Eddy Y. Wong

Active device tracking and high-resolution intravascular MRI using a novel catheter-based, opposed-solenoid phased array coil.

A novel two‐element, catheter‐based phased array coil was designed and built for both active MR device tracking and high‐resolution vessel wall imaging. The device consists of two independent solenoid coils that are wound in opposite directions, connected to separate receive channels, and mounted collinearly on an angiographic catheter. The elements were used independently or together for tracking or imaging applications, respectively. The arrays dual functionality was tested on a clinical 1.5 T MRI scanner in vitro, in vivo, and in situ. During real‐time catheter tracking, each element gave rise to a high‐amplitude peak in the respective projection data, which enabled reliable and robust device tracking as well as automated slice positioning. In vivo microimaging with 240 μm in‐plane resolution was achieved in 9 s using the device and TrueFISP imaging. Therefore, a single device was successfully implemented that met the combined requirements of intravascular device tracking and imaging. Magn Reson Med 51:668–675, 2004.

Real-Time Catheter Tracking and Adaptive Imaging

To evaluate the performance of a real‐time MR system for interventional procedures that adjusts specific image parameters in real time based on a catheters speed of insertion.

A method for fast 3D tracking using tuned fiducial markers and a limited projection reconstruction FISP (LPR-FISP) sequence

This work demonstrates the feasibility of using wireless, tuned fiducial markers with a limited projection reconstruction–fast imaging with steady‐state free precession sequence (LPR‐FISP) to accurately obtain tracking information necessary for interactive scan plane selection in magnetic resonance imaging (MRI). The position and orientation of a rigid interventional device can be uniquely determined from the 3D coordinates of three fiducial markers mounted in a known configuration on the device. Three fiducial markers were tuned to the proton resonant frequency in a 0.2T open MR scanner and mounted to the surface of a cylindrical water phantom. An LPR‐FISP sequence was developed to suppress the water phantom signal while preserving that of the fiducial markers through a nonselective low‐tip‐angle excitation and a dephaser gradient applied prior to data acquisition. A localization algorithm was developed to accurately calculate the 3D coordinates of the fiducial markers using four LPR‐FISP projections in two orthogonal scan planes. The sequence repetition time (TR = 21 msec) and the limited projection set resulted in fast LPR‐FISP coordinate acquisition times of approximately 170 msec with an accuracy (max error) of 3 mm on a 0.2T MR system. This fast, accurate tracking method provides the fundamental technology for interactive MRI scan plane definition for rigid interventional devices without the need for stereotactic cameras or reference frames. J. Magn. Reson. Imaging 2001;14:617–627.

Image-guided and -monitored renal artery stenting using only MRI

To demonstrate the ability of a unique interventional MR system to be used safely and effectively as the only imaging modality for all phases of MR‐guided stent‐supported angioplasty.

Toward rapid high resolution in vivo intravascular MRI: Evaluation of vessel wall conspicuity in a porcine model using multiple imaging protocols

To assess magnetic resonance (MR) pulse sequences for high resolution intravascular imaging.