Comparison of 250 MHz electron spin echo and continuous wave oxygen EPR imaging methods for in vivo applications

作者：Epel Boris^*; Sundramoorthy Subramanian V; Barth Eugene D; Mailer Colin; Halpern Howard J

来源：Medical Physics, 2011, 38(4): 2045-2052.

DOI：10.1118/1.3555297

• electron paramagnetic resonance
• oxymetry
• hypoxia

Purpose: The authors compare two electron paramagnetic resonance imaging modalities at 250 MHz to determine advantages and disadvantages of those modalities for in vivo oxygen imaging.
Methods: Electron spin echo (ESE) and continuous wave (CW) methodologies were used to obtain three-dimensional images of a narrow linewidth, water soluble, nontoxic oxygen-sensitive trityl molecule OX063 in vitro and in vivo. The authors also examined sequential images obtained from the same animal injected intravenously with trityl spin probe to determine temporal stability of methodologies.
Results: A study of phantoms with different oxygen concentrations revealed a threefold advantage of the ESE methodology in terms of reduced imaging time and more precise oxygen resolution for samples with less than 70 torr oxygen partial pressure. Above similar to 100 torr, CW performed better. The images produced by both methodologies showed pO(2) distributions with similar mean values. However, ESE images demonstrated superior performance in low pO(2) regions while missing voxels in high pO(2) regions.
Conclusions: ESE and CW have different areas of applicability. ESE is superior for hypoxia studies in tumors.

• 出版日期2011-4