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

Scientific Session • MR-Guided Interventions

Thursday 4 June 2015

Room 701 B

13:30 - 15:30


Charles L. Dumoulin, Ph.D., Bruno Quesson, Ph.D.

13:30 0863.   Speeding-up MR acquisitions using ultrasound signals, and scanner-less real-time MR imaging
Frank Preiswerk1, W. Scott Hoge1, Matthew Toews1, Jr-yuan George Chiou1, Laurent Chauvin1, Lawrence P. Panych1, and Bruno Madore1
1Department of Radiology, Harvard Medical School, Brigham and Women's Hospital, Boston, MA, United States

Imaging respiratory motion in the abdomen using MR is a challenge because of the limited speed of subsequent MR acquisitions. We developed a hybrid MR-US setup that exploits the very high acquisition rates of a 1d ultrasound probe for boosting the temporal resolution of MR image sequences. The 1d ultrasound data provides a fingerprint of the complex abdominal configuration at any respiratory state. Previously-acquired MR data are combined based on these fingerprints to produce a high-speed image sequence. The system even allows to continue "acquiring" MR images outside the scanner, based solely on the US signal.

13:42 0864.   
Pushing X-ray CT out of the equation: In vivo RASOR MRI-based seed detection for post-implant dosimetry in LDR prostate - permission withheld
Peter Roland Seevinck1, Cornelis A van den Berg2, Frank Zijlstra1, Marielle E Philippens2, Stan Jelle Hoogcarspel2, Jan J Lagendijk2, Maximus A Viergever1, and Marinus Adriaan Moerland2
1Image Sciences Institute, University Medical Center Utrecht, Utrecht, Netherlands, 2Department of Radiotherapy, University Medical Center Utrecht, Netherlands

This study demonstrates the feasibility of in vivo MRI-based localisation of implanted brachytherapy seeds with positive contrast and high specificity, using a robust, clinically available imaging sequence with RASOR reconstruction and straightforward post-processing. This approach may enable MRI-only postimplant dosimetry, preventing the need for CT-based seed detection and image fusion and all related disadvantages, including radiation exposure, registration errors and additional costs. Interestingly, the optimized RASOR sequence facilitates visualisation of bone structures. As a consequence other applications of the proposed technique may be bone and fiducial imaging for MRI-based treatment planning in external beam radiotherapy and attenuation correction in PET-MRI.

13:54 0865.   Improved cortical bone segmentation using a spectral-spatial selective pulse to reduce water/fat in-phase echo time
Matteo Maspero1, Peter R. Seevinck2, Anna Andreychenko1, Sjoerd Crijns1, Alessandro Sbrizzi3, Max Viergever2, Jan J. W. Lagendijk1, and Cornelis A. T. van Den Berg1
1Radiotherapy, UMC Utrecht, Utrecht, Utrecht, Netherlands, 2Image Sciences Institute, UMC Utrecht, Utrecht, Utrecht, Netherlands, 3Radiology, UMC Utrecht, Utrecht, Utrecht, Netherlands

This paper purposes an automatic method for bone segmentation in the pelvic region based on in-phase and out-of-phase images acquired on a reduced TE through the use of a custom designed spectral-spatial selective excitation pulse. A segmentation bone mask is obtained through a k-mean algorithm and compared with a similar mask calculated on reference in-phase and out-of-phase images. The suggested method shows an improvement in the false positive reduction in the bowel area compared to the reference bone mask and is eligible to produce good Digitally Reconstructed Radiography.

14:06 0866.   Synthetic CT generation from T2 weighted MRI using a hybrid regression and multi-atlas approach
S. Ghose1, D. Rivest Henault1, J. Mitra1, J. Sun2, P. Pichler3, P. Greer3, and J. Dowling4
1Australian e-Health Research Centre, CSIRO Digital Productivity Flagship, Herston, QLD, Australia, 2University of Newcastle, NSW, Australia, 3Department of Radiation Oncology, University of Newcastle, NSW, Australia, 4Australian e-Health Research Centre, CSIRO Digital Productivity Flagship, QLD, Australia

In this work, we propose to use a hybrid atlas and regression-based method to generate synthetic CT images from MRI for MRI based radiation therapy planning for prostate cancer treatment. Compared to a pure regression-based method, an additional UTE sequence is not required to segment the bone, and in comparison to a pure atlas-based method, we use regression-based soft tissue modeling, producing better soft tissue estimation. The proposed hybrid approach achieves a 0.6% dose difference compared to the use of original CT in the dose plan.

14:18 0867.   
Integration of Active MR Tracking into Adaptive Radiation Therapy Treatment Planning
Wei Wang1,2, Akila N Viswanathan2, Antonio L Damato2, Zion T Tse3, Yue Chen3, Ravi T Seethamraju4, Clare M Tempany1, Robert A Cormack2, and Ehud J Schmidt1
1Radiology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, United States, 2Radiation Oncology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, United States, 3The University of Georgia, GA, United States, 4MR R&D, Siemens Healthcare, MA, United States

In interstitial brachytherapy, catheters are normally inserted into the tumor under MRI guidance. Due to the inaccuracy of MRI catheter visualization, CT is required after placement to localize catheters for treatment planning. We propose an adaptive radiation treatment planning process based entirely on MRI, using catheter trajectories generated by an active MR-tracking system specifically developed for fast and accurate localization of metallic catheters. This provides intra-operative dosimetric feedback to clinicians during catheter implantation, which allows for adaptive repositioning or addition of catheters. It will improve tumor coverage, reduce toxicity to normal tissues and potentially eliminate the need for subsequent CT.

