title: Distortion-free magnetic resonance imaging in the zero-field limit.
abstract: MRI is a powerful technique for clinical diagnosis and materials characterization. Images are acquired in a homogeneous static magnetic field much higher than the fields generated across the field of view by the spatially encoding field gradients. Without such a high field, the concomitant components of the field gradient dictated by Maxwell's equations lead to severe distortions that make imaging impossible with conventional MRI encoding. In this paper, we present a distortion-free image of a phantom acquired with a fundamentally different methodology in which the applied static field approaches zero. Our technique involves encoding with pulses of uniform and gradient field, and acquiring the magnetic field signals with a SQUID. The method can be extended to weak ambient fields, potentially enabling imaging in the Earth's field without cancellation coils or shielding. Other potential applications include quantum information processing and fundamental studies of long-range ferromagnetic interactions.
authors: Department of Physics, University of California, Berkeley, CA 94720-7300, USA.
authors: Nathan
authors: N
authors: Kelso
authors: Seung-Kyun
authors: SK
authors: Lee
authors: Louis-S
authors: LS
authors: Bouchard
authors: Vasiliki
authors: V
authors: Demas
authors: Michael
authors: M
authors: Mück
authors: Alexander
authors: A
authors: Pines
authors: John
authors: J
authors: Clarke
mesh_terms: D000465:Algorithms; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity