Room: Karl Dean Ballroom C
Purpose: To assess and optimize MR image quality and performance when using a custom-built flexible radiofrequency (RF) coil directly under the patientâ€™s spine in conjunction with the immobilization device.
Methods: A sixteen channel custom-designed flexible coil has been developed for spine simulation for a 3T Philips MR scanner. Each coil element has a rigid backing which is flexibly linked to the backing of neighboring elements to permit molding of the coil to the shape of the patient. The signal from each element is digitized at the interface-box and sent to the scanner computer via fiber-optics conduits. A low-profile, flat interface-box was designed that rests directly on top of the indexed flat tabletop. The following tests were performed using the phantom: coil sensitivity assessment, decoupling of the coil elements during body coil transmission, mutual inductance between coil elements, B0 mapping. Phantom and volunteers were scanned with both spine coil and built-in FDA-approved posterior coil to compare the SNR and penetration depth.
Results: The coil is 22x26 cmÂ² in size and is designed to image at least 5 vertebrae. A noise correlation matrix showed at least 25dB isolation between all coil elements. SNR calculated on a phantom scan at the approximate depth of the spinal cord was 30 percent higher with spine coil as compared to the posterior coil. B0 maps within the phantom volume showed no susceptibility effect. The body coil B1 transmit map was equivalent with and without the spine coil in place implying that it is decoupled from the body transmit coil. Volunteer imaging showed 50 percent improvement in SNR at the vertebrae level as compared to the posterior coil.
Conclusion: The custom-designed flexible spine coil provided enhanced SNR compared to the FDA-approved coil. Future studies will include testing the coil on patients for spinal cord and tumor imaging.