OBJECTIVES: We tested the feasibility and safety of invasive MRI during clinical percutaneous peripheral artery angioplasty.

BACKGROUND: 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.

METHODS: We describe a combined interventional suite offering both X-ray fluoroscopy and real-time MRI. We used a commercial 0.030” guidewire receiver coil for invasive MRI after initial lesion traversal in patients undergoing percutaneous iliofemoral artery revascularization. Intravascular MRI was compared with noninvasive MRI, digital subtraction angiography and intravascular ultrasound.

RESULTS: Seven eligible patients consented to participate, but three were excluded because of lengthy revascularization procedures. Four remaining patients safely underwent XMR transport, continuous monitoring, and all imaging modalities. There was no device dislodgement, contamination, or evidence of heating. The intravascular MRI coil was well visualized except at the tip and the SNR was greater than that provided by surface coils, 133±53 vs 52±16 (p=0.04). Despite this it did not provide superior imaging compared with surface MRI phased array coils and with intravascular ultrasound. Therefore enrollment was terminated after only four subjects.

CONCLUSIONS: Invasive MRI is feasible and apparently safe during peripheral angioplasty. Patients can safely be handled and monitored in an XMR interventional suite. A “loopless” quarter-wavelength guidewire coil does not provide superior imaging compared with surface coil arrays, but provides satisfactory guidewire visualization. These tools may prove useful for advanced therapeutic procedures in the future.

DNC

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