[Indications and diagnostic sensitivity of CT and MRI in the otorhinolaryngology field].
Of all malignant tumors, 4-5% affect the head and neck region. Computed tomography (CT) and magnetic resonance imaging (MRI) provide the means for us to determine the precise extent and depth of infiltration of space-occupying lesions, detect submucosal growth, stage lymph nodes preoperatively, and thus facilitate better preoperative planning. Thinner collimations of sections and shorter examination times are possible with modern multilayer spiral CT. Two-dimensional and three-dimensional images can be calculated from the volume specifications to assess the skull base (coronal and sagittal sections) and the midline crossover of tumors as well as staging of lymph nodes (coronal section). Examination of laryngeal and hypopharyngeal function as well as determination of tumor perfusion are also possible. Detection of tumors that do not absorb any contrast medium (approximately 15%) is more difficult with CT. In addition to providing a high degree of tissue contrast, MRI makes it possible to directly acquire images in any number of planes. In contrast to CT, metallic artefacts hardly come into play. Infiltration of the dura and the cerebrum can be depicted better with MRI than with CT. The long examination time with MRI carries the risk of movement artefacts. In the head and neck region, it is important to suppress fat in T2-weighted sequences and in T1-weighted sequences after administration of contrast media. Inflammations in the head and neck region are only exceptionally clarified with CT or MRI. It is imperative that CT be performed before functional endoscopic operations of the paranasal sinuses. Further indications for CT and MRI in cases of inflammation are the diagnosis of retrotonsillar and parapharyngeal abscesses and ensuing complications as well as the diagnosis of osteomyelitis. Since conventional sialography is contraindicated in acute inflammation in sialolithiasis, magnetic resonance sialography can be employed.
Greess
H
H
Institut für Diagnostische Radiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg. holger.greess@idr.imed.uni-erlangen.de
Lell
M
M
Römer
W
W
Bautz
W
W
D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008198:Lymph Nodes / Q000473:pathology; D008207:Lymphatic Metastasis; D008279:Magnetic Resonance Imaging; D009367:Neoplasm Staging; D010039:Otorhinolaryngologic Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D012680:Sensitivity and Specificity; D036542:Tomography, Spiral Computed; D014057:Tomography, X-Ray Computed