Dataset Information

MRI Conditional Actively Tracked Metallic Electrophysiology Catheters and Guidewires With Miniature Tethered Radio-Frequency Traps: Theory, Design, and Validation.

ABSTRACT:

Objective

Cardiovascular interventional devices typically have long metallic braids or backbones to aid in steerability and pushability. However, electromagnetic coupling of metallic-based cardiovascular interventional devices with the radiofrequency (RF) fields present during Magnetic Resonance Imaging (MRI) can make a device unsafe for use in an MRI scanner. We aimed to develop MRI conditional actively-tracked cardiovascular interventional devices by sufficiently attenuating induced currents on the metallic braid/tube and internal-cabling using miniaturized resonant floating RF traps (MBaluns).

Method

MBaluns were designed for placement at multiple locations along a conducting cardiovascular device to prevent the establishment of standing waves and to dissipate RF-induced energy. The MBaluns were constructed with loosely-wound solenoids to be sensitive to transverse magnetic fields created by both surface currents on the device's metallic backbone and common-mode currents on internal cables. Electromagnetic simulations were used to optimize MBalun parameters. Following optimization, two different MBalun designs were applied to MR-actively-tracked metallic guidewires and metallic-braided electrophysiology ablation catheters. Control-devices were constructed without MBaluns. MBalun performance was validated using network-analyzer quantification of current attenuation, electromagnetic Specific-Absorption-Rate (SAR) analysis, thermal tests during high SAR pulse sequences, and MRI-guided cardiovascular navigation in swine.

Results

Electromagnetic SAR simulations resulted in ≈20 dB attenuation at the tip of the wire using six successive MBaluns. Network-analyzer tests confirmed ∼17 dB/MBalun surface-current attenuation. Thermal tests indicated temperature decreases of 5.9 °C in the MBalun-equipped guidewire tip. Both devices allowed rapid vascular navigation resulting from good torquability and MR-Tracking visibility.

Conclusion

MBaluns increased device diameter by 20%, relative to conventional devices, providing a spatially-efficient means to prevent heating during MRI.

Significance

MBaluns allow use of long metallic components, which improves mechanical performance in active MR-guided interventional devices.

SUBMITTER: Alipour A

PROVIDER: S-EPMC7341984 | biostudies-literature | 2020 Jun

REPOSITORIES: biostudies-literature

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Publications

MRI Conditional Actively Tracked Metallic Electrophysiology Catheters and Guidewires With Miniature Tethered Radio-Frequency Traps: Theory, Design, and Validation.

Alipour Akbar A Meyer Eric S ES Dumoulin Charles L CL Watkins Ronald D RD Elahi Hassan H Loew Wolfgang W Schweitzer Jeffrey J Olson Gregory G Chen Yue Y Tao Susumu S Guttman Michael M Kolandaivelu Aravindan A Halperin Henry R HR Schmidt Ehud J EJ

IEEE transactions on bio-medical engineering 20190913 6

<h4>Objective</h4>Cardiovascular interventional devices typically have long metallic braids or backbones to aid in steerability and pushability. However, electromagnetic coupling of metallic-based cardiovascular interventional devices with the radiofrequency (RF) fields present during Magnetic Resonance Imaging (MRI) can make a device unsafe for use in an MRI scanner. We aimed to develop MRI conditional actively-tracked cardiovascular interventional devices by sufficiently attenuating induced cu ...[more]

