ISMRM 23rd Annual Meeting & Exhibition • 30 May - 05 June 2015 • Toronto, Ontario, Canada

Electronic Poster Session • Interventional
4041 -4064 Thermometry & Thermotherapy
4137 -4160 MR-Guided Inteventions

Note: The videos below are only the slides from each presentation. They do not have audio.

Wednesday, 3 June 2015
Exhibition Hall 10:00 - 11:00

  Computer #  
4041.   73 MR-ARFI for the Quantification of Tissue Elastic Properties
Tetiana Dadakova1, Ali Caglar Özen1, Axel Joachim Krafft1, Jurgen Fütterer2, Martijn Hoogenboom2, Jürgen Walter Jenne3, Erik Dumont4, Christakis Damianou5, Jan Gerrit Korvink6, and Michael Bock1
1Department of Radiology - Medical Physics, University Medical Center Freiburg, Freiburg, Germany, 2Department of Radiology and Nuclear medicine, Radboud University Medical Center, Nijmegen, Netherlands, 3Fraunhofer MEVIS, Bremen, Germany, 4Image Guided Therapy, Pessac, France, 5Department of Electrical Engineering, Computer Engineering and Informatics, Cyprus University of Technology, Limassol, Cyprus, 6Department of Microsystems Engineering (IMTEK), University of Freiburg, Freiburg, Germany

High intensity focused ultrasound (HIFU) under MR guidance allows for pre-treatment planning, post-treatment assessment and real-time temperature monitoring during treatment in ablative hyperthermia of tumors. In addition to heating, HIFU causes micrometer transient displacements in the tissue, which is most pronounced at the focal spot. The displacement can be visualized with MRI (acoustic radiation force imaging, ARFI) using motion encoding gradients. The time-dependency of the displacement can be described by an overdamped harmonic oscillator model, which has two parameters: the maximum tissue displacement ∆x, and the rise time τ. The rise time is related to the mechanical tissue properties, and its quantification is needed for modelling of the tissue response during ARFI, and to distinguish tissues based on their stiffness. In this work we developed a method to quantify τ from MR-ARFI data. To assess whether tissue stiffness changes with heating, τ was calculated in 4 regions of a porcine muscle ex vivo phantom, which received different thermal doses.

4042.   74 Acoustic Radiation Force Imaging (ARFI) Based on Fast Spin Echo
Yuval Zur1
1GE Healthcare, Tirat Carmel, Israel

MR guided Focused Ultrasound treats noninvasively many brain disorders. The skull bone in the brain induces significant distortions of the ultrasonic wave field. It is necessary to measure the acoustic field and correct it. This field is measured with Acoustic Radiation Force Imaging (ARFI) where the ultrasound induced tissue displacement, in conjunction with a gradient generates a phase shift which is read by EPI. In this abstract we describe a new ARFI sequence based on Fast Spin Echo. The new sequence is artifact free and is not affected by b0 field inhomogeneity. In addition the phase sensitivity is higher than EPI ARFI.

4043.   75 Dynamic 3D MR Acoustic Radiation Force Imaging for Tissue Property Estimation
Joshua Thomas de Bever1,2, Henrik Odéen2,3, and Dennis L. Parker2,4
1School of Computing, University of Utah, Salt Lake City, Utah, United States, 2Utah Center for Advanced Imaging Research, Salt Lake City, Utah, United States, 3Department of Physics, University of Utah, Salt Lake City, Utah, United States, 4Department of Radiology, University of Utah, Salt Lake City, Utah, United States

A 3D method for characterizing the dynamic response of tissue due to acoustic radiation force is tested. This 3D MR-ARFI technique can provide valuable information about the state of tissue elastic properties and assist with phase correction algorithms for beam focusing through aberrating tissue environments such breast and skull.

4044.   76 Temperature and Thermal Dose Analysis Associated with Acoustic Radiation Force from High Intensity Focused Ultrasound in Phantom for Viscoelasticity Measurement
Jiming Zhang1, Amol Pednekar2, Pei-Herng Hor3, and Raja Muthupillai1
1Diagnostic and Interventional radiology, CHI St Lukes' Health, Houston, TX, United States, 2Philips Healthcare, TX, United States, 3Physics, University of Houston, Houston, TX, United States

Magnetic resonance acoustic radiation force imaging (MR-ARFI) has been used to either localize the focal spot during high intensity focused ultrasound (HIFU) surgery or measure tissue viscoelasticity from temporally tracking the shear wave propagation initialize by acoustic radiation force (ARF) by an impulse excitation of HIFU. In addition to the mechanical effect of ARF, its thermal effect will potentially result in temperature increase during the MR-ARFI acquisition and may cause tissue damage in vivo study due to the repeat application of HIFU pulse. The results from the tissue mimicking gel phantom demonstrate the associated temperature rise and accumulated thermal dose during the acquisition of tracking shear wave propagation.

4045.   77 Real-time MR Thermometry Feedback Control for Prostate Hyperthermia with a Commercial HIFU System
Eugene Ozhinsky1, Vasant A. Salgaonkar2, Chris J. Diederich2, and Viola Rieke1
1Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, United States, 2Radiation Oncology, University of California San Francisco, San Francisco, CA, United States

We implemented and evaluated an MR Thermometry feedback control system for hyperthermia therapy using a commercially available prostate ablation system.

