The quadrature coil has been known to have various advantages compared with conventional single coil. Saving of transmitted power and improvements of radio-frequency magnetic field homogeneity as well as the signal-to-noise ratio could be very useful especially in high field magnetic resonance imaging. A quadrature coil pair named as quadrature-quadrature coil for simultaneous proton and sodium imaging in high field MRI system is introduced. The quad.-quad. coil is composed of two quadrature coils, one of which is for proton imaging and the other is for sodium imaging. The proton quadrature coil is composed of two identical ring resonator coils which have been found to be one of the suitable coils for high field MRI. While, the sodium quadrature coil is composed of two identical saddle coils well-known in low field MRI. Design scheme of each coil is considered. Experimental improvements with quadrature coils reach theoretical predictions verifying the advantages of quadrature excitation and detection in high field MRI. Also, some theoretical considerations on quadrature excitation and detection are given.
핵자기 공명 단층 촬영에서 중요한 부분중의 하나가 고주파 코일이다. 특히 정자기장의 세기가 커짐에 따라 감도가 커지기는 하나 전력 소모에 기인한 불균일성 현상이 생길 뿐만 아니라, 나트륨과 같은 화학원소의 감도는 아직도 부족한 점이 있다.
이 논문에서는 신호대 잡음비의 개선뿐만 아니라, 전력 소모를 줄일 수 있고 또한 고주파 자장의 균일성을 개선할 수 있는 쿼더러처 코일에 대해 분석을 하였으며, 이를 수소와 나트륨 영상에 적용하여 실험적으로 입증하였다.
