title: Construction and evaluation of a switch-tuned (13) C - (1) H birdcage radiofrequency coil for imaging the metabolism of hyperpolarized (13) C-enriched compounds.
abstract: OBJECTIVE
  To construct a switch-tuned (13) C - (1) H birdcage radiofrequency (RF) coil system capable of metabolic imaging of hyperpolarized (13) C-enriched metabolic probes for co-registration with MRI morphology using protons.
  
  
  METHODS
  The switch-tuned coil was constructed using PIN diodes for rapid switching of the resonant frequency of the coil. Identical, single-tuned, (1) H and (13) C birdcage RF coils have also been constructed for comparison of imaging performance. A (13) C receive-only surface RF coil has been integrated with the switch-tuned coil for transmit-only, receive-only operation (TORO) to increase local (13) C signal for improved signal-to-noise ratio (SNR).
  
  
  RESULTS
  The SNR achieved with the switch-tuned coil in transmit/receive mode was 87% that of the single-tuned (1) H coil. For (13) C imaging, the SNR for the switch-tuned coil was 55% that of the single-tuned (13) C coil. TORO operation of the switch-tuned coil with the surface coil increased SNR for by a factor of 4.2 over transmit/receive operation of the switch-tuned coil alone.
  
  
  CONCLUSIONS
  A surface coil can be integrated with a switch-tuned (13) C - (1) H coil for (13) C TORO operation producing improved SNR. In vivo metabolic imaging of [1-(13) C]pyruvate in a rat model of glioma is demonstrated using TORO operation, which is co-registered with (1) H-imaged anatomy.
authors.affiliation: Department of Medical Biophysics, Western University, London, Ontario, Canada.
authors.forename: Heeseung
authors.initials: H
authors.lastname: Lim
authors.forename: Kundan
authors.initials: K
authors.lastname: Thind
authors.forename: Francisco M
authors.initials: FM
authors.lastname: Martinez-Santiesteban
authors.forename: Timothy James
authors.initials: TJ
authors.lastname: Scholl
mesh_terms: D000818:Animals; D001932:Brain Neoplasms / Q000378:metabolism*; D066241:Carbon-13 Magnetic Resonance Spectroscopy / Q000295:instrumentation*; D004867:Equipment Design; D005910:Glioma / Q000378:metabolism*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D009368:Neoplasm Transplantation; D019047:Phantoms, Imaging; D011522:Protons; D019289:Pyruvic Acid / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D011522:Protons; D019289:Pyruvic Acid
keywords: Carbon-13; chemical shift imaging; dual-frequency RF hardware; hyperpolarized imaging