4046.   78 Pre-Clinical Head-Mounted MRgFUS Device for Large Animals
Robb Merrill1, Henrik Odeen1, Emilee Minalga1, J. Rock Hadley1, Dennis Parker1, and Allison Payne1
1Radiology, University of Utah, Salt Lake City, UT, United States

This work describes an MRgFUS system for conducting ultrasound procedures on large animals on a Siemens 3T MRI scanner. A craniotomy was performed on a pig to provide unobstructed passage of ultrasound during treatment. A seven-channel phased array RF coil was used for ultrasound guidance and MR thermometry. A multi-axis adjustment mechanism suspended the ultrasound transducer above the prone animal, and allowed for a treatment envelope covering the majority of the brain volume. Two brain locations were targeted and heating was successfully observed, verifying the ultrasound focus position. The system can be easily adapted to other animals and anatomy.

4047.   79 Investigating the utility of diffusion-weighted imaging (DWI) for monitoring treatment efficacy during MR guided High Intensity Focused Ultrasound (MRgHIFU) therapy in bone applications
Sharon L Giles1, Jessica M Winfield2, Ian Rivens3, David J Collins2, Gail R ter Haar3, and Nandita M deSouza2
1MRI Unit, Royal Marsden Hospital, Sutton, Surrey, United Kingdom, 2CRUK Cancer Imaging Centre, The Institute of Cancer Research, Sutton, Surrey, United Kingdom, 3Therapeutic Ultrasound, The Institute of Cancer Research, Sutton, Surrey, United Kingdom

This study assesses the utility of DWI for detecting tissue changes during MRgHIFU by evaluating repeatability of ADC measurements and ADC changes after sonication in n=7 lamb legs. Measurements were made in soft tissues immediately adjacent to bone. Imaging appearances were macroscopically compared with dissected tissues. The coefficient of variation for repeat ADC measurements was 1.0% and the degree of ADC change increased with increasing power of sonications. A 20% sustained increase in ADC produced visible lesions on dissection, unapparent on T1- or T2-W imaging, making DWI a potential tool for monitoring damage during MRgHIFU in bone applications.

4048.   80 Clinical feasibility of motion compensation for MR-based thermometry for treatment in the head and neck region using magnetic resonance-guided focused ultrasound
Samuel Pichardo1,2, Justin Lee3, and Kullervo Hynynen4
1Thunder Bay Regional Research Institute, Thunder Bay, ON, Canada, 2Electrical Engineering & Physics, Lakehead University, Thunder Bay, Ontario, Canada, 3Odette Cancer Centre, Toronto, Ontario, Canada, 4Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada

We propose to use Magnetic resonance image (MRI) guided high intensity focused ultrasound (MRgHIFU) as an adjuvant therapy to radio-therapy for the treatment of recurrent head and neck tumours. A previous pre-clinical study using a porcine model showed the importance of artifacts in MR-based temperature calculation and a method was developed and tested to compensate this source of noise. This paper presents the first results of using this method in a clinic context with patients with primary cancer in the neck area.

4049.   81 The changes of uterine fibroidsprime or minute diffusion and perfusion status after MR-guided HIFU ablation evaluated from IVIM MR imaging with different b-values combination
Jia Liu1, Bilgin Keserci2, Juan Wei3, Queenie Chan4, Yu Zhang5, Rong Rong1, and Xiaoying Wang1
1Radiology, Peking University First Hospital, Beijing, Beijing, China, 2Philips Healthcare, Seoul, Korea, 3Philips Research China, Shanghai, China, 4Philips Healthcare, Hong Kong, China, 5Philips Healthcare, Beijing, China

Multiple b-values DWI scan was performed on all 23 patients before and 6 months after HIFU ablation of fibroids using 3.0 T MR acquisition systems. For all b-values no larger than 100 s/mm2 and 200 s/mm2, mono-exponential model was used to calculate the diffusion coefficient respectively. For all b-values, bi- exponential IVIM model was used to calculate D, D* and f. Fibroids diffusion increased apparently accompanied with less microcirculation perfusion 6 months after HIFU treatments. IVIM MR imaging may serve as a valuable tool in emphasizing such diffusion and perfusion changes by using all b-values and/or low b-values no larger than 100 s/mm2.

4050.   82 MRI Guided High Intensity Focused Ultrasound (HIFU) of Visceral Fat in Overweight Rats - permission withheld
Patrick Winter1, Matthew Lanier1, Ari Partanen2, and Charles Dumoulin1
1Radiology, Cincinnati Children’s Hospital, Cincinnati, OH, United States, 2Clinical Science MR Therapy, Philips Healthcare, Andover, MA, United States

MRI-guided HIFU (MR-HIFU) allows non-invasive ablation of deep tissues. MR-HIFU could be used to treat obesity and diabetes by heating body fat. Conventional MR thermometry methods cannot monitor temperature changes in fat. Instead, we used T2 mapping to evaluate the effects of HIFU on fat at 1.5T. Whole body heating experiments showed that fat T2 increased by 3.3 ms for every °C of heating. Immediately after HIFU, the T2 at the target increased by 17.7 ms, corresponding to 42.4 °C. A clear therapeutic effect was observed ten days after MR-HIFU, with rats losing 7.5 ± 1.2 % body weight.

Maythem Saeed1, Loi Do1, Mark W Wilson1, and Roland Krug1
1Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, Ca, United States

This swine study aimed to demonstrate the perfusion deficits, as an early indicator, of successful thermal MRg-HIFU ablation. Kidneys (n=12) were ablated after minimizing diaphragm motion using rocuronium injection and breath-hold. Saturation recovery-GRE was used after ablation to monitor regional perfusion in ablated, viable and aortic blood to obtain perfusion data. This study shows the potential of perfusion imaging as an early indicator of successful ablation. Thermal MRg-HIFU causes loss of vascular and cellular integrity. The severity of injury is dependent on the energy used. Thus, the used energy must be optimized in the kidney for future translation to clinic.

