title: High-resolution vascular imaging of the rat spine using liposomal blood pool MR agent.
abstract: OBJECTIVE
  High-resolution, vascular MR imaging of the spine region in small animals poses several challenges. The small anatomic features, extravascular diffusion, and low signal-to-noise ratio limit the use of conventional contrast agents. We hypothesize that a long-circulating, intravascular liposomal-encapsulated MR contrast agent (liposomal-Gd) would facilitate visualization of small anatomic features of the perispinal vasculature not visible with conventional contrast agent (gadolinium-diethylene-triaminepentaacetic acid [Gd-DTPA]).
  
  
  METHODS
  In this study, high-resolution MR angiography of the spine region was performed in a rat model using a liposomal-Gd, which is known to remain within the blood pool for an extended period. The imaging characteristics of this agent were compared with those of a conventional contrast agent, Gd-DTPA.
  
  
  RESULTS
  The liposomal-Gd enabled acquisition of high quality angiograms with high signal-to-noise ratio. Several important vascular features, such as radicular arteries, posterior spinal vein, and epidural venous plexus were visualized in the angiograms obtained with the liposomal agent. The MR angiograms obtained with conventional Gd-DTPA did not demonstrate these vessels clearly because of marked extravascular soft-tissue enhancement that obscured the vasculature.
  
  
  CONCLUSIONS
  This study demonstrates the potential benefit of long-circulating liposomal-Gd as a MR contrast agent for high-resolution vascular imaging applications.
authors.affiliation: Department of Chemical Engineering, University of Houston, Houston, Texas, USA.
authors.forename: K B
authors.initials: KB
authors.lastname: Ghaghada
authors.forename: K H J
authors.initials: KH
authors.lastname: Bockhorst
authors.forename: S
authors.initials: S
authors.lastname: Mukundan
authors.forename: A V
authors.initials: AV
authors.lastname: Annapragada
authors.forename: P A
authors.initials: PA
authors.lastname: Narayana
mesh_terms: D000818:Animals; D001011:Aorta / Q000473:pathology; D001158:Arteries / Q000473:pathology; D016477:Artifacts; D003287:Contrast Media / Q000008:administration & dosage*; D005119:Extravasation of Diagnostic and Therapeutic Materials / Q000473:pathology; D019786:Gadolinium DTPA / Q000008:administration & dosage*; D007089:Image Enhancement / Q000379:methods*; D008081:Liposomes; D018810:Magnetic Resonance Angiography / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012680:Sensitivity and Specificity; D013126:Spinal Nerve Roots / Q000098:blood supply; D013131:Spine / Q000098:blood supply*; D014680:Veins / Q000473:pathology; D014682:Vena Cava, Inferior / Q000473:pathology
chemical_list: D003287:Contrast Media; D008081:Liposomes; C064925:gadodiamide; D019786:Gadolinium DTPA