High-resolution intravascular magnetic resonance imaging - Monitoring of plaque formation in heritable hyperlipidemic rabbits

Background-The individual makeup of atherosclerotic plaque has been identif ied as a dominant prognostic factor. With the use of an intravascular magne tic resonance (MR) catheter coil, we evaluated the effectiveness of high-re solution MR in the study of the development of atherosclerotic lesions in h eritable hyperlipidemic rabbits. Methods and Results-Sixteen hyperlipidemic rabbits were investigated at the ages of 6, 12, 24, and 36 months. The aorta was studied with digital subtr action angiography and high-resolution MR with the use of a surface coil an d an intravascular coil that consisted of a single-loop copper wire integra ted in a 5F balloon catheter, Images were correlated with histological sect ions regarding wall thickness, plaque area, and plaque components, Digital subtraction angiography revealed no abnormalities in the 6- and 12-month-ol d rabbits and only mild stenoses in the 24- and 36-month-old rabbits. High- resolution imaging with surface coils resulted in an in-plane resolution of 234x468 mu m. Delineation of the vessel wall was not possible in younger r abbits and correlated only poorly with microscopic measurements in the 36-m onth-old rabbits. Intravascular images achieved an in-plane resolution of 1 17x156 mu m. Increasing thickness of the aortic wall and plaque area was ob served with increasing age. In the 24- and 36-month-old animals, calcificat ion could be differentiated from fibrous and fatty tissue on the basis of t he T2-fast spin echo images, as confirmed by histological correlation. Conclusions-Atherosclerotic evolution of hyperlipidemic rabbits can be moni tored with high-resolution intravascular MR imaging. Image quality is suffi cient to determine wall thickness and plaque area and to differentiate plaq ue components.