Validation of the transmission-line modelling method for the electromagnetic characterisation of magnetic resonance imaging radio-frequency coils

The aim of this work was to perform a comprehensive theoretical and experimental validation on the use of the commercially available Transmission Line Modelling (TLM) method, as applied to MRI RF coil design, using simple test criteria. Theoretical validation was performed by comparing the TLM determined resonance frequency, equivalent lumped element circuit components of resistance, inductance, and capacitance, quality factor, mutual inductance, and the axial field profile, for single loop circular surface coils, to theoretical values for these parameters using analytical expressions. Experimental validation was performed by comparing resonance frequency, Q, impedance matching requirements, 90° pulse length (for maximised detection of nuclear magnetisation and hence a measure of the SNR) and B₁ field profiles using an Alderman-Grant coil. Limitations to the TLM method are identified, and future developments are discussed.