What is the NMR phenomenon?

Everything in the world is made up of molecules, and molecules are made up of atoms, which are made up of nuclei and electrons revolving around the nucleus, which in turn are made up of positively charged protons and uncharged neutrons. The motion of many atomic nuclei is similar to a "spin body", constantly spinning at a certain frequency, if you try to make it enter a constant magnetic field, it will rotate in the direction of the magnetic field, then use a specific radio frequency electromagnetic wave to irradiate these objects containing atomic nuclei, the object will significantly absorb the electromagnetic wave, which is the nuclear magnetic resonance phenomenon.

In the 80s of the 20th century, a new scanning technology - magnetic resonance imaging (MRI) appeared. This is a scanning technique that allows the body to avoid X-ray damage; It is the crystallization of advanced sciences such as electronics, electronic computer technology, CT technology and magnetic resonance spectroscopy.

There is a large amount of water (H2O) in the human body, MRI is the use of hydrogen (H) atoms in the human body, in the strong magnetic field after being excited by the pulse, the magnetic resonance phenomenon, through space coding technology, the electromagnetic waves emitted in the magnetic resonance process (i.e., magnetic resonance signal) and the proton density, relaxation time, flow effect and other parameters related to these electromagnetic waves, receive and convert, through the processing of electronic computers, and finally form an image to make a diagnosis.

In the use of MRI, the patient does not need to be exposed to ionizing radiation, thus avoiding the damage that X-rays can cause to the human body. MRI can not only provide images of anatomical information of the examined parts like CT, but also provide us with images of physiological and biochemical information about tissues, distinguish normal or abnormal tissues more sensitively than CT, provide us with correct organ function and physiological conditions, and clearly show the location and scope of the lesion through the image, and often warn people before the shape and function of the organ at the lesion have not changed significantly, so it is of great help to the early detection of the tumor and the identification of the nature of the tumor.

The nucleus of an atom can rotate in a magnetic field, and the frequency and direction of its rotation are determined by the strength and direction of the magnetic field. The nucleus that rotates in the magnetic field can absorb electromagnetic waves of the same frequency, increasing the energy of the nucleus; When the nucleus returns to its original state, the absorbed energy is released in the form of electromagnetic waves. This phenomenon is called the NMR phenomenon.

This is applied in chemistry. NMR is one of the most important methods used to detect organic matter.

What is NMR? What is Spin? Fundamentals of NMR.

Magnetic resonance imaging is a technique that reveals "chemical images" of the interaction of the body's "superatomic structure (protons)".

To understand this technique, it is necessary to know what the NMR phenomenon is.

The nucleus of any atom that has an odd number of protons or neutrons, or both, in its nucleus has the property of being charged and spinning around a spin axis in a certain direction. In this way, there is a weak magnetic field around the nucleus. We can think of each atom as a "magnetic needle" with a certain magnetic moment.

In the tissues of our human body, there are quite a few atoms with this property, such as hydrogen, fluorine, sodium, phosphorus, and many more. In medicine, nuclear magnetic resonance imaging is the use of the largest amount of hydrogen in the human body, accounting for 70% of the body's body weight, the resonance imaging of its protons.

So, why don't hydrogen protons in the human body show magnetism in general?This is because the spin shafts of these protons are arranged out of order, have no certain direction, and cancel out the magnetic moments of each other.

If you put the human body in a strong external magnetic field, the situation is different. At this time, the magnetic axes of the protons with electromagnetism in the body will be rearranged parallel to each other according to the direction or reverse of the external magnetic field, and the magnetic axis will be in a low-energy state if it conforms to the direction of the external magnetic field, and vice versa. On this basis, a short radio frequency pulse perpendicular to the direction of the external magnetic field is added, which excites the spin protons to obtain a transverse magnetic moment and produces a propulsion motion, and part of the spin protons absorb the energy of the radio frequency pulse, transitions to a high-energy state, and even pauses the pulse and emits an electromagnetic wave signal, which is a series of processes, which is the magnetic resonance phenomenon.

The time it takes for a spin proton to fully recover to its equilibrium state before being excited by a radiofrequency pulse is called the "relaxation time".

Human tissues and organs and their diseases, in the process of magnetic resonance, different tissues, their magnetic resonance signal intensity is different, the relaxation time is also different, so as to show different images. Such images not only provide clear anatomical details, but also provide physical, chemical, biological, and biochemical diagnostic information inside and outside tissues, organs, and lesions.

Everything in the world is made up of molecules, and molecules are made up of atoms, which are made up of nuclei and electrons that revolve around the nucleus, which in turn is made up of bands.

Positive charge. of protons and uncharged neutrons. The motion of many atomic nuclei is similar to that of a "spin body", constantly spinning at a certain frequency, if you try to make it enter a constant magnetic field, it will rotate in the direction of this magnetic field, and then use a specific radio frequency electromagnetic wave to irradiate these objects containing atomic nuclei, and the object will significantly absorb the electromagnetic wave, which is.

Nuclear magnetic resonance. Phenomenon.

In the 80s of the 20th century, a brand new. Scanning technology.

MRI.

MRI for short appeared. This is a scanning technique that allows the body to avoid X-ray damage; It's electronics

Computer.

technology, CT technology, and magnetic resonance spectroscopy, etc.

Advanced science. crystallization.

There is a large amount of water (H2O) in the human body, MRI is the use of hydrogen (H) atoms in the human body, in the strong magnetic field after being excited by pulses, the magnetic resonance phenomenon, through space coding technology, the electromagnetic waves (that is, magnetic resonance signals) emitted in the magnetic resonance process and the proton density related to these electromagnetic waves,

Relaxation time. , flow effect and other parameters, receiving and converting, processing by electronic computer, and finally forming an image to make a diagnosis.

In the use of MRI, the patient does not need to be touched.

ionizing radiation, thus avoiding the damage that X-rays can cause to the human body. MRI can not only provide images of anatomical information of the examined parts like CT, but also provide us with images of physiological and biochemical information about tissues, distinguish normal or abnormal tissues more sensitively than CT, provide us with correct organ function and physiological conditions, and clearly show the location and scope of the lesion through the image, and often warn people before the shape and function of the organ at the lesion have not changed significantly, so it is of great help to the early detection of the tumor and the identification of the nature of the tumor.