Design and comparison of two eight-channel transmit/receive radiofrequency arrays for in vivo rodent imaging on a 7 T human whole-body MRI system

• Published in: Medical physics (Lancaster) 2010-05, Vol.37 (5), p.2225-2232
• Main Authors: Orzada, Stephan, Maderwald, Stefan, Göricke, Sophia L., Parohl, Nina, Ladd, Susanne C., Ladd, Mark E., Quick, Harald H.
• Format: Article
• Language: English
• Subjects: 7 Tesla; Animals; biomedical MRI; Brain; Brain - radiation effects; Capacitors; Coils; Female; G factor; Humans; Magnetic resonance; Magnetic resonance imaging; Magnetic Resonance Imaging - instrumentation; Medical image noise; Medical imaging; Medical magnetic resonance imaging; Mice; parallel MRI; patient monitoring; phantoms; Radio Waves; Rats; rodent imaging; Spatial resolution; transmit/receive RF array; ultra high field; Whole Body Imaging - instrumentation
• ISSN: 0094-2405; 2473-4209
• DOI: 10.1118/1.3378478

Purpose: Magnetic resonance imaging (MRI) of rodents can be expected to be a growing application, particularly when translatory imaging research “from mouse to man” is envisioned. 7 T high-field human whole-body MR systems provide a powerful platform for high-resolution small animal imaging. For achieving adequate spatial resolution, dedicated radiofrequency coils have to be designed to provide the necessary signal-to-noise ratio (SNR). Methods: Two different multichannel transmit/receive radiofrequency (RF) arrays for high-resolution imaging of rodents on a human whole-body 7 T MR system have been developed and evaluated in comparativein vitro phantom experiments and in vivo experiments in rats. The first coil was a one-channel birdcage RF transmit/eight-channel loop RF receive phased-array coil; the second coil was an eight-channel RF transmit/receive stripline phased-array coil with inverted microstrip lines—A coil design that here is described for the first time for dedicated small animal MR imaging. Results: Both coil setups provided the high SNR necessary for high-resolution MRI in rodents. The eight-channel loop RF array, with its larger inner diameter and transparent layout, provided better overall signal homogeneity and enabled easy visual monitoring; the eight-channel stripline RF array provided overall higher SNR and better parallel imaging acceleration performance. Conclusions: The results show that both coil designs are suitable for small animal imaging on 7 T whole-body systems; the preferred coil depends on the demands of the application.