14:30 0868.   Two-channel visualization of a passive nitinol guidewire with iron oxide maker created from a single image acquisition
Adrienne E Campbell-Washburn1, Burcu Basar1,2, Toby Rogers1, Merdim Sonmez1, Ozgur Kocaturk1,2, Robert J Lederman1, Michael S Hansen1, and Anthony Z Faranesh1
1Cardiovascular and Pulmonary Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD, United States, 2Institute of Biomedical Engineering, Bogazici University, Istanbul, Turkey

MRI-guided procedures rely on the accurate visualization of devices. Here, a method was developed to isolate distinct signatures of the tip and the shaft of a passive nitinol guidewire with an iron oxide marker. A single spiral image was acquired, and reconstructed three times at three different frequencies (on-resonance and ±100Hz off-resonance). The characteristic dark-bright-dark pattern generated from magnitude image subtraction was used to isolate the iron oxide marker and the nitinol guidwire shaft was isolated from complex image subtraction. The tip and shaft are overlaid as two separate color channels on an anatomical image to assist procedural guidance.

14:42 0869.   Real-time MRI Guided Cardiac Cryo-ablation
Eugene G. Kholmovski1,2, Ravi Ranjan2, Nicolas Coulombe3, Joshua Silvernagel2, and Nassir F. Marrouche2
1UCAIR, Department of Radiology, University of Utah, Salt Lake City, Utah, United States, 2CARMA Center, University of Utah, Salt Lake City, Utah, United States, 3Medtronic CryoCath, Montreal, Quebec, Canada

Cardiac cryo-ablation is being increasingly used for treatment of atrial fibrillation and ventricular tachycardia. However, reported success rate of the procedures is moderate and serious complications have been observed. MRI has a potential to improve success rate of cardiac cryo-ablations and reduce complications. In this study, feasibility of real-time MRI guided cardiac cryo-ablation procedure was studied.

14:54 0870.   Visualization of porcine gastric ulcer in vivo using intracavitary RF probe and its navigation system
Yuichiro Matsuoka1,2, Yoshinori Morita3, Yoshiki Hashioka4, Etsuko Kumamoto5, Hiromu Kutsumi2, Takeshi Azuma2, and Kagayaki Kuroda6
1Center for Information and Neural Networks, National Institute of Information and Communications Technology, Suita, Japan, 2Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan, 3Department of Gastroenterology, Kobe University School of Medicine, Kobe, Japan,4Faculty of Engineering, Kobe University, Kobe, Japan, 5Information Science and Technology Center, Kobe University, Kobe, Japan, 6School of Information Science and Technology, Tokai University, Hiratsuka, Japan

An integrated MR-endoscope system that provides high quality MR images with an endoscopic view and information of the scope location has been developed to improve the accuracy and safety of endoscopy and endoscopic surgeries. To examine the feasibility of this system, the MR imaging of a gastric ulcer in animal experiments was conducted in vivo. Using an intra-cavitary RF coil for 1.5T-MRI with navigation, the gastric ulcer region was visualized in T1- and T2-weighted images with sufficient SNR and CNR. These MR images could correspond to a histological specimen of ulcer region. Therefore, the feasibility of this system was demonstrated.

15:06 0871.   
Minimally Invasive Magnetic Resonance Imaging-Guided Delivery of Neural Stem Cells into the Porcine Spinal Cord
Jason J Lamanna1,2, Lindsey N Urquia1, Carl V Hurtig1, Juanmarco Gutierrez1, Cody Anderson3, Pete Piferi4, Thais Federici1, Nicholas M Boulis1,2, and John N Oshinski2,5
1Neurosurgery, Emory University, Atlanta, GA, United States, 2Biomedical Engineering, Emory University & Georgia Institute of Technology, Atlanta, GA, United States, 3Physics, Emory University, Atlanta, GA, United States, 4MRI Interventions, Inc., Memphis, TN, United States, 5Radiology, Emory University, Atlanta, GA, United States

Transplantation of cellular therapeutics to the spinal cord is conventionally done with either systemic administration, or local injection following surgical exposure of the spinal cord. For intraparenchymal transplantation, targeting to the spinal cord is based on a combination pre-operative MRI measurements and anatomical landmarks. Our group developed an MR-compatible spinal cord injection system capable of replacing invasive surgical procedures. Here we present the proof-of-principle for percutaneous, intraparenchymal transplantation of stem cells into the spinal cord of a live Gottingen minipig under MRI guidance.

15:18 0872.   Wide-Bore MRI Guided DBS Surgery: Initial Experience
Karl K Vigen1, Deborah Rusy2, Laura Buyan-Dent3, Nancy L Ninman3, and Karl A Sillay4,5
1Radiology, University of Wisconsin-Madison, Madison, WI, United States, 2Anesthesiology, University of Wisconsin-Madison, Madison, WI, United States,3Neurology, University of Wisconsin-Madison, Madison, WI, United States, 4Semmes-Murphy Neurologic and Spine Institute, Memphis, TN, United States,5Neurosurgery and Electrical Engineering & Computer Science, University of Tennessee, Memphis, TN, United States

MRI-guided surgery for deep-brain stimulator (DBS) placement has emerged as a promising alternative for conventional awake DBS surgery. We report initial experience and the targeting accuracy of the procedure in an initial cohort of patients using a 70-cm bore MRI system in a purposely designed MR-OR suite.