ISMRM 21st Annual Meeting & Exhibition 20-26 April 2013 Salt Lake City, Utah, USA

Of Catheters, Guidewires & Needles: MR-Guided Interventions
Wednesday 24 April 2013
Room 155 EF  13:30 - 15:30 Moderators: Charles L. Dumoulin, Graham Wright

13:30 0469.   Evaluation of an Integrated MR-EP Suite and Catheter-Navigated Local MR Lesion Monitoring After RF Ablation
Steffen Weiss1, Sascha Krueger1, Peter Koken1, Gregg Stenzel2, Steve Wedan2, Ronald Holthuizen3, Jouke Smink4, Anne Krogh Grøndal5, Lars Ølgaard Bloch5, James Harrison6, Mark O'Neill6, Reza Razavi6, and Tobias Schaeffter6
1Innovative Technologies, Research Laboratories, Philips Technologie GmbH, Hamburg, Germany, 2Imricor Medical Systems, Burnsville, MN, United States, 3MR Clinical Functionality, Philips Healthcare, Best, Netherlands, 4MR Clinical Science, Philips Healthcare, Best, Netherlands, 5MR Research Centre, Aarhus University Hospital, Aarhus, Denmark, 6Division of Imaging Sciences and Biomedical Engineering, King’s College London, London, United Kingdom

An MR-EP suite was developed that closely integrates all components required for clinical EP procedures. This includes wireless transmission of the ECG from the patient monitor to the EP recorder, automatic transmission of activation time delays from the EP recorder with on-the-fly generation of color-coded time maps based on a cardiac model, and automatic planning of scan orientations based on the position of the active tracking catheter. The suite was evaluated in pre-clinical mapping and ablation sessions in pigs. It enabled time-efficient mapping and ablation including catheter-navigated monitoring of catheter-tissue contact and lesion formation including wall thickening.

13:42 0470.   
Atrial Wall Thickness Imaging for Cavotricuspid Isthmus Ablation -permission withheld
Tobias Voigt1, Peter Koken2, James Harrison3, Steffen Weiss2, Sascha Krueger2, and Tobias Schaeffter3
1Clinical Research Europe, Philips Research, London, London, United Kingdom, 2Tomographic Imaging Systems, Philips Research, Hamburg, Hamburg, Germany, 3Division of Imaging Sciences, King's College London, London, London, United Kingdom

In this work a fully integrated MR Wall Thickness Imagin (WTI) procedure for cavotricuspid isthmus (CTI) ablation is described. The treatment of cardiac arrhythmias by RF ablation has grown rapidly in recent years. The main goal of atrial ablation procedures is to block unwanted conduction pathways by creating transmural lesions. A major challenge is given by the unknown atrial wall thickness. MR atrial wall thickness imaging (WTI) may provide this information and contribute to increase in ablation success rates. The proposed technique is validated in a phantom study and applied in healthy volunteers and an atrial flutter patient.

13:54 0471.   
MR-Guided Sclerotherapy of Low-Flow Vascular Malformations: Visualization and Needle Guidance Using Contrast-Prepared SSFP (CP-SSFP)
Di Xu1, Daniel A. Herzka2, Paul A. DiCamillo3, Wesley D. Gilson4, Elliot R. McVeigh1, Jonathan S. Lewin3, and Clifford R. Weiss3
1Biomedical Engineering, The Johns Hopkins School of Medicine, Baltimore, MD, United States, 2Biomedical Engineering, Johns Hopkins University, Baltimore, MD, United States, 3Radiology, The Johns Hopkins School of Medicine, Baltimore, MD, United States, 4Siemens Corporation, Corporate Technology, Baltimore, MD, United States

Venous and lymphatic malformations (VMs/LMs) are diagnostically visualized using T2-weighted fat-suppressed turbo spin echo. Once identified, lesions typically are treated percutaneously using ultrasound and fluoroscopic guidance. Treatment is limited in lesions that are deep, lie beneath scar, or within bone. Additionally, almost all patients require multiple treatments, accruing significant exposure to ionizing radiation. Real-time MR-guided intervention serves as a safer alternative, with better visualization of critical structures. Conventional sequences are limited: with blurry, distorted edges (HASTE) or with inferior VM/LM delineation because of poor T2-weighting (SSFP). We present real-time imaging for the VMs/LMs visualization during MR-guided sclerotherapy: Contrast-Prepared SSFP.

14:06 0472.   
Catheters for Interventional MR: LaserLathe Fabrication of Micro-Coils for Remote Catheter Tip Deflection
Prasheel Lillaney1, Vincent Malba1, Leland Evans1, Anthony Bernhardt1, Mark Wilson1, Timothy Roberts2, Alastair Martin1, Maythem Saeed1, Ronald Arenson1, and Steven W. Hetts1
1Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California, United States, 2Radiology Department, University of Pennsylvania, Philadelphia, PA, United States

This work presents a method for the fabrication of micro-coils assembled onto the tips of catheters for use in guiding a catheter in an MR field. The approach utilizes the static magnetic field of an MR system to interact with a magnetic moment created by passing an electric current through coils placed at the catheter tip.

