title: Evaluation of the RF field uniformity of a double-tuned 31P/1H birdcage RF coil for spin-echo MRI/MRS of the diabetic foot.
abstract: OBJECTIVE
  To evaluate the B1 field uniformity of a double-tuned birdcage coil designed for (31)P/(1)H MRI/MRS spin-echo (SE) imaging of the metatarsal head region of the foot in neuropathic diabetic patients.
  
  
  METHODS
  A low-pass double-tuned (31)P/(1)H RF birdcage coil was constructed to fit over the adult forefoot. Flip angle (FA) maps were created from B1 data acquired at the 3T (31)P (four normal subjects) and (1)H (five normal subjects) frequencies. T2-weighted (T2-W) (1)H images, (31)P rapid acquisition with relaxation enhancement (RARE) images, and composite SE pulse CSI data were acquired to demonstrate the uniformity of the resulting images and data.
  
  
  RESULTS
  The means and standard deviations (SDs) of the range of FAs across the feet of the volunteer subjects indicated good uniformity (the maximum coefficients of variation (CVs) for all of the (31)P and (1)H FA maps were 7.6% and 7.3%, respectively). The FA values across the metatarsal head region indicated a maximum signal intensity variation of +/-3% in a RARE image acquired using an echo train length of 32.
  
  
  CONCLUSIONS
  A (31)P/(1)H birdcage coil constructed for MRI/MRS studies of the human forefoot provided sufficient signal uniformity of SE data to facilitate accurate (31)P concentration measurements in muscle.
authors.affiliation: Department of Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02115, USA. rgreenma@bidmc.harvard.edu
authors.forename: Robert L
authors.initials: RL
authors.lastname: Greenman
authors.forename: Rebecca
authors.initials: R
authors.lastname: Rakow-Penner
mesh_terms: D017719:Diabetic Foot / Q000175:diagnosis*; D004867:Equipment Design; D006801:Humans; D006859:Hydrogen; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation* / Q000379:methods; D008684:Metatarsus; D010759:Phosphorus Isotopes
chemical_list: D010759:Phosphorus Isotopes; D006859:Hydrogen