High-resolution MRI of deep-seated atherosclerotic arteries using motexafin gadolinium.

PURPOSE: To evaluate the potential of using motexafin gadolinium (MGd) to characterize atherosclerotic plaques of deep-seated arteries with MRI. MATERIALS AND METHODS: We exposed vascular endothelial cells (EC) and smooth muscle cells (SMC) in vitro to varying concentrations of MGd. The fluorescence properties of MGd were then exploited using confocal microscopy to image exposed cells. For an in vivo validation study, we performed surface coil-based and intravascular coil-based high-resolution MRI of the iliac arteries and the abdominal aorta of three atherosclerotic Yucatan pigs. Subsequently, MGd enhancement of the target vessel walls was quantitatively evaluated and MR images were correlated with histology of the target vessels. RESULTS: The in vitro study confirmed the intracellularization of MGd in both cell types and determined the optimum MGd dosage of 0.004 mmol/kg that produced the sufficiently high intracellular fluorescent intensity. The in vivo study showed a steady increase of MGd enhancement to approximately 25% at three hours postinjection of MGd. MRI showed areas of strong enhancement along the lumen boundary, which corresponded to fibrous tissue seen in histology. CONCLUSION: This study provides initial evidence that MGd may enhance MR vessel wall imaging for the characterization of plaque in deep-seated arteries.

Development of a 0.014-inch magnetic resonance imaging guidewire.

The purpose of this study was to develop a standard 0.014-inch intravascular magnetic resonance imaging guidewire (MRIG), a coaxial cable with an extension of the inner conductor, specifically designed for use in the small vessels. After a theoretical analysis, the 0.014-inch MRIG was built by plating/cladding highly electrically conductive materials, silver or gold, over the inside and outside of the coaxial conductors. The conductors were made of superelastic, nonmagnetic, biocompatible materials, Nitinol or MP35N. Then, in comparison with a previously designed 0.032-inch MRIG, the performance of the new 0.014-inch MRIG in vitro and in vivo was successfully evaluated. This study represents the initial work to confirm the critical role of highly conductive and superelastic materials in building such small-size MRIGs, which are expected to generate high-resolution MR imaging of vessel walls/plaques and guide endovascular interventional procedures in the small vessels, such as the coronary arteries.