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

Scientific Session • Thermometry & Thermotherapy

Monday 1 June 2015

Room 701 B

10:45 - 12:45


Allison H. Payne, Ph.D., Elena A. Kaye, Ph.D.

10:45 0035.   MRI-Guided Focal Laser Ablation for Localized Prostate Cancer: A Single Center Report on Technique and Intermediate-Term Outcomes
Sherif G Nour1,2, Tracy E Powell2,3, and Peter J Rossi4,5
1Radiology & Imaging Sciences, Emory University, Atlanta, GA, United States, 2Interventional MRI Program, Emory University, GA, United States,3Radiology & Imaging Sciences, Emory University, GA, United States, 4Radiation Oncology, Emory University, GA, United States, 5School of Medicine, Emory University, GA, United States

We report the technical aspects and outcome results of a minimally-invasive focal treatment using laser ablation under MRI guidance and monitoring to treat localized low-intermediate risk prostate cancer while preserving the rest of the gland. 14 treatment-naïve foci of localized prostate cancer were treated with MRI-guided and monitored focal laser ablation. The technique is feasible and well tolerated as an outpatient procedure. This small series indicates a promising efficacy for up to 24-month recurrence-free follow-up durations. Prospective assessment of safety and efficacy awaits further evaluation on a larger cohort of subjects.

10:57 0036.   Multi-parametric MRI Assessment of Tumor Response to High-Intensity Focused Ultrasound in a Rat Glioma Model
Yi Zhang1, Dong-Hoon Lee1, Kai Zhang1, Antonella Mangraviti2, Chen Yang1, Hye-Young Heo1, Betty Tyler2, Ari Partanen3, Keyvan Farahani1,4, Paul Bottomley1, Peter van Zijl1,5, and Jinyuan Zhou1,5
1Division of MR Research, Department of Radiolgoy, Johns Hopkins University, Baltimore, Maryland, United States, 2Department of Neurosurgery, Johns Hopkins University, Baltimore, Maryland, United States, 3Clinical Science MR Therapy, Philips Healthcare, Andover, Massachusetts, United States,4National Cancer Institue, Bethesda, Maryland, United States, 5F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, United States

MRI-guided HIFU is a promising non-invasive therapy for treating tumors. Amide proton transfer-weighted (APTw) imaging is an emerging MRI technique that is sensitive to changes in tissue protein and peptide levels and molecular exchange properties. Here, APTw imaging is used to assess the effects of HIFU treatment effects in a longitudinal rat brain tumor model up to 6 days post-treatment. APTw measurements are compared with conventional MRI indices–relaxation times, diffusion, perfusion and the magnetization transfer ratio. The results suggest that APTw–MRI may detect treatment changes earlier than other MRI metrics.

11:09 0037.   MR-Guided Blood-Brain Barrier Disruption by Transcranial Focused Ultrasound: Preclinical Testing on a Trans-Human Skull Pig Model
Yuexi Huang1, Ryan Alkins1, Michael L. Schwartz2, and Kullervo Hynynen1,3
1Sunnybrook Research Institute, Toronto, ON, Canada, 2Division of Neurosurgery, Sunnybrook Health Sciences Centre, Toronto, ON, Canada,3Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada

Magnetic resonance-guided focused ultrasound has been demonstrated to reversibly disrupt the blood-brain barrier for targeted drug delivery. Many small and large animal models have been developed to investigate the effectiveness and characteristics of BBB disruptions. However, in translation for a clinical trial, the treatment protocol needs to be optimized according to properties of human skulls and capabilities of the current clinical prototype device. In addition, a cavitation-based safety mechanism needs to be tested in vivo for minimizing risks of hemorrhage. In this study, a BBB disruption protocol was developed in a trans-human skull pig model with human applications in mind. The trans-human skull pig model demonstrated the feasibility and safety of the ExAblate system for BBB disruptions in preparation for human applications.

11:21 0038.   
Respiration Artifact Correction in PRF MR Thermometry using Phase Navigators
Bryant T. Svedin1,2, Allison Payne1,3, and Dennis L Parker1,4
1Utah Center for Advanced Imaging Research, Salt Lake City, Utah, United States, 2Physics, University of Utah, Salt Lake City, Utah, United States,3Mechanical Engineering, University of Utah, Salt Lake City, Utah, United States, 4Radiology, University of Utah, Salt Lake City, Utah, United States

Respiration induced resonance offsets cause artifacts when imaging the breast. These artifacts lead to erroneous PRF temperature measurements. A phase correction method is applied to k-Space data to correct the respiration induced artifacts and improves accuracy of PRF temperature measurements while allowing free breathing of the patient, and without the need to have a multibaseline library. Two FID within-sequence phase correction navigators are collected and used to estimate the slope of the phase offset (radians/ms) during each TR. The phase of the k-Space lines acquired each TR is adjusted by the slope during that TR times TE.

11:33 0039.   
White-Matter-Nulled MP-RAGE Permits Patient-Specific Tracking of Focused Ultrasound Thalamic Ablation for Essential Tremor
Jason Su1, Thomas Tourdias2, Manojkumar Saranathan3, Casey Halpern4, Kim Butts-Pauly3, Jaimie Henderson4, Pejman Ghanouni3, and Brian K. Rutt3
1Electrical Engineering, Stanford University, Stanford, California, United States, 2Neuroradiology, Bordeaux University Hospital, Bordeaux, France,3Neuroradiology, Stanford University, Stanford, California, United States, 4Neurosurgery, Stanford University, Stanford, California, United States

The treatment of 7 essential tremor patients with MR guided focused ultrasound (MRgFUS) ablation of the ventral intermediate nucleus (Vim) in the thalamus was visualized with the white matter nulled MP-RAGE contrast (WMnMPRAGE). Manual segmentation of thalamic nuclei was performed on 7T scans, then registered to post-treatment 3T images. Overlays were produced showing the ablation zone and its position within the nucleus of interest. The ablation zone was revealed to be consistently between the center and inferior edge of Vim, within 1-2mm of the inferior edge. The consistent location demonstrated the functional validity of our thalamic imaging and segmentation methodology.

