Pallav Kolli, Fabio Settecase, Matthew Amans, and Robert Taylor from UCSF, Tim Roberts from University of Pennsylvania
Funding Sources
NIH National Heart Lung Blood Institute (NHLBI) Award (M. Wilson): 1R01HL076486 American Society of Neuroradiology Research and Education Foundation Scholar Award (S. Hetts)
NIH National Institute of Biomedical Imaging and Bioengineering (NIBIB) Award (S. Hetts): 1R01EB012031

1. Microcoil Fabrication
<ol>
 <li>Obtain a commercially available microcatheter (e.g. 2.3F Rapid Transit Cordis Neurovascular Catheter, Raynham, MA) for a substrate.</li>
 <li>Ensure catheters have no ferrous components, are considered MR-safe, and range in size 2.3-3.0 F.</li>
 <li>Sputter a titanium adhesion layer followed by a copper seed layer unto a 1 to 2 mm OD insulating tube. Possible materials include polyimide or alumina (Ortech Advanced Ceramics, Sacramento, CA).</li>
 <li>Electrodeposit a positive...

<ol>
	<li>Molyneux, A. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=International+subarachnoid+aneurysm+trial+(ISAT)+of+neurosurgical+clipping+versus+endovascular+coiling+in+2143+patients+with+ruptured+intracranial+aneurysms:+a+randomised+comparison+of+effects+on+survival,+dependency,+seizures,+rebleeding,+subgroups,+and+aneurysm+occlusion.">International subarachnoid aneurysm trial (ISAT) of neurosurgical clipping versus endovascular coiling in 2143 patients with ruptured intracranial aneurysms: a randomised comparison of effects on survival, dependency, seizures, rebleeding, subgroups, and aneurysm occlusion.</a> Lancet. 366, 809-817 (2005).</li><li>Razavi, M. K., Hwang, G., Jahed, A., Modanlou, S., Chen, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Abdominal+myomectomy+versus+uterine+fibroid+embolization+in+the+treatment+of+symptomatic+uterine+leiomyomas.">Abdominal myomectomy versus uterine fibroid embolization in the treatment of symptomatic uterine leiomyomas.</a> AJR Am. J. Roentgenol. 180, 1571-1575 (2003).</li><li>Hoffman, S. N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+meta-analysis+of+randomized+controlled+trials+comparing+coronary+artery+bypass+graft+with+percutaneous+transluminal+coronary+angioplasty:+one-+to+eight-year+outcomes.">A meta-analysis of randomized controlled trials comparing coronary artery bypass graft with percutaneous transluminal coronary angioplasty: one- to eight-year outcomes.</a> J. Am. Coll. Cardiol. 41, 1293-1304 (2003).</li><li>McDougall, C. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Causes+and+management+of+aneurysmal+hemorrhage+occurring+during+embolization+with+Guglielmi+detachable+coils.">Causes and management of aneurysmal hemorrhage occurring during embolization with Guglielmi detachable coils.</a> J. Neurosurg. 89, 87-92 (1998).</li><li>Willinsky, R. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neurologic+complications+of+cerebral+angiography:+prospective+analysis+of+2,899+procedures+and+review+of+the+literature.">Neurologic complications of cerebral angiography: prospective analysis of 2,899 procedures and review of the literature.</a> Radiology. 227, 522-528 (2003).</li><li>Veith, F. J., Marin, M. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endovascular+technology+and+its+impact+on+the+relationships+among+vascular+surgeons,+interventional+radiologists,+and+other+specialists.">Endovascular technology and its impact on the relationships among vascular surgeons, interventional radiologists, and other specialists.</a> World J. Surg. 20, 687-691 (1996).</li><li>Miller, D. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinical+radiation+management+for+fluoroscopically+guided+interventional+procedures.">Clinical radiation management for fluoroscopically guided interventional procedures.</a> Radiology. 257, 321-332 .</li><li>Balter, S., Hopewell, J. W., Miller, D. L., Wagner, L. K., Zelefsky, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluoroscopically+guided+interventional+procedures:+a+review+of+radiation+effects+on+patients'+skin+and+hair.">Fluoroscopically guided interventional procedures: a review of radiation effects on patients' skin and hair.</a> Radiology. 254, 326-341 (2010).</li><li>Wagner, L. K., McNeese, M. D., Marx, M. V., Siegel, E. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Severe+skin+reactions+from+interventional+fluoroscopy:+case+report+and+review+of+the+literature.">Severe skin reactions from interventional fluoroscopy: case report and review of the literature.</a> Radiology. 213, 773-776 (1999).</li><li>Koenig, T. R., Wolff, D., Mettler, F. A., Wagner, L. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Skin+injuries+from+fluoroscopically+guided+procedures:+part+1,+characteristics+of+radiation+injury.">Skin injuries from fluoroscopically guided procedures: part 1, characteristics of radiation injury.</a> AJR Am. J. Roentgenol. 177, 3-11 (2001).</li><li>Koenig, T. R., Mettler, F. A., Wagner, L. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Skin+injuries+from+fluoroscopically+guided+procedures:+part+2,+review+of+73+cases+and+recommendations+for+minimizing+dose+delivered+to+patient.">Skin injuries from fluoroscopically guided procedures: part 2, review of 73 cases and recommendations for minimizing dose delivered to patient.</a> AJR Am. J. Roentgenol. 177, 13-20 (2001).</li><li>Arenson, R. L. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Magnetically+directable+remote+guidance+systems,+and+methods+and+use+thereof.">Magnetically directable remote guidance systems, and methods and use thereof.</a> United States Patent. , (2001).</li><li>Roberts, T. P., Hassenzahl, W. V., Hetts, S. W., Arenson, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Remote+control+of+catheter+tip+deflection:+an+opportunity+for+interventional+MRI.">Remote control of catheter tip deflection: an opportunity for interventional MRI.</a> Magn. Reson. Med. 48, 1091-1095 (2002).</li><li>Malba, V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laser-lathe+lithography+-+a+novel+method+for+manufacturing+nuclear+magnetic+resonance+microcoils.">Laser-lathe lithography - a novel method for manufacturing nuclear magnetic resonance microcoils.</a> Biomed. Microdevices. 5, 21-27 (2003).</li><li>Bernhardt, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Steerable+catheter+microcoils+for+interventional+MRI+reducing+resistive+heating.">Steerable catheter microcoils for interventional MRI reducing resistive heating.</a> Academic radiology. 18, 270-276 (2011).</li><li>Muller, L., Saeed, M., Wilson, M. W., Hetts, S. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Remote+control+catheter+navigation:+options+for+guidance+under+MRI.">Remote control catheter navigation: options for guidance under MRI.</a> Journal of Cardiovascular Magnetic Resonance : Official Journal of the Society for Cardiovascular Magnetic Resonance. 14, 33 (2012).</li><li>Wilson, M. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Magnetic+catheter+manipulation+in+the+interventional+MRI+environment.">Magnetic catheter manipulation in the interventional MRI environment.</a> J. Vasc. Interv. Radiol. , (2013).</li></ol>

