What is the meaning of T 1T2 signal in the nuclear magnetic resonance diagnosis report?

According to the principle of action, MRI contrast agents can be divided into longitudinal relaxation contrast agents (T 1 preparation) and transverse relaxation contrast agents (T2 preparation).

T 1 Preparation Through the direct interaction between hydrogen nuclei in water molecules and paramagnetic metal ions, T 1 is shortened, thus enhancing the signal and making the image brighter.

T2 preparation can shorten T2 by interfering with the inhomogeneity of external local magnetic environment, so that adjacent hydrogen protons can rapidly generate phase during relaxation, thus weakening the signal and darkening the image.

According to the magnetic composition, MRI contrast agents can be divided into paramagnetic, ferromagnetic and superparamagnetic. Gadolinium contrast agent commonly used in clinic belongs to paramagnetic contrast agent.

Extended data

Basic principles of nuclear magnetic resonance;

Atoms, electrons and nuclei all have angular momentum, and the ratio of their magnetic moments to the corresponding angular momentum is called magnetic rotation ratio γ. The magnetic moment m is acted by the moment MBsinθ(θ is the angle between m and b) in the magnetic field b, which makes the magnetic moment precess around the magnetic field. The angular frequency of precession ω=γB, ωo is called larmor frequency. Due to the damping effect, this precession will soon decay, that is, when m reaches parallel to b, the precession will stop.

However, if a high-frequency magnetic field b(ω) is applied in the vertical direction of the magnetic field B (the angular frequency is ω), the moment generated by the action of b(ω) will make M leave B, which is contrary to the damping effect. If the angular frequency of high-frequency magnetic field is equal to the larmor (angular) frequency ω =ωo of magnetic moment precession, the effect of b(ω) is the strongest, and the precession angle of magnetic moment m (the included angle between m and b) is also the largest. This phenomenon is called magnetic vibration.

Baidu encyclopedia-magnetic vibration