Journal Article

Three-dimensional CT-guided Bronchoscopy with a real-time electromagnetic position sensor : A comparison of two image registration methods

WHITE, Peter JR, SOLOMON, Stephen B, ORENS, Jonathan B, WIENER, Charles M, KO PEN WANG

2000

Overview

To compare two different image registration methods for accurately displaying the position of a flexible bronchoscope on a previously acquired three-dimensional CT scan during bronchoscopy. Bronchoscopy suite of a university hospital. Fifteen adult patients scheduled for nonemergent bronchoscopy. A miniature electromagnetic position sensor was placed at the tip of a flexible bronchoscope. Previously acquired three-dimensional CT scans were registered with the patient in the bronchoscopy suite. Registration method 1 used multiple skin fiducial markers. Registration method 2 used the inner surface of the trachea itself for registration. Method 1 was objectively assessed by measuring the error distance between the real skin marker position and the computer display position. Methods 1 and 2 were subjectively assessed by the bronchoscopist correlating visual bronchoscopic anatomic location with the computer display position on the CT image. The error distance (+/- SD) from known points for registration method 1 was 5.6 +/- 2.7 mm. Objective error distances were not measured for method 2 because no accurate placement of the bronchoscope sensor could be correlated with CT position. Subjectively, method 2 was judged more accurate than method 1 when compared with the fiberoptic view of the airways through the bronchoscope. Additionally, method 2 had the advantage of not requiring placement of fiducial markers before the CT scan. Respiratory motion contributed an error of 3.6 +/- 2.6 mm, which was partially compensated for by a second tracking sensor placed on the patient's chest. Image registration method 2 of surface fitting the trachea rather than method 1 of fiducial markers was subjectively judged to be superior for registering the position of a flexible bronchoscope during bronchoscopy. Method 2 was also more practical inasmuch as no special CT scanning technique was required before bronchoscopy.

• Publisher: American College of Chest Physicians
• Subject: Biological and medical sciences / Biopsy / Bronchoscopy / Electromagnetic Phenomena / Endoscopy / Female / Humans / Investigative techniques, diagnostic techniques (general aspects) / Male / Medical imaging / Medical sciences / Methods / Patients / Radiography, Interventional / Registration / Sensors / Skin / Tomography, X-Ray Computed