteleon
authors.forename: Maximilian
authors.initials: M
authors.lastname: Reiser
authors.forename: Christoph
authors.initials: C
authors.lastname: Zech
mesh_terms: D003287:Contrast Media / Q000008:administration & dosage*; D005260:Female; D019786:Gadolinium DTPA / Q000008:administration & dosage*; D006801:Humans; D007275:Injections, Intravenous; D008107:Liver Diseases / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D059629:Signal-To-Noise Ratio; D018709:Statistics, Nonparametric
chemical_list: D003287:Contrast Media; C073590:gadolinium ethoxybenzyl DTPA; D019786:Gadolinium DTPA