As an extension of the previously developed microstrip transmission line (MTL) RF coil design, a high-frequency RF volume coil using multiple inverted MTL (iMTL) resonators for human head imaging at high magnetic field strength of 7 tesla (T) is reported. Compared to conventional MTL resonators, iMTL resonators can operate at higher frequency with lower losses and, thus, are suitable for designs of high-frequency RF volume coils with large coil size for human MR imaging and spectroscopy at high fields. An approach using capacitive terminations was analyzed and applied to the design of the iMTL volume coil for improving RF field homogeneity and broadening frequency-tuning range. A performance-comparison study was conducted between the prototype iMTL volume coil and a custom-built TEM volume coil at 7 T. The iMTL volume coil presents a comparable SNR and intrinsic B1 homogeneity to the TEM volume coil. Phantom and the human head images acquired using the iMTL volume coil are also presented. The proposed iMTL volume coil provides an efficient and alternative solution to design high-frequency and large-size volume coils for human MR applications at very high fields.
Bibliographical noteFunding Information:
Manuscript received January 15, 2004; revised July 17, 2004. This work was supported in part by National Institutes of Health (NIH) under Grant EB00513, Grant NS38070, Grant NS39043, Grant NS41262, Grant EB00329, and Grant P41 RR08079 (a National Research Resource grant from NIH), and in part by the W. M. Keck Foundation and the MIND institute. Asterisk indicates corresponding author.
- High field
- Human brain
- Inverted microstrip transmission line resonator
- MR imaging
- MTL volume coil
- RF coil