Volume-selective magnetic resonance imaging using an adjustable, single-sided, portable sensor
Portable, single-sided NMR sensors can operate under conditions inaccessible to conventional NMR while featuring lower cost, portability, and the ability to analyze arbitrary-sized objects. Such sensors can nondestructively probe the interior of samples by collecting images and measuring relaxation and diffusion constants, and, given careful shimming schemes, even perform chemical analysis. The inherently strong magnetic-field gradients of single-sided sensors developed so far has prevented imaging of materials with high water content, such as biological tissues, over large volumes whereas designs with more homogeneous fields suffer from low field strength and typically cannot probe volumes larger than 10 cm3. We present a design with a continuously adjustable sensitive volume, enabling the effective volume to be enlarged several fold. This process allows for imaging in reasonable times of much bigger objects and opens the door to the possibility of clinical imaging with portable sensors. We demonstrate MRI in axial and saggital planes, at different depths of the sensitive volume and T1-weighted contrast in a tissue sample.