Magnetic resonance imaging of the experimental atheroma in rabbits

The localized potential of the Mn (III) complex of tetrakis (4-sulfonatophenyl) porphyrin (Mn-TPPS4) for a normal aortic wall and experimental atheroma were investigated in twenty-one male New Zealand White rabbits by means of a 2.0 T magnetic resonance imaging system. Forty-eight hours after intravenous administration of 0.25-0.50 mmol/kg of Mn-TPPS4, the selective contrast enhancing effects in a normal aortic wall and the diet-induced atheromas were observed using an ECG-gated T1 weighted sequence. An intense internal surface was observed in the noninvolved lesions and a mild brownish one in the atheromatous lesions. Histological findings revealed a resemblance between these atheromatous lesions and early atheroma. As a result of accumulation of Mn-TPPS4 by the atheroma, identified on macroscopic examination and by an in vitro MR imaging, experimental atheromatous lesions are rendered apparent on in vivo MR imaging. They are significantly enhanced after injection of Mn-TPPS4. These preliminary results indicate that Mn-TPPS4 might be a suitable MRI contrast agent for the localization of the normal aorta and atheroma. However, the 0.25 mmol/kg of Mn-TPPS4 administered to nine animals, caused fatal arthythmia in three of them. (author)