|Year : 2017 | Volume
| Issue : 3 | Page : 67-73
Role of multislice computed tomography and three-dimensional rendering in the evaluation of maxillofacial injuries
N Sreenivasa Raju, Prashanth Ishwar, Rumpa Banerjee
Department of Radiodiagnosis, Adichunchanagiri Institute of Medical Sciences, Mandya, Karnataka, India
|Date of Web Publication||18-Dec-2017|
Dr. N Sreenivasa Raju
KB, Adichunchanagiri Institue of Medical Sciences, B.G Nagara, Nagamangala Taluk, Mandya - 571 448, Karnataka
Source of Support: None, Conflict of Interest: None
Aims and Objectives: The aim of this is to identify and classify maxillofacial fractures using multislice computed tomography (CT) and identify the advantages of three-dimensional (3D) rendered images over two-dimensional axial images in evaluating maxillofacial injuries. Materials and Methods: This was a descriptive study. Multislice CT evaluation was done on 60 patients with maxillofacial injuries using a 16-slice CT scanner. 3D rendered images, as well as coronal reformatted images, were reconstructed. Statistical Analysis: Descriptive study. Results: Individuals within the age group of 36–45 years were most commonly affected by maxillofacial injuries with males being more common. The most common cause of these injuries was road traffic accident in 40 (80%) cases. The mandible was the most involved region observed in 37 cases, maxillary and nasoorbitoethmoid region being the next common regions seen in 32 (53.3%) cases. 3D rendered images were similar or superior to axial images (in the assessment of fractures) in most patients and were inferior when the fractures involved the thin bones of the orbital region. Conclusion: This study demonstrates that Multislice CT with 3D images provides better perception of the pattern of the fracture lines, and the displacement of the bony fragments thus helping in the faster and improved communication of the information to the referring physician. However, the 3D images alone have a limited role in evaluating orbital region fractures and also when there is minimal displacement of the fractured fragment.
Keywords: Maxillofacial injuries, multislice computed tomography, three-dimensional rendering
|How to cite this article:|
Raju N S, Ishwar P, Banerjee R. Role of multislice computed tomography and three-dimensional rendering in the evaluation of maxillofacial injuries. J Oral Maxillofac Radiol 2017;5:67-73
|How to cite this URL:|
Raju N S, Ishwar P, Banerjee R. Role of multislice computed tomography and three-dimensional rendering in the evaluation of maxillofacial injuries. J Oral Maxillofac Radiol [serial online] 2017 [cited 2018 Sep 21];5:67-73. Available from: http://www.joomr.org/text.asp?2017/5/3/67/221076
| Introduction|| |
Maxillofacial injuries are one of the most frequently encountered emergencies with road traffic accident (RTA) and violence being the most common reasons which have led to their increased frequency. Due to rapid progression of multislice computed tomography (CT) and three-dimensional (3D) volume rendering imaging techniques, accuracy of detection of injuries, and outcome of maxillofacial traumas has dramatically improved.
3DCT is accurate at assessing mandibular, zygomaticomaxillary complex, and comminuted fractures of the middle third of the face with no additional scanning time or radiation exposure.
Clinically relevant radiology reports can be constructed, which facilitates improved communication with referring clinicians.
| Materials and Methods|| |
Sixty patients with clinical evidence of maxillofacial injuries underwent multislice CT examination in Adichunchanagiri Institute of Medical Sciences, were included in this study with following inclusion and exclusion criteria.
All patients with clinical evidence of maxillofacial injuries who undergo multislice CT examination and are shown to be positive for fractures.
Patients with maxillofacial injuries in whom a CT examination is contraindicated, for example, Pregnancy Imaging equipment used was GE machine 16 SLICE CT BRIVO 385.
The following imaging protocol was followed:
- Noncontrast axial 16-slice helical series
- Beam collimation 10 mm
- Detector configuration 16 × 0.625
- Pitch 1.375:1
- Tube current 200 mAs
- Voltage 120kv
- Total exposure time 6.5s
- Total radiation – 81.3 mGy.
