2D Image Construction from Object-Traversing Parallel 1D Iso-Frequency Projections in MRI: a Theoretical Formalism

Abstract

A theoretical formalism and its computational requirements are presented showing that a 2D cross-sectional image, of diagnostic image quality, can be constructed from a large number of 1D object-traversing parallel iso-1H precession frequency projections in magnetic resonance imaging. The proposed image construction technique, based on a single spin echo (SE) signal, relies on a relatively high sampling frequency (e.g., 1.024 MHz) and application of a strong oblique read gradient across the image array to allow pixel intensities to be calculated via large-scale simultaneous solution of the SE's Fourier signal. The proposed technique can also theoretically provide 72 mapping via the collection of a second SE collected at a different echo time for the same 90° radiofrequency pulse. Signal-to-noise ratio is theoretically enhanced by the fact that no phase gradient is applied. Current maximum available gradient strengths (≈40 mT/m) conservatively limit the technique to a 128 × 128 image array with pixel areas of approximately 5 mm2. Construction for a 256 × 256 image array is possible but with compromised image quality. With continued rapid advancements in gradient strength technology expected, the technique could in the future offer an alternative to fast imaging sequences, such as echo planar imaging, but with the advantage of no phase propagation artifacts or adverse effects of ultrafast gradient systems.