Radiology of the Midface Structures

*Natalya Serova, Sergey Ternovoy and Olga Pavlova*

## **Abstract**

The midface contains very important structures within the facial skeleton. There are number of diseases and pathological conditions that can happen in this region, which is why choosing the proper diagnostic tactic is very important for the benefit of the patients. The chapter "Radiology of the midface structures" covers the main features of bone and soft tissue structure diagnostics, including all the radiology methods such as X-rays, multislice computed tomography, cone-beam computed tomography, magnetic resonance imaging, and ultrasound. In the chapter, you can find the advantages and disadvantages of each method as well as the limitation of its usage. Every radiologist, ENT specialist, maxillo-facial surgeon, as well as residents and young doctors, should be very aware of the radiological anatomy of the midface structures and different pathological conditions and its radiological presentation. Therefore, a detailed review on the radiological state of the midface structures in normal and pathological conditions is presented.

**Keywords:** paranasal sinuses, radiology, diagnostics, anatomy, MSCT, MRI, CBCT, US

## **1. Introduction**

The skeleton of the head is made up of paired and unpaired bones, which together are called the skull (cranium). There are two sections in the skull, different in development and function. The cranium (neurocranium) forms a cavity for the brain and some sensory organs. It consists of a vault (calvaria) and a base (basis). The facial skull (viscerocranium) is the place for most of the sensory organs and the initial parts of the respiratory and digestive systems [1].

Some bones of the skull—the frontal, ethmoid, sphenoid, temporal, and maxilla contain cavities lined with mucous membrane and filled with air. These bones are called air-bearing bones. The bones of the facial skull form the bony basis of the cavities of the nose, mouth, and paranasal sinuses [1, 2].

The orbit is a paired formation and has the shape of a four-sided pyramid, the base of which is the entrance to the orbit (aditus orbitalis), facing outward, and the apex facing inward and posteriorly. The orbit contains the eyeball, optic nerve, extraocular muscles, lacrimal gland, blood vessels, nerves, and fatty tissue. There are four walls of the orbit: superior, inferior, medial, and lateral (**Figure 1**) [1].

There are four paired sinuses, all lined with pseudostratified columnar epithelium: the maxillary sinuses, the largest ones located under the eyes in the maxillary

**Figure 1.** *Anatomy of the orbit.*

**Figure 2.** *Anatomy of the paranasal sinuses.*

*Radiology of the Midface Structures DOI: http://dx.doi.org/10.5772/intechopen.114097*

bones; the frontal sinuses, superior to the eyes within the frontal bone; the ethmoid sinuses, formed from several air cells within the ethmoid bone between the nose and eyes; and the sphenoid sinuses, located within the body of the sphenoid bone (**Figure 2**) [1, 2].

The function of the paranasal sinuses is debated. However, they are believed to be implicated in several roles: decreasing the relative weight of the skull, increasing the resonance of the voice, providing a buffer against facial trauma, insulating sensitive structures from rapid temperature fluctuations in the nose, and humidifying and heating inspired air. Furthermore, they also play a role in immunological defense [1, 2].

The maxillary sinus is the largest of the paranasal sinuses. Sinus volume has age-related and individual differences. The sinus can continue into the alveolar, zygomatic, frontal, and palatine processes. The sinus is divided into superior, medial, anterolateral, posterolateral, and inferior walls [2].

The frontal sinus is a highly variable air-filled anatomical structure located superior to the orbit and within the frontal bone. It is divided into two cavities by the frontal septum [2].

The sphenoid sinus is located centrally and posteriorly within the body of the sphenoid bone, and it is posteriorly and superiorly bounded by the sella turcica. Several important structures have a close relation to the sphenoid sinus, including the internal carotid artery and the optic nerve [2].

The ethmoid bone is formed by a multitude of cells with an intricated structure through which all the paranasal sinuses drain. They are located between the eyes, on either side of the septum [2].

The anterior ethmoid cells drain into the ethmoid infundibulum in the middle meatus. The posterior ethmoid cells drain into the sphenoethmoidal recess located in the superior meatus [2].