4052.   84 Localized hyperthermia in rodent models using a MRI-compatible high-intensity focused ultrasound system
Chenchen Bing1, Joris Nofiele1, Robert Staruch1,2, Yonatan Chatzinoff1, Michele Harbeson3, Danny Maples3, Jerry Malayer3, Samuel Pichardo4, Ashish Ranjan3, and Rajiv Chopra1
1Radiology, UT Southwestern Medical Center, Dallas, TX, United States, 2Clinical Sites Research Program, Philips Research North Amarica, Briarcliff Manor, NY, United States, 3Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, United States, 4Thunder Bay Regional Research Institute, Thunder Bay, ON, Canada

Temperature-sensitive drug carriers are able to induce a fast release of active drugs in the target region, which will solve the problem of causing systemic toxicity during traditional chemotherapy. An MRI-compatible high-intensity focused ultrasound (MR-HIFU) system was developed to perform localized hyperthermia in rodent models. This MR-HIFU system can conduct precise-controlled thermal therapies to allow heat-mediated drug delivery in small animal models. Feasibility and performance of the system is well evaluated with phantom and in-vivo experiment.

4053.   85 MR thermometry in in-vitro flows
Waltraud B. Buchenberg1, Florian Wassermann2, Sven Grundmann2, Bernd Jung3, and Robin Simpson1
1Dept. of Radiology, Medical Physics, University Medical Center Freiburg, Freiburg, Germany, 2Center of Smart Interfaces, Technische Universität Darmstadt, Darmstadt, Germany, 3Institute of Diagnostic, Interventional and Pediatric Radiology, University Hospital, Bern, Switzerland

There is a need in thermo-fluidic disciplines to measure temperature distributions in flowing liquids, for example to investigate heat transfer for performance improvement of devices. Although primarily used for medical applications, MR thermometry (MRT) has the potential to provide these measurements. This work applied MRT to investigate temperature distributions in a heat exchanger using different flow rates, demonstrating that MRT can provide high-quality 3D measurements of temperature fields in such setups. Collaboration with thermo-fluidic engineers can also benefit the medical community, for example through the investigation into MR compatible materials that could be used in medical devices.

4054.   86 A New Time Shifted Fast Spin Echo Thermometry Sequence
Yuval Zur1
1GE Healthcare, Tirat Carmel, Israel

MR guided Focused Ultrasound (MRgFUS) is used to treat noninvasively many brain disorders. Currently gradient echo (GRE) is used for thermometry imaging using the PRF shift. In this work we present a new thermometry sequence which is based on Fast Spin Echo. It is shown that this sequence is not sensitive to field inhomogeneity, provides higher temperature signal to noise ratio, and acquire 3 slices simultaneously during heating.

4055.   87 Proton Resonance Shift based Temperature Mapping with Field Monitoring
David O. Brunner1, Simon Gross1, Lars Kasper1, Bertram J. Wilm1,2, Christoph Barmet1,2, and Klaas P. Pruessmann1
1Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland, 2Skope Magnetic Resonance Technologies LLC, Zurich, Switzerland

Temperature mapping based on the temperature dependence of the chemical shift of water protons offers high sensitivity, however it is also subject to many confounds. Mainly drifts in the magnetic fields have to be corrected for in order to achieve high accuracy. Therefore field monitoring based on an array of 16 temperature stabilized NMR field probes is used to reconstruct phase based temperature maps for field drifts up to 3rd order in space. Sub-degree accuracy was achieved even in the presence of comparably strong dynamic field perturbation in-vitro in comparison to fluoroptic temperature reference probes.

4056.   88 T1-Based MR Thermometry Close to Metal
Hans Weber1, Daehyun Yoon1, Valentina Taviani1, Kim Butts Pauly1,2, and Brian A Hargreaves1
1Radiology, Stanford University, Stanford, California, United States, 2Bioengineering, Stanford University, Stanford, California, United States

Within this study, we propose a technique for MR thermometry close to metal. The technique utilizes a multispectral imaging approach and the temperature dependency of the T1 relaxation time. Within a phantom experiment, initial feasibility is demonstrated by tracking the T1 change close to a metal implant during heating.

4057.   89 Feasibility of Temperature Imaging of Knee Joint Cartilage under Thermal Therapy using Water Proton Resonance Frequency Shift
Atsushi Shiina1, Kenji Takahashi2, Jiro Nakano3, and Kagayaki Kuroda1
1Graduate School of Engineering, Tokai University, Hiratsuka, Kanagawa, Japan, 2Department of Orthopaedic Surgery, Nippon Medical School, Bunkyo, Tokyo, Japan, 3School of Information Science and Technology, Tokai University, Hiratsuka, Kanagawa, Japan

Feasibility of MR temperature imaging for joint cartilage using conventional water proton resonance frequency technique was demonstrated. Laser heating experiments with cartilage samples in vitro excised from porcine knee joints showed clear temperature elevation images of the thin cartilage region of 1-2 mm thickness. The temperature coefficient of the water proton resonance frequency was -0.0108 ppm/degree C. These results may be a first step to apply the noninvasive temperature imaging technique for thermally induced pain-relief for a patient with osteoarthritis.

4058.   90 Direct Virtual Coil (DVC) for bone tumor temperature mapping
Yuxin Hu1, Shuo Chen2, Bingyao Chen3, Jiafei Yang3, Xing Wei3, Shi Wang2, and Kui Ying2
1Tsinghua University, Beijing, Beijing, China, 2Engineering Physics, Tsinghua University, Beijing, China, 3Department of Orthopedics, First Affiliated Hospital of PLA General Hospital, Beijing, China

High speed and temperature accuracy are required in MR thermometry. While parallel imaging can speed up the acquisition, the corresponding reconstruction usually requires significant computation, especially when large coil arrays are used. This work evaluates the feasibility of direct virtual coil (DVC) for MR thermometry on bone tumor thermotherapy, in which parallel imaging and coil combination are combined into one step to reduce reconstruction time. It has been demonstrated that DVC can achieve similar temperature mapping accuracy compared to traditional parallel imaging method under different acceleration factors while it can be about twice faster.

