Exhibit Hall | Forum 1
Purpose: To investigate new radiofrequency (RF) coil configurations aiming to improve image quality for framed Gamma Knife (GK) MRI.
Methods: A large ACR MRI phantom was imaged on a 3T GE Premier using a 3D FSPGR sequence with three different RF coil configurations: (1) a quadrature head coil (qHC) (the standard of care [SOC]); (2) the posterior section of a 48-channel head coil in combination with a 20-channel AIR coil positioned anteriorly (HC+AIR); and (3) a 21-channel AIR coil positioned posteriorly and a 20-channel AIR coil positioned anteriorly (AIR+AIR). Image uniformity correction was applied to the HC+AIR and AIR+AIR configurations. Spatial resolution, low-contrast detectability, and percent image uniformity were measured with the ACR method. Signal-to-noise ratio (SNR) was quantified with the NEMA method. A GK grid phantom was placed inside a GK head frame and scanned in each of the RF coil configurations to assess its compatibility and the geometric distortion.
Results: Posterior GK frame screws were found making contact with the head coil in the HC+AIR configuration, which could lead to patient discomfort. The GK frame cradle also could not fit in this configuration. The AIR+AIR configuration enabled circumferential vicinity of coil elements around the GK frame, and allowed the GK frame cradle to be used, similar to the SOC. SNR of the qHC, HC+AIR, and AIR+AIR configurations were 70.3, 163.5, and 170.0. The HC+AIR and AIR+AIR configurations had similar geometric distortion as the qHC.
Conclusion: The AIR+AIR configuration provided a more than two fold improvement in SNR over the SOC. This new RF coil configuration may not only improve image quality, but can also be used to reduce scan time by reducing the number of averages and/or enabling parallel imaging. Clinical implementation of the new technique is expected to improve lesion detectability and potentially improve treatment plan quality.