2D and 3D visualisation of head and neck tumours from spiral-CT data

Purpose: This paper intends to demonstrate the possibilities of two- and th ree-dimensional visualisation methods from spiral-CT data sets in the head and neck region and demonstrates their value based on various studies. Mate rial and methods: The scanner was a Somatom PLUS 4 (Siemens. Forchheim/Germ any). The patients were scanned using a slice thickness of 3 mm and a table feed of 5 mm (pitch 1.6). The images were reconstructed with an increment of 1 mm. Contrast agent (150 ml) was applied intravenously with a flow of 1 .5 ml/s and a start delay of 80 s. In one study the start delay was 20 s in order to visualise the carotid arteries (extracranial aneurysm). Volumetri c data sets were postprocessed with 'Vitrea' and 'VoxelView' (Vital Images) volume rendering software on a Silicon Graphics O2 workstation (virtual la ryngoscopy). Multiplanar reformation and colour-coded 3D-reconstruction wer e done on a Prominence workstation (Siemens/Forchheim/Germany). Results: In every region of the head and neck MPRs are useful as additional planes (wi th the exception of the hypopharynx and the larynx). SSDs are always useful if there is extensive bony destruction (skull. spine, skeleton larynx). Co lour-coded three-dimensional reformations may be done for extensive tumours and before multi-specially surgery. Perspective volume rendering is alread y in use for virtual endoscopy of the paranasal sinuses and the virtual lar yngoscopy. In temporal bone evaluation, perspective volume rendering is a n ew and promising method of the future to assess the inner ear. Summary: Two - and three-dimensional displays are used to visualise pathological finding s in their topographic relation to anatomical leading structures. Thus. the radiologist carl point out to the clinician the pathological findings by s ome essential images without having to demonstrate all axial slices. (C) 20 00 Elsevier Science Ireland Ltd. All rights reserved.