MRI scanner‐independent specific absorption rate measurements using diffusion coefficients
نویسندگان
چکیده
OBJECTIVE The purpose of this study was to measure specific absorption rate (SAR) during MRI scanning using a human torso phantom through quantification of diffusion coefficients independently of those reported by the scanner software for five 1.5 and 3 T clinical MRI systems from different vendors. METHODS A quadrature body coil transmitted the RF power and a body array coil received the signals. With diffusion tensor imaging, SAR values for three MRI sequences were measured on the five scanners and compared to the nominal values calculated by the scanners. RESULTS For the GE 1.5 T MRI system, the MRI scanner-reported SAR value was 1.58 W kg-1 and the measured SAR value was 1.38 W kg-1 . For the Philips 1.5 T MRI scanner, the MRI system-reported SAR value was 1.48 W kg-1 and the measured value was 1.39 W kg-1 . For the Siemens 3 T MRI system, the reported SAR value was 2.5 W kg-1 and the measured SAR value was 1.96 W kg-1 . For two Philips 3 T MRI scanners, the reported SAR values were 1.5 W kg-1 and the measured values were 1.94 and 1.96 W kg-1 . The percentage differences between the measured and reported SAR values on the GE 1.5 T, Philips 1.5 T, Siemens 3 T, and Philips 3 T were 13.5, 6.3, 24.2, 25.6, and 26.6% respectively. CONCLUSION The scanner-independent SAR measurements using diffusion coefficients described in this study can play a significant role in estimating accurate SAR values as a standardized method.
منابع مشابه
MR Scanner Systems Should Be Adequately Characterized in Diffusion-MRI of the Breast
Breast imaging represents a relatively recent and promising field of application of quantitative diffusion-MRI techniques. In view of the importance of guaranteeing and assessing its reliability in clinical as well as research settings, the aim of this study was to specifically characterize how the main MR scanner system-related factors affect quantitative measurements in diffusion-MRI of the b...
متن کاملQUIPSS II with window-sliding saturation sequence (Q2WISE).
A series of periodic saturation pulses used to minimize the error caused by varying transit delays in assessing perfusion using quantitative imaging of perfusion using a single subtraction II with thin-slice TI(1) periodic saturation (Q2TIPS) increases the specific absorption rate. Quantitative imaging of perfusion using a single subtraction II with window-sliding saturation sequence (Q2WISE) h...
متن کاملAccuracy of q-space derived parameters in MRI - A phantom study of system-induced limitations
Introduction The aim of this study was to compare the accuracy of parameters derived from q-space measurements between a 3.0 T clinical MRI scanner and a 4.7 T NMR spectrometer. In order to do this, measurements were performed on n-decane, at the two systems using similar pulse sequence parameters. Materials and Methods The n-decane is a linear hydrocarbon (C10H22) that gives a diffusion coeffi...
متن کاملAccurate Measurement of RF Power Deposition During 3T MRI.
Introduction. Accurate knowledge of the specific absorption rate (SAR) during an MRI scan is vitally important for patient safety (1). Precise measurement of the total power deposited in the body enables correct SAR prediction and monitoring. The existence of many cases of scanner-associated RF burns reported to the FDA (2), and the irreproducibility of scanner-reported SAR for implanted device...
متن کاملInter-site and inter-scanner diffusion MRI data harmonization
We propose a novel method to harmonize diffusion MRI data acquired from multiple sites and scanners, which is imperative for joint analysis of the data to significantly increase sample size and statistical power of neuroimaging studies. Our method incorporates the following main novelties: i) we take into account the scanner-dependent spatial variability of the diffusion signal in different par...
متن کامل