Comparative Evaluation of the Geometrical Accuracy of Intravascular Magnetic Resonance Imaging: A Phantom Study

Rationale and Objectives. To evaluate and compare the accuracy of cross-sectional imaging using an intravascular antenna in the context of vascular morphological measurements performed during a magnetic resonance imaging (MRI)-guided vascular intervention. Materials and Methods. Cross-sectional imaging of a multimodality vascular phantom was performed using intravascular and surface MRI, multidetector computed tomography, and intravascular ultrasound (IVUS). Using a balanced steady-state free-precession sequence, 18 sequences parameters sets were investigated (12 for intravascular MRI and 6 for surface MRI). Vessel diameters for all images and modalities were computed using an automated vessel segmentation algorithm. Results. Using IVUS as a gold standard, imaging using an intravascular antenna leads to an increase in geometrical accuracy in comparison to traditional surface MRI. This level of accuracy appears to follow a significant inverse proportionality relation in respect to vessel wall signal-to-noise ratio (SNR). Taking into account the rapid decrease in SNR as a function of the distance to the intravascular antenna, these results imply that, for a given level of geometrical accuracy, faster sequences call be used for the imaging of smaller vessels. Conclusion. Imaging using an intravascular antenna appears as a valuable assistance to increase the accuracy of vascular morphological measurements. This increase in geometrical accuracy would be beneficial during the realization of an MRI-guided intervention, either to perform pretreatment measurements or to assess the outcome of the procedure. Acquisition parameters should be tailored to vessel size and procedural time constraints.