91 Real-time online reconstruction of 3D MR thermometry data for MRgFUS applications
Henrik Odéen1,2, John Roberts1, Joshua de Bever1,3, and Dennis L Parker4
1Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, Utah, United States, 2Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah, United States, 3School of Computing, University of Utah, Salt Lake City, Utah, United States,4University of Utah, Salt Lake City, Utah, United States


4060.   92 Improving the referenceless MR thermometry using adaptive ROI
Changjun Tie1, Chao Zou1, and Xin Liu1
1Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China

Most referenceless MR thermometry methods use a large and fixed ROI to ensure to contain the whole heated region. However, the heated region is unknown and hard to estimate before heat occurs. The large ROI also compromises the accuracy in some measurements. This work proposes to use adaptive size of ROI for real-time referenceless thermometry. The size of ROI is decided by the size of heated region, which is measured from previous temperature map. The results would increase the accuracy of referenceless methods and improve the automation of referenceless thermometry for real-time monitoring.

4061.   93 Simultaneous T2 mapping in Near-Field Subcutaneous Fat Layer and PRFS Temperature Mapping in the Target Region using Fast Interleaved Sequences to Monitor MR-HIFU Sonication
Jochen Keupp1, Steffen Weiss1, Jaakko Tolo2, Holger Gruell3,4, and Edwin Heijman3
1Philips Research, Hamburg, Germany, 2Philips Healthcare, Helsinki, Finland, 3Philips Research, Eindhoven, Netherlands, 4Eindhoven University of Technology, Eindhoven, Netherlands

MR guided high-intensity focused ultrasound (MR-HIFU) is establishing as a new treatment option for various diseases that elegantly combines two non-invasive technologies. Near-field ultrasound heating of the skin and heat accumulation in the subcutaneous fat layer can become problematic due to the low thermal conductivity of fat. Currently, temperature mapping based on the proton resonance frequency shift (PRFS) is applied during clinical MR-HIFU treatment. However, reliable PRFS temperature maps can only be acquired in non-adipose tissue, while fat tissue requires different temperature mapping techniques like e.g. based on T2-mapping. Simultaneous temperature monitoring would be desirable in separate FOVs, like the adipose far field and non-adipose tumor regions. We here propose to use an acquisition technology which quickly interleaves a PRFS (gradient-echo) and a T2 (dual spin-echo) sequence on the level of individual repetitions with microsecond latency. Feasibility was demonstrated in a model setup using ablation conditions on a clinical MR-HIFU system.

4062.   94 Multivoxel Proton Magnetic Resonance Spectroscopy for Non-Invasive Thermometry: Improvements in Spectral Quality using semiLASER with GRE Shim - permission withheld
Candace C. Fleischer1,2, Deqiang Qiu3, Xiaodong Zhong4, Hui Mao3, John N. Oshinksi3, Xiaoping Hu1,2, and Seena Dehkharghani3
1Biomedical Imaging Technology Center, Emory University, Atlanta, GA, United States, 2Biomedical Engineering, Emory University, Atlanta, GA, United States, 3Radiology and Imaging Sciences, Emory University Hospital, Atlanta, GA, United States, 4MR R&D Collaborations, Siemens Healthcare, Atlanta, GA, United States

Current brain thermometry methods are costly and highly invasive. Chemical shift imaging (CSI) is a promising technique for non-invasive thermometry utilizing temperature-dependent chemical shift differences between water and N-acetylaspartate. The current standard using a PRESS sequence with automated shimming suffers from poor spatial resolution and chemical shift artifacts. We present a CSI protocol for thermometry with quantitative improvements to shimming and spectral quality in vitro and in vivo: a semiLASER spectroscopy sequence with GRE Shim. Combining the semiLASER advanced voxel localization with a more homogenous magnetic field from GRE Shim will be beneficial for thermometry and other applications of CSI.

4063.   95 Feasibility and Functionality of Quantitative Real-time Monitoring During MRI-guided Percutaneous Cryoablation
Jonathan Scalera1, Gary P. Zientara2, and Kumal Tuncali1
1Brigham and Women's Hospital, Boston, MA, United States, 2US Army Research Institute of Environmental Medicine, Natick, MA, United States

MRI-guided cryoablation is a minimally invasive treatment for renal cell carcinoma for eligible patients. Currently, intra-procedural monitoring of these procedures relies on a subjective assessment of tumor margins and proximity to critical structures by the interventionalist. Quantitative, computerized methods of monitoring and measuring ablation performance in real-time has the potential to improve the safety and success of these procedures. We developed an integrated, real-time intra-procedural monitoring software and determined its feasibility and functionality for cryoablation procedures.

4064.   96 MRI temperature mapping of NIR absorbing gold nanoparticles mediated photothermal therapy
Dong-Hyun Kim1,2, Ken Zhao1, Daniele Procissi1, Andrew Gordon1, Weiguo Li1, and Andrew C Larson1,2
1Department of Radiology, Northwestern University Feinberg School of Medicine, Chicago, IL, United States, 2R.H. Lurie Cancer Center, Chicago, IL, United States

Nanoparticles mediated photo thermal ablation and MR temperature mapping

Wednesday, 3 June 2015
Exhibition Hall 11:00 - 12:00

73 Benefits, Limitations, and Improving the Future of MRI-Guided Endovascular Catheter Tracking
Nicholas Whiting1, Jingzhe Hu1,2, and Pratip Bhattacharya1
1Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, United States, 2Department of Bioengineering, Rice University, Houston, TX, United States

While visualizing the movement of catheters during endovascular interventions is typically accomplished using x-ray fluoroscopy, there are many potential advantages to developing MRI-based approaches that will allow for three-dimensional imaging of the tissue/vasculature interface while monitoring other physiologically-relevant criteria, without exposing the patient or clinician team to potentially harmful ionizing radiation. In this educational session, we will discuss the various benefits and current limitations of MRI-guided catheter tracking, as well as open a dialogue as to how we can improve this technique and allow large-scale adoption of MRI-guided catheter tracking that may benefit patients and clinicians alike.

