Characterization of mandibular fractures using 64-slice multidetector CT

Radiological investigation of acute mandibular injury

This article focuses on the different imaging modalities used to evaluate acute mandibular fractures and explores important concepts relating to their diagnosis, investigation, and treatment. Significant focus will be given to exploring general management principles, considerations regarding first-line imaging, and recent technological advancement. Computed tomography (CT) is the preferred method when attempting to identify acute mandibular fractures, particularly in trauma patients, and has very high specificity and sensitivity. Multidetector CT now represents the standard of care, enabling fast scan times, reduced artifact, accurate reconstructed views, and three-dimensional (3D) reconstructions. Cone-beam CT is a newer advanced imaging modality that is increasingly being used worldwide, particularly in the ambulatory and intraoperative setting. It produces high-resolution images with submillimeter isotropic voxels, 3D and multiplanar reconstruction, and low radiation dose, however is less widely available and more expensive. Ultrasound is a valuable method in identifying a fracture in unstable patients, but is limited in its ability to detect nondisplaced fractures. Magnetic resonance imaging is useful in determining the presence of soft-tissue injury. CT angiography is invaluable in the assessment of potential vascular injury in condylar fracture dislocations.

Multidetector Row Computed Tomography in Maxillofacial Imaging

Multidetector row CT (MDCT) offers superior soft tissue characterization and is useful for diagnosis of odontogenic and nonodontogenic cysts and tumors, fibro-osseous lesions, inflammatory, malignancy, metastatic lesions, developmental abnormalities, and maxillofacial trauma. The rapid advances in MDCT technology, including perfusion CT, dual-energy CT, and texture analysis, will be an integrated anatomic and functional high-resolution scan, which will help in diagnosis of maxillofacial lesions and overall patient care.

Multidetector CT of Mandibular Fractures, Reductions, and Complications: A Clinically Relevant Primer for the Radiologist

After the nasal bones, the mandible is the second most common site of facial fractures, and mandibular fractures frequently require open reduction. In the trauma injury setting, multidetector computed tomography (CT) has become the cornerstone imaging modality for determining the most appropriate treatment management, fixation method, and surgical approach. Multidetector CT is also used to assess the adequacy of the reduction and evaluate potential complications in the postoperative period. For successful restoration of the mandible's form and function, as well as management of posttraumatic and postoperative complications, reconstructive surgeons are required to have a detailed understanding of mandibular biomechanics, occlusion, and anatomy. To provide added value in the diagnosis, treatment planning, and follow-up of mandibular fractures, radiologists should be aware of these concepts. Knowledge of the techniques commonly used to achieve occlusal and anatomic reduction and of the rationale behind the range of available treatment options for different injury patterns-from isolated and nondisplaced fractures to multisite and comminuted fractures-also is essential. This article focuses on the use of multidetector CT for pre- and postoperative evaluation of mandibular fractures and outlines fundamental concepts of diagnosis and management-beginning with an explanation of common fracture patterns and their biomechanical underpinnings, and followed by a review of the common postoperative appearances of these fractures after semirigid and rigid fixation procedures. Specific considerations regarding fractures in different regions of the tooth-bearing and non-tooth-bearing mandible and the unique issues pertaining to the edentulous atrophic mandible are reviewed, and key features that distinguish major from minor complications are described. (©)RSNA, 2016.

The Ongoing Gap in Availability of Imaging Services at Teaching Versus Nonteaching Hospitals

RATIONALE AND OBJECTIVES

This study aimed to characterize associations between availability of imaging services and intensity of teaching among US hospitals.

MATERIALS AND METHODS

Using the American Hospital Association Annual Survey Database, we studied information regarding the availability of imaging services at general hospitals nationwide in 2007 (4102 hospitals) and in 2012 (3876). Teaching intensity was categorized as Council of Teaching Hospitals (COTH) member, non-COTH teaching hospital (non-COTH member with affiliated medical school and/or residency), and nonteaching hospital. Availability in hospitals of reported basic and advanced imaging modalities, as well as beds, number of employed physicians, and case mix index, was analyzed. Univariable and multivariable trends were assessed.

RESULTS

All 15 assessed modalities showed significant increases in availability with increasing hospital teaching intensity (P < 0.001). Modalities showing the largest differences between COTH and nonteaching hospitals in 2012 were image-guided radiation therapy (78% vs. 14%), positron emission tomography/computed tomography (74% vs. 17%), and single-photon emission computed tomography (88% vs. 35%). The gap between COTH and nonteaching hospitals increased from 43% in 2007 to 57% in 2012 for positron emission tomography/computed tomography, and from 34% to 48% for virtual colonoscopy. COTH status was a significant predictor, independent of beds and employed physicians, for 10 modalities (P < 0.001-0.038). Greater case mix index was significantly associated with availability of advanced, although not basic, modalities.

