Source: Panda Radiation
Author: Hua Renqing
A brief analysis of T1 and T2 parameters in nuclear magnetic resonance
1. T1 observes the anatomical structure well.
2. T2 shows good tissue lesions.
3, water is long T1 long T2, fat is short T1 long T2.
4. Long T1 is low signal (dark), short T1 is high signal (bright).
5. Long T2 is high signal (bright), short T2 is low signal (dark).
6, water T1 black, T2 white.
7, fat T1 white, T2 gray.
8. T2 is sensitive to bleeding, because water T2 is white.
T1-weighted imaging, T2-weighted imaging
The so-called weighting means "prominent"
T1-weighted imaging (T1WI) ---- highlight differences in tissue T1 relaxation (longitudinal relaxation).
T2-weighted imaging (T2WI) ---- highlight differences in tissue T2 relaxation (transverse relaxation).
On any sequence image, the larger the lateral magnetization vector at the moment of signal acquisition, the stronger the MR signal.
T1 weighted image short TR, short TE - T1 weighted image, T1 image features: the shorter the T1 of the organization, the faster the recovery, the stronger the signal; the longer the T1 of the organization, the slower the recovery, the weaker the signal.
T2-weighted image Long TR, long TE - T2 weighted image, T2 image characteristics: the longer the T2 of the organization, the slower the recovery, the stronger the signal; the shorter the T2 of the organization, the faster the recovery, the weaker the signal.
Proton density weighted image Long TR, short TE - proton density weighted image, image characteristics: the greater the rH of the tissue, the stronger the signal; the smaller the rH, the weaker the signal. White matter: 65 % Gray matter: 75 % CSF: 97 %
Fat and bone marrow are high signals on T1WI, T2WI, and PDWI (proton-weighted images).
Muscles, tendons, ligaments: Muscles are moderately strong (black gray or gray) on T1WI, T2WI, and PdWI. Tendon and ligament tissue contains more fiber components, its proton density is lower than that of muscle, its signal intensity is slightly lower than that of muscle tissue, the tissue also has long T1 and short T2, and its MR signal is equal signal or lower signal.
Skeletal, calcified: T1WI, T2WI, and PDWI images all have absent (low) signal areas.
Cartilage: The signal strength on T1 and T2 weighted images is not high, showing a medium and low signal
Blood flow: Rapidly flowing blood has low (no) signal vascular shadow on various imaging due to its "emptying effect"; while slow or irregular blood flow, such as turbulence, swirling, etc., increases and uneven intravascular signals.
Lymph nodes: lymph node tissues have a higher proton density and are characterized by longer T1 and shorter T2 relaxation. According to the signal strength formula, the proton density is high and the signal strength is also high. However, in T1WI, because of its long T1 characteristics, its signal strength is not high, showing a medium signal; and on T2WI, because its T2 is not long, the signal strength increases not much, and it is also a medium signal.
Edema:
Regardless of the type of edema, the increase in water content in the intracellular or interstitial space prolongs the T1 and T2 values and decreases the Pd value, so the edema region shows a lower signal in the T1WI and PDWI images, while the high signal is obvious on the T2WI image, and the contrast is stark.
【Copyright Notice】This platform is a public welfare learning platform, reprinted for the purpose of transmitting more learning information, and has indicated the author and source, such as teachers who do not want to be disseminated can contact us to delete