Helical (spiral) CT of the upper airway with three-dimensional imaging: technique and clinical assessment

• Published in: American journal of roentgenology (1976) Vol. 166; no. 2; pp. 293 - 299
• Main Authors: Zeiberg, AS, Silverman, PM, Sessions, RB, Troost, TR, Davros, WJ, Zeman, RK
• Format: Journal Article
• Language: English
• Published: Leesburg, VA Am Roentgen Ray Soc 01-02-1996; American Roentgen Ray Society
• Subjects: Biological and medical sciences; Case-Control Studies; Humans; Hypopharynx - diagnostic imaging; Image Processing, Computer-Assisted; Investigative techniques, diagnostic techniques (general aspects); Laryngeal Diseases - diagnostic imaging; Larynx - diagnostic imaging; Medical sciences; Phantoms, Imaging; Pharyngeal Diseases - diagnostic imaging; Radiodiagnosis. Nmr imagery. Nmr spectrometry; Respiratory system; Retrospective Studies; Tomography, X-Ray Computed - methods; Trachea - diagnostic imaging; Tracheal Diseases - diagnostic imaging; Human; Upper aerodigestive tract; Radiodiagnosis; Exploration; Three dimensional space; Computerized axial tomography; Technique; Respiratory system; Image reconstruction
• ISSN: 0361-803X; 1546-3141
• DOI: 10.2214/ajr.166.2.8553933

The purpose of this study was to evaluate the application of helical CT-generated three-dimensional images of the upper airway.
Thirty patients, 10 healthy and 20 with upper-airway disease, were studied with helical CT (5-mm collimation). Overlapping images at 2-mm intervals were retrospectively generated. In the group of healthy patients, two radiologists in independently compared overlapping with nonoverlapping images, ranked confidence in identifying small airway structures on a scale of 1-5, and tabulated the number of images demonstrating these structures. In the 20 patients with disease, three-dimensional (3D) surface models were rendered on an independent workstation and were reviewed by two radiologists and one otolaryngologist for image quality, appreciation of lesion morphology, and ability to judge lesion extent, using a similar scale. A phantom was used to optimize parameters for the 3D reconstructions.
Viewing of the retrospectively generated overlapping images increased by 122% the number of images in which laryngeal and hypopharyngeal structures could be identified (p < .01). Image confidence scores for the radiologists averaged 3.3 for nonoverlapping and 4.0 for overlapping (p < .05). Radiologists and otolaryngologist rated the quality of the 3D images equally. The otolaryngologist's assessment of the value of the models for understanding the lesion morphology was 3.5 compared with the radiologists assessment of 2.5; and for judging the lesion extent, the otolaryngologist's assessment was 3.8 compared with 2.7 for the radiologist, a statistical significance of p < .01.
Helical CT with the application of overlapping images and 3D reconstructions significantly assists the understanding of upper-airway disease.