CONCLUSIONS

Availability of imaging services increased with greater hospital teaching intensity. Differences were most pronounced and sustained over time for advanced modalities. Our findings reflect the greater advanced imaging resources necessary to support the complexity of care rendered at teaching hospitals. This differential must be considered when exploring adjustments to teaching hospitals' funding levels.

Emergency radiology: Maxillofacial and skull-base trauma

Craniofacial trauma is common following road-traffic accidents, assaults and falls and may occur in isolation or associated with other body injuries. Due to the complexity of the maxillofacial and skull-base region, initial diagnosis may be inaccurate or delayed, leading to significant morbidity. Multidetector computed tomography is the modality of choice following high-energy blunt or penetrating trauma. It allows accurate evaluation of the fracture patterns and associated soft tissue complications and aids the appropriate medical and surgical treatment. In this article, we review and classify the most common traumatic injuries to the maxillofacial and skull-base region and outline the role of imaging in establishing complications and prognosis.

Diagnostic efficacy of cone-beam computed tomography for mandibular fractures

OBJECTIVE

The aim of the study was to determine the clinical efficacy of maxillofacial cone-beam computed tomography (CBCT) for the diagnosis of suspected mandibular fractures and to evaluate whether findings would lead to a change in treatment.

STUDY DESIGN

CBCT imaging was performed for 164 patients with suspected mandibular fractures (231 sites) but equivocal clinical and radiological findings (conventional radiography). Images were interpreted by oral and maxillofacial surgeons and treatment decisions based on pre and postimaging were compared. Linear regression analyses were performed.

RESULTS

For 63.2% of sites (n = 146) the suspected diagnosis was confirmed by CBCT (P < .0001; R(2) = 0.93). For 4.33% of sites (n = 10) no fracture was identified. Additional fractures were identified in 17.75% (n = 41) and additional infractures in 14.72% (n = 34). The treatment plan was altered for 9.52% of sites (n = 22).

CONCLUSIONS

CBCT imaging of suspected mandibular fractures resulted in a change in the treatment plan in 9.52%.

Analysis of mandibular condylar and glenoid fossa fractures with computed tomography

OBJECTIVES

The purpose of this study was to investigate the prevalence of glenoid fossa and condylar fractures in patients with mandibular fractures using multidetector computed tomography (MDCT).

METHODS

A prospective study was performed in 227 patients with mandibular fractures who underwent 64-MDCT. Mandibular fractures were classified into four types: median, paramedian, angle and condylar. Statistical analysis of the relationship between prevalence of condylar fractures and mandibular fracture locations was performed using χ(2) test with Fisher's exact test. A P value less than 0.05 was considered statistically significant.

RESULTS

The prevalence of condylar fracture was 64.8 % of all patients with mandibular fractures, 66.7 % of median type (P = 0.667), 45.5 % of paramedian type (P = 0.001) and 12.3 % of angle type (P = 0.000), respectively. Furthermore, glenoid fossa fracture was seen in 1.4 % of patients with condylar fractures.

CONCLUSIONS

The results of the presented study suggest focusing also on incidental findings such as glenoid fossa fractures.

KEY POINTS

• The prevalence of condylar fracture was 64.8 % in patients with mandibular fractures. • Glenoid fossa fracture was seen in 1.4 % of patients with condylar fractures. • The study suggests a focus on incidental findings such as glenoid fossa fractures.

Mandibular fracture patterns consistent with posterior maxillary fractures involving the posterior maxillary sinus, pterygoid plate or both: CT characteristics

OBJECTIVES

The aim of this study was to determine the incidence of posterior maxillary fractures involving the posterior maxillary sinus wall, pterygoid plate or both, unrelated to major midface fractures in patients with mandibular fractures, and to characterize associated fractures.

METHODS

A CT study was performed in patients with mandibular fractures to identify posterior maxillary fractures. Patients aged under 16 years, those with mandibular fractures involving only dentoalveolar components and those with concurrent major midfacial fractures were excluded.

RESULTS

13 (6.7%) of 194 patients with mandibular fractures also had posterior maxillary fractures (case group). The injury pattern correlated with the external force directed to the lateral side of the mandible (p < 0.001), alcohol consumption (p = 0.049), the presence of multifocal fractures (p = 0.002) and the fracture regions in the symphysis/parasymphysis (p = 0.001) and the angle/ramus (p = 0.001). No significant difference between the case and non-case groups was seen for age, sex or cause of trauma. Non-displaced fractures in the ipsilateral posterior mandible occurred with significant frequency (p = 0.001) when the posterior maxillary fractures involved only the sinus.

CONCLUSIONS

Mandibular fractures accompanied by posterior maxillary fractures are not rare. The finding of a unilateral posterior maxillary fracture on CT may aid the efficient radiological examination of the mandible based on possible patterns of associated fractures, as follows: in the ipsilateral posterior region as a direct fracture when the impact is a medially directed force, and in the symphysis/parasymphysis or contralateral condylar neck as an indirect fracture.