**6. MRI machine**

A magnetic resonance imaging (MRI) machine consists of a main magnet that provides a closed or open scanning system. It is a permanent superconductor. Its power field ranges from 0.23, 0.5, 1.0, 1.5 up to 3.0 Tesla total power field. Internally, the main magnet is composed of homogenizing coils, gradient coils, and radiofrequency (RF) transmitter and receiver coils. These may be located internal or external to the main magnet. The function of these compo‐ nents is to capture the signal or echo generated by the tissues (tissue parameters) when in contact with the magnetic field and technical parameters used [9,10,12]. The machine also comprises computers and image processors, which make it possible to acquire and visualize the image on the operator's console monitor (Figure 12 & Figure 13).

**Figure 13.** Open field magnetic resonance imaging machine [9].

also helps to obtain a better quality of the images [7].

design other section planes from the image formed [16,19].

spiral coils located inside the machine [7,9].

and elderly people [7,9,12].

and axial planes [10,12].

on examination protocols.

The physical principles of the open field MRI are the same as that of the closed field MRI, which uses a strong magnetic field created by the movement of electrical currents within a series of

Spin Echo Magnetic Resonance Imaging http://dx.doi.org/10.5772/53693 43

The open field MRI is a breakthrough technology to obtain images of the human body without constraints for patients with claustrophobia (fear of closed spaces), obesity, as well as children

The advantages of the open-field MRI are associated to a machine having large side openings that allows the patient to be examined with more tranquillity, comfort, and convenience. It

In practical terms, we can consider the MRI machine as a large and powerful magnet. The acquisition of spin-echo images can be understood as follows: The patient is placed into the MRI machine. Once inside the machine all hydrogen ions in the different body tissues will align parallel with the magnetic field of the machine. Then, a coil emits RF pulses that cause the axis of these ions to change 90º. When the coil turns off, the ions tend to realign with the magnetic field, but with different intensities and speeds according to the type of tissue in which they are found. This difference in intensity and time is captured and quantified by the device that locates and defines shades of grey for each point detected. The information is processed by a computer workstation that accomplishes the construction of images in the frontal, sagittal,

The technical parameters are those dependent on the device and set up by the operator based

Initially, the patients are placed on the examining bed. The region (lesion) being examinedis highlighted by a source of light directed and positioned in the center of the magnet. After‐ wards, the device was set up with a specific test protocol according to the limb damaged. Following, we made a first localization sequence in the desired section plane. Thus, we could

The technical parameters are those dependent on the device and set up by the operator based on examination protocols.

Initially, the patients are placed on the examining bed. The region (lesion) being examined is highlighted by a source of light directed and positioned in the center of the magnet. After‐ wards, the device is set up with a specific test protocol according to the limb damaged. Following, we made a first localization sequence in the desired section plane. Thus, we could design other section planes from the image formed [10,12].

**Figure 12.** Closed field magnetic resonance imaging machine [16].

**Figure 13.** Open field magnetic resonance imaging machine [9].

Note all structures with normal anatomic aspects with enhancement in sequence with contrast,

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

A magnetic resonance imaging (MRI) machine consists of a main magnet that provides a closed or open scanning system. It is a permanent superconductor. Its power field ranges from 0.23, 0.5, 1.0, 1.5 up to 3.0 Tesla total power field. Internally, the main magnet is composed of homogenizing coils, gradient coils, and radiofrequency (RF) transmitter and receiver coils. These may be located internal or external to the main magnet. The function of these compo‐ nents is to capture the signal or echo generated by the tissues (tissue parameters) when in contact with the magnetic field and technical parameters used [9,10,12]. The machine also comprises computers and image processors, which make it possible to acquire and visualize

The technical parameters are those dependent on the device and set up by the operator based

Initially, the patients are placed on the examining bed. The region (lesion) being examined is highlighted by a source of light directed and positioned in the center of the magnet. After‐ wards, the device is set up with a specific test protocol according to the limb damaged. Following, we made a first localization sequence in the desired section plane. Thus, we could

the image on the operator's console monitor (Figure 12 & Figure 13).

design other section planes from the image formed [10,12].

