**4. Tissue parameters**

respiratory artifacts are sometimes problematic in cases where the respiratory compensation techniques are not compatible with the programs fast spin-echo, which is counterbalanced to some extent by the fact that shorter examination times in fast spin-echo sequence enable the

36 Imaging and Radioanalytical Techniques in Interdisciplinary Research - Fundamentals and Cutting Edge Applications

There are two differences in contrast between the pulse sequence of the conventional spinecho and fast spin-echo, both of which are due to the 180º pulse repeated at short intervals following the sequence of echoes. First, the adipose tissue remains clear on T2-weighted images due to multiple RF pulses that reduce the effects of spin-spin interactions in this tissue. However, the fat saturation techniques may be used to compensate for this. Second, the 180º repeated pulses may increase the magnetization transfer, so that the muscles appear darker on the fast spin-echo images than on the conventional spin-echo images. Additionally, multiple 180º pulses reduce the effects of magnetic susceptibility, which may be detrimental when

The advantages of fast spin sequence are that metal implant artifacts are significantly reduced

In fast spin-echo T1-weighted images, effective TE and TR are short; on T2-weighted effective TE and TR are long TR; on proton density weighting/T2-weighted images, effective TE is short

The advantages are: Greatly reduced examination times, better image quality, and more information on T2-weighted images. We can use high-resolution matrices and multiple numbers of excitations (NEX). However, some effects of increased flow and movement are incompatible with some options of image acquisition, such as fat tissue bright on T2-weighted images, blurred images can occur because data were collected at different TE time, decreased magnetic susceptibility effect, because multiple 180º pulses produce excellent returning phase,

The "inversion-recovery" sequence is used to promote suppression or fat saturation, high‐ lighting areas of injury. The process was the reverse of the "spin-echo" sequence. There was an inversion followed by a recovery by applying 180º inversion pulses, which inverted the spins of the fatty tissue region examined by 180º, followed by 90º recovery pulse. Subsequently, a 180º repolarizing pulse was applied to produce a spin-echo. In this sequence, the repetition time (TR) is the time between each 180º pulse. The inversion time (TI) is the length of time the

This process allowed the fat to become dark or hypointense, differing itself from the lesions. This happened because the inversion of its spins caused a total loss of energy/magnetization.

The field of view (FOV) determines the size of the anatomy covered during the selection of the tissue section to be analyzed either in a coronal or axial plane.The forming unit of a digital image is the pixel. The brightness of each pixel represents the power of the MR signal produced by a volumetric imaging of the patient or volumetric pixel or Volumetric Picture Element (voxel). The voxel is a volume element representing the tissue inside the patient. It is deter‐

so that one must not use it in case of suspected bleeding [4, 9,10,13,14,15].

fat (spins) took to recover from this complete inversion (Figure 5).

production of images with fewer respiratory artifacts in [9,10,11,13,14,15].

looking for small haemorrhages [10].

and effective TR is long [10,11,13,15].

Consequently, there is no sign for it [10].

in rapid sequences.

The images primarily reflect the distribution of free hydrogen nucleus and the way it responds to an external magnetic field. Thus, this response determines different relaxation times known as T1 and T2. The pathological processes cause relaxation time to change in relation to the tissues of the nervous and musculoskeletal system, and the signal intensity is reflected [7,9,16].
