Small animal large field of view magnetic resonance imaging with metamaterial-inspired resonator

Large field of view magnetic resonance imaging is often required during small animal imaging to cover the entire body of an animal. Large field of view imaging should nevertheless be performed with sufficient signal to noise ratio and resolution. A combination of large signal to noise ratio and high resolution is usually achieved via using small loop coils with small field of view, which is inapplicable in case whole animal or a large portion of its body needs to be imaged. Here, a metamaterial-inspired coil based on an array of parallel wires is employed to perform large field of view imaging. A number of mice are imaged in a 7 T preclinical magnetic resonance scanner. Properties of the resulting images are compared to the ones acquired with commercial coil designated for whole-body imaging as well as a with a commercial small loop antenna designated to provide high signal to noise ratio images in a limited area. The signal to noise ratio is compared between the coils in different tissues and on different distances from the metamaterial-inspired coil plane. The coil is found to provide signal to noise ratio a few times higher than the commercial coil in the optimal reception region and comparable signal to noise ratio off the optimal observation region. The metamaterial-inspired coil is also shown to provide rivaling signal to noise ratio in small field-of-view application, when compared to a small-region loop coil. (paper)