## **2. Multispiral computed tomography**

The introduction of computed tomography into clinical practice has revolutionized the diagnostics algorithm for maxillofacial region diseases. Multislice computed tomography (MSCT) is a method of examination when an X-ray tube-detector rotates around the patient with a spiral trajectory, and as a result, there are multiple axial images of the interested area. Nowadays, modern scanners have the ability to perform fast examinations, obtain high-quality images, and reduce radiation exposure [3–6]. The patient is placed on the deck of the tomograph table in the supine position. The patient's head is previously freed from all removable metal elements and evenly laid on the headrest, the patient's gaze is fixed centrally. When positioning the patient, laser marks are used to accurately determine the tomography area and a topogram is performed to mark the study area (**Figure 3**) [3–5, 7].

Thin axial CT sections with their transformation into multiplanar and 3D reconstructions are obtained (**Figure 4**). In dental implantation, the protocol is complemented by panoramic reconstructions and cross sections [4, 5].

When analyzing MSCT images, there is the possibility of layer-by-layer study of the interested area and measurement of various values of density. The density of the structures is measured in Hounsfield units (HU), while the density of water is taken as

**Figure 3.** *MSCT, a—general view of the scanner, b—the position of the patient when examining the maxillofacial region.*

#### **Figure 4.**

*Multislice computed tomography, maxillofacial region: a—axial view, midface, bone window density, b coronal view, paranasal sinuses, bone window density, c—sagittal view, midface, bone window density, d—3D reconstruction, facial skull.*

*Radiology of the Midface Structures DOI: http://dx.doi.org/10.5772/intechopen.114097*

zero, the density of air is −1000 HU, the density of cortical bone is +1000 ... +1200 HU, the rest of the tissues of the human body occupy intermediate values (**Figure 5**). Metal constructions, foreign bodies, and filling material can reach up to +3000 HU [4].

MSCT not only makes it possible to diagnose pathological changes but also to determine their size, density, accurately establish localization in relation to the most important anatomical structures of the maxillofacial region, determine the topic of the mandibular canal, including in the vestibulo-lingual direction, the anatomy of the maxillary sinus bottom, and thus correctly determine the tactics of surgical treatment (**Figure 6**) [6–9].

There are numerous indications for application of the MSCT for the diagnostics of different pathological conditions of the face bone and soft tissue structures including pre- and postoperative stages of treatment (**Figures 7** and **8**). We can visualize upper and lower jaw, alveolar parts, dental system, temporomandibular joints, paranasal sinuses, orbits, and others (**Figures 9**–**11**) [1, 2, 8].

**Figure 5.** *Hounsfield density scale (HU). Density scale for all types of tissues.*

**Figure 6.**

*Multislice computed tomography, lower jaws. Curved reconstructions (curved-MPR) of the right (a) and left (b) mandibular nerves canals.*

#### **Figure 7.**

*Multislice computed tomography, multiplanar reconstructions (MPR) of the TMJs, oblique projections. a—right TMJ in the position of habitual occlusion; b—right TMJ in the open mouth position; c—left TMJ in position in the position of habitual occlusion; d—left TMJ in the open mouth position. Hyperplasia of the right TMJ head.*

#### **Figure 8.**

*Multislice computed tomography, maxillary sinuses. a—axial view, soft tissue window, fungal left-sided maxillary sinusitis, fungal body, b—sagittal view, bone tissue window, fibrous dysplasia of the alveolar part of the upper jaw with the spread into the maxillary sinus.*

MSCT is by far the obligatory and most informative X-ray method of examination in patients with anomalies of the dentoalveolar system and should be performed at the stage of preparation for the surgical treatment (**Figure 10**). With this type of

*Radiology of the Midface Structures DOI: http://dx.doi.org/10.5772/intechopen.114097*

#### **Figure 9.**

*Multislice computed tomography. Axial views, bone density window: a—posttraumatic changes in the body of the lower jaw, b—posttraumatic changes of the left maxillary sinus walls and coronoid process of the lower jaw on the left.*

#### **Figure 10.**

*Multislice computed tomography, curvilinear reconstruction (curved-MPR) of the upper jaw, bone density window. Congenital dentoalveolar anomaly, dystopic impacted tooth at the roots of teeth 2.1–2.4.*

#### **Figure 11.**

*CBCT, a—general view of the scanner, b—positioning of the patient for examination of the maxillofacial region.*

study, the doctor receives the most comprehensive examination and has the ability to visualize the bone and soft tissue structures in two-dimensional and three-dimensional views [3, 5, 10].