Along with the axial images, 3D volume rendering images were also obtained with 0.5 mm increment. The multidetector CT (MDCT) scans were reviewed using clinical workstation – GE 4.3 version.
The MDCT scans were reviewed using clinical workstation – GE 4.3 version. The fracture detected on CT examination were classified according to the region involved, 3D images were compared with axial images and assessed under headings – fracture detection, extent of fracture, and displacement. Coronal images were compared with axial images for detection of fractures. The descriptive study design was followed.
Imaging findings were assessed in following 5 regions including frontal, zygomatic, nasoorbitoethmoid, maxillary, and mandibular regions.
Frontal bone injuries were further classified (Manolidis) as follows including Type 1 –fractured anterior wall with minimal comminution, Type 2 – Comminuted fracture of anterior wall possibly extending to nasoorbitoethmoid (NOE) or to the orbital rim, Type 3 – Anterior and posterior wall fractures without significant displacement or dural injury, Type 4– Anterior and posterior wall fracture with dural injury and cerebrospinal fluid leak, and Type 5 – Type 4 with severe disruption of anterior cranial fossa or with additional bone loss.
Orbital injuries were assessed according to the wall involved  lateral, medial walls, roof, and the floor.
Maxillary region fractures were described according to the involvement of anterior, lateral, medial wall of sinus, and the alveolar rim.
Mandible was assessed according to the following location  involving condylar, coronoid process, ramus, body, alveolar process, symphyseal, and parasymphyseal region.
Complex midfacial fractures were classified according to the Le Fort system  including Le Fort I, Le Fort II, and Le Fort III types.
Information provided by 3D images was compared with axial CT image, and scoring was done as indicated in [Table 1]. Information provided by coronal reformatted images were also compared with axial CT image and scoring was done as indicated in [Table 2].
|Table 1: Scoring system three-dimensional images compared with axial images|
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|Table 2: Frontal bone Injuries (classified according to Manolidis) (n=22)|
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| Results and Data Analysis|| |
This study comprised of a total of 60 patients with most patients belonging to the age group ranging from 36 to 45 years [Chart 1]. There were 51 males and 9 females in the patients included in the study group. Males were most often injured comprising 85% of total patients.
RTAs were the most common mode of injury, comprising 80% of cases. Assault and fall from height were other common causes.
In the maxillofacial region [Chart 2], the most commonly involved bone was the mandible. The maxilla, especially the anterior walls of its sinus and the NOE regions were the next most commonly involved regions. Zygomatic, frontal, and nasal bone fractures were also observed. The pterygoid plate fractures were noted to be involved in Le Fort injuries.
In our study of trauma to the maxillofacial region, Type II frontal bone fractures were the most common [Table 2]. Type IV and V frontal bone fractures were the least common types [Figure 1]. Frontal bone fracture detection and displacements were well appreciated on 3D images. The extension of the fracture, into roof of orbit or the posterior walls of the sinus were however not adequately visualized on the 3D rendered images. Coronal reformatted images were found to be similar in the detection of fractures in frontal bones compared to the axial images.
|Figure 1: (a) Comminuted depressed fracture of the frontal bones on axial computed tomography. (b) Three-dimensional rendered images showing better description of displacement of the frontal bone fracture; however, the posterior extent could not be appreciated|
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In the evaluation of detection and extent of the zygomatic fractures, 3D rendered images were found to be similar or better compared to the axial images. However, in the evaluation of the displacement patterns of the zygomatic fracture, 3D rendered images were found to be superior to axial images in most patients [Figure 2]a and [Figure 2]b. Detection of zygomatic bone fractures was similar in coronal and axial images with no significant differences.
|Figure 2: (a) Comminuted displaced fracture of the left zygomatic bone on axial computed tomography. (b) Three-dimensional rendered images showing adequate information with enhanced visual perception of the extent of fracture and the displacement of the fracture fragments|
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In orbital region fractures, the medial wall was most common involved, noted in 25 (43.1%) patients. The orbital roof was the least commonly affected site noted in only 9 (15.5%) patients. In the evaluation of detection, extent and displacement of the NOE region fractures, 3D rendered image was inferior compared to the axial sections. Detection of NOE region fractures was superior in coronal sections compared to the axial images, especially in the fractures involving the floor and medial wall of orbit.
