EPR spectrometer for clinical applications

Abstract

This article describes an EPR spectrometer specifically designed and constructed for EPR spectroscopy in humans. The spectrometer is based on a permanent magnet, suitable for measurements at 1200 MHz. The magnet has a full 50 cm gap between the poles, which facilitates accurate and comfortable placement of the subject for the EPR measurement at any location on the human body. The bridge includes features to facilitate clinical operations, including an indicator for phasing of the reference arm and a 2 level RF amplifier. Resonators with holders for each type and site of measurement have been developed that comfortably position the resonator and the patient and prevent artifacts due to motion. The initial applications for which the spectrometer has been designed are for oximetry using loops on the surface, oximetry using implanted resonators for measuring deep sites, and measurements in the teeth for determination of exposures to clinically significant doses of ionizing radiation. Magn Reson Med 54:1317-1320, 2005.

Electron Spin Resonance Spectroscopy of Serum Albumin: A Novel New Test for Cancer Diagnosis and Monitoring

“…Changes in the mobility and accessibility of the spin labels, and the distances between spin labels, enables changes in the secondary and tertiary structure of proteins to be discerned. Results of recent application of ESR spectroscopy in animal models and humans suggest that ESR has great diagnostic potential (10 ). Some promising initial applications include noninvasive, continuous measurement of partial oxygen pressure in tissue and measurement of clinically significant exposure to ionizing radiation (11 ).…”

Molecular electron paramagnetic resonance imaging of melanin in melanomas: a proof‐of‐concept

“…During the last few years, unprecedented progress has been made in in vivo EPR technology and applications (14). The first clinical EPR spectrometer has been built recently and pioneer studies conducted in humans (15,16). These technological developments combined with our present findings may open the way for improved early diagnosis of melanomas using whole-body EPR magnets and surface coils placed over suspect lesions.…”

Experimental procedures for sensitive and reproducible in situ EPR tooth dosimetry

“…In vivo EPR dosimetry is currently performed using the whole-body clinical EPR spectrometer at the Dartmouth EPR Center (Salikhov, et al, 2005, Swartz, et al, 2006, Swartz, et al, 2004. This continuous wave (CW) spectrometer operates at an L-Band frequency (1.2 GHz) and the main magnetic field is produced by a 420 G permanent magnet with 50 cm pole separation.…”

“…These resonators are equipped with automatic tuning control (ATC) circuitry to minimize effects of subject motion. Detailed descriptions of this clinical spectrometer are given in the published reports (Salikhov, et al, 2005, Swartz, et al, 2004 and specific modifications to the instrument for tooth dosimetry are given here. Descriptions of another dedicated transportable spectrometer for tooth dosimetry have also been published (Swartz, et al, 2006.…”

“…These combined considerations call for the development of a non-invasive means to perform EPR dosimetry. This development is underway at Dartmouth Medical School (Iwasaki, et al, 2005a, Iwasaki, et al, 2005b, Salikhov, et al, 2005, Swartz, et al, 2006, Swartz, et al, 2004 in normal volunteers with irradiated teeth placed in their mouths and initial measurements with patients who have undergone radiation therapy have begun.…”