EXPERIMENTAL GASTROINTESTINAL HEMORRHAGE - DETECTION WITH CONTRAST-ENHANCED MR-IMAGING AND SCINTIGRAPHY

PURPOSE: To examine the use of O-methoxy ethylene)glycol-O'succinyl-N- epsilon-poly(L-lysyl) gadblinium diethylenetriaminepentaacetic acid (M PEG-PL-Gd-DTPA) as a potential magnetic resonance (MR) angiographic co ntrast agent for the detection of gastrointestinal (GI) bleeding. MATE RIALS AND 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 con trast 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 w as 0.02 mL. With the superior spatial resolution of MR imaging, indivi dual loops of contrast material-filled bowel were identified and bleed ing points were pinpointed. CONCLUSION: GI hemorrhage can be easily de tected at MR imaging if a long circulating macromolecular contrast age nt is used to decrease the T1 of extravasated blood.