title: Four-channel surface coil array for 300-MHz pulsed EPR imaging: proof-of-concept experiments.
abstract: Time-domain electron paramagnetic resonance imaging is currently a useful preclinical molecular imaging modality in experimental animals such as mice and is capable of quantitatively mapping hypoxia in tumor implants. The microseconds range relaxation times (T1 and T2) of paramagnetic tracers and the large bandwidths (tens of MHz) to be excited by electron paramagnetic resonance pulses for spatial encoding makes imaging of large objects a challenging task. The possibility of using multiple array coils to permit studies on large sized object is the purpose of the present work. Toward this end, the use of planar array coils in different configurations to image larger objects than cannot be fully covered by a single resonator element is explored. Multiple circular surface coils, which are arranged in a plane or at suitable angles mimicking a volume resonator, are used in imaging a phantom and a tumor-bearing mouse leg. The image was formed by combining the images collected from the individual coils with suitable scaling. The results support such a possibility. By multiplexing or interleaving the measurements from each element of such array resonators, one can scale up the size of the subject and at the same time reduce the radiofrequency power requirements and increase the sensitivity.
authors.affiliation: Division of Bioengineering and Bioinformatics, Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Hokkaido, Japan.
authors.forename: Ayano
authors.initials: A
authors.lastname: Enomoto
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hirata
authors.forename: Shingo
authors.initials: S
authors.lastname: Matsumoto
authors.forename: Keita
authors.initials: K
authors.lastname: Saito
authors.forename: Sankaran
authors.initials: S
authors.lastname: Subramanian
authors.forename: Murali C
authors.initials: MC
authors.lastname: Krishna
authors.forename: Nallathamby
authors.initials: N
authors.lastname: Devasahayam
mesh_terms: D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000473:pathology*; D045744:Cell Line, Tumor; D004578:Electron Spin Resonance Spectroscopy / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005240:Feasibility Studies; D005260:Female; D007089:Image Enhancement / Q000295:instrumentation*; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation*; D008280:Magnetics / Q000295:instrumentation*; D051379:Mice; D008809:Mice, Inbred C3H; D019047:Phantoms, Imaging; D010865:Pilot Projects; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014159:Transducers