In the detection of maxilla bone fractures, 3D rendered images were found to be similar to axial images, but superior I cases involving the anterior wall of the maxillary sinus. However, the extent of involvement and its displacement were better seen on axial images rather than 3D images. In the detection of maxillary bone fractures, coronal images provided similar information as the axial images in of most patients.
Mandibular fractures [Table 3] were seen in 44 patients with the most commonly affected region being body of the mandible. Condylar process was the next common affected region [Figure 3]a and [Figure 3]b. Fractures in the parasymphyseal [Figure 4]a and [Figure 4]b and symphyseal region of mandible were less commonly affected sites. In the assessment of the detection, extent, and the displacement of the mandible bone fractures, 3D rendered images were found to be superior to the axial images. In the detection of mandible bone fractures, coronal images provided similar information as the axial images in of most patients.
|Table 3: Classification of mandible fractures according to the site of involvement (n=44)|
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|Figure 3: (a) Axial computed tomography images showing fracture of the left condylar process of the mandible. (b) Three-dimensional rendered images showing better appreciation of the displaced fracture fragment of the left condylar process in the infratemporal fossa|
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|Figure 4: (a) Axial computed tomography images showing displaced linear fracture in the left parasymphyseal region of the mandible. (b) Three-dimensional rendered images showing better understanding fracture pattern and extension|
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Le Fort fracture patterns were seen in 12 patients, among which, Le Fort II pattern was the most common type seen in 9 (69.2%) of the patients. Le Fort III was seen in only patient [Figure 5].
|Figure 5: Three-dimensional image showing better understanding of the fracture lines in Le Fort Type II fracture|
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The most common associated finding [Table 4] in the patients with maxillofacial region trauma was noted to be hemosinus. Subarachnoid hemorrhage (SAH) and extradural hemorrhage (EDH) were the next common findings seen in 10 (16.6%) patients. Other intracranial complications such as pneumocephalus, contusions subdural hemorrhage, and skull base involvement were also noted.
|Table 4: Associated findings in the patients with maxillofacial region trauma (n=60)|
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Maxillary bone fractures were most commonly associated with hemosinus and also with intracranial bleed. Pneumocephalus, skull base involvement, and EDH were most commonly associated with frontal bone fractures. SAH was most common type of intracranial bleed associated commonly with frontal, zygomatic bone, and NOE region fractures. Frontal bone fracture was most commonly associated with EDH. Temporomandibular (TM) joint involvement was most commonly associated with mandibular fractures [Chart 3]a and [Chart 3]b.
| Discussion|| |
The human face is an individual esthetic identification. Loss of facial esthetics due to facial fractures are more common today with increasing RTAs. One of the important factors determining the success of treatment of facial fractures is early and correct diagnosis., MDCT is the imaging modality of choice to display the multiplicity of fragments, the degree of rotation and displacement, or any skull base involvement  supported by the study conducted by Wang et al. and Moustafa et al.,
3D reconstruction from routine CT data is useful in visualizing bone fragments from all angles and planes and also in the ready assessment of the mechanism of the injury. 3D imaging is often preferred by surgeons because it simulates a surgeon's process of visualizing fractures in operative planning and also has helped a lot in patient and family education.,
A total of sixty patients under the age group of 15–70 years who presented with a history of injury to the maxillofacial region, who were subsequently found to have fractures involving the facial bones were included in this study. A 16-slice CT scanner was used for the axial imaging of the maxillofacial region. 3D volume rendered images were used for the comparative evaluation of maxillofacial injuries with the core axial images.
