Atomic and Nuclear Physics

Biography

Biography: Masayoshi Tanaka

Abstract

Though the MRI (Magnetic Resonance Imaging) is widely used as a tool for medical diagnoses, its usefulness is rather restricted because of less pronounced NMR (Nuclear Magnetic Resonance) signals due to the smallness of nuclear polarization created at room and body temperature. As a result, it becomes difficult to obtain the images for low-density organs like a lung in a short measuring time. To break this restriction, we started developing a hyperpolarized MRI, where nuclear polarization is generated artificially by sophisticated technologies in nuclear physics or atomic physics, with which we hope the NMR signals would be orders of magnitudes enhanced relative to the NMR systems used so far, thus enabling us to obtain images with high resolution. Currently, we are constructing a device for hyperpolarized 3He gas by means of the Brute Force method with a strong high magnetic field (~17T) and an extremely low temperature (<100mK) and a device for hyperpolarized 19F in PFC (PerFluoro Carbon) often used as an artificial blood by means of the PHIP (ParaHydrogen Induced Polarization) method. No doubt, the PHIP will be successful, the lung image with the very expensive hyperpolarized 3He may be replaced with the cheap PFC. Further, it will be shortly touched that the hyperpolarized 17O MRI may be a potential tool instead of the risky radioactive 15O PET (Positron Emission Tomography) widely used for diagnosis of the brain diseases such as apoplectic stroke. Finally, let me ask for your attention on possibility to detect cancer cells with the hyperpolarized 13C MRI by measuring the rapid change of the chemical shifts due to the metabolic reactions in the cancer cells.