ELECTRONIC POSTER - ismrm

Thursday 13:30-15:30 Computer 51
13:30 3928. Minimal Acceptable Blocking Impedance for RF Receive Coils
Victor Taracila 1 , Pei Chan 1 , Fraser Robb 1
1 GE Healthcare, Aurora, OH, United States
During the transmit phase of the MR sequence the receiving coils are usually detuned to minimize body coil disturbance. This is
typically achieved with passive or active decoupling parallel tank circuits which, when active, create very high impedance in coil
elements so that the current induced into them is very small and does not affect the process of magnetization tipping. When planning
the build of a coil, the magnitude and the number of decoupling boards required for every receive element needs to be considered. In
this work we deduce a simple rule for quick evaluation of the required blocking impedance.
14:00 3929. Dynamic Modeling of Low Magnetic Moment PIN Diodes for MR Scanner
Applications
Robert Caverly 1 , Ronald Watkins 2 , William Doherty 3
1 Electrical and Computer Engineering, Villanova University, Villanova, PA, United States; 2 Radiology,
Stanford University, Stanford, CA, United States; 3 Lowell Division, Microsemi Corp., Lowell, MA, United
States
A SPICE-compatible PIN diode model suitable for time domain dynamic modeling is presented, with information for both fast
rectifier and higher power devices design shown.
14:30 3930. Overlap Decoupling in Hole-Slotted Arrays
Marcos Alonso Lopez 1,2 , Felix Breuer 2 , Daniel Gareis 1,3 , Peter Michael Jakob 1,2
1 Experimental Physics 5, University of Wuerzburg, Wuerzburg, Bavaria, Germany; 2 Research Center Magnetic
Resonance Bavaria, Wuerzburg, Bavaria, Germany; 3 Noras MRI Products GmbH, Hoechberg, Bavaria,
Germany
The hole-slotted coil design provides a deeper RF penetration into the sample compared to standard loop designs and has already been
shown to operate as an array with capacitive decoupling at 7 T. In this work, the applicability of overlap decoupling in a hole-slotted
loop-geometry array is investigated at 1.5 and 7 T. The overlap ratio for an optimal decoupling has been experimentally found. The
hole-slotted geometry is a well-suited design in an array setup using overlap decoupling. At 7 T has been shown to have
approximately the same RF penetration than the hole-slotted array with capacitive decoupling.
15:00 3931. MRI Compatible (2.4GHz) Bluetooth Communication System: Isolating and
Eliminating Electromagnetic Noise
Jacob Bender 1,2 , Mihaela Jekic 1,2 , Orlando P. Simonetti 1,3
1 The Dorothy M. Davis Heart and Lung Research Institute, Ohio State University, Columbus, OH, United
States; 2 Biomedical Engineering, Ohio State University, Columbus, OH, United States; 3 Radiology, Internal
Medicine, Biomedical Engineering, Ohio State University, Columbus, OH, United States
A 2.4 GHz MRI compatible Bluetooth transceiver was constructed for use with a mouse and keyboard inside of a MRI room.
Shielding and filtering prevented noise from Bluetooth electronics from entering the room. Only a few required small ferromagnetic
parts were incorporated into the design. No noise was generated from the system. This was verified visually with phantom scan, a
frequency spectrum obtained with a network analyzer, quantitatively with RF noise checks, and through technical specification from
the manufacturer, FCC, and ETSI.
Gradient Coil Design
Hall B Monday 14:00-16:00 Computer 52
14:00 3932. Can We Re-Design the Gradient Coil to Make the Eddy Current Field Match the
Primary Gradient Field?
Hector Sanchez 1 , Michael Poole 1 , Adnan Trakic 1 , Stuart Crozier 1
1 Research Group/Affiliation: EMI, School of Information Technology & electrical Engineering, Brisbane, QLD,
Australia
MRI requires rapidly switched magnetic field gradients. This time-dependent magnetic fields induce eddy currents in nearby
conducting structures. These currents generate detrimental transient magnetic fields in the region of interest (ROI) and hence, current
compensation is required to minimize the consequential image distortion. In order to apply successfully current compensation
techniques, it is required that the primary and the secondary magnetic fields possess a similar spatial form in the ROI. In this work we
present two approaches for gradient coil design that produces gradient fields with characteristics similar to those produced by the eddy
currents.