The Physical mechanism of using NMR for cancer detection

As an early developer of using the NMR method for cancer detection, I would like to review the history of the development of this technique and the physical mechanism behind it. Today, the MRI (Magnetic Resonance Imaging) technology is a very powerful tool for detecting cancer development in a patient. Thus, it is important to understand how NMR measurements can differentiate normal cells from pre-neoplastic cells and cancer cells. In this talk, we will review the physical mechanism that allows the NMR measurement to distinguish between the normal cells, the pre-cancer cells and cancer cells. One key point is that the contrast of MRI image was found to be based on difference in nuclear relaxation times (T1 and T2) and spin diffusion rather than based on the concentration difference of cellular water. At present, there is still an active interest to understand the mechanisms behind relaxation time changes of water protons during cancer development. In this talk, I will review several possible physical mechanisms that could explain the relaxation time changes when cells are transformed from the normal state to the pre-cancer, and finally to the cancer state.