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Evaluation of partial k‐space strategies to speed up time‐domain EPR imaging
Author(s) -
Subramanian Sankaran,
Chandramouli Gadisetti V. R.,
McMillan Alan,
Gullapalli Rao P.,
Devasahayam Nallathamby,
Mitchell James B.,
Matsumoto Shingo,
Krishna Murali C.
Publication year - 2013
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.24508
Subject(s) - k space , fourier transform , electron paramagnetic resonance , space (punctuation) , phase space , ellipsoid , physics , nuclear magnetic resonance , computer science , optics , quantum mechanics , astronomy , operating system
Narrow‐line spin probes derived from the trityl radical have led to the development of fast in vivo time‐domain EPR imaging. Pure phase‐encoding imaging modalities based on the single‐point imaging scheme have demonstrated the feasibility of three‐dimensional oximetric images with functional information in minutes. In this article, we explore techniques to improve the temporal resolution and circumvent the relatively short biological half‐lives of trityl probes using partial k‐space strategies. There are two main approaches: one involves the use of the Hermitian character of the k‐space by which only part of the k‐space is measured and the unmeasured part is generated using the Hermitian symmetry. This approach is limited in success by the accuracy of numerical estimate of the phase roll in the k‐space that corrupts the Hermiticy. The other approach is to measure only a judicially chosen reduced region of k‐space (a centrosymmetric ellipsoid region) that more or less accounts for >70% of the k‐space energy. Both of these aspects were explored in Fourier transform‐EPR imaging with a doubling of scan speed demonstrated by considering ellipsoid geometry of the k‐space. Partial k‐space strategies help improve the temporal resolution in studying fast dynamics of functional aspects in vivo with infused spin probes. Magn Reson Med 70:745–753, 2013. © 2012 Wiley Periodicals, Inc.