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Planar‐pair local coils for high‐resolution magnetic resonance imaging, particularly of the temporomandibular joint
Author(s) -
Hyde James S.,
Froncisz Wojciech,
Jesmanowicz Andrzej,
Kneeland J. Bruce
Publication year - 1986
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.595934
Subject(s) - electromagnetic coil , planar , optics , materials science , physics , dipole , nuclear magnetic resonance , resolution (logic) , excitation , image resolution , magnetic resonance imaging , medicine , computer graphics (images) , quantum mechanics , artificial intelligence , computer science , radiology
The two‐loop–one‐gap loop–gap resonator (planar pair) has been investigated as a local receiving coil for high‐resolution proton imaging at 1.5 T (63.8 MHz). Sensitivity contours were determined on the bench by measuring the voltage induced in the coil when it is placed on the surface of a tank containing 0.1‐M NaCl, as a function of the coordinates and orientation of a radiating dipole inside the tank. Contours were obtained as a function of the diameter D of the two loops, and their separation d . For comparison, considerable data also were obtained for single‐turn circular loops as a function of loop diameter. Coil quality factors, Q 's, are reported in free space and the saline tank as a function of geometric parameters. Contours also were obtained using phantoms in a whole‐body imager. Planar‐pair coils couple to slabs of approximately (2 D + d )× D cross section, and are superior to circular coils for imaging anatomic structures that are somewhat elongated. A particularly important feature of planar‐pair local coils is that they are intrinsically isolated from the whole‐body coil of the imager, and no special passive or active circuits are required when the whole‐body coil is used for excitation. Planar‐pair local coils have been optimized for imaging of the temporomandibular joint, and an image is shown.