Avdievich N I, Hetherington H P
Department of Radiology, Albert Einstein College of Medicine, Bronx, NY, USA.
J Magn Reson. 2007 Jun;186(2):341-6. doi: 10.1016/j.jmr.2007.03.001. Epub 2007 Mar 3.
Typically 31P in vivo magnetic resonance spectroscopic studies are limited by SNR considerations. Although phased arrays can improve the SNR; to date 31P phased arrays for high-field systems have not been combined with 31P volume transmit coils. Additionally, to provide anatomical reference for the 31P studies, without removal of the coil or patient from the magnet, double-tuning (31P/1H) of the volume coil is required. In this work we describe a series of methods for active detuning and decoupling enabling use of phased arrays with double-tuned volume coils. To demonstrate these principles we have built and characterized an actively detuneable 31P/1H TEM volume transmit/four-channel 31P phased array for 4 T magnetic resonance spectroscopic imaging (MRSI) of the human brain. The coil can be used either in volume-transmit/array-receive mode or in TEM transmit/receive mode with the array detuned. Threefold SNR improvement was obtained at the periphery of the brain using the phased array as compared to the volume coil.
通常，体内磷-31磁共振波谱研究受到信噪比（SNR）因素的限制。尽管相控阵可以提高信噪比，但迄今为止，用于高场系统的磷-31相控阵尚未与磷-31容积发射线圈相结合。此外，为了给磷-31研究提供解剖学参考，在不将线圈或患者从磁体中移出的情况下，需要对容积线圈进行双调谐（磷-31/氢-1）。在这项工作中，我们描述了一系列用于有源失谐和解耦的方法，从而能够将相控阵与双调谐容积线圈配合使用。为了证明这些原理，我们构建并表征了一种用于人脑4T磁共振波谱成像（MRSI）的有源可失谐磷-31/氢-1横向电磁（TEM）容积发射/四通道磷-31相控阵。该线圈既可以在容积发射/阵列接收模式下使用，也可以在阵列失谐的TEM发射/接收模式下使用。与容积线圈相比，使用相控阵在脑周边区域获得了三倍的信噪比提升。
