ELECTRONIC POSTER - ismrm

14:30 4144. TMAP @ IFE - A Framework for Guiding and Monitoring Thermal Ablations
Eva Rothgang 1,2 , Wesley David Gilson 2 , Joerg Roland 3 , Joachim Hornegger 1 , Christine
H. Lorenz 2
1 Pattern Recognition Lab, Department of Computer Science, University of Erlangen-Nuremberg, Erlangen,
Germany; 2 Center for Applied Medical Imaging, Siemens Corporation, Corporate Research, Baltimore, MD,
United States; 3 Siemens Healthcare, Erlangen, Germany
Thermal ablations are increasingly used for minimally invasive local treatment of solid malignancies, supplementing systemic
treatment strategies such as chemotherapy and immunotherapy. We present an intuitive application for monitoring thermal treatment
independent of heating source, in real-time, with multiplanar MRI. Systematic quality control of thermal maps is carried out on-line to
ensure reliability of the displayed thermal data. The application is fully integrated into the Interactive Front End (IFE) which allows
real-time MRI-guided placement of the heating device. Thus, the presented application supports the thermal ablation workflow from
placing the ablation device to online monitoring the progress of ablation.
15:00 4145. Imitation of Radiofrequency Ablation Scars with Laser System for MR Guided
Ablation of Atrial Fibrillation
Can Kerse 1,2 , Bulent Oktem 3 , Fatih Omer Ilday 4 , Ergin Atalar, 2,5
1 Department of Electrical and Electronics Engineering , Bilkent University, Ankara, Turkey; 2 UMRAM
(National Research Center for Magnetic Resonance), Ankara, Turkey; 3 Material Science and Nanotechnology
Graduate Program, Bilkent University, Ankara, Turkey; 4 Physics Department, Bilkent University, Ankara,
Turkey; 5 Department of Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey
Fiber delivery of laser energy has no MR compatibility issues and is used with MR guidance in the field. But, it is not widely used as
the cure of Atrial Fibrillation, since there is risk of perforating the myocardial wall. Several diffusing tip designs to emit light in
cylindrical symmetry exist, but, due to their orientation with respect to the cardiac chamber, common RF delivery methods cannot be
applied directly. In our study, we propose a novel multiple fiber laser energy delivery with catheter approach and a system that
imitates the scars created with RF probes under MR guidance.
Thursday 13:30-15:30 Computer 65
13:30 4146. Feasibility of Multipolar Radiofrequency Ablation in the Pig Liver Under
Simultaneous Real-Time MR Thermometry
Matthieu Lepetit-Coiffe 1 , Alexandru Cernicanu 2 , Olivier Seror, 1,3 , Thomas Stein 4 ,
Yasmina Berber 1 , Mario Ries 1 , Chrit T. Moonen 1 , Bruno Quesson 1
1 Laboratoire IMF CNRS UMR 5231 / Universite Bordeaux 2, Bordeaux, France; 2 Philips Healthcare, Suresnes,
France; 3 Service de Radiologie, Hopital Jean Verdier, Bondy, France; 4 Celon/Olympus, Teltow, Germany
The feasibility of real-time MR thermometry for monitoring multipolar RF ablation was demonstrated both ex vivo and in vivo on a
pig liver. The quality of the real-time thermal dose maps appeared satisfactory in the presence of respiratory motion and cyclic
switching between the different pairs of RF electrodes. The large (about 250 cm3) resulting thermal coagulation volume was spatially
homogeneous as predicted by the real-time lethal thermal dose maps and confirmed by the post procedural MR imaging and histology.
14:00 4147. Breath Hold Phase Correction for Water-Fat Separated MR Thermometry Using
B0 Field Changes
Cory Robert Wyatt 1 , Brian J. Soher 2 , James R. MacFall 2
1 Department of Biomedical Engineering, Duke University, Durham, NC, United States; 2 Department of
Radiology, Duke University Medical Center, Durham, NC, United States
Proton resonance frequency shift (PRFS) thermometry of the breast is often confounded not only by the presence of fat in the tissue
but also by respiration-induced B0 changes even in the absence of detectable breast motion. In this work, field fitting techniques used
previously are used to extrapolate fat referenced B0 changes measured using fat-water separation methods to B0 changes in a wateronly
simulated tumor in a fat-water breast phantom. Results show that the B0 map extrapolation method reduces PRFS temperature
errors between breath holds from a maximum of 5.55°C to less than 0.53°C.
14:30 4148. Real-Time Non Subtraction Thermometry Using Artificial Neural Networks
Manivannan Jayapalan 1
1 MR SW & Applications Engg, GE Healthcare, Bangalore, Karnataka, India
Thermal monitoring in focused ultrasound applications is crucial step where MR is most widely used as it provides better thermal
monitoring capability than others. Regular PRF shift technique involves, some form of image subtraction using a baseline pretreatment
images. Subject motion and tissue deformation due to coagulation can severely distort these techniques. Self-referenced
methods require a large area of tissue around the ablation for polynomial fitting and can’t be used when tissue cooling is applied to
sensitive structures. Here a new method of thermal monitoring using Radial Basis Function Neural Network (RBFNN) trained by
orthogonal least square algorithm is proposed. This method eliminates the need for baseline subtraction and also tolerates subject
motion to a great extent. A feed forward, radial basis neural network is used with 2 input, 1 output and a hidden layer where the
number of units in that layer is obtained using orthogonal least square algorithm learning method. Gaussian function is used as kernel
whose centers are obtained through network learning. 2-D surface co-ordinates of phase image in a selected ROI is used as inputs
while its corresponding phase value are used as output to train the network. Then the network is tested, where, the phase values
obtained from the network and the actual values are compared. It was observed that the network output matches very well with the
actual values which clearly proves that the neural networks approximates the phase distribution function very well.