Aj. Schwarz et al., SAR and tissue heating with a clinical P-31 MRS protocol using surface coils, adiabatic pulses, and proton-decoupling, MAGN RES M, 44(5), 2000, pp. 692-700
Citations number
25
Categorie Soggetti
Radiology ,Nuclear Medicine & Imaging","Medical Research Diagnosis & Treatment
In MRS studies using surface transmit coils, accurate assessment of local S
AR and RF heating represents a difficult problem involving the coil geometr
y and electromagnetic and geometric tissue properties. Methodologies to det
ermine the optimum operating parameters for dual-resonant surface coil meas
urements are presented, based on a standardized coil and protocol used in a
multicenter P-31 NIRS clinical trial, using adiabatic pulses and bilevel p
roton decoupling. Spatial distributions of absorbed radiation in human calf
and in a tissue-equivalent gel phantom were modeled using finite-element s
imulations and realistic conductivity and permittivity values. Local SAR in
worst-case 1 cm(3) volumes of interest (VOIs) in calf is predicted to be b
elow international guidelines, and the temperature at the skin surface was
found to increase due to the RF by less than 2 degreesC and remain below 37
degreesC, The heating rate and maximum temperature in the gel, at position
s guided by the simulations, were within guideline values for both extremit
ies and trunk and in reasonable agreement with that predicted. (C) 2000 Wil
ey-Liss, Inc.