Title :
A fast interpolation approach for the calculation of permittivity and conductivity to estimate the SAR
Author :
Priyadarshi, Sanjay ; Pitman, Sam ; Glover, Paul ; Shah, Simon ; Jianqiao Ye ; Bobo Hu ; Letizia, Rosa
Author_Institution :
Dept. of Eng., Lancaster Univ., Lancaster, UK
Abstract :
The conductivity and permittivity of biological tissue are critical to estimating local radiofrequency (RF) power deposition (also known as specific absorption rate SAR) for Ultra High Field Magnetic Resonance Imaging (UH-MRI). These electrical properties may also have diagnostic value as malignant tissue types have been shown to have higher permittivity and conductivity than surrounding healthy tissue [1]. Recently a new SAR calculation method of using the transmit B1+ map to obtain tissue electrical property has been proposed as a fast SAR calculation method, and has demonstrated great potential for practical applications. However the current numerical technique used in the B1+ map based electrical property calculation is based on a traditional Finite-Difference algorithm, and therefore it requires high-resolution original B1+ map to achieve accurate electrical property calculation. In this study, we have proposed the Spline interpolation of low resolution MRI B1+ map at 1.5T. The proposed method is robust in approximating complex shapes in medical images through curve fitting and therefore could provide sufficiently accurate approximation of the high resolution B1+ map through the low resolution raw data. This will prove to be useful in the fast real time estimation of local specific absorption rate without compromising the accuracy of SAR calculation. It is found that the Spline interpolation method helps in the reduction of MRI scan time and fast estimation of the SAR.
Keywords :
bioelectric phenomena; biological tissues; biomedical MRI; curve fitting; diseases; dosimetry; electrical conductivity; feature extraction; finite difference methods; geometry; image resolution; interpolation; medical image processing; permittivity; real-time systems; splines (mathematics); B1+ map based electrical property calculation; MRI scan time reduction; SAR calculation accuracy; UH-MRI; biological tissue conductivity calculation; biological tissue permittivity calculation; complex shape approximation; curve fitting; diagnostic value; electrical properties; electrical property calculation accuracy; fast interpolation method; fast real-time local SAR estimation; finite difference algorithm; healthy tissue conductivity; healthy tissue permittivity; high resolution B1+ map approximation; local RF power deposition estimation; local radiofrequency power deposition estimation; low resolution MRI B1+ map; magnetic flux density 1.5 T; malignant tissue conductivity; malignant tissue permittivity; malignant tissue type; numerical technique; specific absorption rate estimation; spline interpolation; transmit B1+ map; ultra high field magnetic resonance imaging; Conductivity; Equations; Interpolation; Mathematical model; Permittivity; Phantoms; Splines (mathematics);
Conference_Titel :
RF and Wireless Technologies for Biomedical and Healthcare Applications (IMWS-Bio), 2014 IEEE MTT-S International Microwave Workshop Series on
Conference_Location :
London
Print_ISBN :
978-1-4799-5445-2
DOI :
10.1109/IMWS-BIO.2014.7032447