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MRPM 2026 - IFSC USP
Lucio Frydman - Confirmed Speaker - MRPM2026.jpg

New Steady State NMR and MRI Techniques for Structural, Biological and Dynamic Investigations

The steady-state free-precession (SSFP) experiment, proposed nearly 70 years ago and studied/employed in over 20000 papers. SSFP is composed by a rapid train of pulses applied at repetition times TR<<T2, T1, leading to a steady transverse emission of up to 50% of the thermal equilibrium magnetization. While this could provide a superior sensitivity than current FT-NMR experiments, it is also known that SSFP cannot achieve high spectral resolution, that its rapid pulsing leads to “blind” spectral regions, and that it is incompatible with sophisticated multiple-resonance polarization transfer techniques. Hence, although very widely used in MRI and initially assayed also for NMR, SSFP has been almost entirely dropped from the realm of spectroscopy. The present study introduces ways to overcome SSFP’s handicaps, leading to a new approach to high resolution NMR matching or exceeding the sensitivity of FT-NMR methods. It is also shown that coherent polarization transfers can be combined with these SSFP schemes, to enhance even further the sensitivity gains.  This can in turn be used to endow 13C spectroscopic imaging with sufficient sensitivity, to image metabolic aberrations associated with the presence of tumors without requiring hyperpolarized approaches. I will also discuss numerous new physical features of this decades-old experiment, particularly in connection with J-couplings, chemical exchange, magic-angle spinning – and many other challenges remaining to be solved!

Lucio Frydman

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