科研之友
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摘要
The ability to produce hyperpolarized noble gases He-3 and Xe-129 has opened up exciting possibilities for pulmonary magnetic resonance imaging (MRI). We have recently built a hyperpolarizer with the goal of using hyperpolarized He-3 gas for MRI in neonatal lungs in a dedicated small foot-print 1.5 T MR scanner developed at our institution and sited in our Neonatal Intensive Care Unit. Although hyperpolarized gas imaging can provide unique insights into lung ventilation, acinar microstructure, and gas-exchange dynamics, there is an undiminished need for H-1 MRI of the lung to provide anatomic references, B-1 and B-0 maps, and H-1 images of lung parenchyma. To address this need, we designed, built and tested a novel radiofrequency body coil that provides a high-pass birdcage coil that can be used for both He-3 and H-1 frequencies (48.65 and 63.86 MHz, respectively, at 1.5 T). To switch between frequencies, the birdcage coil has a large mechanical actuator that simultaneously changes the capacitance between every rung of the birdcage. Advantages of this coil design include: 1) quadrature excitation and reception at the He-3 and H-1 frequencies, 2) identical B-1 field maps for He-3 and H-1 imaging, 3) excellent signal-to-noise ratio and B-1 homogeneity at both frequencies, and 4) rapid (10-20 s) switching times between He-3 and H-1 operation. This report provides details of the coil's design and fabrication. Images of hyperpolarized He-3 and H-1 in phantoms and ex vivo rabbit lungs demonstrate the image quality obtained with the coil.
- 出版日期2015-10
