An efficient scheme for fast three dimensional acquisition of sodium MR images is described. This scheme relies on the use of three dimensional k-space trajectories with constant sample density to achieve significant (60-70%) reductions in total data acquisition time over conventional projection imaging schemes. The performance of this data acquisition scheme is demonstrated with acquisition of sodium data sets on phantoms and normal human volunteers at 1.5 and 3.0 Tesla. The experimental results demonstrate that high quality three dimensional sodium images (0.2 cc voxel size, 10:1 signal-to-noise ratio) can be acquired at clinical field strengths (1.5 Tesla) in under 10 min.

A scheme for the reduction of T2 signal attenuation effects in three-dimensional twisted projection imaging is presented. By purposely reducing the sample density at the high spatial frequencies, a considerable reduction in readout time is achieved. The reduction in readout time leads to decreased T2 signal attenuation which translates into improved signal-to-noise ratio (SNR). The SNR improvement is achieved without decreasing the image's resolution since the point spread function depends on the sample weighting as well as the T2 attenuation. The results indicate that SNR improvements of up to 40% can be achieved using the proposed scheme.

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Jitter Amplification is a real concern in the design of PCB clock channels if the frequency of the clock is high and the PCB trace is relatively long. In this paper, we confirm the earlier finding of clock channel jitter amplification [1], using a multiple edge response (MER) simulation method instead of jitter impulse response for the channel. However, we show that both white Random Jitter (wRJ) and Sinusoidal Jitter (SJ) amplification are a function of the signal loss in the channel, and as such, are reduced significantly with equalization. Furthermore, simulated CMOS Tx RJ, which is dominated by its low frequency components, is amplified less than is wRJ, even for channels with >20dB signal loss. Measurement results are correlated with simulations for 2-6 GHz clocks on a channel containing 24-inches of PCB trace.

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