The work presented here demonstrates the extension of nuclear spin-noise-detected imaging [1] to 3D imaging. Spin noise detection provides a high potential for application at nano-sized samples, is implicitly free of rf-related artifacts and allows for fast recycling times owed to the independence from longitudinal magnetization recovery. Also no rf-related power restrictions need to be considered. Applying the enhancements and insights of over 10 years of spin noise research [2] the realization of this intrinsically insensitive experiment has become possible. The advancements include sliding window processing [3] of the continuously recorded time-domain data, avoiding T/R switching related ?transient effects? [4], and optimal tuning of the probe tuning for spin noise detection [5]. With these improvements in the experimental setup and advanced data processing, it is now possible to record 3D nuclear spin-noise-detected images in a reasonable time frame using a state-of-the-art high resolution spectrometer. When recording conventional (rf-pulse excitation based) NMR experiments there is a trade-off between the resolution and the S/N ratio (which is determined mostly by the number of scans), which needs to be decided before starting the experiment. For spin-noise-detected experiments this trade-off can be adjusted as part of the data processing after the recording is complete. This involves novel iterative image reconstruction techniques based on the algebraic reconstruction algorithm [6]. Even molecular imaging (spatially resolved spectroscopy) becomes feasible that way.
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