title: Experimental gastrointestinal hemorrhage: detection with contrast-enhanced MR imaging and scintigraphy.
abstract: OBJECTIVE
  To examine the use of O-methoxy poly(ethylene)glycol-O'-succinyl-N-epsilon-poly(L-lysyl) gadolinium diethylenetriaminepentaacetic acid (MPEG-PL-Gd-DTPA) as a potential magnetic resonance (MR) angiographic contrast agent for the detection of gastrointestinal (GI) bleeding.
  
  
  METHODS
  MPEG-PL-Gd-DTPA was used for blood pool enhancement, and MPEG-PL-technetium-99m DTPA was used for planar nuclear imaging studies. GI bleeding was tested in rats by controlled injection of contrast material-doped blood through a jejunostomy catheter. MR imaging was performed at 1.5 T.
  
  
  RESULTS
  Ideal flip angle, used with a spoiled gradient-echo pulse sequence, was 40 degrees. The smallest amount of hemorrhage detected at MR imaging was 0.05 mL; at nuclear imaging it was 0.02 mL. With the superior spatial resolution of MR imaging, individual loops of contrast material-filled bowel were identified and bleeding points were pinpointed.
  
  
  CONCLUSIONS
  GI hemorrhage can be easily detected at MR imaging if a long circulating macromolecular contrast agent is used to decrease the T1 of extravasated blood.
authors.affiliation: Department of Radiology, Massachusetts General Hospital, Boston 02114, USA.
authors.forename: H
authors.initials: H
authors.lastname: Gupta
authors.forename: R
authors.initials: R
authors.lastname: Weissleder
authors.forename: A A
authors.initials: AA
authors.lastname: Bogdanov
authors.forename: T J
authors.initials: TJ
authors.lastname: Brady
mesh_terms: D000818:Animals; D003287:Contrast Media; D019786:Gadolinium DTPA; D006471:Gastrointestinal Hemorrhage / Q000175:diagnosis* / Q000000981:diagnostic imaging; D008279:Magnetic Resonance Imaging; D008961:Models, Structural; D004369:Pentetic Acid / Q000031:analogs & derivatives*; D011092:Polyethylene Glycols; D011107:Polylysine / Q000031:analogs & derivatives*; D011877:Radionuclide Imaging; D051381:Rats; D017207:Rats, Sprague-Dawley; D016284:Technetium Tc 99m Pentetate / Q000031:analogs & derivatives
chemical_list: D003287:Contrast Media; C081299:monomethoxypolyethylene glycol-polylysine-gadolinium DTPA; C094185:technetium Tc 99m methoxypoly(ethylene)glycol-polylysyl-DTPA; D011107:Polylysine; D011092:Polyethylene Glycols; D004369:Pentetic Acid; D019786:Gadolinium DTPA; D016284:Technetium Tc 99m Pentetate