HELICAL (SPIRAL) CT OF THE UPPER AIRWAY WITH 3-DIMENSIONAL IMAGING - TECHNIQUE AND CLINICAL-ASSESSMENT

OBJECTIVE, The purpose of this study was to evaluate the application o f helical CT-generated three-dimensional images of the upper airway. M ATERIALS AND METHODS, Thirty patients, 10 healthy and 20 with upper-ai rway disease, were studied with helical CT (5-mm collimation). Overlap ping images at 2-mm intervals were retrospectively generated, In the g roup of healthy patients, two radiologists independently compared over lapping with nonoverlapping images, ranked confidence in identifying s mall 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 independen t workstation and were reviewed by two radiologists and one otolaryngo logist for image quality, appreciation of lesion morphology, and abili ty to judge lesion extent, using a similar scale, A phantom was used t o optimize parameters for the 3D reconstructions. RESULTS, Viewing of the retrospectively generated overlapping images increased by 122% the number of images in which laryngeal and hypopharyngeal structures cou ld be identified (p < .01), Image confidence scores for the radiologis ts averaged 3.3 for nonoverlapping and 4.0 for overlapping (p < .05). Radiologists and otolaryngologist rated the quality of the 3D images e qually, The otolaryngologist's assessment of the value of the models f or understanding the lesion morphology was 3.5 compared with the radio logists assessment of 2.5; and for judging the lesion extent, the otol aryngologist's assessment was 3.8 compared with 2.7 for the radiologis ts, a statistical significance of p < .01. CONCLUSION. Helical CT with the application of overlapping images and 3D reconstructions signific antly assists the understanding of upper-airway disease.