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[Spiral CT in arytenoid cartilage dislocation: the optimization of the study parameters with a cadaver phantom and its clinical evaluation].

PURPOSE
To evaluate an optimal scan protocol in a cadaver phantom and its clinical assessment in 40 patients.


MATERIALS AND METHODS
In a cadaver larynx phantom helical CT (HiSpeed Advantage; GE, Milwaukee, Wis) was performed with increasing collimation (1-10 mm) and pitch (1.0-3.0). 40 patients with an immobile vocal cord were randomly assigned to undergo CT with a certain protocol.


RESULTS
Best resolution was obtained with a collimation of 1 mm and pitch 1. The pitch could be increased up to 2 without losing information. With a collimation of 3 mm and higher, anatomical details were missed. In the patient studies a combination of 1 mm collimation with a pitch of 2.0 showed less motion artifacts than a pitch of 1.0.


CONCLUSION
The quality of CT imaging of the arytenoid cartilage depends greatly on the scanning parameters, the compliance of the patients and the mineralisation of the cartilage. For clinical assessment a collimation of 1 mm with a pitch of 2 is recommended. The increase pitch has the advantage of shorter acquisition times and decreased radiation exposure.