Chapter

Oral and maxillofacial imaging for the anaesthetist

Neil Heath and Iain Macleod

in Oxford Textbook of Anaesthesia for Oral and Maxillofacial Surgery

Published on behalf of Oxford University Press

Published in print June 2010 | ISBN: 9780199564217
Published online July 2011 | e-ISBN: 9780199697854 | DOI: http://dx.doi.org/10.1093/med/9780199564217.003.0013

Series: Oxford Textbook in Anaesthesia

 Oral and maxillofacial imaging for the anaesthetist

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The oral and facial structures are a problematical area for both the anaesthetist and maxillofacial surgeon as the oral cavity and nasal passages provide a common portal for both airway access and surgical intervention. Obviously an understanding of the anatomy of these structures and their variations is essential. In addition, the jaws provide radiographic challenges by virtue of their unique anatomy.

Dental imaging is a specialist area, which utilizes radiographic techniques that are unusual in their acquisition. For example, the use of non-screen film for intraoral views that give high resolution images is the main way in which teeth and their supporting structures are demonstrated. Such techniques include bitewings, periapical, and occlusal views.

The dental panoramic tomogram (DPT), sometimes called the orthopantomogram (OPG) is the ‘work horse’ of jaw imaging. However, this view has unusual anomalies which are created by virtue of the way it is formed. These units produce an image of the dental arches using a variation on the technique of tomography that involves rotating the X-ray tube and film, producing blurring of the structures on either side of the centres of rotation.

In dental panoramic tomography, a horseshoe-shaped in-focus plane (focal trough) is created by moving the centre of rotation during the exposure. Care must be taken in patient positioning to ensure that the teeth lie within the trough otherwise, the resultant image will be distorted. Advances in dental imaging include cross-sectional modalities such as modified dental panoramic views, conventional computed tomography (CT) and cone beam CT scans. Cone beam CT is a new process that, when compared with conventional CT, uses a lower radiation dose and a cross-sectional imaging technique which acquires a volume of data that can be presented in a number of formats, e.g. panoramic or as axial, coronal, or sagittal slices similar to those seen using conventional CT.

The use of magnetic resonance imaging (MRI) is becoming invaluable in helping to characterize neoplasia presenting in the head and neck. Cysts, inflammatory lesions, and bone pathology can also be assessed using this modality. MRI is now the gold standard for investigation of temporomandibular joint (TMJ) pathologies owing to its ability to resolve and demonstrate the complexities of the internal features of this atypical joint.

Cross-sectional imaging has simplified much of the clinical problem-solving carried out in the oral and maxillofacial region. The remainder of this chapter will address some of the key aspects of oral and maxillofacial imaging now available.

Chapter.  5102 words.  Illustrated.

Subjects: Anaesthetics ; Radiology

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