Parallel imaging: system design and limitations

Parallel imaging using relatively low acceleration factors (two to three) has become commonplace in clinical MRI. Of interest now are the practical limits to parallel imaging. Factors limiting the use of high acceleration factors are the available number of independent receiver channels and the unavoidable decrease in signal-to-noise ratio with higher acceleration factors. This paper will discuss system design for parallel imaging, including prototype 64 channel MR receivers and 64 element RF coil arrays. These systems have enabled single echo acquisition (SEA) MR imaging. Parallel imaging applications during transmit have also been suggested, and new techniques for implementing independent transmit chains will also be discussed.