In this study, male predominance of facial trauma was noted consistent with the study conducted by Kaur J. The most common mode of injury was RTA comprising 80% of cases. These results are in the study is consistent with the popular studies.,,
The Type 2 frontal bone fractures were more commonly seen in this study occurring 9 (40.9%) times. Type 3 is the next common type occurring six times (27.2%). Type 1 and Type 4 fractures were seen three times (13.6%). Type 5 was the least common injury seen only once in this study. Similar results were also documented by Solomen et al.
Frontal bone fracture detection and displacements of the frontal bone fractures were well appreciated on 3D images. The extension of the fracture, into roof of orbit or the posterior walls of the sinus were however not adequately visualized on the 3D rendered images.
Assessment of displacement and extent of zygomatic bone fractures were found to be better in 3D rendered images compared to the axial images, consistent with findings in standard studies.,
Coronal images were similar to axial images in the detection of frontal and zygomatic bone fractures.
In the orbit, the medial wall and the floor were the most commonly involved sites. This is consistent with studies of orbital fractures.,, Coronal reformatted images were better at assessing orbital fractures as proved in the study conducted by Moustafa et al.
The 3D rendered images were found to be inferior in the assessment of detection, extent, and displacement of fractures in the orbital region when compared with axial images in most patients consistent with the study conducted by Fox et al. The thin bones in these regions causing partial volume averaging resulting in “pseudoforamina” and considerable bony overlap could explain this finding as described in the study conducted Kaur and Chopra.
The body of the mandible was the most commonly involved region in the mandibular fractures with the condyle being the next most common site which is consistent with a study conducted by Kruger and Hall and Thomas., 3D rendered images offered a definitive advantage over the axial images in the evaluation of the displacement of the mandibular fractures, the findings which were consistent with a study conducted by Costa e Silva et al. on the mandibular fractures. Coronal images were similar to axial images in the detection of mandibular fractures.
The most common Le Fort fractures identified was the Le Fort II which was seen 9 times (69.2%). Le Fort I fracture lines were identified 3 times (23%). Le Fort III fractures were noted to occur only once (5.2%). This is consistent with the studies done by Duval and Benovitz who showed the Le Fort II fractures to be the most common. In this study, as well it was seen that the 3D reconstructions were helpful in the evaluation of complex Le Fort fractures consistent popular studies.,,
Hemosinus was the most common associated finding in the patients who presented with facial trauma which was most commonly associated with fracture of the anterior wall of the maxillary sinus. Frontal bone fractures were the next common region to be associated with hemosinus.
Lambert et al. found that the absence of free paranasal sinus fluid (''clear sinus'' sign) in facial CT is a highly reliable criterion for excluding fractures involving the paranasal sinus walls. However, we found three patients with clear sinus had maxillary bone fractures. Thus, the clear sinus sign is of valuable aid, but a lack of free paranasal sinus fluid does not completely exclude the possibility of midfacial fractures.
Subarachnoid hemorrhage was the next common finding seen in 16 (26.6%) patients which was most commonly associated with frontal bone fractures. Skull base involvement was most commonly associated with frontal bone fractures, finding consistent with this study conducted by Solomen et al. The TM joint was most commonly involved with mandibular fractures.
| Conclusion|| |
MDCT provides excellent spatial resolution in the evaluation of fractures in the maxillofacial region. 3D rendered images provide a better perception of the pattern of the fracture lines and the displacement of the bony fragments, especially in the mandible and zygomatic bone thus helping in the faster and improved communication of the information to the referring surgeon. 3D images were also better in the identification of Le Fort fracture lines.
However, the 3D rendered images have a limited role in evaluating orbital region fractures and also when there is minimal displacement of the fractured fragment. The coronal reconstructed images are superior in the detection of fractures in the orbit.
MDCT is an accurate, non-invasive technique for the evaluation of patients with maxillofacial injuries with an added advantage of shorter scan time and easy availability. Multiplanar reformation and 3D images help better evaluation of fractures detected on axial images.
Financial support and sponsorship
This study was financially supported by Adichunchanagiri Institue of Medical Sciences.
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2], [Table 3], [Table 4]