In one aspect, a method of inducing nuclear magnetic resonance (NMR) signals from a region of an object having at least a portion of at least one pulmonary vein using at least one coil adapted to emit electromagnetic signals to induce an NMR effect is provided. The method comprises operating the at least one coil to provide at least one imaging sequence at an effective off-resonance frequency adapted to cause NMR signals to be emitted from the at least one pulmonary vein, and detecting at least some of the NMR signals to obtain NMR data corresponding to the at least one pulmonary vein.