PMID: 31535979

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Project description:PurposeCatheters and guidewires are used extensively in cardiac catheterization procedures such as heart arrhythmia treatment (ablation), angioplasty, and congenital heart disease treatment. Detecting their positions in fluoroscopic X-ray images is important for several clinical applications, for example, motion compensation, coregistration between 2D and 3D imaging modalities, and 3D object reconstruction.MethodsFor the generalized framework, a multiscale vessel enhancement filter is first used to enhance the visibility of wire-like structures in the X-ray images. After applying adaptive binarization method, the centerlines of wire-like objects were extracted. Finally, the catheters and guidewires were detected as a smooth path which is reconstructed from centerlines of target wire-like objects. In order to classify electrode catheters which are mainly used in electrophysiology procedures, additional steps were proposed. First, a blob detection method, which is embedded in vessel enhancement filter with no additional computational cost, localizes electrode positions on catheters. Then the type of electrode catheters can be recognized by detecting the number of electrodes and also the shape created by a series of electrodes. Furthermore, for detecting guiding catheters or guidewires, a localized machine learning algorithm is added into the framework to distinguish between target wire objects and other wire-like artifacts. The proposed framework were tested on total 10,624 images which are from 102 image sequences acquired from 63 clinical cases.ResultsDetection errors for the coronary sinus (CS) catheter, lasso catheter ring and lasso catheter body are 0.56 ± 0.28 mm, 0.64 ± 0.36 mm, and 0.66 ± 0.32 mm, respectively, as well as success rates of 91.4%, 86.3%, and 84.8% were achieved. Detection errors for guidewires and guiding catheters are 0.62 ± 0.48 mm and success rates are 83.5%.ConclusionThe proposed computational framework do not require any user interaction or prior models and it can detect multiple catheters or guidewires simultaneously and in real-time. The accuracy of the proposed framework is sub-mm and the methods are robust toward low-dose X-ray fluoroscopic images, which are mainly used during procedures to maintain low radiation dose.

Project description:BackgroundCardiovascular magnetic resonance (CMR) fluoroscopy allows for simultaneous measurement of cardiac function, flow and chamber pressure during diagnostic heart catheterization. To date, commercial metallic guidewires were considered contraindicated during CMR fluoroscopy due to concerns over radiofrequency (RF)-induced heating. The inability to use metallic guidewires hampers catheter navigation in patients with challenging anatomy. Here we use low specific absorption rate (SAR) imaging from gradient echo spiral acquisitions and a commercial nitinol guidewire for CMR fluoroscopy right heart catheterization in patients.MethodsThe low-SAR imaging protocol used a reduced flip angle gradient echo acquisition (10° vs 45°) and a longer repetition time (TR) spiral readout (10 ms vs 2.98 ms). Temperature was measured in vitro in the ASTM 2182 gel phantom and post-mortem animal experiments to ensure freedom from heating with the selected guidewire (150 cm × 0.035″ angled-tip nitinol Terumo Glidewire). Seven patients underwent CMR fluoroscopy catheterization. Time to enter each chamber (superior vena cava, main pulmonary artery, and each branch pulmonary artery) was recorded and device visibility and confidence in catheter and guidewire position were scored on a Likert-type scale.ResultsNegligible heating (< 0.07°C) was observed under all in vitro conditions using this guidewire and imaging approach. In patients, chamber entry was successful in 100% of attempts with a guidewire compared to 94% without a guidewire, with failures to reach the branch pulmonary arteries. Time-to-enter each chamber was similar (p=NS) for the two approaches. The guidewire imparted useful catheter shaft conspicuity and enabled interactive modification of catheter shaft stiffness, however, the guidewire tip visibility was poor.ConclusionsUnder specific conditions, trained operators can apply low-SAR imaging and using a specific fully-insulated metallic nitinol guidewire (150 cm × 0.035" Terumo Glidewire) to augment clinical CMR fluoroscopy right heart catheterization.Trial registrationClinicaltrials.gov NCT03152773 , registered May 15, 2017.

Dataset Information

MRI Conditional Actively Tracked Metallic Electrophysiology Catheters and Guidewires With Miniature Tethered Radio-Frequency Traps: Theory, Design, and Validation.

Objective

Method

Results

Conclusion

Significance

Publications

MRI Conditional Actively Tracked Metallic Electrophysiology Catheters and Guidewires With Miniature Tethered Radio-Frequency Traps: Theory, Design, and Validation.

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