MR-Guided Intravascular & Percutaneous Interventions
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Tuesday 8 May 2012
Room 210-211  10:00 - 12:00 Moderators: John A. Carrino, R. Jason Stafford

10:00 0205.   
A Closed-loop MRI-powered Actuator for Robotic Interventions
Lei Qin1, Panagiotis Vartholomeos2, and Pierre Dupont2
1Dana-Farber Cancer Institute, Boston, MA, United States, 2Children's Hospital Boston, Boston, MA, United States

This paper presents a novel closed-loop controlled actuation technology for robotically assisted MRI-guided interventional procedures. Compact and wireless, the actuators are both powered and controlled by the MRI scanner. The principle of operation is based on one or more small ferromagnetic bodies embedded in the actuator that serves to convert the electromagnetic energy of the MR gradients into mechanical energy. A MR tracking sequence is performed to track the position of the needle in real-time for closed-loop control. A prototype was constructed, which showed accurate control of the needle.

10:12 0206.   MRI-compatible Voltage-based Electro-Anatomic Mapping System for Cardiac Electrophysiological Interventions
Zion Tsz Ho Tse1, Charles L Dumoulin2, Ronald Watkins3, Israel Byrd4, Jeffrey Schweitzer4, Raymond Y Kwong5, Gregory F. Michaud5, William G. Stevenson5, and Ehud J. Schmidt1
1Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States, 2Radiology, Cincinnati Children’s Hospital Medical Center,3Radiology, Stanford University, 4Atrial Fibrillation Division, St Jude Medical, Inc., 5Cardiology, Brigham and Women’s Hospital, Harvard Medical School

An MRI-compatible St Jude Medical EnSite NavX (ESN) voltage-based navigational system was used for Electro-Anatomic-Mapping (EAM) and catheter tracking during MR imaging. The system also allowed Electro-Physiological (EP) procedures to be performed inside and outside MRI. The ESN was equipped with an electronic blanking circuit to block ESN tracking signals during gradient-ramps-&-radiofrequency transmission (GR&RF). EP catheters with MR-tracking coils and ESN tracking electrodes were used. The ESN was validated in a cardiac phantom and three swine models with EAM and simultaneous imaging. The system showed <6mm catheter positional error, <1oC temperature rise, and <5% image quality reduction.

10:24 0207.   
Comparison Between Multi-Contrast Late Enhancement Magnetic Resonance Imaging And Electroanatomical Voltage Mapping, For Ventricular Tachycardia Substrate Characterization, Using A Real-Time MR-Guided Electrophysiology System
Samuel O Oduneye1,2, Labonny Biswas2, Roey Flor2, Sudip Ghate2, Venkat Ramanan2, Jennifer Barry2, and Graham A Wright1,2
1Medical Biophysics, University Of Toronto, TORONTO, ONTARIO, Canada, 2Imaging Research, Sunnybrook Research Institute, TORONTO, ONTARIO, Canada

Integration of MRI-derived scar maps with electroanatomical mapping (EAM) has implications for catheter ablation of ventricular tachycardia and for targeting the scarred regions. The purpose of this study was to compare the potentially arrhythmogenic regions and characterize the relationship and morphology between chronic myocardial scar detectable by multi-contrast late enhancement (MCLE) MRI and EAM of endocardial substrate obtained with a real-time MR-guided electrophysiology system.

10:36 0208.   
Parallel transmit with integrated toroidal transceive device visualization
Maryam Etezadi-Amoli1, Pascal Stang1, Adam Kerr1, John Pauly1, and Greig Scott1
1Electrical Engineering, Stanford University, Stanford, CA, United States

A toroidal transceiver enables high-SNR positive contrast visualization of conductive interventional devices such as guidewires and EP catheters. Effective device visualization can be achieved with very low transmit power levels (~12mW). Integration within a parallel transmit platform is a promising approach to RF safety during interventional procedures.

10:48 0209.   Remote MR-Compatible Catheter Navigation System
Mohammad Ali Tavallaei1,2, Yogesh Thakur3, Syed Haider1, and Maria Drangova1,4
1Imaging Research Laboratories, Robarts Research Institute, London, Ontario, Canada, 2Biomedical Engineering Graduate Program, The University of Western Ontario, London, Ontario, Canada, 3Radiology, Vancouver Coastal Health Authority, Vancouver, British Columbia, Canada, 4Medical Biophysics, The University of Western Ontario, London, Ontario, Canada

An MR compatible master-slave robot for catheter navigation is described. The robot uses a master/slave approach, where the motions of a catheter manipulated by the interventionalist are measured by the master, an embedded system sends commands to a pair of ultrasonic motors and an MR compatible manipulator replicates the interventionalist’s motions on a patient catheter within the magnet bore. The accuracy of the system in remotely controlling the position of the catheter in the magnet, its time delay and the effect of the system on image SNR is evaluated. This robot promises to facilitate MRI guided catheterization procedures.