Thus, computed tomography is a highly informative method in maxillofacial surgery.

## **3. Cone-beam computed tomography**

Today, cone-beam computed tomography (CBCT) is widely used in dentistry, maxillofacial surgery and otorhinolaryngology [3, 4, 11].

Cone-beam computed tomography appeared in the 1990s and was used as an alternative diagnostic method compared to MSCT, which was expensive and difficult to access at that time. The CBCT technique was originally developed for usage in angiography. However, in the late 1990s, the application of the method became a breakthrough in dentistry, as this technology made it possible to move from X-rays and orthopantomograms to volumetric images of the maxillofacial region with the possibility of reconstructions in axial, sagittal, and coronal planes and three-dimensional modeling [3, 4, 11, 12].

Cone-beam computed tomography is a mix of orthopantomography and computed tomography with the conical shape of the radiation beam. When examining the patient, the tube rotates around the patient and as a result we are getting high-quality images in a short time (no more than 2 min for a patient) [3, 4, 12, 13].

The study is performed in a standing or sitting position, the patient's head is placed between the X-ray tube and the detector, the level of the scanner adjusts to the height of the patient, while the patient's shoulders should be slightly below the edge of the scanner to avoid collision between the X-ray tube and the patient's body. The patient's head is fixed on both sides with special fixators and laser marking is used for more accurate positioning. The patient's hands during the study are on special support

#### *Radiology of the Midface Structures DOI: http://dx.doi.org/10.5772/intechopen.114097*

for a more stable position (**Figure 11**). At the end of the tube rotation and the registration of the image, the patient's head is released from the fixator [3, 4].

Further, all images are reconstructed in 3D using an original algorithm developed specifically for CBCT. Radiation exposure with CBCT is several times lower compared with MSCT [3, 4]. Image processing takes place at the workstation of the CBCT scanner in bone mode, using multiplanar reconstructions in the axial, coronal, and sagittal planes and 3D models (**Figure 12**).

Today, the technical characteristics of CBCT are at the peak of their development, and there are many software applications that, in addition to multiplanar and threedimensional reconstructions, allow planning and modeling surgical treatment and performing postoperative monitoring. Given the ever-increasing demands of clinicians for radiology in this area, new programs and applications, such as face scan and 3D photography, are appearing on the market, which are becoming more accessible and applicable in dentistry and maxillofacial surgery [12, 13].

There are numerous advantages of CBCT including high-quality bone visualization, multiplanar and 3D models, low radiation exposure and short examination time, sitting or standing position of the patient, additional software for surgical treatment planning. Unfortunately, there is almost complete absence of soft tissue differentiation.

In recent years, the CBCT technique has been widely used in dental implantology. All CBCT devices have software for planning dental implantation, which makes it possible to estimate the width and height of the alveolar process of the upper jaw and the alveolar part of the lower jaw, to measure the distance to various anatomical structures and to analyze the density and quality of the bone tissue. The CBCT software

#### **Figure 12.**

*Cone-beam computed tomography, workstation screen, multiplanar reconstructions in the axial, coronal, and sagittal planes and 3D models.*

**Figure 13.**

*Cone-beam computed tomography, workstation screen. A specialized program for planning dental implantation and additional sinus lift surgery.*

allows one to choose the optimal implant system and calculate the exact volume of the required osteoplastic material for its installation (**Figure 13**) [13].

