Single acquisition quantitative single-point electron paramagnetic resonance imaging.
PURPOSE
Electron paramagnetic resonance imaging has emerged as a promising noninvasive technology to dynamically image tissue oxygenation. Owing to its extremely short spin-spin relaxation times, electron paramagnetic resonance imaging benefits from a single-point imaging scheme where the entire free induction decay signal is captured using pure phase encoding. However, direct T2 (*)/pO2 quantification is inhibited owing to constant magnitude gradients which result in time-decreasing field of view. Therefore, conventional acquisition techniques require repeated imaging experiments with differing gradient amplitudes (typically 3), which results in long acquisition time.


METHODS
In this study, gridding was evaluated as a method to reconstruct images with equal field of view to enable direct T2 (*)/pO2 quantification within a single imaging experiment. Additionally, an enhanced reconstruction technique that shares high spatial k-space regions throughout different phase-encoding time delays was investigated (k-space extrapolation).


RESULTS
The combined application of gridding and k-space extrapolation enables pixelwise quantification of T2 (*) from a single acquisition with improved image quality across a wide range of phase-encoding time delays. The calculated T2 (*)/pO2 does not vary across this time range.


CONCLUSIONS
By utilizing gridding and k-space extrapolation, accurate T2 (*)/pO2 quantification can be achieved within a single data set to allow enhanced temporal resolution (by a factor of 3).
['Jang|Hyungseok|H|', 'Subramanian|Sankaran|S|', 'Devasahayam|Nallathamby|N|', 'Saito|Keita|K|', 'Matsumoto|Shingo|S|', 'Krishna|Murali C|MC|', 'McMillan|Alan B|AB|']
D000465:Algorithms D016477:Artifacts D004578:Electron Spin Resonance Spectroscopy D007089:Image Enhancement D007090:Image Interpretation, Computer-Assisted D008279:Magnetic Resonance Imaging D057054:Molecular Imaging D010092:Oximetry D010100:Oxygen D019047:Phantoms, Imaging D015203:Reproducibility of Results D012680:Sensitivity and Specificity
tissue oxygenation gridding EPR imaging hypoxia quantitative imaging single point imaging