Dr. Hetts has received grant support from Stryker Corporation and is a paid consultant for Silk Road Medical, Inc.

Here we describe the protocol for deflection of a microcatheter in a MR scanner. The key parameters for success are accurate application of current and measurement of deflection angle. Inaccurate measurement of deflection angle is the most probable error encountered in this protocol. The angles captured in MR images during the waterbath experiment may differ from actual values due to slight differences in the orientation by which the medium is positioned with respect to the bore of the magnet. To address this issue in th...

Endovascular procedures performed in interventional medicine use x-ray guidance as a tool for catheter navigation through vasculature to treat several major illnesses, such as brain aneurysm, ischemic stroke, solid tumors, atherosclerosis and cardiac arrhythmias targeting over one million patients per year worldwide1-5. With the use of contrast media, navigation through vasculature is achieved through manual rotation of the catheter and mechanical advancement by the interventionist's hand6. However, navigation through small tortuous blood vessels around many vascular bends becomes increasingly difficult, elongating the time before reaching the target site. This poses a problem for time-sensitive procedures such as the removal of a clot in an occluded blood vessel. Additionally, prolonged procedures increase the radiation dose and create the potential for adverse events7-11. However, endovascular procedures performed under magnetic resonance imaging may provide a solution.
 The strong homogenous magnetic field of an MRI scanner can be exploited for catheter tip navigation by remote control12,13. Current applied to a microcoil located at a catheter tip induces a small magnetic moment, which experiences a torque as it aligns with the bore of the MRI scanner13 (Figure 1). If electric current is activated in an individual coil, the catheter tip can be deflected in one plane by remote control. If three coils at a catheter tip are energized, catheter tip deflection can be achieved in three-dimension. Thus, magnetically facilitated steering of a catheter has the potential to increase the speed and efficacy of vascular navigation in endovascular procedures, which could reduce procedure times and improve patient outcomes. In this study, we examined if current applied to a microcoil-tipped endovascular catheter can produce reliable and controlled deflections under MR-guidance as preliminary testing of catheter navigation studies.

