title: Performance Characterization of an Actively Cooled Repetitive Transcranial Magnetic Stimulation Coil for the Rat.
abstract: OBJECTIVE
  This study characterizes and validates a recently developed dedicated circular rat coil for small animal repetitive Transcranial Magnetic Stimulation (rTMS).
  
  
  METHODS
  The electric (E) field distribution was calculated in a three-dimensional (3D) spherical rat head model and coil cooling performance was characterized. Motor threshold (MT) in rats (n = 12) was determined using two current directions, MT variability (n = 16) and laterality (n = 11) of the stimulation was assessed. Finally, 2-deoxy-2-((18) F)fluoro-D-glucose ([(18) F]-FDG) small animal Positron Emission Tomography (µPET) after sham and 1, 10, and 50 Hz rTMS stimulation (n = 9) with the new Cool-40 Rat Coil (MagVenture, Denmark) was performed.
  
  
  RESULTS
  The coil could produce high E-fields of maximum 220 V/m and more than 100 V/m at depths up to 5.3 mm in a ring-shaped distribution. No lateralization of stimulation was observed. Independent of the current direction, reproducible MT measurements were obtained at low percentages (27 ± 6%) of the maximum machine output (MO, MagPro X100 [MagVenture, Denmark]). At this intensity, rTMS with long pulse trains is feasible (1 Hz: continuous stimulation; 5 Hz: 1000 pulses; 10 Hz and 50 Hz: 272 pulses). When compared to sham, rTMS at different frequencies induced decreases in [(18) F]-FDG-uptake bilaterally mainly in dorsal cortical regions (visual, retrosplenial, and somatosensory cortices) and increases mainly in ventral regions (entorhinal cortex and amygdala).
  
  
  CONCLUSIONS
  The coil is suitable for rTMS in rats and achieves unprecedented high E-fields at high stimulation frequencies and long durations with however a rather unfocal rat brain stimulation. Reproducible MEPs as well as alterations in cerebral glucose metabolism following rTMS were demonstrated.
authors: Molecular Imaging Center Antwerp, Universiteitsplein 1 - 2610 Wilrijk, University of Antwerp, Antwerp, Belgium.
authors: Joke
authors: J
authors: Parthoens
authors: Molecular Imaging Center Antwerp, Universiteitsplein 1 - 2610 Wilrijk, University of Antwerp, Antwerp, Belgium.
authors: Jeroen
authors: J
authors: Verhaeghe
authors: Molecular Imaging Center Antwerp, Universiteitsplein 1 - 2610 Wilrijk, University of Antwerp, Antwerp, Belgium.
authors: Stijn
authors: S
authors: Servaes
authors: Molecular Imaging Center Antwerp, Universiteitsplein 1 - 2610 Wilrijk, University of Antwerp, Antwerp, Belgium.
authors: Alan
authors: A
authors: Miranda
authors: Molecular Imaging Center Antwerp, Universiteitsplein 1 - 2610 Wilrijk, University of Antwerp, Antwerp, Belgium.|Department of Nuclear Medicine, Wilrijkstraat 10 - 2650 Edegem, University Hospital Antwerp, Antwerp, Belgium.
authors: Sigrid
authors: S
authors: Stroobants
authors: Molecular Imaging Center Antwerp, Universiteitsplein 1 - 2610 Wilrijk, University of Antwerp, Antwerp, Belgium.
authors: Steven
authors: S
authors: Staelens
mesh_terms: D000818:Animals; D001703:Biophysics; D001921:Brain / Q000000981:diagnostic imaging / Q000502:physiology*; D007839:Functional Laterality / Q000502:physiology; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D049268:Positron-Emission Tomography; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D015898:Tomography Scanners, X-Ray Computed; D050781:Transcranial Magnetic Stimulation / Q000379:methods*
keywords: Neurostimulation; functional imaging; motor evoked potentials; rats; transcranial magnetic stimulation