The analysis of diagnostic information obtained from CBCT includes an assessment of the quantitative parameters of the jaws, the structure of the bone tissue, as well as information about the state of the maxillary sinuses and mandibular canals (**Figure 14**) [3, 4, 14].

#### **Figure 14.**

*Cone-beam computed tomography, a—axial plane, fibrous dysplasia of the lower jaw on the left, b—sagittal plane, foreign body in the cavity of the maxillary sinus near the root of the tooth after the endodontic treatment, corresponding to the filling material resulting into the maxillary odontogenic sinusitis with the association of the fungal infection.*

#### **Figure 15.**

*Cone-beam computed tomography, a—coronal plane, b—3D reconstruction, posttraumatic changes in the left zygomatic-orbital complex and walls of the left maxillary sinus, enlargement of the left orbital volume and prolapse of the left orbital structures into the left maxillary sinusitis.*

At the stages of the initial examination, the possibilities of CBCT in the diagnosis of bone-traumatic injuries are significantly higher compared to traditional radiography due to the absence of overlapping of anatomical structures. In the visualization of bone structures, the possibilities of CBCT are almost completely comparable with the results of MSCT. In patients with trauma to the facial skeleton, CBCT is used to determine traumatic injuries to all walls of the orbits, paranasal sinuses, zygomatic bone, and nasal cavity; it is possible to measure the volumes of the orbits and sinuses (**Figure 15**). However, a significant limitation of CBCT is poor visualization of soft tissue [3, 4, 13, 14].

This method can be considered highly informative in the determining the location of high-density foreign bodies, since in CBCT there are no such pronounced artifacts from metal foreign structures as in MSCT.

Modern CBCT devices allow using of DICOM images to create 3D stereolithographic models of the facial skeleton.

Thus, today CBCT is one of the rapidly developing methods of radiological diagnostics. Knowledge of the technical aspects, advantages, and disadvantages of the method is necessary for its successful application in maxillofacial surgery and dentistry.

## **4. Magnetic resonance imaging**

Magnetic resonance is a physical phenomenon based on the properties of certain atomic nuclei, when placed in a magnetic field, to absorb energy in the radio frequency (RF) range and radiate it after the cessation of the RF pulse. In this case, the strength of the constant magnetic field and the frequency of the radio frequency magnetic field must strictly correspond to each other which is called nuclear magnetic resonance. The nature of the signal intensity in MRI is determined mainly by four parameters: proton density (the number of protons in the tissue), spin-lattice relaxation time (T1), spinspin relaxation time (T2), motion, or diffusion of the structures [3, 4].

Various pulse sequences have been developed for MRI, which, depending on the purpose, determine the contribution of one or another parameter to the image intensity of the structures in order to obtain the optimal contrast between normal and altered tissues. To create magnetic resonance, a constant, stable, and uniform

#### **Figure 16.**

*Magnetic resonance imaging, TMJ, sagittal planes: a—the state of the closed mouth (habitual occlusion), b—the state of the maximum open mouth. Anterior dislocation of the left articular disc without repositioning when opening the mouth. The arrow—the position of the articular disc.*

magnetic field is required. Depending on the strength of the magnetic field, all MRI scanners are usually classified into ultra-low (less than 0.1 T), low-field (0.1–0.4 T), medium-field (0.5 T), high-field (1–2 T), ultrahigh-field (above 2 T) [3, 4].

There is no radiation exposure, possibility to noninvasively visualize different tissues, contrast from moving blood, detailed differentiation of soft tissues, MR-perfusion, MR-spectroscopy, or functional MR examination. Unfortunately, it takes a long time to acquire the images (minimum 20–30 min for one area), a lot of possible artifacts from dental implants or respiratory movements, low differentiation of stones and calcifications or some pathology of bone structures as well as many direct or non-direct contraindications for performance of MRI [3, 4, 15].

The application of MRI within the head and neck region is highly required. We can visualize soft tissues of the face, lymph nodes, salivary glands, orbital structures, as well as TMJs in the open and closed mouth (including the articular disc, displacement of the disc, subluxation in the joint, the condition of articular cartilage, and periarticular soft tissues) (**Figure 16**) [3, 15, 16].

