Objective: To evaluate the influence of different spiral CT examination protocols suitable for clinical use on image quality and to assess the observer dependence in interactive real-time virtual bronchoscopy.
Methods and patients: Real-time perspective volume rendering of the airways in twenty normal patients based on four different spiral CT examination protocols was evaluated by four observers in regard to the order of depictable bronchi.
Results: Best results were obtained using an examination protocol with a small beam collimation and a maximum pitch. Depending on the observer's ability to control the fly path and the orientation of the bronchi with respect to the slice plane up to sixth order bronchi could be depicted. Inter-observer variability was up to two branching orders.
Conclusion: The performance of virtual bronchoscopy strongly depends on the applied CT examination protocol and the observers experience with perspective volume rendering. Both of which have to be taken into account when virtual bronchoscopy is compared with fiberoptic bronchoscopy.