4138.   74 Interventional MRI-Guided Local Delivery of Agents into Swine Bile Duct Walls Using MR Compatible Needle-Integrated Balloon Catheter System
Feng Zhang1, Zhibin Bai1, Yaoping Shi1, Jianfeng Wang1, Longhua Qiu1, Yonggang Li1, and Xiaoming Yang1
1Radiology, University of Washington, SEATTLE, WA, United States

Systemic chemotherapy has limited therapeutic effect on pancreatobiliary cancers due to the insufficient drugs delivered to the tumors. To address this problem, we successfully developed a technique of using interventional magnetic resonance imaging (MRI) to guide intrabiliary agent delivery into pig common bile duct (CBD) walls with a newly-designed MR compatible needle-integrated balloon catheter system.

4139.   75 MR-Guided Treatment of Low-Flow Vascular Malformations
Clifford R. Weiss1, Daniel M. O'Mara2, Paul A. DiCamillo2, Di Xu3, Wesley D. Gilson4, Daniel A. Herzka3, and Jonathan S. Lewin2
1Vascular and Interventional Radiology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States, 2Department of Radiology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States, 3Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, United States, 4Siemens Healthcare USA, Baltimore, MD, United States

Low-flow vascular malformations (venous and lymphatic) are traditionally treated using ultrasound and fluoroscopy guided percutaneous sclerotherapy. However, certain lesions are particularly difficult to visualize and/or treat using these modalities. Real-time MR-guided intervention may serve as a safer alternative with better visualization of surrounding critical soft tissue structures and with less or no exposure to ionizing radiation. We present here our experiences with targeting and treating low-flow vascular malformations using real-time MR imaging.

4140.   76 MRI compatible-3D localization system for Real-Time catheter navigation
Olivia Garandeau1, Maxime Bories1, Fabrice Marquet1, Remi Dubois2, Pierre Jais3, and Bruno Quesson1
1IHU Liryc/CRCTB Inserm U1045, University of Bordeaux, Pessac, Aquitaine, France, 2IHU Liryc/CRCTB Inserm U1045, ESPCI Paris Tech, Pessac, Aquitaine, France, 3CHU bordeaux, Pessac, Aquitaine, France
Catheter exploration, key procedure for cardiac arrhythmia diagnosis and treatment, could benefit from MRI guidance and procedure monitoring. In this work, we present a homemade MR compatible 3D and real-time catheter navigation device based on electric field detection. The system was validated in vitro providing catheter positions with a maximum error of 5.5 mm at 25 frames per second. In vivo feasibility was also demonstrated in a swine model. Such work opens perspectives for catheter guidance and 3D slice tracking during MR exam enabling real-time visualization of the targeted area and respiratory motion correction.

4141.   77 In Vivo Assessment of Renal Artery Embolization Using a Magnetically Assisted Remote Controlled (MARC) Catheter
Prasheel Lillaney1, Aaron D Losey1, Alastair J Martin1, Bradford RH Thorne1, Leland B Evans1, Vincent Malba1, Maythem Saeed1, Ronald Arenson1, and Steven W Hetts1
1Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, United States

This study evaluates the in vivo performance of the magnetically assisted remote controlled (MARC) catheter in a renal embolization model using MR image guidance. The MARC catheter is navigated through the aorta and into the origin of the renal artery at which point embolic spheres (100 to 300 uM in size) are delivered through the catheter into the kidney. The intervention is repeated using X-ray guidance and performance parameters are compared between the two imaging modalities.

4142.   78 Imaging Assessment and Feasibility of a Hydrostatically Actuated Robotic System for Real-Time MRI-Guided Interventions
Samantha Mikaiel1,2, Rashid Yasin3, Samuel Ross4, M. Wasil Wahi-Anwar1, James Simonelli3, David Lu2, Kyung Sung1,2, Tsu-Chin Tsao3, and Holden H. Wu1,2
1Biomedical Physics, University of California Los Angeles, Los Angeles, CA, United States, 2Radiological Sciences, University of California Los Angeles, Los Angeles, CA, United States, 3Mechanical and Aerospace Engineering, University of California, Los Angeles, CA, United States, 4Santa Monica College, Santa Monica, CA, United States

In this work, we present a new robotic system prototype based on hydrostatic actuation that enables 3-degree-of-freedom (DOF) remote control of interventional devices inside the scanner bore under real-time MRI guidance. We observed negligible effects on MR image artifact, SNR, and distortion. We also demonstrated the feasibility of our new robotic system for 3-DOF control and to achieve needle placement within 1.6 mm of defined targets under real-time MRI guidance. Our new MRI-compatible robotic system can potentially provide physicians continuous access to patients during real-time MRI-guided interventions with improved visualization and accuracy.

