Patent ID: 7348780

Claim:
A method for designing apparatus for use in a magnetic resonance system for receiving a magnetic resonance signal having a predetermined radio frequency, said apparatus and said magnetic resonance system having a common longitudinal axis, said method comprising designing the apparatus by treating the apparatus as a transmitter of a radio frequency field having the predetermined radio frequency and then designing said transmitter by: (a) defining a target region in which the radial magnetic component of the radio frequency field is to have desired values, said target region surrounding said longitudinal axis; (b) specifying desired values for said radial magnetic component of the radio frequency field at a preselected set of points within the target region; (c) determining a complex current density function J, having real and imaginary parts, on a specified cylindrical surface by: (i) defining the complex current density function as a sum of a series of basis functions multiplied by complex amplitude coefficients having real and imaginary parts; and (ii) determining values for the complex amplitude coefficients using an iterative minimization technique applied to a residue vector obtained by taking the difference between calculated field values obtained using the complex amplitude coefficients at the preselected points and the desired values at those points; and (d) converting said complex current density function J into a set of capacitive elements located on the specified cylindrical surface and a set of inductive elements located on the specified cylindrical surface by: (i) converting the complex current density function into a curl-free component J curl-free and a divergence-free component J div-free using the relationships: J curl-free =∇ψ, and J div-free =∇×S, where ψ and S are functions obtained from the complex current density function through the equations: ∇ 2 ψ=∇·J, −∇ 2 S=∇×J , and −∇ 2 ( n·S )= n·∇×J, where n is a vector normal to the specified cylindrical surface; (ii) calculating locations on the specified cylindrical surface for the set of capacitive elements by contouring the function ψ; and (iii) calculating locations on the specified cylindrical surface for the set of inductive elements by contouring the function n·S.