RESUMEN
Stripline high frequency resonators or transmission line resonators (TLRs) manufactured as concentric RF coils at the opposite sides of a dielectric sheet serve as wireless self-resonant transmitters-receivers in MRI. Owing to their high quality factor relative to traditional RF coils composed of bulk inductor and capacitors, frequency selectivity of TLRs is high, making them promising elements for single-nucleus MRI. However, the computation of their resonance frequencies is cumbersome, and numerous mathematical mistakes and typos in publications lead to incorrect results. The present publication is the first to summarize the corrected formulas for computations and presents comparison of such computations to real measurements.
Asunto(s)
Diseño de Equipo , Imagen por Resonancia Magnética/instrumentación , Imagen por Resonancia Magnética/métodos , Algoritmos , Capacidad Eléctrica , Impedancia Eléctrica , Ensayo de Materiales , Modelos Estadísticos , Ondas de Radio , Reproducibilidad de los Resultados , VibraciónRESUMEN
A flexible transceiver array based on transmission line resonators (TLRs) combining the advantages of coil arrays with the possibility of form-fitting targeting cardiac MRI at 7â¯T is presented. The design contains 12 elements which are fabricated on a flexible substrate with rigid PCBs attached on the center of each element to place the interface components, i.e. transmit/receive (T/R) switch, power splitter, pre-amplifier and capacitive tuning/matching circuitry. The mutual coupling between elements is cancelled using a decoupling ring-based technique. The performance of the developed array is evaluated by 3D electromagnetic simulations, bench tests, and MR measurements using phantoms. Efficient inter-element decoupling is demonstrated in flat configuration on a box-shaped phantom (Sijâ¯<â¯-19â¯dB), and bent on a human torso phantom (Sijâ¯<â¯-16â¯dB). Acceleration factors up to 3 can be employed in bent configuration with reasonable g-factors (<1.7) in an ROI at the position of the heart. The array enables geometrical conformity to bodies within a large range of size and shape and is compatible with parallel imaging and parallel transmission techniques.