4143.   79 Dynamic Scan Plane Control for Effective MRI-Guided Robotic Intervention
Mahamadou Diakite1, Steve Roys1, Yeongjin Kim2, Taehoon Shin1, Mark J Simard3, Jaydev P Desai2, and Rao P Gullapalli1
1Center for Metabolic Imaging and Therapeutics, Depart. of Diagnostic Radiology and Nuclear Medicine, University of Maryland, School of Medicine, Baltimore, MD, United States, 2Mechanical Engineering, University of Maryland, College Park, MD, United States, 3Neurosurgery, University of Maryland, School of Medicine, Baltimore, MD, United States

Real-time tracking and navigation is important for effective use of surgical robotic devices with multiple degrees-of-freedom, and especially ones that have multiple end effector functions including cauterization. The goal of this study is to develop a real-time MRI system for tracking and visualizing the interventional device using a passive magnetic sensor and a closed-loop control algorithm. Its technical feasibility is demonstrated on a phantom.

4144.   80 Tactics: An Open-Source Platform for Planning Stereotactic Surgery
D. Adair1,2, K. S. Gomes3, Y. P. Starreveld3,4, Z. H.T. Kiss3, and D. G. Gobbi1,4
1Calgary Image Processing and Analysis Centre, Calgary, Alberta, Canada, 2Biomedical Engineering, University of Calgary, Calgary, Alberta, Canada, 3Clinical Neuroscience and Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada, 4Atamai Inc., Calgary, Alberta, Canada

Framed stereotaxic surgery remains the most accurate and precise method for targeting deep-brain stimulation (DBS) but lacks effective planning software. We developed a novel tool (Tactics) for a clinical study on DBS in treating depression. Targeting was performed with both Tactics and a stereotactic frame and a mean software accuracy of 0.7 mm was calculated, demonstrating a high level of accuracy. The system is open-source and can be extended to include other functional and electrophysiological mapping data. Tactics has demonstrated to be both effective and intuitive and has been adopted by an ongoing clinical study as their standard tool.

4145.   81 MR Guided CED of a Novel Therapeutic for Parkinson’s Disease: The Importance of Imaging Feedback
Alastair J Martin1, Krystof Bankiewicz2, John Bringas2, Chad Christine3, Marin Thompson2, Janine Beyer2, and Paul Larson2
1Radiology and Biomedical Imaging, UCSF, San Francisco, CA, United States, 2Neurological Surgery, UCSF, San Francisco, CA, United States, 3Neurology, UCSF, San Francisco, CA, United States

MR guidance is used to monitor convection enhanced delivery of a novel gene therapy agent (AAV2-hAADC) in patients with Parkinson’s disease. The therapeutic is infused bilaterally into the putamen and targeting is performed with intra-operative MR guidance. Two infusions are performed in each putamen in order to maximize coverage of the anatomic structure. Continuous infusion monitoring with MR imaging revealed sub-optimal distributions such as reflux along the cannula tract and shunting along vascular channels. Detection of these effects permitted adjustments to infusion strategy, including changing cannula depth and aborting ineffective infusions.

82 Inducing magnetic torque inside an MRI scanner using pulsed magnetic gradients
Alexandre Bigot1, Maxime Latulippe1, Charles Tremblay1, and Sylvain Martel1
1Nanorobotics Laboratory, Polytechnique Montreal, Montreal, Quebec, Canada

Magnetic Resonance Imaging scanners have the potential to control endoscopic capsules for gastrointestinal (GI) examination. The correct imaging and detection of small abnormal tissues along the GI tract require fine adjustment of the capsule position and of the capsule angle. We therefore demonstrate that gradients can generate eddy currents in a small coil and therefore induce a torque on a small capsule. With time-varying magnetic field below stimulation levels, a 2.5-cm capsule rotates from 35° to 0° (aligned with B0) in less than 20 seconds. This work may open the way to the development of MR actuated endoscopic capsules.

4147.   83 Characterization of Thermochemical Ablation Injections using 23Na MRI - permission withheld
Florian Maier1, Erik N. K. Cressman2, Moritz C. Berger1, David Fuentes3, R. Jason Stafford3, Christopher J. MacLellan3, Reiner Umathum1, and Armin M. Nagel1
1Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany, 2Interventional Radiology, The University of Texas MD Anderson Cancer Center, Houston, TX, United States, 3Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, United States

Thermochemical ablation (TCA) provides a novel concept in minimally invasive ablative procedures in which two reactive solutions, such as acetic acid and sodium hydroxide, release heat as they react prior to entering the tissue as sodium acetate (NaOAc) solution. Besides thermal damage, additional damage is caused by the hyperosmolar environment after injection. In this work, 23Na MRI is used to image NaOAc distributions to provide more detailed insight for effective delivery. 23Na MRI of TCA injections will facilitate a platform for the design and optimization of applicators as well as development and validation of computational models, and progress towards clinical translation.

4148.   84 Multinuclear (19F + 1H) MRI at 3T using an internal probe
Shashank Sathyanarayana Hegde1, Li Pan2, Guan Wang1,3, Martin Radvany1, Yingli Fu1, and Dara L Kraitchman1
1Radiology, Johns Hopkins University, Baltimore, Maryland, United States, 2Siemens Healthcare, Baltimore, Maryland, United States, 3Electrical and Computer Engineering, Johns Hopkins University, Maryland, United States

We developed and characterized an internal probe at 3T designed for interchangeable 1H and 19F use. The internal probe demonstrated increased signal-to-noise ratio with respect to a conventional 19F surface coil for structures deeper than 2 cm from the surface. 19F imaging of ~7.5mL of a 10-fold dilution (e.g., 5 mg/ml) of fluorouracil (5-FU) was possible in 2 minutes. Multinuclear MRI of perfluorooctyl bromide (PFOB) microcapsules was performed in tissue samples ex vivo and a rabbit thigh in vivo. High-resolution (0.2 mm 1H and 0.8 mm 19F in-plane) MRI of PFOB capsules was possible and was concordant with cone beam computed tomography (CT) imaging of the radiopaque microcapsules.

