- Poster presentation
- Open Access
Stiffness-matched segmented metallic guidewire for interventional cardiovascular MRI
© Basar et al; licensee BioMed Central Ltd. 2015
- Published: 3 February 2015
- Fiber Optic Probe
- Core Wire
- Systematic Temperature Measurement
- High Flip Angle
- Standing Wave Formation
Conductive guidewires and intravascular catheters are at risk of RF-induced heating under MRI . Heating is found predominantly at the tip of conductive wires , and is modulated by wire diameter, length and insulation thickness . Non-conductive materials, such as polymer, impart unsatisfactory mechanical properties on guidewires in terms of flexibility, stiffness, and torquability, for navigating tortuous cardiovascular structures and for safely delivering catheter devices.
We developed a novel MRI guidewire design that avoids RF heating yet preserves the mechanical features of conventional X-ray guidewires. Short non-resonant segments of nitinol are connected using stiffness-matched insulated notched couplers, preventing standing wave formation yet appearing mechanically indistinguishable from nitinol guidewires.
RF heating was measured in an ASTM F2182 gel phantom. Tip and shaft temperature was measured using a fiber optic probe (OpSense) at 1.5T (Aera, Siemens) . Heating was measured at high flip angle (75°) bSSFP (TR/TE, 2.88/1.44 ms; thickness, 6 mm; FOV, 350×350 mm; matrix, 192×144) and compared to a custom non-segmented nitinol core wire with identical jacketing serving as a control.
We demonstrate a simple and intrinsically safe new design for passive metallic MRI guidewires. The guidewire exhibits negligible heating at high flip angles in conformance with ISO standards (<2°C) , yet mechanically resembles a high-performance conventional metallic guidewire. This may represent a significant advance once applied in clinical MRI catheterization.
Supported by NHLBI Z01-HL006041. BB, OK, and RJL are co-inventors on patent applications assigned to NIH.
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