MRI is also used to assess other structures of the maxillofacial region: salivary glands, lymph nodes, soft tissues of the face, with suspicion of the mass and inflammatory changes in this zone and vascular pathology.

The usage of MRI in the diagnosis of injuries of the maxillofacial region has significant limitations. This is due to the difficulty in detecting small bone fragments, calcifications, with the appearance of pronounced artifacts from the movements of patients, the duration of the procedure, and also with a contraindication for conducting this study in the presence of metallic foreign bodies.

## **5. Ultrasonography**

Ultrasound diagnostics (ultrasound) is a method of examining organs and tissues of the human body using ultrasonic waves. The method is based on the registration of

#### *Radiology of the Midface Structures DOI: http://dx.doi.org/10.5772/intechopen.114097*

ultrasonic waves reflected from internal structures—echo. A special receiving sensor captures these changes, translating them into a graphic image that can be captured both on a monitor and on special photographic paper [3, 4].

Ultrasound is widely used in clinical practice. Over the past few decades, the method has become one of the most common and important, which provides the diagnosis of many diseases. The technique has no contraindications, is safe, and is distinguished by sufficiently high diagnostic efficiency, simplicity, no radiation exposure, non-invasiveness, the possibility of multiple studies, cost-effectiveness, real-time conduction, and the possibility of examining non-transportable patients. The limitations of the method include the dependence of the quality of the image on the type of the scanner, subjectivity in the interpretation of the images, limitations in the study of a number of organs, and systems (lungs, brain in adults, intestines filled with gas) [3, 4].

The ultrasound protocol can be represented by the following modes: A-mode, B-mode, M-mode, Doppler modes, combined modes, modes with volumetric imaging (3D and 4D), and elastography.

The ultrasound method allows for the acquisition of information about the structural state of organs and tissues and characterizes the blood flow in vessels. This ability is based on the Doppler effect—a change in the frequency of the received sound when moving relative to the medium of the source or receiver of the sound or the body that scatters the sound. Doppler modes allow you to evaluate the main parameters of blood flow—speed, direction, laminarity, as well as the degree of vascularization of the area [3, 4].

The introduction of high-resolution ultrasound to assess pathological changes in the soft tissues of the face and neck is necessary for accurate and prompt diagnosis, which largely determines the tactics of treatment, the decision on the need for surgical intervention, and the prognosis of the disease.

Ultrasound is performed on various ultrasound scanners using linear scan sensors. Studies of the maxillofacial area include: B-mode, color Doppler and energy mapping, and pulsed wave Doppler (**Figure 17**). A sequential examination of the symmetrical areas of the face and neck is carried out, as well as a polypositional scanning of the interested area. Intraoral ultrasound is also used to examine the tongue and soft tissues of the oral cavity [4, 17–19].

#### **Figure 17.**

*Ultrasound of the lower facial zones, submandibular salivary gland. Echograms of the unchanged submandibular salivary gland in B-mode (a) and in Doppler mapping mode (b).*

High-resolution ultrasound is the method of choice for the primary diagnosis and dynamic control of the soft tissues of the maxillofacial region in adult and pediatric patients. In recent years, the method of high-resolution ultrasound diagnostics has become widespread in ophthalmological practice.

## **6. Radiology of odontogenic sinusitis**

Odontogenic maxillary sinusitis is an inflammatory disease of the mucous membrane of the maxillary sinus caused by the spread of the pathological process from foci of odontogenic infection. Despite modern diagnostic and treatment capabilities, odontogenic maxillary sinusitis still causes difficulties in diagnosis-making [3, 4, 14].