**Figure 12.** Closed field magnetic resonance imaging machine [16].

indicated by arrows [21].

on examination protocols.

**6. MRI machine**

The physical principles of the open field MRI are the same as that of the closed field MRI, which uses a strong magnetic field created by the movement of electrical currents within a series of spiral coils located inside the machine [7,9].

The open field MRI is a breakthrough technology to obtain images of the human body without constraints for patients with claustrophobia (fear of closed spaces), obesity, as well as children and elderly people [7,9,12].

The advantages of the open-field MRI are associated to a machine having large side openings that allows the patient to be examined with more tranquillity, comfort, and convenience. It also helps to obtain a better quality of the images [7].

In practical terms, we can consider the MRI machine as a large and powerful magnet. The acquisition of spin-echo images can be understood as follows: The patient is placed into the MRI machine. Once inside the machine all hydrogen ions in the different body tissues will align parallel with the magnetic field of the machine. Then, a coil emits RF pulses that cause the axis of these ions to change 90º. When the coil turns off, the ions tend to realign with the magnetic field, but with different intensities and speeds according to the type of tissue in which they are found. This difference in intensity and time is captured and quantified by the device that locates and defines shades of grey for each point detected. The information is processed by a computer workstation that accomplishes the construction of images in the frontal, sagittal, and axial planes [10,12].

The technical parameters are those dependent on the device and set up by the operator based on examination protocols.

Initially, the patients are placed on the examining bed. The region (lesion) being examinedis highlighted by a source of light directed and positioned in the center of the magnet. After‐ wards, the device was set up with a specific test protocol according to the limb damaged. Following, we made a first localization sequence in the desired section plane. Thus, we could design other section planes from the image formed [16,19].

The obtained images are recorded and photographed on film (Figure 14). The final appearance will depend not only on intrinsic properties of tissues but also on technical aspects such as pulse sequences or time factors that are chosen and machine quality.

**7. Examples of MRI protocols and applications by SE sequence**

This method has been widely used in the diagnosis of diseases located in the structures of the nervous and musculoskeletal systems. Thus, MRI is an imaging method that provides excellent contrast between soft tissues, due to its high spatial resolution. Therefore, from the anatomical point of view, MRI is the best choice for evaluation of the structures that make up the muscu‐ loskeletal system. The protocols on Table 1 and Table 2 were used to acquire the images of the

> **AX Cor T1 T1 GDL GDL**

Spin Echo Magnetic Resonance Imaging http://dx.doi.org/10.5772/53693 45

SE 35 IR 35

SE 750 IR2000

> SE 25 IR 90

> SE 10 IR 10

> SE 12 IR 12

> > SE 5 IR 5

> > SE 4 IR 1

192x256 256x256

> SE 8 IR 11

SE30 SE 30

SE 40 SE 25

SE10 SE 10

SE 12 SE 11

SE 5 SE 5

SE 2 SE 4

256x192 256x192

SE 10

SE 10 SE 850

SE 2000

following images which represents examples of very interesting applications of MRI.

SE30 IR 25

SE850 IR2000

> SE25 IR 90

**TE(2º) in ms** - - SE80 - -

SE10 IR 12

SE11 IR 12

SE 5 IR 5

SE 4 IR 1

256x192 224x256 256x192

IR 11

**Table 1.** Exam protocol and values of technical parameters and tissue for evaluation of lesions in the lower limb (0.5

**TI in ms** IR 25 IR 25

**Section planes Cor loc AXT1 AXT2**

SE10

192x192

**(F1)** - SE10

**FOV** SE42

**TR in ms** SE30

**TE in ms** SE25

**Interval** SE15

**NAQ** SE 1

**IR IR**

**Number of sections** SE 6

Thickness in Mm

**Matrix SE**

Tesla MRI). Body and head coils.

**Figure 14.** MRI obtained in SE sequence in the axial plane of the skull [19].

For each type of exam of any region of the human body, there is a specific protocol to obtain MR images, most are used for detecting soft-tissue lesions of the structures that make up the central nervous system and skeletal muscle.
