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"It appears that some disbelief was generated by my statement that: "clinical imaging will be possible at 8 tesla and that reasonable quality images can be obtained at this field strength". As a parallel, it is interesting that the first MRI results of the 1980’s were certainly not excellent by today’s standard, yet they were indeed clinically important. While Dr. Roschmann may think that our statement is premature, I believe that it remains appropriate relative to the expectations in existence that human head imaging would be difficult, if not impossible at fields in excess of 5 T. For instance, less than one year ago there were real questions as to whether or not a whole-body 8 tesla magnet could be constructed. In addition, the RF coil technology was thought by many to present a potentially insurmountable hurdle. Most importantly, it was thought that RF power requirements would be much too high at 8 tesla, that RF penetration would render imaging impossible and that dielectric resonance would act to destroy image quality. With all this in mind, I highlight that the first image published in our initial article at 8T is precisely that, the first image. We have now produced many more images and there is no longer any question in my opinion that meaningful and important results will be obtained at this field strength.
...The question of signal to noise at 8 tesla which Dr. Roschmann raises in his letter has also been examined. Initially, we reported that SNR was lower than expected at this field strength. However, after continued effort, we find that the proton SNR at 8.0 tesla is much higher than initially reported, increasing at least linearly with field strength, perhaps even to a greater extent. It is now clear that the proton signal to noise on this system is spectacular and we intend to provide exact numbers in the near future.
...The accompanying letter to the editor also refers to the study of heat exchange and thermal processes and "models like the ultraviolet catastrophe" as irrelevant. In the end, this is the basis of much of the controversy that our first publication has caused.1 Nonetheless, I believe that the entire NMR experiment should be viewed as a quantum mechanical process and that quantum phenomena should be invoked both in dealing with the spins and in addressing issues such as the exchange of heat and RF power. First and foremost, Planck’s work deals with the quantized nature of heat exchange.8 When we are pulsing into our samples, we are also involved in the exchange of heat.""
P.-M. L. Robitaille et. al. NMR Biomedicine 12, 318-319 (1999)