الفهرس 
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Abstract
Imaging techniques play a crucial role in pre-therapeutic and post therapeutic diagnostics. The radiologist employs a conventional x-ray, swallow examination as well as contrast-enhanced Multidetector Computed Tomography (MDCT), Magnetic Resonance Imaging (MRI), and ultrasound depending on the medical problem in question.
The Plain-film is a relatively simple method of demonstrating the anatomy of the larynx and pharynx and it shows the air/soft-tissue interface and the surrounding bony structures, it uses the air as a differentiating contrast medium within the soft tissues of the neck.
The best plain film view is given by the lateral projection with the pharynx and larynx clear of the cervical spine .The anteroposterior views are excellent for examining the glottic and subglottic area but it is limited in interpretive capabilities because the overlapping cervical spine obscures an adequate assessment in most instances.
The Modified barium swallow is designed to:
(a) Examine the anatomy and physiology of the oral cavity and pharynx during deglutition.
(b) Identify the disorders in movement patterns of oropharyngeal structures that control the bolus and cause aspiration or inefficient swallowing (residue).
(c) Define treatment strategies that will eliminate aspiration and/or increase swallow efficiency.
(d) Multi-views videofluoroscopy used to assess the velopharyngeal port in patients with velopharyngeal incompetence for proper management of such patients.
Computerized Tomography has long been favoured for laryngeal and pharyngeal imaging because the rapidity of image acquisition minimizes breathing and swallowing artifacts. Patients who are unable to remain still in the supine position because of concomitant chronic lung disease or excessive pharyngeal secretions also are more readily evaluated with CT.
Rapid, thin-slice imaging with MDCT allows three-dimensional (3D) reconstruction formats such as volume and surface rendering and virtual laryngoscopy that may offer improved evaluation of the larynx. The modified Valsalva technique (exhalation against a closed glottis or blowing through a straw) or the phonation technique (the patient exhales with a constant ‘‘eeeeee’’ sound during image acquisition) may be used to expand the pyriform sinuses and distend the laryngeal ventricles, thus allowing better delineation of these structures.
Virtual laryngoscopy is a computer technique for creating anatomic simulations in a way that is analogous to conventional laryngoscopy by reconstructing two dimensional CT images of the larynx.
from the prospective of patient care Virtual laryngoscopy unlike conventional endoscopy doesn’t cause discomfort to the patient or side effects including perforation, infection or haemorrhage, it also allow examination of inflamed sites and inaccessible areas such as the subglottic area.
Modern MRI instruments are capable of producing images in the form of 3D blocks, which may be considered a generalisation of the single-slice, tomographic concept. Unlike CT, MRI does not involve the use of ionizing radiation and is therefore not associated with the same health hazards.
Because CT and MRI are sensitive to different tissue properties, the appearance of the images obtained with the two techniques differ markedly.
Superior soft tissue contrast is the most striking advantage of MRI in comparison to CT. Drawbacks are relatively long examination time, cost, demands more co-operation from the patients than CT and can’t be done with claustrophobia , sever dyspnea, odynophagia or in the presence of electronic implants.
Till date very little ultrasonographic investigations have been carried out to evaluate the larynx as it was considered unsuitable for examination of air containing structures. However, modern real time ultrasound is capable of high resolution and soft tissue discrimination. The examination is not affected by the patient movements and provides an opportunity to study vocal fold mobilit