Three-dimensional CT-Guided Bronchoscopy With a Real-Time Electromagnetic Position Sensor

• Published in: Chest Vol. 118; no. 6; pp. 1783 - 1787
• Main Authors: Solomon, Stephen B., White Jr, Peter, Wiener, Charles M., Orens, Jonathan B., Wang, Ko Pen
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.12.2000; American College of Chest Physicians
• Subjects: bronchoscopy; computers; image-guided surgery; stereotaxy; image-guided surgery; CT; TBNA; computers; bronchoscopy; stereotaxy
• ISSN: 0012-3692; 1931-3543
• DOI: 10.1378/chest.118.6.1783

To compare two different imageregistration methods for accurately displaying the position of aflexible bronchoscope on a previously acquired three-dimensional CTscan during bronchoscopy. Bronchoscopy suiteof a university hospital. Fifteen adultpatients scheduled for nonemergent bronchoscopy. A miniature electromagnetic positionsensor was placed at the tip of a flexible bronchoscope. Previouslyacquired three-dimensional CT scans were registered with the patient inthe bronchoscopy suite. Registration method 1 used multiple skinfiducial markers. Registration method 2 used the inner surface of thetrachea itself for registration. Method 1 was objectively assessed bymeasuring the error distance between the real skin marker position andthe computer display position. Methods 1 and 2 were subjectivelyassessed by the bronchoscopist correlating visual bronchoscopicanatomic location with the computer display position on the CTimage. The error distance (± SD) from knownpoints for registration method 1 was 5.6 ± 2.7 mm. Objective errordistances were not measured for method 2 because no accurate placementof the bronchoscope sensor could be correlated with CT position. Subjectively, method 2 was judged more accurate than method 1 whencompared with the fiberoptic view of the airways through thebronchoscope. Additionally, method 2 had the advantage of not requiringplacement of fiducial markers before the CT scan. Respiratory motioncontributed an error of 3.6 ± 2.6 mm, which was partially compensatedfor by a second tracking sensor placed on the patient’s chest. Image registration method 2 of surface fittingthe trachea rather than method 1 of fiducial markers was subjectivelyjudged to be superior for registering the position of a flexiblebronchoscope during bronchoscopy. Method 2 was also more practicalinasmuch as no special CT scanning technique was required beforebronchoscopy.