<table border="1">
<tbody>
 <tr>
 <td>Name of Reagent/Material</td>
 <td>Company</td>
 <td>Catalog Number</td>
 <td>Comments</td>
 </tr>
 <tr>
 <td>GdDTPA Contrast Media (Magnevist)</td>
 <td>Bayer HealthCare Pharmaceuticals Inc. </td>
 <td>1240340</td>
 <td>McKesson Material Number</td>
 </tr>
 <tr>
 <td>Positive Photoresist</td>
 <td>Shipley</td>
 <td>N/A</td>
 <td>PEPR-2400, Replacement: Dow Chemicals Intervia 3D-P </td>
 </tr>
 <tr>
 <td>Copper Sulfate</td>
 <td>ScienceLab</td>
 <td>SLC3778</td>
 <td>Crystal form</td>
 </tr>
 <tr>
 <td>Sulfuric Acid</td>
 <td>ScienceLab</td>
 <td>SLS1573</td>
 <td>50% w/w solution</td>
 </tr>
 <tr>
 <td>Parrafin Wax</td>
 <td>Carolina</td>
 <td>879190</td>
 <td></td>
 </tr>
 <tr>
 <td>Potassium Carbonate </td>
 <td>Acros Organics</td>
 <td>424081000</td>
 <td></td>
 </tr>
</tbody>
 </table>

magnetically-assisted remote controlled microcatheter tip deflection under magnetic resonance imaging

X-ray fluoroscopy-guided endovascular procedures have several significant limitations, including difficult catheter navigation and use of ionizing radiation, which can potentially be overcome using a magnetically steerable catheter under MR guidance.
	The main goal of this work is to develop a microcatheter whose tip can be remotely controlled using the magnetic field of the MR scanner. This protocol aims to describe the procedures for applying current to the microcoil-tipped microcatheter to produce consistent and controllable deflections.
	A microcoil was fabricated using laser lathe lithography onto a polyimide-tipped endovascular catheter. In vitro testing was performed in a waterbath and vessel phantom under the guidance of a 1.5-T MR system using steady-state free precession (SSFP) sequencing. Various amounts of current were applied to the coils of the microcatheter to produce measureable tip deflections and navigate in vascular phantoms.
	The development of this device provides a platform for future testing and opportunity to revolutionize the endovascular interventional MRI environment.

From the protocol described above, an angle of deflection between 0 and 90 degrees should be observed from application of 50-300 mA of current delivered simultaneously to both coils of a combined solenoid and Helmholtz coil microcatheter system (Figure 2E). An increase in applied current should result in an increase in microcatheter deflection angle, while a reversal in current polarity should result in deflection in the exact opposite direction as observed with positive current (Figures 5A-5C</s...

Watch this Scientific Journal Video about Magnetically-Assisted Remote Controlled Microcatheter Tip Deflection under Magnetic Resonance Imaging at JoVE.com

Magnetically-Assisted Remote Controlled Microcatheter Tip Deflection under Magnetic Resonance Imaging

Current applied to an endovascular microcatheter with microcoil tip made by laser lathe lithography can achieve controllable deflections under magnetic resonance (MR) guidance, which may improve speed and efficacy of navigation of vasculature during various endovascular procedures.

X-ray fluoroscopy-guided  endovascular procedures have several significant limitations, including  difficult catheter navigation and use of ionizing ...

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12.3K vistas.  University of California, San Francisco. La corriente aplicada a un microcatéter endovascular con punta microespiral hecha por láser litografía torno puede lograr deflexiones bajo controlables por resonancia magnética (MR) de orientación, que puede mejorar la velocidad y eficacia de la navegación de la vasculatura durante diversos procedimientos endovasculares.