ELECTRONIC POSTER - ismrm

sonication, a significant drift of the maximum heating location below the treatment plane towards the transducer was noticed for circle
or disk trajectories. Line scan sonications up to 24mm size provided symmetric and drift-free thermal build up. The latter pattern
should be considered for fast and safe volumetric ablation with MRgHIFU.
14:00 4139. inter-Costal Liver Ablation Under Real-Time MR-Thermometry with Partial
Activation of a HIFU Phased Array Transducer
Bruno Quesson 1 , Mathilde Merle 1 , Max Köhler 2 , Charles Mougenot 3 , Sebastien Roujol 1 ,
Baudouin Denis de Senneville 1 , Chrit T. Moonen 1
1 laboratory for molecular and functional imaging, bordeaux, France; 2 Philips healthcare, Vantaa, Finland;
3 Philips Healthcare, bordeaux, France
The partial obstruction of the High Intensity Focused Ultrasound beam by the rib cage complicates the treatment of liver tumors. A
method for selective deactivation of the transducer elements located in front of the ribs (visualized on 3D anatomical MR images) is
proposed. The effectiveness of the method for HIFU liver ablations is demonstrated ex vivo and in vivo in pigs during breathing with
real-time, motion compensated, MR thermometry. No loss in heating efficacy was observed at the focal point and an important
reduction of the heating in tissues surrounding the bones was obtained with deactivation of the transducer elements.
14:30 4140. Multi-Parametric Monitoring of Thermal Ablations Using Rapid Chemical Shift
Imaging
Brian Allen Taylor 1,2 , Andrew M. Elliott 1 , Ken-Pin Hwang, 1,3 , John D. Hazle 1 , Roger
Jason Stafford 1
1 Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, United States; 2 The
University of Texas Graduate School of Biomedical Sciences, Houston, TX, United States; 3 Applied Science
Laboratory, GE Healthcare, Waukesha, WI, United States
A rapid chemical shift imaging technique is presented that provides T2* values and T1-W amplitudes of multiple chemical species in
addition to accurate and precise temperature estimates. Temperature response of each parameter is correlated with Arrhenius rate
analysis to determine if measurements can aid in verifying treatment goals.
15:00 4141. Real-Time Bioheat Transfer Models for Computer Driven MR Guided LITT
David Fuentes 1 , Yusheng Feng 2 , Andrew Elliott 1 , Anil Shetty 1 , Roger McNichols 3 , J
Tinsley Oden 4 , R Jason Stafford 1
1 Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, United States; 2 The
University of Texas at San Antonio; 3 BioTex Inc; 4 ICES, The University of Texas at Austin
Treatment times of computationally assisted MR guided LITT are determined by the convergence behavior of PDE constrained
optimization problems. This work investigates the feasibility of applying real-time bioheat transfer constrained model calibration to
patient specific data and rigorously validates model calibrations against MR temperature imaging data. The calibration techniques
attempt to adaptively recover the patient specific bio-thermal heterogeneities within the tissue and result in a formidable real time PDE
constrained optimization problem. The calibrations are critical to the predictive power of the simulation during therapy which may be
further exploited for treatment optimization to maximize the efficiency of the therapy control loop.
Wednesday 13:30-15:30 Computer 65
13:30 4142. MR-Guided Trans-Perineal Cryoablation of Locally Recurrent Prostate
Adenocarcinoma Following Radical Prostatectomy
David Arthur Woodrum 1 , Lance Mynderse 2 , Akira Kawashima 1 , Krzysztof Gorny 1 ,
Thomas Atwell 1 , Fred Mcphail 2 , Bradley Bolster 3 , Wesley Gilson 3 , Kimberly Amrami 1 ,
Haraldur Bjarnason 1 , Matthew Callstrom 1
1 Radiology, Mayo Clinic, Rochester, MN, United States; 2 Urology, Mayo Clinic, Rochester, MN, United States;
3 Siemens Medical Solutions, Inc.
Prostate cancer recurrence after definitive therapy can be as high as 25% after 15 years. Detection of these recurrences can be
achieved using serial PSA coupled with dynamic contrast enhanced (DCE) MRI. Our hypothesis is MR-guided cryoablation can be
used in the setting of prostate bed PAC recurrence to perform a precise image-guided focal ablation. Two patients with prior RRP and
dynamic contrast enhancement(DCE) MRI abnormalities in the prostate bed were treated using MR-guided cryoablation. Both patients
with recurrent prostate cancer in the prostate bed were successfully treated with MR-guided cryoablation. Immediate post-ablation
DCE MRI demonstrated no definite residual tumor.
14:00 4143. Truly Simultaneous Clinical US/MRI: Dual Mode Visualization of Bubble Creation
During RFA Inducing Susceptibility Variations Corrupting PRFS Thermometry
Magalie Viallon 1 , Joerg Roland 2 , Sylvain Terraz 1 , Christoph D Becker 1 , Rares salomir 1
1 Radiologie, Hopital Universitaire de Genève, Geneva, Switzerland; 2 MREA, Siemens Medical Solutions,
Erlangen, Germany
Recent work reported spatially related errors in temperature maps and TD during power application, while using 2D GRE-EPI PRFS
imaging with orthogonal interleaved slices (1). We demonstrate that RFA induced cavitationâ€s effects are the primary source of
errors in PRFS imaging using truly simultaneous ultrasonography and MRI.