4149.   85 Near Infrared Optical Tomography at MR resolution: Photo-magnetic Imaging
Alex Luk1, Yuting Lin2, David Thayer3, Seunghoon Ha4, and Gultekin Gulsen1
1UC Irvine, Irvine, California, United States, 2Harvard Medical School, Massachusetts, United States, 3UC Irvine Medical, Irvine, California, United States,4UC Irvine, Irvine, california, United States

Diffuse optical imaging is advantageous in enhancing tumor diagnosis by providing functional information but suffers from low resolution. We combined MR thermometry and diffuse optical tomography and built the first prototype photo magnetic imaging system. It provides in-vivo functional information with MR resolution and helps to monitor different optical contrast agents such as Indocyanine green. A finite element based forward simulation of the laser induced temperature change map has been compared with PMI measurements. The forward simulation accurately estimates the temperature tomography collected by MR thermometry. By solving the inverse problem with multiple wavelengths, we will be able to reconstruct MR resolution tomography of different chromophores concentrations.

4150.   86 3 Tesla MR-guided Scalene Muscle Injections in Patients with Neurogenic Thoracic Outlet Syndrome
Jan Fritz1, Margaret W Arnold2, Holly Grunebach2, Kendall Likes2, Jonathan S Lewin1, and Ying W Lum2
1Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States,2Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, United States

Neurogenic thoracic outlet syndrome is often caused by brachial plexus compression in the scalene triangle and costoclavicular space. As such, scalene muscles are the principle target for intramuscular diagnostic and therapeutic injections. MRI guidance offers cross-sectional imaging with high soft tissue contrast, absence of ionizing radiation, and the ability to visualize injectants without a contrast agent. We describe a technique of 3 Tesla MR-guided scalene muscle injections, which combines high accuracy, a favorable safety profile, the absence of ionizing radiation, and the ability to accurately visualize the injectant without the need of a contest agent.

4151.   87 Localization of an HDR brachytherapy source using MR artifact simulation and phase-only cross correlation
Ellis Beld1,2, Marinus A. Moerland1, Job G. Bouwman2, Frank Zijlstra2, Jan J.W. Lagendijk1, Max A. Viergever2, and Peter R. Seevinck2
1Department of Radiotherapy, University Medical Center Utrecht, Utrecht, Utrecht, Netherlands, 2Image Sciences Institute, University Medical Center Utrecht, Utrecht, Utrecht, Netherlands

Image guidance is of great importance in high-dose-rate (HDR) prostate brachytherapy. A robotic MR-guided HDR brachytherapy treatment is being developed and one of the aims is real-time tracking of the HDR source. In this study, localization of an HDR brachytherapy source was performed retrospectively, by simulating the artifact of the source in a gradient echo image and matching the simulated artifact to the experimental image by means of phase-only cross correlation. Furthermore, it was investigated to what extent the localization depends on the materials of the interventional devices.

4152.   88 Automatic Fiducial Detection in T2 Weighted MRI in a Manifold Learning and Gaussian Mixture Modeling Framework
S. Ghose1, J. Mitra1, D. Rivest Henault1, A. Fazlollahi1, P. Stanwell2, P. Greer3, P. Pichler3, J. Fripp1, and J. Dowling1
1Australian e-Health Research Centre, CSIRO Digital Productivity Flagship, Herston, QLD, Australia, 2University of Newcastle, NSW, Australia, 3Department of Radiation Oncology, Calvary Mater Newcastle Hospital, NSW, Australia

Gold seeds or fiducials implanted in the prostate prior to radiation treatment are frequently used to enable the rigid registration of the two modalities required for the transfer of the prostate contours from MRI to CT. An automatic efficient detection method for the fiducials from MRI is necessary to automate the procedure. This work proposes Gaussian mixture modeling (GMM) and spectral clustering based methods for fiducial candidate selection and a similarity score based fiducial detection. The proposed approach detects fiducials with an accuracy of 95% when compared to the manual detection.

4153.   89 Exploring the feasibility of the coherent half-FOV replication passive tracking technique for controllable susceptibility devices in the presence of motion
Justin Y.C. Lau1,2, Jennifer Barry2, and William Dominguez-Viqueira2
1Medical Biophysics, University of Toronto, Toronto, Ontario, Canada, 2Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada

The feasibility of locating a controllable device, with susceptibility effects that can be turned ON and OFF, in the presence of motion is examined in the common iliac artery of a porcine model. A 2D fast spoiled gradient echo sequence was modified with a phase-encoding scheme that acquires odd k-space lines first, followed by a pause to allow manual toggling of the susceptibility effect before the acquisition of even k-space lines. Despite severe motion artifacts, the device was located unambiguously in vivo. Further optimization of the sequence allowed in vitro location of both the device and a clinical balloon catheter in less than 5 seconds.

4154.   90 Real-time tracking for MR-guided breast biopsies: dream or reality? - permission withheld
Robert D Darrow1, Mark Schneider2, Eric W Fiveland1, Xiaofeng Liu1, and Ileana Hancu1
1Global Research Center, GE, Niskayuna, New York, United States, 2NDI Ascension, Shelburne, Vermont, United States

Many factors can contribute to an inaccurate MR-guided breast biopsy. The lack of real-time visualization of tool advancement towards the biopsy site increases the time to perform the biopsy, and likely contributes to the false negative rate. In this work, we have acquired preliminary evidence, indicating breast immobility during the procedure. Secondly, we have shown that electromagnetic (EM) tracking in the strong fringe field of 3T MRI magnets is feasible. Retrofitting breast biopsy tools with EM sensors could enable real time visualization of tool advancement towards the lesion, hence significantly increase the accuracy and decrease the time needed for breast biopsy procedures.

