Analysis of a flexible surface-coil-type resonator for magnetic resonance measurements

Hirata, Hiroshi; Iwai, Hisako; Ono, Mitsuhiro

doi:10.1063/1.1145351

Cited by 31 publications

(19 citation statements)

References 15 publications

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“…la). This coil diameter is a theoretically and experimentally optimized value for EPR measurements at ah EPR frequency of 700 MHz [6]. The second coil, 10 mm wide, was constructed from a copper plate 0.5 mm thick (Fig.…”

Section: Scrsmentioning

confidence: 99%

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Development of surface-coil-type resonators consisting of an irradiation and receiver coil system for EPR measurements at 700 MHz

Yokoyama

Sato

2005

Appl. Magn. Reson.

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Surface-coil-type resonators (SCRs) consisting of irradiation and receiver coils that are highly isolated from each other were developed for electron paramagnetic resonance (EPR) measurements. Their sample space was open to ffee space. For these coils, a circular single-turn one-loop receiver coil anda square single-turn twin-loop irradiation coil were fabricated. The transmission lines were set to resonate at about 700 MHz. A phantom (agar, including a nitroxide radical and physiological saline solution) is located on the receiver coil, and the irradiation coil is under the receiver coil. In this condition, the isolation between the receiver and irradiation SCRs was about 40 dB at the resonant frequency. When radiowaves that were divided from the line to the irradiation SCR were applied to the line from the receiver SCR at the appropriate phase and power to cancel the direct coupling between both SCRs, the isolation increased to more than 70 dB. In the conventional SCR, the noise level increased at high incident power. Because such ah increase in the noise was not observed in the irradiation-receiver SCR system, high sensitivity at high incident power was obtained.

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Section: Scrsmentioning

confidence: 99%

“…A surface-coil-type resonator (SCR) is one of the EPR resonators that operate in the ultrahigh-frequency (UHF) band [5][6][7]. It is composed of a singleturn col!…”

Section: Introductionmentioning

confidence: 99%

Development of surface-coil-type resonators consisting of an irradiation and receiver coil system for EPR measurements at 700 MHz

Yokoyama

Sato

2005

Appl. Magn. Reson.

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“…[16][17][18] The SCR consisted of a single-turn coil (f = 10 mm) and transmission lines that were formed by the flexible coaxial cables. 15 The SCR was connected to the microwave circuit through a three-stub tuner and driven at a resonant frequency of approximately 720 MHz.…”

Section: A Radiofrequency Esr Spectrometermentioning

confidence: 99%

“…been shown to have good signal responses to the nitroxyl radicals, such as 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPOL), which is used as a redox probe. A surface-coil-type resonator (SCR) that is mechanically flexible was first developed by Hirata et al 15 We previously fabricated three types of SCRs and performed temporal ESR measurements at several sites in rats (liver, kidney, stomach, rectum, vein, and skin) following the injection of TEMPOL. 16 Results of our studies have suggested that the SCR method may be useful in the direct evaluation of the in vivo redox status in localized organs.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Antioxidative Effects of Sesamin on the In vivo Hepatic Reducing Abilities by a Radiofrequency ESR Method

et al. 2013

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Antioxidative effects of sesamin (a mixture of sesamin and episesamin) were evaluated in the liver, kidney and inferior vena cava of living rats using a radiofrequency ESR method. TEMPOL, 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl, was used as an in vivo redox probe, the half-life of which is believed to be correlated with the antioxidant status. The oral administration of sesamin (250 mg/kg rat weight) 3 h before ESR measurements shortened the half-life of TEMPOL in the liver by 10 -15% as compared with the controls, but did not affect the other organs. This effect was maintained for at least 3 h after the administration, and then disappeared at 24 h, corresponding to the results of our preliminary pharmacokinetic studies. Changes in the reducing ability were observed only in the hepatic sites of the sesamin-treated rats. These findings suggest that sesamin exhibits effective antioxidant activity in the liver via modulation of the intracellular redox status related to TEMPOL reduction.

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“…12 Hirata et al developed an improved external loop resonator with an automatic matching control system for in vivo ESR. 13 This loop resonator system allows one to measure an ESR signal while compensating perturbations due to movement of the subject animal. This modified system appears to be potentially valuable in applying in vivo ESR to human subjects, where the need to reduce noise from movements is also a major concern.…”

Section: Introduction: History Of In Vivo Epr or Esrmentioning

confidence: 99%

Detection of bioradicals by in vivo L‐band electron spin resonance spectrometry

Fujii

Berliner

2004

NMR in Biomedicine

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The applications of in vivo electron paramagnetic resonance (EPR) or electron spin resonance (ESR) spectroscopy have been impressive over a relatively short period despite the many obstacles which had to be overcome, such as dielectric absorption and biodestruction. The loop-gap resonators and modified loop coil systems have emerged as the most suitable resonators for in vivo EPR experiments. This paper briefly discusses instrumental aspects as a prelude to several examples related to the in vivo monitoring and detection of bioradicals. Recent progress in detection of bioradicals induced by drugs or chemicals is discussed with regard to nitrosocompounds, nitric oxide and metals in vivo. A clinical EPR application is also discussed.

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Analysis of a flexible surface-coil-type resonator for magnetic resonance measurements

Cited by 31 publications

References 15 publications

Development of surface-coil-type resonators consisting of an irradiation and receiver coil system for EPR measurements at 700 MHz

Development of surface-coil-type resonators consisting of an irradiation and receiver coil system for EPR measurements at 700 MHz

Evaluation of Antioxidative Effects of Sesamin on the In vivo Hepatic Reducing Abilities by a Radiofrequency ESR Method

Detection of bioradicals by in vivo L‐band electron spin resonance spectrometry

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