Computed tomography versus standard radiography in the assessment of fractures of the mandible

A review of mandibular angle fractures

AFTER STUDYING THIS ARTICLE, THE READER WILL BE ABLE TO: (1) review the incidence and etiology of mandibular angle fractures; (2) gain an understanding of patient evaluation and general management principles; and (3) discuss indications and available techniques for management of mandibular angle fractures. Angle fractures represent the highest percentage of mandibular fractures. Two of the most common causes of mandibular angle fractures are motor vehicle accidents and assaults or altercations. With any patient who has sustained facial trauma, a thorough history and comprehensive physical examination centering on the head and neck region as well as proper radiological assessment are essential. These elements are fundamental in establishing a diagnosis and developing an appropriate treatment plan for any mandibular fracture.

The Identification of Mandible Fractures by Helical Computed Tomography and Panorex Tomography

The introduction of computed tomography (CT) in 1972 revolutionized the radiographic evaluation of patients who have experienced trauma. However, panoramic tomography (PT) continued to be superior in sensitivity to CT in the identification of mandible fractures and has been considered the gold standard for the past 3 decades. In 1989, a faster, higher-resolution spiral or helical CT (HCT) became widely available, and its efficacy in multiplanar evaluation and diagnosis of fractures of the upper two thirds of the face has been well established. The sensitivity of this new-generation HCT in comparison to PT in the detection of mandible fractures has not been determined. The purpose of this study was to compare the sensitivity, physician interpretation error, and interphysician agreement of HCT and PT in the identification of mandible fractures. The number and anatomical location of mandible fractures identified by HCT and PT was not significantly different. However, the number and location of 96% of fractures identified by HCT was agreed on by neuroradiologists compared with only 91% of fractures identified by PT. Furthermore, the interphysician agreement when no fracture was identified was 96% by HCT versus only 81% by PT. In conclusion, HCT has enhanced imaging quality, equivalent sensitivity in identification of fractures, decreased interpretation error, and greater interphysician agreement in the identification of mandible fractures. HCT has surpassed PT as the current gold standard for the radiographic evaluation and diagnosis of mandible fractures.

Prospective comparison of panoramic tomography (zonography) and helical computed tomography in the diagnosis and operative management of mandibular fractures

This prospective study compared the sensitivity of panoramic tomography (zonography) and helical computed tomography (CT) in diagnosing 73 mandibular fractures in 42 consecutive patients and correlated the results with known surgical findings. The purpose of the study was to determine the optimal radiologic examination for the diagnosis and operative management of mandibular fractures. The attending surgeons' interpretations of panoramic tomograms and helical CT images in the axial plane were compared with the patients' known surgical findings. A series of questions assessed the relative contribution of these two radiologic examinations in formulating an optimal operative plan for each patient. In the 42 patients studied, the sensitivity of helical CT was 100 percent in diagnosing mandibular fractures; this compared with 86 percent (36 of 42) for panoramic tomography, in which significantly more fractures were missed (p = 0.0412). In the six patients with fractures not visualized, the operative management was altered because of the new fracture visualized on helical CT. Of the seven missed fractures, six were in the posterior portion of the mandible. Comparing fracture detection by region, seven fractures found on helical CT were not visualized on panoramic tomography. Helical CT improved the understanding of the nature of mandibular fractures by providing additional information regarding fracture displacement and comminution and by locating injuries missed using panoramic tomography. This study suggests that helical CT alone may be more diagnostic than panoramic tomography alone in evaluating mandibular fractures. Helical CT sufficiently demonstrated details of fractures in 41 of 42 patients; in one patient, the nature of a dental root fracture was better delineated by panoramic tomography.

Pantomography vs mandibular series for the detection of mandibular fractures

OBJECTIVE

The two primary radiographic techniques used for the evaluation of mandible injury are a pantomographic series (PS) and the standard four-view mandibular series (MS). Despite a tenuous foundation, there is apparent bias in favor of PS compared with MS. Many emergency departments do not have ready access to the specialized equipment necessary to perform a pantomographic study. The hypothesis of this study was that a high-quality standard MS is as sensitive and specific as a PS in the detection of mandibular fractures.

METHODS

This was a prospective, blinded study of 54 patients presenting with acute mandibular injury comparing MS and PS. The study design used two board-certified emergency physicians and a single staff radiologist who read a series of MS and PS films in a randomized fashion without access to clinical information or identifying patient data. The absolute number of fractures present was determined by a neuroradiologist with access to both MS and PS simultaneously as well as pertinent clinical information.

RESULTS

Thirty patients had 47 mandibular fractures. The sensitivity for fracture detection for each physician was 0.85, 0.77, and 0.89 with MS and 0.79, 0.74, and 0.83 with PS (p > or = 0.51, p > or = 1.00, and p > or = 0.51, respectively, McNemar's binomial test). The specificity for fracture detection for each physician was 0.88, 0.92, and 0.96 for MS and 0.96, 1.00, and 0.92 for PS (p > 0.625, p > 0.50, and p = 1.00, respectively, McNemar's binomial test).

CONCLUSIONS

A standard mandibular series is as sensitive and specific as pantomography in the detection of mandibular fractures.

Helical CT and three-dimensional CT of facial and orbital injury

Knowledge of the regions of the face and their buttresses and knowledge of the types of facial injuries frequently encountered simplifies the diagnostic task. The indications for CT include detection of suspected fractures and preoperative planning. The cost of facial CT to the hospital has declined and is little different than the cost of plain films. CT may become the screening modality of choice depending on the cost structure at any given hospital.

An association between imaging and acute posttraumatic ear bleeding with trismus

OBJECTIVES

Computed tomography findings for each of 94 patients with unilateral ear bleeding and trismus correlated with either comminuted temporal bone fracture (26 cases) or bilateral temporomandibular joint fracture (68 cases).

STUDY DESIGN

Ninety-four patients with post-traumatic unilateral ear bleeding and 10 asymptomatic adults underwent coronal computed tomography examinations of their temporomandibular joints. Of these, 26 patients with intact temporomandibular joints underwent axial computed tomography of the temporal bones. For 23 of the 94 symptomatic patients, computed tomography was the final imaging procedure; for the other 71 symptomatic patients, it was the first imaging procedure. Quantifications of the radiation dose and the per-patient cost of imaging were performed. Measurement of the maximal mandibular movements in vertical and horizontal directions was performed clinically in the 10 asymptomatic adult control subjects and in the 94 patients with trismus and ear bleeding.

RESULTS

Ten control subjects had maximal opening values of 40 mm or more, and horizontal movement exceeded 24 mm. In 68 symptomatic patients, coronal computed tomography demonstrated bilateral fracture: there was bilateral high condylar fracture in 35 patients, and there was ipsilateral to the bleeding high condylar fracture with contralateral subcondylar fracture dislocation in 33 patients. Axial computed tomography scans in 26 symptomatic patients with intact temporomandibular joints demonstrated comminuted petrous bone fracture ipsilateral to the ear bleeding.

CONCLUSIONS

Patients with post-traumatic ear bleeding associated with trismus should first be evaluated by computed tomography. Any other initial procedure doubles the radiation dose as well as the cost of the imaging.