title: Chemical shift MR imaging methods for the quantification of transcatheter lipiodol delivery to the liver: preclinical feasibility studies in a rodent model.
abstract: OBJECTIVE
  To demonstrate the feasibility of using chemical shift magnetic resonance (MR) imaging fat-water separation methods for quantitative estimation of transcatheter lipiodol delivery to liver tissues.
  
  
  METHODS
  Studies were performed in accordance with institutional Animal Care and Use Committee guidelines. Proton nuclear MR spectroscopy was first performed to identify lipiodol spectral peaks and relative amplitudes. Next, phantoms were constructed with increasing lipiodol-water volume fractions. A multiecho chemical shift-based fat-water separation method was used to quantify lipiodol concentration within each phantom. Six rats served as controls; 18 rats underwent catheterization with digital subtraction angiography guidance for intraportal infusion of a 15%, 30%, or 50% by volume lipiodol-saline mixture. MR imaging measurements were used to quantify lipiodol delivery to each rat liver. Lipiodol concentration maps were reconstructed by using both single-peak and multipeak chemical shift models. Intraclass and Spearman correlation coefficients were calculated for statistical comparison of MR imaging-based lipiodol concentration and volume measurements to reference standards (known lipiodol phantom compositions and the infused lipiodol dose during rat studies).
  
  
  RESULTS
  Both single-peak and multipeak measurements were well correlated to phantom lipiodol concentrations (r(2) > 0.99). Lipiodol volume measurements were progressively and significantly higher when comparing between animals receiving different doses (P < .05 for each comparison). MR imaging-based lipiodol volume measurements strongly correlated with infused dose (intraclass correlation coefficients > 0.93, P < .001) with both single- and multipeak approaches.
  
  
  CONCLUSIONS
  Chemical shift MR imaging fat-water separation methods can be used for quantitative measurements of lipiodol delivery to liver tissues.
authors.affiliation: Department of Electrical Engineering and Computer Science and Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Yin
authors.forename: Yang
authors.initials: Y
authors.lastname: Guo
authors.forename: Weiguo
authors.initials: W
authors.lastname: Li
authors.forename: Eugene
authors.initials: E
authors.lastname: Huo
authors.forename: Zhuoli
authors.initials: Z
authors.lastname: Zhang
authors.forename: Jodi
authors.initials: J
authors.lastname: Nicolai
authors.forename: Robert A
authors.initials: RA
authors.lastname: Kleps
authors.forename: Diego
authors.initials: D
authors.lastname: Hernando
authors.forename: Aggelos K
authors.initials: AK
authors.lastname: Katsaggelos
authors.forename: Reed A
authors.initials: RA
authors.lastname: Omary
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Larson
mesh_terms: D000704:Analysis of Variance; D015901:Angiography, Digital Subtraction; D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage*; D004621:Embolization, Therapeutic; D004998:Ethiodized Oil / Q000008:administration & dosage*; D005240:Feasibility Studies; D005471:Fluoroscopy; D008099:Liver / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D023421:Models, Animal; D019047:Phantoms, Imaging; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D003287:Contrast Media; D004998:Ethiodized Oil