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Bio-magnetic field testing and imaging

Release time:2019-11-12
Funded by ShanghaiTech University (¥2,000,000)
Magnetic field imaging can be utilized for organism inspection. The measured magnetic field can be induced by the electrical activity of the organism or by certain external excitation. For example, electrical activity in the heart produces an ultra-low magnetic field, which can be measured with extremely sensitive devices. If the magnetic field is measured using array sensors, a map of the magnetic field is obtained over the chest; from such a map, using mathematical algorithms that take into account the conductivity structure of the torso, it is possible to locate the source of the activity.
Magnetic resonance imaging (MRI) is an important tool in medical applications. At the heart of all MRI is the nuclear magnetic resonance (NMR). Conventional magnetic resonance imaging (MRI) is moving toward the use of stronger and stronger magnetic fields. However there is another branch of MRI, namely Low Field MRI where the magnetic fields are several orders of magnitude smaller. While conventional high-field MRI remains the gold standard, there are several situations that low field MRI could provide a solution, due to the facts that (1) the MRI contrast can be measured at varied field strengths because the magnetic fields are easier to manipulate;(2) the information obtained at these lower field is different than at high field strength, and (3) in the absence of large magnetic field, certain applications are enabled (e.g., the potential for portable systems for rural or emergency setting).

磁场成像可用于生物检查。测量的磁场由生物体的电活动或某些外部激励引起。例如,心脏电活动产生的超低磁场可以用极其灵敏的探测器测到。如果用阵列传感器测量,则在胸部上方可以得到磁场分布图; 根据躯干的电导率结构并结合数学算法,可以在该分布图上定位活动源。
磁共振成像(MRI)是医学应用领域的重要工具。磁共振成像的核心是核磁共振(NMR)。传统的磁共振成像(MRI)正朝着使用更强磁场的方向发展。然而,MRI还有另一个分支,即低场MRI,其磁场的大小低几个数量级。虽然传统的高场MRI仍然是黄金标准,但是基于以下事实:(1) 由于磁场更容易操控,可以获得在变化场强下的MRI的对比度;(2)低场下获得的信息不同于高场情况;(3)在无强磁场的情况下,某些应用是低场可实现的(例如,用于农村或紧急情况下的便携式系统的潜力) ,在某些情况下,低场MRI可以为实际应用提供解决方案。

Magnetic field of human heart

Pulse sequence of low field MRI