14:18 0473.   Accelerated, Motion-Corrected High-Resolution Intravascular MRI at 3T
Shashank Sathyanarayana Hegde1, Yi Zhang2, and Paul A. Bottomley1
1Radiology, Johns Hopkins University, Baltimore, Maryland, United States, 2Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland, United States

High-resolution intravascular (IV) MRI is susceptible to degradation from physiological motion, and requires high frame-rates for true endoscopy. Fortunately, IV MRI detectors have intrinsically radial and sparsely-localized sensitivity profiles, and high local signal-to-noise ratios. Here, compressed sensing with sparse reconstruction is combined with motion correction using frame-by-frame projection shifting based on a singularity at the probe’s location, to provide up to four-fold effective speed-up in image acquisition and a significant reduction in motion sensitivity. We present data acquired in phantoms, and human vessel specimens. These strategies can greatly facilitate high-resolution (~100 micron) real-time MRI endoscopy.

14:30 0474.   in vivo Active Visualization of an Ablation Guidewire for the Revascularization of Occlusive Arterial Disease
Kevan Anderson1, Nicolas Yak1, Labonny Biswas1, Jennifer Barry1, and Graham Wright1,2
1Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada, 2Medical Biophysics, University of Toronto, Toronto, Ontario, Canada

Studies investigating the use of MRI for lesion revascularization have focused on the development of specialized active catheters and guidewires that incorporate receive coils to enable device visualization. There are many engineering challenges associated with this approach and the added complexity will typically limit device performance. In this study we evaluate the ability to actively visualize a commercially available radio-frequency ablation guidewire in an animal model of occlusive arterial disease. The selected technique utilizes an external coupling device that is magnetically coupled to the guidewire and the capacity to visualize the guidewire in vivo is demonstrated.

14:42 0475.   Quantification of Intra-Procedural Gland Motion During Transperineal MRI-Guided Prostate Biopsy
Andriy Fedorov1, Kemal Tuncali1, Tobias Penzkofer1,2, Junichi Tokuda1, Sang-Eun Song1, Nobuhiko Hata1, and Clare Tempany1
1Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States, 2Department of Diagnostic and Interventional Radiology, RWTH Aachen University Hospital, Aachen, North Rhine-Westphalia, Germany

Interventional applications of MRI in PCa management include MRI-guided core needle biopsy that can be recommended for some patient populations, and may lead to improved accuracy of cancer detection. In this work we apply deformable registration retrospectively to recover and quantify intra-procedural motion of the pelvis and prostate gland. Our results show significant motion of the gland, which cannot be fully recovered by compensating for pelvis motion. This can lead to significant errors between the planned and true location of the biopsy target. Application of intra-procedural registration is recommended for intra-procedural quantification and recovery of target motion.

14:54 0476.   SPIO-Labeled 90Y Microspheres Permit Accurate Quantification of Macroscopic Intra-Hepatic Biodistribution
Weiguo Li1,2, Zhuoli Zhang1, Yang Guo1, Jodi Nicolai1, Reed A. Omary1, and Andrew C. Larson1
1Radiology, Northwestern University, Chicago, Illinois, United States, 2Research Resource Center, University of Illinois at Chicago, Chicago, Illinois, United States

Visualization and quantification of Yttrium-90 (90Y) microsphere biodistribution using conventional radiologic modalities is challenging. Whereas labeling 90Y microspheres with SPIOs offers the potential to use MRI to visualize in vivo biodistribution, optimization of the amount of SPIO included within these microspheres may be critical. In this study, we have demonstrated the potential to optimize SPIO content for future studies intended to quantify microsphere concentrations in vivo; we found that spheres with 2% SPIO contents will be ideal candidates for in vivo studies.

15:06 0477.   
An Experimental Setup to Simulate the Magnetohydrodynamic (MHD)-Effect with Respect to Intra Cardiac ECG Signals
Waltraud Brigitte Buchenberg1, Ramona Lorenz1, Peter Laudy2, Wolfgang Mader3, Carsten Bienek4, and Bernd Jung1
1Dept. of Radiology, Medical Physics, University Medical Center, Freiburg, Baden-Württemberg, Germany, 2CardioTek B.V., Maastricht-Airport, Limburg, Netherlands, 3Freiburg Center for Data Analysis and Modeling, Albert-Ludwigs-University, Freiburg, Baden-Württemberg, Germany, 4R&D, Schwarzer GmbH, Heilbronn, Baden-Württemberg, Germany

The analyses of the magnetohydrodynamic (MHD) effect occurring in electro-physiologic (EP) examinations carried out in an MR environment is of importance in order to establish tool boxes to remove MHD related effects from intra-cardiac ECG signals. The aim in this work was to establish an experimental setup to simulate the MHD effect in a model system using standard EP-measurement equipment with respect to a characterization of the pure MHD signal.

15:18 0478.   Boosting MR Temporal Resolution Using Rapid Ultrasound Measurements, for Motion-Tracking Purposes
Matthew Toews1, Chang-Sheng Mei1, Renxin Chu1, W. Scott Hoge1, Benjamin M. Schwartz1, Guangyi Wang1,2, Lawrence P. Panych1, and Bruno Madore1
1Department of Radiology, Harvard Medical School, Brigham and Women's Hospital, Boston, MA, United States, 2Department of Radiology, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, China

A frame rate of twenty frames per second or more is often considered necessary to properly resolve breathing motion for MR-guided therapies. But images with the overall quality, information content and spatial coverage required for effective guidance often cannot be acquired that fast. The present work proposes a system for boosting MR temporal resolution by incorporating ultrasound (US) measurements with high temporal resolution. Experiments showed that predicted MR images could be used to accurately localize anatomical targets in in-vivo liver data, in the presence of breathing motion.