Imaging of nitroxides at 250MHz using rapid-scan electron paramagnetic resonance

Abstract

Projections for 2D spectral-spatial images were obtained by continuous wave and rapid-scan electron paramagnetic resonance using a bimodal cross-loop resonator at 251 MHz. The phantom consisted of three 4 mm tubes containing different 15N,2H-substituted nitroxides. Rapid-scan and continuous wave images were obtained with 5 min total acquisition times. For comparison, images also were obtained with 29 s acquisition time for rapid scan and 15 min for continuous wave. Relative to continuous wave projections obtained for the same data acquisition time, rapid-scan projections had significantly less low-frequency noise and substantially higher signal-to-noise at higher gradients. Because of the improved image quality for the same data acquisition time, linewidths could be determined more accurately from the rapid-scan images than from the continuous wave images.

Rapid Scan Electron Paramagnetic Resonance Opens New Avenues for Imaging Physiologically Important Parameters <em>In Vivo</em>

“…Figure 3) and 15 minutes (full spectrum of 5 µM BMPO-OH, Figure 5). Method development with the phantoms shows use of RS-EPR images supersedes the conventional CW-EPR imaging technique 23,24 , and opens new avenues for in vivo imaging using EPR probes.…”

Improved Sensitivity for Imaging Spin Trapped Hydroxyl Radical at 250 MHz

“…[15] The improvement in S/N that can be obtained by recording the projections for EPRI at 250 MHz by rapid scan compared with CW EPR has been demonstrated for phantoms containing multiple nitroxide radicals. [20] To achieve about the same S/N for an image of the phantom required about 10 times as long for CW as for rapid scan. [20] Rapid scan EPR is the second technology exploited in this study to improve sensitivity per unit time.…”

“…[20] To achieve about the same S/N for an image of the phantom required about 10 times as long for CW as for rapid scan. [20] Rapid scan EPR is the second technology exploited in this study to improve sensitivity per unit time.…”

“…A new image reconstruction algorithm has been demonstrated that permits reconstruction of the full spectrum with much more modest sweep width requirements. [20] This is the third technology advance exploited in this study.…”

“…This concentration of spin adduct is about two orders of magnitude lower than the concentrations of 15 N and deuterium substituted nitroxides that have been imaged previously at 250 MHz. [22] …”