RESUMEN
In this paper, we present the initial experimental investigation of a two-coil receive/transmit design for small animals imaging at 7T MRI. The system uses a butterfly-type coil tuned to 300 MHz for scanning the 1H nuclei and a non-resonant loop antenna with a metamaterial-inspired resonator with the ability to tune over a wide frequency range for X-nuclei. 1H, 31P, 23Na and 13C, which are of particular interest in biomedical MRI, were selected as test nuclei in this work. Coil simulations show the two parts of the radiofrequency (RF) assembly to be decoupled and operating independently due to the orthogonality of the excited RF transverse magnetic fields. Simulations and phantom experimental imaging show sufficiently homogeneous transverse transmit RF fields and tuning capabilities for the pilot multiheteronuclear experiments.
Asunto(s)
Imagen por Resonancia Magnética , Ondas de Radio , Animales , Diseño de Equipo , Fantasmas de Imagen , SodioRESUMEN
Ultrafast laser cutting of a glass substrate at an oblique angle is demonstrated using a phase-corrected Bessel beam. Simulations are used to predetermine the ideal phase of the incident Bessel beam such that an unaberrated Bessel beam is formed inside the tilted substrate. Additional corrections to the beam such as shortening, moving the intensity of the beam within the substrate, and the formation of an elliptical focal spot were necessary to ensure consistent chamfering of the substrate and are discussed herein. Three cuts are combined to create a damage tract in the glass substrate in the shape of a chamfer, and then the glass is separated using a CO2 laser resulting in a chamfered edge.
RESUMEN
Currently, human magnetic resonance (MR) examinations are becoming highly specialized with a pre-defined and often relatively small target in the body. Conventionally, clinical MR equipment is designed to be universal that compromises its efficiency for small targets. Here, we present a concept for targeted clinical magnetic resonance imaging (MRI), which can be directly integrated into the existing clinical MR systems, and demonstrate its feasibility for breast imaging. The concept comprises spatial redistribution and passive focusing of the radiofrequency magnetic flux with the aid of an artificial resonator to maximize the efficiency of a conventional MR system for the area of interest. The approach offers the prospect of a targeted MRI and brings novel opportunities for high quality specialized MR examinations within any existing MR system.