Biomagnetic Resonance and Ultra-low Field Nuclear Magnetic Resonance
관련링크
본문
" Matching the nuclear magnetic resonance (NMR) frequency to the frequency of a periodic electrophysiological activity enables direct visualization of the corresponding bio-function. I named the technique biomagnetic resonance. As for the applications of the biomagnetic resonance techniques, I introduce heart magnetic resonance (HMR) [1] and brainwave magnetic resonance (BMR) [2]. HMR could be applied to development of a medical instrument localizing an abnormal myocardial excitation in hearts. In arrhythmia like atrial fibrillation or flutter, the excitation has rhythmic activity with its own characteristic frequency. The main idea of HMR is to match the NMR frequency to the specific frequency of the abnormal heart activity so that we could find the position of the reentry current generation by using the conventional magnetic resonance imaging (MRI) methods. In BMR, matching the NMR frequency to the frequency of a periodic neural oscillation like alpha- or gamma-band waves enables direct visualization of the brain functional connectivity by MRI. Generally, the frequency of electrophysiological oscillation is very low, we need a new measurement technique other than using an inductive coil, which has consistent sensitivity even for such a low frequency. Currently, micro-Tesla NMR techniques based on superconducting quantum interference device (SQUID) are widely spreading in various applications like T1-enhanced contrast imaging for mapping cancer tissues. I demonstrate the feasibility of the new ideas by conducting numerical simulations and multi-source phantom MRI experiments with a SQUID-based micro-Tesla MRI equipment.
Meanwhile the micro-Tesla NMR has its own principal advantages in specific measurements. However, it has also intrinsic disadvantages like slowness in the pulse sequence, need of prepolarization, low signal to noise ratio from wide detection bandwidth. In this talk, I introduce several breakthrough techniques which circumvent the disadvantages; rotary pulse excitation breaking the pulse-strength limitation from Bloch-Siegert effect and its applications, robust Baysian T1 estimation for low SNR measurements, artifact rejection in high-prepolarization measurements, etc.
[1] K. Kim, Toward cardiac electrophysiological mapping based on micro-Tesla NMR: a novel modality for localizing the cardiac reentry, AIP Adv. 2, 022156 (2012).
[2] K. Kim, S.-J. Lee, C.S. Kang, S.-m. Hwang, Y.-H. Lee, K.K. Yu, Toward a brain functional connectivity mapping modality by simultaneous imaging of coherent brainwaves, Neuroimage 91(1; cover article), 63-69 (2014)."
Meanwhile the micro-Tesla NMR has its own principal advantages in specific measurements. However, it has also intrinsic disadvantages like slowness in the pulse sequence, need of prepolarization, low signal to noise ratio from wide detection bandwidth. In this talk, I introduce several breakthrough techniques which circumvent the disadvantages; rotary pulse excitation breaking the pulse-strength limitation from Bloch-Siegert effect and its applications, robust Baysian T1 estimation for low SNR measurements, artifact rejection in high-prepolarization measurements, etc.
[1] K. Kim, Toward cardiac electrophysiological mapping based on micro-Tesla NMR: a novel modality for localizing the cardiac reentry, AIP Adv. 2, 022156 (2012).
[2] K. Kim, S.-J. Lee, C.S. Kang, S.-m. Hwang, Y.-H. Lee, K.K. Yu, Toward a brain functional connectivity mapping modality by simultaneous imaging of coherent brainwaves, Neuroimage 91(1; cover article), 63-69 (2014)."
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