Invasive human magnetic resonance imaging: Feasibility during revascularization in a combined XMR suite

We tested the feasibility and safety of invasive magnetic resonance imaging (MRI) during peripheral angioplasty. Real-time MRI can image soft tissue and may potentially guide therapeutic procedures without ionizing radiation or nephrotoxic contrast. MRI-guided diagnostic catheterization has been described recently, but safe and conspicuous catheter devices are not widely available. An active guidewire, which serves as an MRI receiver antenna, might be useful to guide catheterization or even to image atheroma. We describe a combined interventional suite offering both X-ray fluoroscopy and real-time MRI. We used a 0.030" active guidewire receiver coil for invasive MRI after X-ray lesion traversal in patients undergoing percutaneous iliofemoral artery revascularization. Intravascular MRI was compared with noninvasive MRI, X-ray angiography, and intravascular ultrasound (IVUS). Seven eligible patients consented to participate, but three were excluded because of lengthy revascularization procedures. Four remaining patients safely underwent combined X-ray fluoroscopy and real-time magnetic resonance imaging (XMR) transport, continuous monitoring, and all imaging modalities. There was no device dislodgment, contamination or evidence of heating. The intravascular MRI coil was well visualized except at the tip, but did not provide superior mural imaging compared with IVUS. Therefore, because an adequate safety and workflow experience was obtained, enrollment was terminated after only four subjects. Invasive MRI is feasible and apparently safe during peripheral angioplasty. Patients can safely be transported and monitored in an XMR interventional suite. An active quarter-wavelength guidewire coil does not provide superior imaging compared with IVUS, but provides satisfactory guidewire visualization. These tools may prove useful for advanced therapeutic procedures in the future.