Local specific absorption rate (SAR), global SAR, transmitter power, and excitation accuracy trade-offs in low flip-angle parallel transmit pulse design
نویسندگان
چکیده
منابع مشابه
Local SAR, global SAR, transmitter power and excitation accuracy trade-offs in low flip-angle parallel transmit pulse design
Purpose—We propose a constrained optimization approach for designing parallel transmit (pTx) pulses satisfying all regulatory and hardware limits. We study the trade-offs between excitation accuracy, local and global SAR, and maximum and average power for small flip-angle pTx (8 channels) spokes pulses in the torso at 3 T and in the head at 7 T. Methods—We compare the trade-offs between the abo...
متن کاملLocal SAR in parallel transmission pulse design.
The management of local and global power deposition in human subjects (specific absorption rate, SAR) is a fundamental constraint to the application of parallel transmission (pTx) systems. Even though the pTx and single channel have to meet the same SAR requirements, the complex behavior of the spatial distribution of local SAR for transmission arrays poses problems that are not encountered in ...
متن کاملLocal and global SAR constrained large tip angle 3 D kT - points parallel transmit pulse design at 7 T
In the last decade, there has been a push towards higher main field strengths in magnetic resonance imaging (MRI) to achieve better contrast and higher signal to noise ratio (SNR). A drawback to current imaging systems at high field is transmit magnetic field inhomogeneity, which degrades both SNR and contrast. This inhomogeneity can be mitigated through radio frequency (RF) pulse design with c...
متن کاملDesigning Rf Pulses with Optimal Specific Absorption Rate (sar) Characteristics and Exploring Excitation Fidelity, Sar and Pulse Duration Tradeoffs
INTRODUCTION: Recent methods of designing RF pulses for multi-coil TX systems have focused on solving regularized systems of equations. These techniques linearize the equations relating the RF waveforms to the resulting excitation and then penalize RF candidates with high peak and root-mean-square (RMS) voltages (VP and VRMS, respectively) in an attempt to limit SAR [1,2]. This is sensible beca...
متن کاملComparison of simulated parallel transmit body arrays at 3 T using excitation uniformity, global SAR, local SAR, and power efficiency metrics.
PURPOSE We compare the performance of eight parallel transmit (pTx) body arrays with up to 32 channels and a standard birdcage design. Excitation uniformity, local specific absorption rate (SAR), global SAR, and power metrics are analyzed in the torso at 3 T for radiofrequency (RF)-shimming and 2-spoke excitations. METHODS We used a fast cosimulation strategy for field calculation in the pres...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Magnetic Resonance in Medicine
سال: 2013
ISSN: 0740-3194
DOI: 10.1002/mrm.24800