SBIR Phase II: Low-Cost, High-Efficiency Power Amplifiers for Magnetic-Resonance Imaging

This Small Business Innovation Research Phase II will develop and test a prototype low-cost, high-efficiency transmitter for magnetic-resonance-imaging (MRI) systems. Existing MRI transmitters use conventional power amplifiers (PAs), which makes them inefficient and consequently large, heavy, and expensive. Phase I has demonstrated the feasibility of using developed high-efficiency amplification techniques to produce significantly more power from a given transistor, thus lowering the cost. Also demonstrated was the feasibility of using these amplifiers to produce the pulsed-RF signals used by MRI. Phase II will develop a prototype transmitter that combines high-efficiency power amplification with digital signal processing to provide both low cost and superior signal quality. This in turn will produce superior image quality, resulting in improved diagnostics. The transmitter will be organized into broadband RF-power modules that can be combined in building-block fashion to produce transmitters for different MRI applications. The prototype transmitter will be configured into a manufacture able form to facilitate transition to Phase-III commercialization. Finally, the prototype transmitter will be tested in an MRI system and images obtained will be compared to those obtained with a conventional transmitter.

The primary commercial application for the new transmitter is medical imaging. Every MRI system includes a high-power RF transmitter. The manufacturers of MRI systems purchase transmitters from smaller manufacturers. The RF transmitter is the most expensive subsystem, and keeping the cost down is of great interest. The building-block approach allows all market segments to be addressed, beginning with the lower-power "1-T" systems for specialized applications and moving subsequently to higher-power "3-T" systems for high-resolution whole body scans. The combination of lower cost and superior signal quality is expected to make the proposed transmitter very attractive to systems manufacturers. Secondary applications include security systems such as suitcase scanners and communication radios for both civilian and military applications.