Evaluation and Comparison of Pulsed and Continuous Wave Radiofrequency Electron Paramagnetic Resonance Techniques for in Vivo Detection and Imaging of Free Radicals

Yamada, Ken Ichi; Murugesan, Ramachandran; Devasahayam, Nallathamby; Cook, John A.; Mitchell, James B.; Subramanian, S.; Krishna, Murali C.

doi:10.1006/jmre.2001.2487

Cited by 62 publications

(54 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This leads to a differential loss in the integrated intensity of the projections, causing artifacts in the back-projected image. 74 Such artifacts will be significant for oblong objects under large gradients. Attempts to increase the resolution by increasing the magnitude of the gradients will lead to further reduction of T seriously affected by the relaxation time, capable of providing artifact free images is crucial for the development of time-domain RF EPR in vivo imaging.…”

Section: Alternate Methods Of Spatial Encoding In Time-domain Eprimentioning

confidence: 99%

“…74 Using the same resonator (except for altered Q-factors), identical samples and filling factors, the two techniques have been evaluated for their potentials and limitations for in vivo spectroscopic and imaging applications. The assessment is based on the merits such as sensitivity, spatial and temporal resolution, field of view, image artifacts, viable spin probes and subjects of study.…”

Section: Comparison Between Cw Epr and Time-domain Eprmentioning

confidence: 99%

“…The specification of our 300 MHz CW and 300 MHz time-domain spectrometers and their performance with respect to minimum detectable spins were published previously, 74 and Tables 2 and 3 summarize the results.…”

Section: Cw Eprmentioning

confidence: 99%

See 2 more Smart Citations

Radio frequency continuous‐wave and time‐domain EPR imaging and Overhauser‐enhanced magnetic resonance imaging of small animals: instrumental developments and comparison of relative merits for functional imaging

et al. 2004

Self Cite

View full text Add to dashboard Cite

Electron paramagnetic resonance (EPR) imaging in the continuous wave (CW) and time-domain modes, as well as Overhauser-enhanced magnetic resonance imaging in vivo is described. The review is based mainly on the CW and time-domain EPR instrumentation at 300 MHz developed in our laboratory, and the relative merits of these methods for functional in vivo imaging of small animals to assess hypoxia and tissue redox status are described. Overhauser imaging of small animals at magnetic fields in the range 10-15 mT that is being carried out in our laboratory for tumor imaging and the evaluation of tumor hypoxia based on quantitative evaluation of Overhauser enhancement is also described. Alternate approaches to spectral-spatial imaging using the transverse decay constants to infer in situ line widths and hence in vivo pO 2 using CW and time-domain EPR imaging are also discussed. The nature of the spin probes used, the quality of the images obtained in all the three methods, the achievable resolution, limitations and possible future directions in small animal functional imaging with these modalities are summarized.

show abstract

Section: Alternate Methods Of Spatial Encoding In Time-domain Eprimentioning

confidence: 99%

Section: Comparison Between Cw Epr and Time-domain Eprmentioning

confidence: 99%

See 1 more Smart Citation

Radio frequency continuous‐wave and time‐domain EPR imaging and Overhauser‐enhanced magnetic resonance imaging of small animals: instrumental developments and comparison of relative merits for functional imaging

et al. 2004

Self Cite

View full text Add to dashboard Cite

show abstract

“…42 The pulse method has the advantage of speed of data acquisition compared with that of the CW method, while the sensitivity is compromised mainly due to large 'dead-times' required before capturing the signal. This loss of sensitivity, however, is compensated by the fast repetitive scan rates of 10-100 kHz that are possible in pulse EPR imaging.…”

Section: Cw Vs Pulse Imagingmentioning

confidence: 99%

Cardiac applications of EPR imaging

Kuppusamy

Zweíer

2004

NMR in Biomedicine

View full text Add to dashboard Cite

This review summarizes the development and application of a variety of EPR imaging modalities including spatial, spectral-spatial (spectroscopic), gated-imaging and oxygen mapping to cardiovascular studies. It has been hypothesized that free radical metabolism, oxygenation and nitric oxide generation in biological organs such as the heart may vary over the spatially defined tissue structure. We have developed instrumentation optimized for 3D spatial and 3D or 4D spectral-spatial imaging of free radicals at 1.2 GHz. Using this instrumentation high quality 3D spectral-spatial imaging of nitroxyl (nitroxide) metabolism was performed, as well as spatially localized measurements of oxygen concentrations, based on the oxygen-dependent line-broadening of the EPR spectrum. Both exogenously infused probes and endogenous radicals were used to obtain the images. It is demonstrated that the EPR imaging is a powerful tool which can provide unique information regarding the spatial localization of free radicals, oxygen and nitric oxide in biological organs and tissues.

show abstract

“…But it requires the use of narrow-line spin probes such as trityl radicals. On the other hand, the CW mode enables the use of a variety of spin probes and still dominates current applications (10). However, due to the nature of field sweep, the imaging time in CW EPRI is relatively long (11).…”

Section: Introductionmentioning

confidence: 99%

Fast 3D spatial EPR imaging using spiral magnetic field gradient

Deng

Petryakov

et al. 2007

Journal of Magnetic Resonance

View full text Add to dashboard Cite

Electron paramagnetic resonance imaging (EPRI) provides direct detection and mapping of free radicals. The continuous wave (CW) EPRI technique, in particular, has been widely used in a variety of applications in the fields of biology and medicine due to its high sensitivity and applicability to a wide range of free radicals and paramagnetic species. However, the technique requires long image acquisition periods, and this limits its use for many in vivo applications where relatively rapid changes occur in the magnitude and distribution of spins. Therefore, there has been a great need to develop fast EPRI techniques. We report the development of a fast 3D CW EPRI technique using spiral magnetic field gradient. By spiraling the magnetic field gradient and stepping the main magnetic field, this approach acquires a 3D image in one sweep of the main magnetic field, enabling significant reduction of the imaging time. A direct one-stage 3D image reconstruction algorithm, modified for reconstruction of the EPR images from the projections acquired with the spiral magnetic field gradient, was used. We demonstrated using a home-built L-band EPR system that the spiral magnetic field gradient technique enabled a 4 to 7-fold accelerated acquisition of projections. This technique has great potential for in vivo studies of free radicals and their metabolism.

show abstract

Evaluation and Comparison of Pulsed and Continuous Wave Radiofrequency Electron Paramagnetic Resonance Techniques for in Vivo Detection and Imaging of Free Radicals

Cited by 62 publications

References 46 publications

Radio frequency continuous‐wave and time‐domain EPR imaging and Overhauser‐enhanced magnetic resonance imaging of small animals: instrumental developments and comparison of relative merits for functional imaging

Radio frequency continuous‐wave and time‐domain EPR imaging and Overhauser‐enhanced magnetic resonance imaging of small animals: instrumental developments and comparison of relative merits for functional imaging

Cardiac applications of EPR imaging

Fast 3D spatial EPR imaging using spiral magnetic field gradient

Contact Info

Product

Resources

About