High Resolution MRI Coil for Rat Brain at 7 Tesla

Magnetic resonance imaging (MRI) is a very powerful, non-ionizing, non-invasive clinical and research modality for soft tissue imaging. MRI applications such as, real-time cardiac imaging, functional brain imaging and contrast enhanced MRI require fast and high resolution recording. Main limitation in fulfilling these requirements is intrinsically low signal to noise ratio (SNR) in MRI. In principle SNR can be improved either by increasing signal or by decreasing noise. Thus far, increasing the SNR of an MRI system turned out to be very challenging due to fundamental limitation regarding the received signals. These signals are intrinsically small since they are generated only by a very limited number of nuclei. In addition, the noise floor in the MRI systems is set up by ever-present thermal noise. There are two dominant sources of thermal noise, one coming from the receiver sensor and the other resulting from eddy currents induced in an imaged conducting object. Eddy currents in a body can-not be avoided, but reduction of conductive losses in the receiver coil and optimization of its sensitivity is possible. The primary objective of this study is to maximize SNR by optimizing coil size and geometry for imaging small animals using scanners operating at 7 Tesla. The goal is to identify and characterize all components of losses with emphasis on losses related to coil and coil-body geometry. Such characterization provides information regarding SNR-optimized coils.