4155.   91 Impact of B1 field inhomogeneity on DESPOT-based T1 and T2 mapping at 1.5T
Yulia Shcherbakova1, Cornelis A.T. van den Berg1, Jan J.W. Lagendijk2, Chrit T.W. Moonen2, and Lambertus W. Bartels1
1Imaging Division, University Medical Center, Utrecht, Utrecht, Netherlands, 2Imaging Division, University Medical Center, Utrecht, Netherlands

Rapid quantitative imaging is very important for planning and guidance of MRI-guided oncological therapy. The normal liver tissue and metastases have different T1 and T2 relaxation times and their ratio T1/T2 , which makes these parameters relevant quantitative imaging biomarkers. Conventional T1 and T2 mapping techniques are relatively time-consuming, which has led to the development of promising rapid techniques, such as DESPOT1 and DESPOT2. However, in practice, even at 1.5T, electromagnetic fields are imperfect, which may influence the accuracy and precision of quantitative imaging techniques. In this study we have investigated the impact of B1 field inhomogeneity on the performance of 3D DESPOT1 and DESPOT2 methods and demonstrated that DESPOT1 method is sensitive to B1 field inhomogeneity, even at 1.5T. A 5% error in nominal flip angle significantly influences the calculated T1 value and leads to a 10% error in the observed T1 value. However, the T2 estimates are minimally affected, when T2 is calculated using non-B1 corrected T1 values. Thus, the influence of B1 deviations on T2 mapping is negligible, so, B1 field correction for T2 mapping based on DESPOT2 method, is not required.

4156.   92 Carbon fiber needle for MRI-guided radiofrequency ablation - permission withheld
Jijun Han1, Shuai Song1, and Bensheng Qiu1
1University of Science and Technology of China, Hefei, Anhui, China

Carbon fiber needle for MRI-guided radiofrequency ablation

4157.   93 Reducing Needle Induced Image Artifacts in Interventional MRI while Maintaining Soft Tissue Contrast - permission withheld
Thomas Boyd Martin1,2, Holden Wu1, Danny JJ. Wang3, and Kyung Sung2
1Biomedical Physics Interdepartmental Program, University of California Los Angeles, Los Angeles, California, United States, 2Radiological Sciences, University of California Los Angeles, Los Angeles, California, United States, 3Neurology, University of California Los Angeles, Los Angeles, California, United States

MRI has great potential to provide an improved ability 1) to track the needle position, 2) to distinguish diseased from healthy tissue and 3) to monitor treatment effect for image guidance procedures. Balanced-SSFP (bSSFP) offers good T2/T1 tissue contrast and is a fast imaging technique that minimizes patient motion, but severe needle induced banding artifacts are present. Gradient Spoiled (GRE) and RF-Spoiled Gradient-Echo (SPGR) sequences decrease needle-induced artifacts, but result in lower soft tissue contrast. This study demonstrates a special case of a GRE sequence, integrated-SSFP (iSSFP), that reduces needle induced banding artifacts from bSSFP, while maintaining similar T2/T1 contrast.

4158.   94 Susceptibility-Based Positive-Contrast MRI for Interventional Devices
Ying Dong1, Guoxi Xie2, and Jim Xiuquan Ji1
1Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX, United States, 2Paul C. Lauterbur Research Center for Biomedical Imaging, Chinese Academy of Sciences, Shenzhen, Guangdong, China

Interventional devices normally show as dark features (negative contrast) on MRI. Several methods have been proposed to generate positive-contrast device images in interventional MRI. These methods generally rely on the off-resonance effects due to the device’s high susceptibility, which highlight the surrounding areas instead of the devices themselves. Recently, we developed a novel method to generate positive contrast images of small devices such as brachytherapy seeds by direct susceptibility mapping. Technical advances of the method are reported here on imaging of medium/large devices such as biopsy needles on 3T systems.

4159.   95 Modulation of Magnetic Susceptibility Markers with Laser-induced Demagnetization of Nickel Nanoparticles
Hirad Karimi1,2, William Dominguez-Viqueira2, and Charles H Cunningham1,2
1Medical Biophysics, University of Toronto, Toronto, Ontario, Canada, 2Imaging Research, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada

Performing catheter and needle-based interventional procedures under MRI guidance remains a promising area, where the extra soft tissue contrast can be used to improve outcomes in certain procedures. Passive tracking with susceptibility effects offers an easy-to-make and cost efficient method for tracking interventional devices, however difficulty locating devices when they are out-of-slice, or in projection images, is a major drawback. Laser-induced demagnetization of metal films has been used in magneto-optic devices. In this abstract, the possibility of using laser-induced demagnetization to modulate the susceptibility artifact from Ni nanoparticles in MR-images was investigated, making the artifact “flicker” and enabling detection in projection images.

4160.   96 To Spoil or To Balance? A Comparison of the White Marker Phenomenon in Gradient Echo Pulse Sequences
Simon Reiß1, Axel Joachim Krafft1,2, Klaus Düring3, Constantin von zur Mühlen4, and Michael Bock1
1Radiology - Medical Physics, University Medical Center Freiburg, Freiburg, Germany, 2German Cancer Consortium (DKTK), Heidelberg, Germany, 3MaRVis Medical GmbH, Hannover, Germany, 4Department of Cardiology and Angiology I, University Heart Center Freiburg, Germany

The white marker phenomenon has been proposed for passive localization in MR-guided interventions. A positive contrast of interventional devices is generated by dephasing background signal while preserving signal in the proximity of the device by unbalanced gradient schemes, and has been implemented in FLASH and bSSFP sequences. In this work, we compare these sequences to optimize the white marker signal of small platinum markers and an MR-compatible guidewire. Our results indicate that the bSSFP sequence is optimally suited to generate high contrast even for small paramagnetic objects which could be used for the localization of vascular scaffolds.