MRI Pulse Sequences

MRI – pulse sequences, like spin - echo-, gradient - echo-, inversion recovery sequence + relaxation of a spin

This app is a learning aid for the medicine students. It give you a better understanding for the basic physics of an MRI. In the special case of the pulse sequences and relaxation. The pulse sequences are used in medicine to create measurable 2D images for the definition and precise localization of the tissue areas to be examined.

This app you can use in English and German. Our further reading system let you find more information for MRI in books or other media`s very quickly.
This application is suitable for the cooperation with interactive whiteboards and tablets.


Short explanation to the pulse sequences.
The pulse sequences are selected on the basis of:
- the non-homogeneity of the coil magnetic field
- the material (tissue) to be examined and the magnetization properties of the sample
- the chemical environment of the sample

One flaw in sequence measurement technology is the fact that the signal intensity falls drastically if measurements are repeated before longitudinal relaxation has been completed. In this case, different tissue structures cannot be clearly differentiated and contrasted. To avoid this problem, it is necessary to carry out a number of measurements (pulse sequences) with a repetition time TR which is relatively short with reference to the relaxation time T1, with a relatively long TR and with a TR in the same range as T1.

(a) Spin echo sequence – repetition time TR in roughly the same range: TRT1

(b) Gradient echo sequence - short repetition time TR: TR
(c) Inversion recovery sequence - long repetition time TR : TR>T1