Previously, only 10–12% of cases of sinusitis were associated with odontogenic infections; however, according to recent publications, odontogenic etiology of chronic

#### **Figure 18.**

*MSCT. Odontogenic maxillary sinusitis, periapical changes. a—Sagittal reconstruction, bone window mode. In the periapical region 2.5, the interradicular region, and also periapically in the region of the buccal-mesial root 2.6, a rounded focus of bone tissue resorption is visualized, with clear and even contours. The lower wall of the sinus in this area is displaced upward and thinned. In the lower and partially anterior sections of the left maxillary sinus, hypertrophic thickening of the mucous layer is determined. b—sagittal reconstruction, bone window mode. In the periapical region 2.6, a focus on the resorption of the bone tissue is visualized with rounded, clear, and even contours. The lower wall of the sinus in this area is displaced upward, with a defect. In the lower and partially anterior sections of the left maxillary sinus, hypertrophic thickening of the mucous layer is determined. c—sagittal reconstruction, bone window mode. In the periapical area 2.8, there is a focus on bone tissue resorption of a rounded shape, with clear and even contours. The lower wall of the sinus in this area is displaced upward, with a defect. The left maxillary sinus is subtotal filled with pathological content.*

#### *Radiology of the Midface Structures DOI: http://dx.doi.org/10.5772/intechopen.114097*

sinusitis can occur in 30–51%. According to statistics, odontogenic maxillary sinusitis is more common in chronic forms (including in the acute stage) than in acute forms. This occurs due to several reasons: the patient's late visit to the doctor, the carelessness of dentists in the early diagnosis of acute maxillary sinusitis in patients with various forms of periodontitis of the upper premolars and molars, the difficulties of early diagnosis of odontogenic sinusitis [14].

The most informative diagnostic method for identifying changes in the maxillary sinuses, as well as monitoring dental treatment and surgical interventions, is computed tomography, which allows one to identify radiological criteria for the odontogenic etiology of maxillary sinusitis, which determines further treatment tactics for patients [14].

Multislice computed tomography is considered the gold standard for visualizing the maxillary sinuses and alveolar processes of the maxilla due to its high spatial resolution, detailed assessment of bone tissue, the ability to construct various reconstructions, and detect inflammatory changes in the sinuses. Multiplanar reconstructions

#### **Figure 19.**

*CBCT. Maxillary sinuses. Odontogenic maxillary sinusitis, condition after implantation. a—coronal reconstruction. The left maxillary sinus is subtotal filled with content, and an implant 2.5 is visualized, the apex of which is located 3.6 mm above the sinus lower wall. In the right maxillary sinus, there is an uneven thickening of the mucous membrane; the implant 1.4 is visualized, perforating the floor of the maxillary sinus. b—sagittal reconstruction, left maxillary sinus (same patient). c—sagittal reconstruction. In the lower sections of the right maxillary sinus, there is a parietal thickening of the mucosal layer above the osteoplastic material (condition after sinus lifting); the osteoplastic material is visualized fragmentarily, the 1.4 implant is completely located above the sinus lower wall within the osteoplastic material.*

make it possible to identify the relationship of periapical changes with defects of the sinus lower wall and determine the exact localization of the foreign body in the maxillary sinus [14].

Odontogenic maxillary sinusitis is most often identified on CT images as thickening of the mucous membrane ≥2–4 mm associated with areas of inflammation in the periapical areas, with the presence of foreign bodies in the sinus cavity (filling material, tooth roots, and dental implant), when an oroantral anastomosis is detected. In 2017, Vidal et al. [20] published a work based on the results of which it was noted that thickening of the mucous membrane of the maxillary sinus may be associated with the presence in the corresponding tooth of one or more of the following pathological signs: caries, a defect in the restoration of the coronal part, the presence of a periapical zone of bone rarefaction tissue, or edentulous area after tooth extraction (**Figure 18**) [14].

Currently, thanks to new advances in the development of three-dimensional imaging systems, cone-beam computed tomography (CBCT) has become widespread in dental and ENT practice. CBCT is actively used to determine indications and directly plan sinus lifting performed before dental implantation, as well as to evaluate the effectiveness of treatment in the postoperative period. The disadvantage of this method is the absence of soft tissue differentiation (**Figure 19**).

