Abstract
PurposeReal-time magnetic resonance imaging (MRI) is a promising alternative to X-ray fluoroscopy for guiding cardiovascular catheterization procedures. Major challenges, however, include the lack of guidewires that are compatible with the MRI environment, not susceptible to radiofrequency-induced heating, and reliably visualized. Preclinical evaluation of new guidewire designs has been conducted at 1.5T. Here we further evaluate the safety (device heating), device visualization, and procedural feasibility of 3T MRI-guided cardiovascular catheterization using a novel MRI-visible glass-fiber epoxy-based guidewire in phantoms and porcine models.MethodsTo evaluate device safety, guidewire tip heating (GTH) was measured in phantom experiments with different combinations of catheters and guidewires. In vivo cardiovascular catheterization procedures were performed in both healthy (N = 5) and infarcted (N = 5) porcine models under real-time 3T MRI guidance using a glass-fiber epoxy-based guidewire. The times for each procedural step were recorded separately. Guidewire visualization was assessed by measuring the dimensions of the guidewire-induced signal void and contrast-to-noise ratio (CNR) between the guidewire tip signal void and the blood signal in real-time gradient-echo MRI (specific absorption rate [SAR] = 0.04 W/kg).ResultsIn the phantom experiments, GTH did not exceed 0.35°C when using the real-time gradient-echo sequence (SAR = 0.04 W/kg), demonstrating the safety of the glass-fiber epoxy-based guidewire at 3T. The catheter was successfully placed in the left ventricle (LV) under real-time MRI for all five healthy subjects and three out of five infarcted subjects. Signal void dimensions and CNR values showed consistent visualization of the glass-fiber epoxy-based guidewire in real-time MRI. The average time (minutes:seconds) for the catheterization procedure in all subjects was 4:32, although the procedure time varied depending on the subject’s specific anatomy (standard deviation = 4:41).ConclusionsReal-time 3T MRI-guided cardiovascular catheterization using a new MRI-visible glass-fiber epoxy-based guidewire is feasible in terms of visualization and guidewire navigation, and safe in terms of radiofrequency-induced guidewire tip heating.
Highlights
Real-time magnetic resonance imaging (MRI) provides excellent soft-tissue contrast without radiation exposure [1], and is emerging as a promising alternative to X-ray fluoroscopy for intra-procedural guidance of cardiovascular catheterization [2,3,4] and closed chest percutaneous interventions [5]
Guidewire visualization was assessed by measuring the dimensions of the guidewire-induced signal void and contrastto-noise ratio (CNR) between the guidewire tip signal void and the blood signal in real-time gradient-echo MRI
The catheter was successfully placed in the left ventricle (LV) under real
Summary
Real-time magnetic resonance imaging (MRI) provides excellent soft-tissue contrast without radiation exposure [1], and is emerging as a promising alternative to X-ray fluoroscopy for intra-procedural guidance of cardiovascular catheterization [2,3,4] and closed chest percutaneous interventions [5]. The risk for catheter kinking is especially high in procedures under real-time MRI guidance where, in general, catheters not braided with metallic wires are used to avoid radiofrequency (RF) induced heating. In this context, a novel braid-reinforced catheter with discontinuous metal wires has been recently shown [14] to preserve mechanical properties and kink resistance similar to the ones of braided catheters while limiting RF-induced heating. Despite the possibility to use an MR safe catheter, guidewires are still needed to guide the catheter and avoid vessel damage
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