11:00 0210.   Initial In Vivo Experience with a Novel Type of Fully MR-Safe Detachable Coils for MR-guided Embolizations
Ann-Kathrin Homagk1, Reiner Umathum1, Michael Bock2, Wolfhard Semmler1, and Peter Hallscheidt3
1Dept. of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany, 2Dept. of Radiology, Medical Physics, University Hospital Freiburg, Freiburg, Germany, 3Dept. of Diagnostic and Interventional Radiology, University Heidelberg, Heidelberg, Germany

Conventional detachable embolization coils are made from platinum or stainless steel, and may thus be an MR safety hazard due to resonant device heating. In this work a novel type of non-metallic and therefore intrinsically MR safe embolization coils is investigated in a pig model. The contrast enhanced injection of three polymer embolization coils into the renal artery was monitored in real time. 40 minutes after embolization, the perfusion deficit was clearly identified on high resolution contrast enhanced 3D FLASH data sets. With this initial experiment, the usability of the novel polymer coils for MR-guided embolization procedures could be demonstrated.

11:12 0211.   DBS Electrode Positioning Accuracy in the STN and GPi with Intraoperative MR Guidance
Alastair Martin1, Paul Larson1, Geoffrey Bates2, and Philip Starr1
1University of California - San Francisco, San Francisco, CA, United States, 2MRI Interventions, Irvine, CA, United States

MR guided DBS electrode implantation is evaluated in a series of patients with Parkinson’s disease and dystonia. Both the STN and GPi are targeted and a novel optimized implantation system is employed. Targeting accuracies of 0.7±0.4mm were achieved when targeting both the STN and GPi and only a single brain penetration was necessary in 97% of electrodes implanted. There was no demonstrable bias in the direction of the error with either target. The achieved results with the optimized system are shown to exceed those obtained with our initial DBS implantation approach.

11:24 0212.   Spinal infiltrations and biopsies using an advanced real-time MR guidance approach: preliminary clinical report
Elodie Breton1, Eva Rothgang2,3, Li Pan2, Julien Garnon4, Georgia Tsoumakidou4, Xavier Buy4, Christine H. Lorenz2, Michel de Mathelin1, and Afshin Gangi1,4
1LSIIT - AVR, University of Strasbourg - CNRS, Strasbourg, France, 2Center for Applied Medical Imaging, Siemens Corporate Research, Baltimore, MD, United States, 3Pattern Recognition Lab, Friedrich-Alexander University, Erlangen, Germany, 4Interventional Radiology Department, Nouvel Hôpital Civil, Strasbourg, France

The multiplanar imaging capabilities of MR are of great advantage for real-time needle guidance. The focus of this work is to clinically evaluate an advanced MR guidance approach for percutaneous needle interventions providing an interactive, real-time multi-slice pulse sequence (Beat_IRTTT) in combination with an interventional MRI software package (Interactive Front End, IFE). This approach was used for 9 spinal infiltrations and 6 abdominal biopsies. To our experience, automatic real-time slice alignment greatly simplifies the workflow. The proposed real-time slice layout with three slices along the planned trajectory orthogonal to each other further allows for efficient and safe needle placement.

11:36 0213.   MRI-guided Sclerotherapy of Low-flow Vascular Malformations at 1.5T using Tri-Plane Gradient-echo Pulse Sequences with Variable Frame Rates: Our Experience and Imaging Times
Gurpreet S Sandhu1, Jamal J Derakhshan1, Jeffrey L Duerk1, Jeffrey L Sunshine1, Mark A Griswold1, and Daniel P Hsu1
1Radiology, University Hospitals, Case Western Reserve University, Cleveland, Ohio, United States

Multiplanar imaging is a crucial advantage in diagnostic magnetic resonance imaging (MRI) when compared to other imaging modalities. Our group uses fast tri-plane gradient-echo pulse sequences for image-guided minimally invasive procedures. These sequences allow alignment of each of the three imaging planes in any desired orientation. Tri-plane imaging enables concurrent visualization of the interventional device and target lesion as well as adjacent vital structures. Now, we have developed different versions of these sequences with higher frame rates. We describe our experience including needle time with these sequences for MRI-guided sclerotherapy of low-flow vascular malformations on a 1.5T imaging system.

11:48 0214.   MR-guided sclerotherapy of vascular and lymphatic malformations: our first year experiences
Paul Allen DiCamillo1, Wesley D Gilson2, Aaron J Flammang2, Li Pan2, Jonathan S Lewin1, and Clifford R Weiss3
1Department of Radiology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States, 2Siemens Corporate Research, Baltimore, Maryland, United States, 3Vascular and Interventional Radiology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States

Venous malformations (VM) and lymphatic malformations (LM) are congenital lesions that may develop anywhere in the body, leading to functional or cosmetic impairment, pain or bleeding. These lesions are typically treated percutaneously using ultrasound and fluoroscopic guidance. However, certain lesion locations complicate treatment by those modalities. Real-time MR-guided intervention serves as a safer alternative, with better visualization of surrounding critical soft tissue structures. We present our first year of experience with this technique using a short bore 1.5T MRI/X-Ray "Miyabi" suite.