11:45 0040.   
Screen Printed HIFU Compatible Receive Coil
Joseph Russell Corea1, Patrick Ye2, Anita Flynn1, Kim Butts-Pauly2, Ana Claudia Arias1, and Michael Lustig1
1University of California Berkeley, Berkeley, California, United States, 2Radiology, Stanford, Stanford, California, United States

Taking advantage of recent advances in printed electronics, we created a flexible receive coil that is nearly transparent to High Intensity Focused Ultrasound (HIFU) energy. We fabricated the coil from solution using screen-printing, a high volume manufacturing technique. We discuss the performance of the coil and compare the printed components to traditional components with various imaging and acoustic power attenuation testing. We also demonstrate major steps toward clinical usability with the first phantom images - showing promise for use in MR guided HIFU therapy.

11:57 0041.   Hybrid MR/US-guided HIFU for abdominal targets: in vivo demonstration of 3D motion correction and focal point locking on an absolute reference marker - permission withheld
Lorena Petrusca1, Gibran Manasseh2, Zarko Celicanin3, Romain Breguet4, Oliver Bieri3, Vincent Auboiroux5, Christoph D Becker4, Sylvain Terraz4, and Rares V. Salomir6
1University of Geneva, Geneva, Geneva, Switzerland, 2Radiology, University Hospitals of Geneva, Geneva, Switzerland, 3University Hospital Basel, Basel, Switzerland, 4University Hospitals of Geneva, Geneva, Switzerland, 5LETI CEA, Grenoble, France, France, 6Radiology, University Hospitals of Geneva, Geneva, Geneva, Switzerland

Treatments using high-intensity focused ultrasound (HIFU) in the abdominal region remain challenging due to respiratory organ motion. Various methods have been attempted in the past to achieve motion-compensated HIFU therapy, using ultrasound (US) imaging, magnetic resonance imaging (MRI), or both simultaneously. Here, a truly hybrid US-MRI guided HIFU (US-MRgHIFU) method was used to plan and control the treatment in vivo. 3D prospective motion correction was implemented at a frame rate of 15Hz on pig liver and kidney. An absolute target was used to demonstrate the spatial accuracy of the method, which was found to be in the sub-millimeter range.

12:09 0042.   Motion correction strategies for cardiac MR thermometry during RF-ablation.
Valéry Ozenne1, Solenn Toupin1,2, Baudouin Denis de Senneville3, Pierre Bour1, Fanny Vaillant1, Matthieu Lepetit-Coiffé2, Pierre Jaïs1, and Bruno Quesson1
1L'Institut de Rythmologie et Modélisation Cardiaque, Bordeaux, France, 2SIEMENS Healthcare, Saint Denis, France, 3IMB, UMR 5251 CNRS/University of Bordeaux, Bordeaux, France

Performing magnetic resonance thermometry during cardiac radiofrequency ablation (RFA) requires dealing with motion and susceptibility artifacts due to cardiac and respiratory motion. In this study, the suitability of three in-line thermometry processing methods was evaluated in vivo on the heart of ten healthy volunteers under free breathing conditions. We demonstrated that the temporal temperature standard deviation was minimized with Principal Component Analysis (PCA) based method: 2.2°C instead of 2.7°C with state-of-the-art multi-baseline method. This approach offers robust motion estimation in regions prone to local signal variations on magnitude images during RFA performed on ex-vivo working pig heart.

12:21 0043.   
Model-Based Multi-Echo Water/Fat-Separated MR Thermometry
Megan E Poorman1,2, Chris J Diederich3, Graham Sommer4, Kim Butts Pauly4, and William A Grissom1,2
1Biomedical Engineering, Vanderbilt University, Nashville, TN, United States, 2Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States, 3Radiation Oncology, University of California, San Francisco, CA, United States, 4Radiology, Stanford University, Stanford, CA, United States

A model-based technique is proposed for water/fat-separated multi-echo PRF-shift MR thermometry that leverages recent advancements in water/fat separation to achieve high-quality signal separations while maintaining real-time-compatible compute times. The method is validated in simulations and compared to 3-point Dixon-based temperature maps in canine prostate temperature maps during a transurethral focused ultrasound ablation.

12:33 0044.   
Interventional Magnetic Resonance Elastography for MRI-guided percutaneous procedures.
Nadège Corbin1, Jonathan Vappou1, Elodie Breton1, Quentin Boehler1, Laurent Barbé1, Pierre Renaud1, and Michel de Mathelin1
1ICube, Université de Strasbourg, CNRS, IHU Strasbourg, Strasbourg, France

Monitoring thermal therapies is essential to ensure precise and complete ablation of diseased tissues. Since tissue elasticity is modified by thermal ablation, this work aims at developing interventional magnetic resonance elastography (MRE) dedicated to the monitoring of percutaneous thermal ablations. A piezoelectric needle MRE driver is triggered on a fast interactive MR-pulse sequence with motion encoding. An inverse problem solver provides elastograms in real-time using an optimized number of phase-offsets and a sliding window scheme. In vivo feasibility was established in swine liver, and feasibility to monitor elasticity changes in real-time (every 2.56s) was demonstrated in a gelifying phantom.