Automatic tuning and matching of a small multifrequency saddle coil at 4.7 T.
A new circuit design for automatically tuning and matching a saddle coil for small animal imaging is presented. This design allows working at (1)H, (19)F, and (3)He resonance frequencies in a 4.7 T spectrometer. It is based on a balanced circuit with commercial variable capacity diodes controlled by a computer using digital potentiometers. The change between two different frequencies can be accurately performed in a few seconds. System Q is compared, between 140-210 MHz, to the same coil tuned and matched with high Q variable capacitors. Differences lower than 5% were found with a loaded coil. The proposed design has initially been evaluated in (19)F and (1)H NMR images acquired with a five-tube phantom. An application is also shown for the acquisition of (3)He, (19)F, and (1)H lung images in a control rat.
de Alejo
Rigoberto Pérez
RP
Instituto de Estudios Biofuncionales, Universidad Complutense de Madrid, Madrid 28040, Spain. pdeafr@ieb.ucm.es
Garrido
Carlos
C
Villa
Palmira
P
Rodriguez
Ignacio
I
Vaquero
Juan José
JJ
Ruiz-Cabello
Jesús
J
Cortijo
Manuel
M
D000703:Analog-Digital Conversion; D000818:Animals; D004867:Equipment Design; D005461:Fluorine; D006371:Helium; D006859:Hydrogen; D007089:Image Enhancement / Q000295:instrumentation*; D007554:Isotopes; D008168:Lung / Q000033:anatomy & histology; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation; D019047:Phantoms, Imaging; D011199:Potentiometry / Q000295:instrumentation; D051381:Rats; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation
D007554:Isotopes; D006371:Helium; D005461:Fluorine; D006859:Hydrogen