Interventional MRA using actively visualized catheters, TrueFISP, and real‐time image fusion

Abstract

An integrated system for performing interventional magnetic resonance angiography (MRA) with actively visualized instruments and real-time image fusion was implemented on a 1.5 T scanner. True fast imaging with steady precession (TrueFISP) imaging provided high acquisition speed paired with high signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) for the simultaneous visualization of active instruments and arterial morphology. The system enabled simultaneous image reconstruction and image postprocessing of multiple receiver channels, with subsequent image fusion display in real time. Optional interleaved image acquisition in two planes provided additional important information for biplanar instrument guidance. Various vascular interventions, including selective catheterization and subsequent selective MRA of the abdominal aorta, renal arteries, superior mesenteric artery (SMA), hepatic artery, and aortic arch, were performed on 10 pigs under MR guidance. In terms of instrument contrast, image acquisition, reconstruction, and fusion speed, the setup represents a powerful platform for performing interventional MRA procedures.

Morphing steady‐state free precession

“…A second six-element phased array RF body surface coil was placed anterior to the pig. The animal was heparinized with 5000 IU 2 h prior to the intervention and was subsequently anesthetized according to the protocol described in more detail by Quick et al (13). An 7F introducer sheath was inserted into the right iliac artery via arterial cutdown and the guidewire was inserted through the introducer sheath and guided through the vasculature utilizing real-time Cartesian and projection reconstruction bSSFP imaging for guidewire tracking.…”

Passive catheter tracking during interventional MRI using hyperpolarized 13C

“…Real-time catheter tracking has previously been performed using active catheter configurations (19,20), passive gadolinium-filled catheters (16,17), and 19 F catheters (12). However, no real-time nonproton in vivo experiment has yet been reported in which the entire length of the catheter was visualized.…”

“…Catheter visualization and localization have been performed with 19 F MRI in conjunction with proton imaging, using catheters filled with perfluorooctylbromide (PFOB) (12). The natural concentration of 19 F in the body is low compared to the catheter compound concentration; hence only the catheter will be visible in the 19 F images. The feasibility of the 19 F catheter technique was demonstrated for small-FOV phantom imaging, and no large-FOV in vivo data have yet been reported.…”

MR‐guided intravascular interventions: Techniques and applications

“…With use of a mechanically extended RF coil (48) or by implementation of a longitudinal dipole antenna (49,50) into the catheter instrument, the distal curvature or even the whole lengths of the device can be visualized (profiling) (Fig. 4).…”

“…Contrast agents, however, are not necessarily required for endovascular interventions in MRI, because balanced SSFP pulse sequences such as TrueFISP also allow visualizing the blood vessels with high signal intensities (50,66). During catheter advancement True-FISP pulse sequences are well suited for visualizing both the arteries and the surrounding tissue.…”