ELECTRONIC POSTER - ismrm

14:30 4130. Polyethylene Glycol (PEG) Labeled Liposomal Drug Delivery Systems as a Source
for Dynamic Absolute MR Thermometry
Roel Deckers 1 , Sara M. Sprinkhuizen 1 , Bart J. Crielaard 2 , J H. Ippel 3 , R Boelens 3 , Twan
Lammers 2,4 , C. J. Bakker 1 , L W. Bartels 1
1 Image Sciences Institute, University Medical Center Utrecht, Utrecht, Netherlands; 2 Department of
Pharmaceutics, Utrecht University, Utrecht, Netherlands; 3 Department of NMR Spectroscopy, Bijvoet Center
for Biomolecular Research, Utrecht University, Utrecht, Netherlands; 4 Department of Experimental Molecular
Imaging, RWTH Aachen, Aachen, Germany
Dynamic absolute MR thermometry may be of great interest for the precise and accurate spatio-temporal control of hyperthermia in
local drug delivery applications using MR guided HIFU. In this study we evaluate the use an mFFE sequence in combination with
polyethylene glycol (PEG) labeled liposomes for dynamic absolute MR thermometry. PEG provides a temperature insensitive proton
resonance frequency (PRF) that can serve as reference for the temperature sensitive PRF of water. The frequency difference between
the PRFs of PEG and water, and thus the absolute temperature, can be deduced from the signal evolution in time over 32 echoes
acquired with the mFFE sequence.
15:00 4131. Volumetric Ablation of Tissue Using Magnetic Resonance Imaging Guided High
Intensity Focused Ultrasound (MRgFUS) with Feedback Control and Multi-Slice Thermal
Monitoring: Initial Experience in a Pig Model
Jiming Zhang 1 , Ann Marie Marciel 2 , Tiina Karjalainen 3 , Ari Partanen 4 , Charles
Mougenot, Amol Pednekar 3 , Gil Costas 5 , Jesse Rios 5 , Fredd Clubb 5 , John Fischer 2 ,
Robert Zurawin 6 , Pei Hor 1 , Raja Muthupillai 2
1 Dept of Physics, University of Houston, Houston, TX, United States; 2 Diagnostic and Interventional
Radiology, St. Luke's Episcopal Hospital, Houston, TX, United States; 3 Clinical Science, Philips Medical
Systems, Cleveland, OH, United States; 4 Clinical Science, Philips Healthcare, Cleveland, OH, United States;
5 Texas Heart Institute; 6 Baylor College of Medicine
Preliminary results from a pig model suggest that it is feasible to create volumetric thermal lesions within in-vivo tissue using dynamic
movement of the focal point of a High-Intensity Focused Ultasound beam with real-time multi-slice monitoring, and feedback control.
The measured thermal dose diameters and lengths correspond closely with planned dose diameters for treatment cell sizes ranging
from 4-16 mm in diameter.
Thursday 13:30-15:30 Computer 64
13:30 4132. SNR Trade-Offs in MR-ARFI of Focused Ultrasound in the Brain
Elena Kaye 1,2 , Kim Butts Pauly 1
1 Radiology, Stanford University, Palo Alto, CA, United States; 2 Electrical Engineering, Stanford University,
Palo Alto, CA, United States
MRgFUS is of interest in the treatment of various brain pathologies, such as tumors and neuropathic pain. One way to visualize the
focal spot prior to the treatment relies on MR acoustic radiation force imaging. A recent implementation of MR-ARFI used a
diffusion-weighted 2DFT sequence with a low b-value. The goal of this work was to find the optimum b-value for the displacement
sensitizing gradient in MR-ARFI, relevant to in vivo human imaging. The optimal b-value of 33 s/mm2 was found to minimize the
ghosting artifacts in vivo human brain images, and maximize displacement in the focal spot of ex vivo porcine brain, while keeping
ultrasound energy minimal.
14:00 4133. Therapeutic MRI-Guided High Intensity Focused Ultrasound Ablation of Uterine
Fibroids with Volumetric Heating Technique: Early Clinical Experience in South Korea
Bilgin Keserci 1,2 , Young-sun Kim 3 , Max Oskar Köhler 4 , Hyunchul Rhim 3 , Hyo Keun Lim 3
1 Philips Healthcare, Seoul, Korea, Republic of; 2 Samsung Medical Center,Department of Radiology,
Sungkyunkwan University School of Medicine, Seoul, Korea, Republic of; 3 Samsung Medical Center,
Department of Radiology, Sungkyunkwan University School of Medicine, Seoul, Korea, Republic of; 4 Philips
Healthcare, Finland
As an alternative sonication method in magnetic resonance guided high intensity focused ultrasound treatment, volumetric sonication
method with feedback control under volumetric MRI thermometry for the ablation of uterine fibroids was presented. This method
efficiently utilizes the inherent heat diffusion by electronically switching the focal point between a number of predetermined locations
situated at outwards-moving concentric circles with diameters of upto 16 mm. A significant improvemet in symptom severity score at
1month follow-up over baseline was observed. Volumetric treatment allows for complete and uniform cell coverage, and the delivery
of optimal thermal dose significantly minimizing the risk of overtreatment.