Transceiver 4-leg birdcage for high field MRI: knee imaging

Abstract

The radiofrequency coil is a crucial component of the magnetic resonance imaging scanners, so that a solid knowledge on the design and physical characteristics is important for those interested in its development. A birdcage coil with a 10 cm radius and 4 legs (length = 12cm), and a separation between the copper strips of 4 cm, was developed for magnetic resonance imaging (MRI) of the human knee and tuned at the resonance frequency of protons at 4 Tesla (170.3 MHz). MR images were acquired with this coil in phantoms and in the knee of a healthy volunteer using a standard spin echo sequence, The phantom images demonstrated the high uniformity of the radiofrequency field with high signal-to-noise ratio, a characteristic of all birdcage RF coils. The in vivo knee images demonstrated that this birdcage geometry is ideal for knee imaging, promising MR images of the knee with higher spatial resolution at 4 Tesla. This work also demonstrates that volume coils are a good choice for high-field MRI applications.