## **7. Radiology of midface trauma**


#### *Radiology of the Midface Structures DOI: http://dx.doi.org/10.5772/intechopen.114097*

Severe injuries to the face are often associated with deformations, changes in the orbital volume, impaired eye mobility, and, as a consequence, functional disorders of varying severity. Classic semiotics includes: enophthalmos, hypothalamus, limitation of eye mobility in the vertical plane, the appearance of vertical binocular diplopia, impaired sensitivity of the facial skin in the area of innervation of the infraorbital nerve, deepening of the orbital-palpebral groove. When the lower part of the orbit is damaged, the inferior rectus muscle-inferior oblique muscle complex often becomes involved. Even minimal mechanical restriction of ocular mobility can be accompanied by significant diplopia [21–24].

There are different classifications of midface injuries depending on the location and extent of the injuries. Thus, according to the number of injured structures of the facial skeleton involved, it is customary to divide injuries into isolated, multiple, and combined. The French maxillofacial surgeon Rene Le Fort identified three types of injuries based on the trajectory of the facial skull fracture lines (Le Fort I, Le Fort II, and Le Fort III). Bone-traumatic injuries of the facial skeleton are divided according to localization into injuries of the upper, middle, and lower areas of the face [21–24].

Based on the location of traumatic injuries, the most detailed classification is divided into injuries to the central and lateral parts of the midface. Among the injuries of the central department are the following injuries: frontal sinus, frontobasal fractures, sphenoid sinus, nasal bones, nasal septum, nasoethmoidal complex (nasoorbitoethmoidal complex), and orbital fractures. As part of the injury to the lateral parts of the midface, the following injuries occur: zygomatic-orbital complex, isolated injuries of the zygomatic bone, maxillary sinus, and orbital fractures [21–24].

The organ of vision is one of the most important anatomical and functional structures of the midface; therefore, today, there are several classifications of orbital injury, both clinical-anatomical and radiological. The term "blowout fracture" was first proposed in 1957 and reflects a specific condition of the orbital walls, in which displacement of wall fragments occurs while the orbital ring is intact [21–24].

In the clinical classification of globe injuries, they are distinguished into injuries to the globe and adnexa of the eye, penetrating and non-penetrating injuries, involving the bone structures of the orbit, with the presence of foreign bodies, and also

#### **Figure 20.**

*MSCT, bone tissue window, orbital injury. A—coronal reconstruction, prolapse of the contents of the orbit into the maxillary sinus (red arrow), B—axial view, enophthalmos, trauma to the walls of the left orbit as well as the left temporal bone, ethmoidal bone, and nasal bones.*

indicating the nature of the injury, its prevalence and combinations with damage to other areas of the facial skeleton [21–24].

Computed tomography is the method of choice when examining patients with facial trauma. MSCT of the orbit in standard mode in axial projection followed by multiplanar and three-dimensional reconstructions makes it possible to evaluate the bone and soft tissue injury of the orbital structures (**Figure 20**).

## **8. Conclusion**

The midface contains very important structures within the facial skeleton. There are number of diseases and pathological conditions that can happen in this region which is why choosing the proper diagnostic tactic is very important for the benefit of the patients. Radiologists who are working within the head and neck region must have a general basic knowledge of different pathological conditions to be able to give clinicians the most comprehensive protocols. Knowledge of the anatomy of the midface is essential, as well as understanding the application of different radiological methods depending on the pathology.

## **Funding**

The work is presented as part of the implementation grant of the President of Russian Federation for supporting the leading scientific school НШ-599.2022.3 "Non-invasive functional radiological technologies in screening, early diagnostics and treatment and rehabilitation follow-up of socially significant diseases" (the leader— N.S. Serova).

## **Conflict of interests**

Authors have no conflict of interest to declare.

## **Note section**

The information in the chapter considering imaging of the tempromandibular joint is based on the previously published article—Serova et al. [25].

*Radiology of the Midface Structures DOI: http://dx.doi.org/10.5772/intechopen.114097*

## **Author details**

Natalya Serova, Sergey Ternovoy and Olga Pavlova\* Radiology Department, I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow, Russia

\*Address all correspondence to: olgapavlova@gmail.com

© 2024 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Section 3
