Patent ID: 6924150

Claim:
A method for performing magnetic resonance imaging on a selected portion of a sample, the method comprising: providing a selected ferrimagnetic material into the sample by chemically bonding the ferrimagnetic material in particle format to the sample, the ferrimagnetic material having known ferromagnetic spin resonance characteristics, at least one resonant frequency ω=ω 0 , and a diameter no greater than 1 μm, the ferrimagnetic material now a constituent of a selected portion of the sample; applying an excitation electromagnetic field to the sample using an electromagnetic wave generator, the excitation electromagnetic field having at least one of a static component and a time varying component with a frequency ω=ω 1 ≈ω 0 , a selected magnetic field strength, and a selected magnetic field direction relative to the sample portion; applying an external gradient magnetic field to the sample, the external gradient magnetic field having at least one of a static component and a time varying component, a selected magnetic field direction, and at least first and second selected magnetic field strengths at at least first and second selected locations, respectively, within the sample portion; measuring at or near the resonant frequency ω 0 of the ferrimagnetic material at least one of (i) a real component μ′(ω′) of the complex permeability parameter, and (ii) an imaginary component μ″(ω 1 ) of the complex permeability parameter of the sample portion at each of the selected locations to determine at least one value of a material parameter at each of the selected locations; and constructing an image of the sample portion, by comparing the measured parameter values with corresponding reference values for the selected ferrimagnetic constituent for each of the selected locations.