In the se sequence te is the time from the 90° pulse to signal generation.
se sequence this means spin echo is a scanning sequence of nuclear magnetic **** vibration, a method of determining the transverse relaxation time in the case of inhomogeneous static magnetic field can not be determined.
It in the static magnetic field hanging with the direction plus 90 ° - τ - 180 ° electromagnetic pulse sequence. 90 ° pulse so that the magnetization intensity at the flip in the y axis, become the magnetization intensity of the transverse component of the non-uniform magnetic field under the influence of the phase is quickly dispersed.
The echo time TE is the time interval from the midpoint of the pulse that produces the macroscopic transverse magnetization vector to the midpoint of the echo.Substantially the echo time TE is defined differently on different sequences:
1.In the spin echo SE sequence, TE is the time from the midpoint of the 90° pulse excitation to the midpoint of the echo signal generation.
2, in the fast self-selecting echo sequence FSE, because after the 90-degree pulse excitation, followed by a lot of focusing pulses, this time after how many focusing pulses, our echo chain length ETL is how much, at this time, the introduction of the effective echo time (ETE), is that there are more than one echo signal generated in the sequence after an RF pulse excitation, one time to fill in the k-space on one coding line.
3. Effective echo time was also introduced in planar echo imaging (EPI).
4, In a gradient echo sequence echo time TE refers to the time interval between the midpoint of the small angle excitation pulse and the midpoint of the gradient echo generation.
Introduction of nuclear magnetic **** vibration:
Nuclear magnetic **** vibration, also known as magnetic **** vibration imaging, is a kind of imaging equipment used for medical imaging examination, magnetic **** vibration imaging, is more commonly used in hospitals as a kind of imaging method, the principle of work and ct is completely different, no radiation.
Magnetic **** vibration imaging is a method of clinical medicine auxiliary diagnostic examination, the principle of nuclear magnetic **** vibration is through the advanced medical technology acquisition and contrast analysis, electromagnetic signals in the human body after the changes in the various tissues, organs, in the form of images to show.
Magnetic **** vibration imaging is generally widely used central nervous system examination methods, generally speaking is to check the cranial magnetic **** vibration, cervical thoracic spine, thoracic spine magnetic **** vibration, lumbar vertebrae magnetic **** vibration, the brain parenchyma, spinal cord is the most ideal effect of the examination, in addition to the examination of the abdominal organs and so on.