Traditional Posters: Interventional - ismrm

1825. Modified Balanced SSFP Sequence for Better Temperature Sensitivity
Mahamadou Diakite 1 , Nick Todd 1 , Dennis L. Parker 2
1 Physics, University of Utah, Salt lake, UT, United States; 2 Radiology, Utah Center for Advanced Imaging
Research (UCAIR), Salt lake, UT, United States
Safety and efficacy of tumor treatment using high intensity focus ultrasound requires accurate temperature measurement throughout
the thermal procedure. In this work, we investigate how the noise in temperature measurements can be reduced by variations to this
new ub-SSFP sequence.
1826. Hyperthermia Induced Gadodiamide Release from Thermosensitive Liposomes in
Solid Tumors and Muscle Tissue
Michael Peller 1 , Martin Hossann 2 , Tungte Wang 2,3 , Steven Sourbron 1 , Lars H. Lindner 2,3
1 Institute of Clinical Radiology, University Hospital of Munich, Munich, Germany; 2 Department of Internal
Medicine III, University Hospital Munich; 3 CCG-Hyperthermia, Helmholtz Zentrum München, German
Research Center for Environmental Health, Germany
Purpose was to investigate the dynamics of mild temperature induced contrast agent release from phosphatidylglyc-eroglycerol
containing thermosensitive liposomes with encapsulated Gd-DTPA-BMA (Gd-TSL) in tumor tissue. Tumor bearing mice were
investigated at 1.5T after intravenous injection. The temperature induced release of contrast agent at 42°C caused a fast and strong
increase of T1-weighted signal. Immediately after i.v. injection heated tumor tissue was distinguishable from unheated tumor and
muscle tissue. Unheated muscle tissue may thus be less affected by a potential anti tumor therapy based on TSL.
1827. MRgRFA: Physical Model and First Order Correction of PRFS Thermometry
Corrupted by Magnetic Susceptibility-Mediated Cavitation’s Effects
Rares Salomir 1 , Magalie Viallon 1 , Sylvain Terraz 1 , Christoph D Becker 1
1 Radiologie, Hopital Universitaire de Genève, Geneva, Switzerland
MR thermometry based on the proton resonance frequency (PRF) method (1) has gained good acceptance for guiding RF ablation of
liver tumors (2). Major artifacts in the PRFS thermometry have recently been reported related to per-operatory changes of the tissue
bulk susceptibility during RF heating (3). They are originating from gas bubbles formation, known as white cavitations’ artifacts in
US imaging. We propose here a theoretical description of the effects and a first order correction that confirm the source of the
spatially related errors in temperature maps and TD during power application.
1828. MR Thermometry in Moving Objects Using a Novel Referenceless and User-
Independent Approach
Bruno Madore 1 , Renxin Chu 1 , Chang-Sheng Mei 1,2 , Lawrence P. Panych 1
1 Radiology Department, Brigham and Women's Hospital, Harvard Medical School , Boston, MA, United States;
2 Department of Physics, Boston College, Chestnut Hill, MA, United States
MR thermometry in moving organs is a challenging application, as fairly subtle temperature-induced changes must be accurately
measured in the presence of often much larger motion-induced changes. A novel approach at doing so is proposed here, which is both
referenceless (does not require a baseline reference image) and user-independent.
1829. Air Susceptibility Effects on Proton Resonance Frequency Temperature Mapping
Markus Nikola Streicher 1 , Andreas Schäfer 1 , Dimo Ivanov 1 , Robert Turner 1
1 Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
MR thermometry is usually based on the temperature dependence of the proton resonance frequency (PRF), thus any magnetic field
changes might be misinterpreted as temperature changes. Here we report on the effects of changes of susceptibility of surrounding air
on the magnetic field inside an object. When the air was heated by 46 ºC, its susceptibility changed from χ air = 3.6×10 -7 to χ air =
2.7×10 -7 , inducing an apparent additional temperature change of 1.9°C inside the object. For a more realistic surrounding air
temperature increase of 10°C this could result in an error of 0.75°C.
1830. Real-Time MR-Thermometry and Dosimetry for Interventional Guidance on
Abdominal Organs
Sébastien Roujol 1,2 , Mario Ries 1 , Bruno Quesson 1 , Chrit Moonen 1 , Baudouin Denis de
Senneville 1
1 laboratory for molecular and functional imaging: from physiology to therapy, CNRS/ University Bordeaux 2,
Bordeaux, Aquitaine, France; 2 LaBRI, University Bordeaux 1, Talence, Aquitaine, France
A computationally efficient pipeline for 2D motion compensated PRF-thermometry and thermal dose measurements on moving
abdominal organs is presented. The method is designed to address both, inter-scan and intra-scan artifacts by applying high frame-rate
MRI coupled with a real-time image processing. The proposed MR-thermometry method was evaluated in both liver and kidney of 11
healthy volunteers and achieved a precision of less than 2 °C in 70 % of the pixels. The ability to perform MR-Thermometry and
Dosimetry in-vivo was demonstrated on one HIFU-heating experiment on a porcine kidney.