Work

RASER MRI: Magnetic resonance images formed spontaneously exploiting cooperative nonlinear interaction

Year: 2026

Type: article

Abstract: The spatial resolution of magnetic resonance imaging (MRI) is limited by the width of Lorentzian point spread functions associated with the transverse relaxation rate 1/T2*. Here, we show a different contrast mechanism in MRI by establishing RASER (radio-frequency amplification by stimulated emission of radiation) in imaged media. RASER imaging bursts emerge out of noise and without applying radio-frequency pulses when placing spins with sufficient population inversion in a weak magnetic field gradient. Small local differences in initial population inversion density can create stronger image contrast than conventional MRI. This different contrast mechanism is based on the cooperative nonlinear interaction between all slices. On the other hand, the cooperative nonlinear interaction gives rise to imaging artifacts, such as amplitude distortions and side lobes outside of the imaging domain. Contrast mechanism and artifacts are explored experimentally and predicted by simulations on the basis of a proposed RASER MRI theory.

Source: UNC Libraries

DOI: 10.17615/pcag-9v24

Authors: Appelt, Stephan, Lehmkuhl, Sören, Lohmann, Lars, Fleischer, Simon, Chekmenev, Eduard Y, Rosen, Matthew S, Theis, Thomas, Adams, Alina

Institution: University of North Carolina at Chapel Hill

Topic: Advanced MRI Techniques and Applications

Subfield: Radiology, Nuclear Medicine and Imaging

Field: Medicine

Domain: Health Sciences

Open Access status: green

Funders: U.S. Department of Defense, U.S. Department of Energy, Imperial College London, Forschungszentrum Jülich, Directorate for Mathematical and Physical Sciences, National Heart, Lung, and Blood Institute, National Institute of Biomedical Imaging and Bioengineering, Biological and Environmental Research

OpenAlex ID: W7213624003

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