CONTRAST-ENHANCED MRI WITH GADODIAMIDE INJECTION IN RAT-DISEASE MODELS

The present study was designed to confirm the usefulness of contrast-e nhanced magnetic resonance imaging (MRI) in diagnosing strokes of stro ke-prone spontaneously hypertensive rats (SHRSP) and middle cerebral a rtery (MCA) occlusion, hepatocellular carcinoma and hydronephrosis of each experimental rat model. Male Sprague-Dawley rats (250-500 g), mal e SHRSP (ca. 250 g) and male F344 rats (ca. 300 g) were used for the i nvestigation. Gadodiamide injection (Omniscan, Daiichi Pharmaceutical Co., Ltd. and Nycomed AS, Norway) was administered intravenously as th e contrast agent at a dose of 0.1 mmol/kg except in hydronephrosis, wh ere a dose of 0.05 mmol/kg was used. Magnetic resonance (MR) images we re obtained with a 1.5 T or a 2.0 T magnetic field strength MRI unit. The signal intensity of the stroke lesions was increased after adminis tration of gadodiamide injection in SHRSP and MCA-occluded rats. Hepat ocellular carcinoma was undetectable without the use of the contrast a gent, but the signal intensity of the tumor increased after administra tion of the gadodiamide injection, allowing the lesions to be detected . The signal intensity of the renal medulla increased in the non-ligat ed kidney, but not in the hydronephrotic kidney. The information given by the post-contrast images were superior to those obtained from the pre-contrast images in all the models. Contrast effects in SHRSP and M CA-occluded rats were related to differences in capillary permeability , those in rats with hepatocellular carcinoma depended on differences in vascularity, and those in hydronephrotic rats depended on blood flo w and permeability.