Hybrid electromagnetic and image-based tracking of endoscopes with guaranteed smooth output.

PURPOSE: Flexible fiber-optic bronchoscopy is a widespread medical procedure for the diagnosis and treatment of lung diseases. Navigation systems are needed to track the flexible endoscope within the bronchial tree. Electromagnetic (EM) tracking is currently the only technology used clinically for this purpose. The registration between EM tracking and patient anatomy may become inaccurate due to breathing motion, so the addition of image-based tracking has been proposed as a hybrid EM-image-based system. METHODS: When EM tracking is used as an initialization for image registration, small changes in the initialization may lead to different local minima and noise is amplified by hybrid tracking. The tracking output is modeled as continuous and uses splines for interpolation, thus smoothness is greatly improved. The bronchoscope pose relative to computed tomography data is interpolated using Catmull-Rom splines for position and spherical linear interpolation (SLERP) for orientation. RESULTS: The hybrid method was evaluated using ground truth poses manually selected by experts, where mean inter-expert agreement was determined as 1.26 mm. Using four dynamic phantom data sets, the accuracy was 4.91 mm, which is equivalent to previous methods. Compared to state-of-art methods, inter-frame smoothness was improved from 2.77-3.72 to 1.24 mm. CONCLUSIONS: Hybrid image and electromagnetic endoscope guidance provides a more realistic and physically plausible solution with significantly less jitter. This quantitative result is confirmed by visual comparison of real and virtual video, where the virtual video output is much more consistent and robust, with fewer occasions of tracking loss or unexpected movement compared with previous methods.

Deformable registration of bronchoscopic video sequences to CT volumes with guaranteed smooth output.

We present a novel approach to tracking of flexible bronchoscopes by modeling the output as spatially continuous over time. Bronchoscopy is a widespread clinical procedure for diagnosis and treatment of lung diseases and navigation systems are highly needed. Tracking of the bronchoscope can be regarded as a deformable registration problem. In our approach we use hybrid image-based and electromagnetic tracking, and the bronchoscope pose relative to CT data is interpolated using Catmull-Rom splines for position and SLERP for orientation. We evaluate the method using ground truth poses manually selected by experts, where mean inter-expert agreement was determined as 1.26 mm. For four dynamic phantom data sets, the accuracy of our method is between 4.13 and 5.93 mm and shown to be equivalent to previous methods. We significantly improve inter-frame smoothness from 2.35-3.08 mm to 1.08-1.51 mm. Our method provides a more realistic and physically plausible solution with significantly less jitter. This quantitative result is confirmed by video output, which is much more consistent and robust, with fewer occasions of tracking loss or unexpected movement.

Monitoring of glucocorticoid therapy by assessment of CD14(+)CD16(+) monocytes: a case report.

Bronchiolitis obliterans with organizing pneumonia (BOOP) is a disease affecting small airways and alveoli. It is characterized by interstitial inflammation rich in foamy macrophages and by fibroblastic connective tissue expanding into the airway and alveolar lumen. We report herein on a 54-year-old male BOOP patient who was treated with glucocorticoids (GCs) and who over a 5-year period had three relapses. At diagnosis the patient showed elevated CD14(+)CD16(+) monocyte numbers (85 cells/microl) and increased serum C-reactive protein (CRP) levels (29.4 mg/l). With GC therapy both parameters decreased within a few days. Diagnosis of relapse was preceded by a rise in CD14(+)CD16(+) monocyte numbers and in CRP levels which again responded to GC treatment. We conclude that determination of CD14(+)CD16(+) monocytes is a useful marker for monitoring of BOOP diagnosis and GC therapy.

Inhalative vaccination with pneumococcal polysaccharide in patients with chronic obstructive pulmonary disease.

In order to determine the feasibility of inhalative vaccination with polysaccharide antigen in patients with chronic obstructive pulmonary disease (COPD), we used controlled inhalation of a defined dose of Pneumovax in a randomized 3-arm study. The vaccine was either deposited in the alveoli (alveolar vaccination) or in the large airways (bronchial vaccination) and these were compared to standard intramuscular vaccination. Adverse effects were minor and never exceeded WHO grade 2. There was frequent cough, headache and shivering in the bronchial vaccination group, frequent fatigue only in the alveolar vaccination group and no frequent adverse effects in the intramuscular vaccination group. Specific serum IgG antibody was measured before and at 4 and 12 weeks after vaccination. At 12 weeks there was a greater than twofold rise in 7 out of 10 individuals in every vaccination group. Mean antibody levels of responders at 12 weeks were 278 mg/l for alveolar vaccination, 238 mg/l for bronchial vaccination and 737 mg/l for standard intramuscular vaccination. The data show that polysaccharide vaccine can be safely administered by controlled inhalation in COPD patients and that it can induce a rapid serum antibody response.

Inhalative vaccination with pneumococcal polysaccharide in healthy volunteers.

In order to determine the feasibility of inhalative vaccination with polysaccharide antigen, we used controlled inhalation of a defined dose of Pneumovax in a randomized 3-arm study. The vaccine was either deposited in the alveoli (alveolar vaccination) or in the large airways (bronchial vaccination) and this was compared to standard intra-muscular vaccination. Adverse effects were minor and never exceeded WHO grade 2. There was frequent cough in the inhalative groups and frequent local pain at the injection site in the intra-muscular group. Specific serum IgG antibody measured before, and 4 and 12 weeks after, vaccination showed a greater than 2-fold rise in 4 out of 10 individuals after alveolar vaccination and in 6 out of 10 individuals after bronchial vaccination as compared to 10 out of 10 in the intra-muscular vaccination group. Average antibody levels of responders at 12 weeks were 350 microg/ml for alveolar vaccination, 200 microg/ml for bronchial vaccination and 1010 microg/ml for standard intra-muscular vaccination. Analysis of antibodies for 9 specific serotypes showed a more than 3-fold rise to 7-9 of the serotypes in the intra-muscular group. In both the bronchial and the alveolar group, all subjects responded but this was restricted to 2-4 of the 9 serotypes. The data show that polysaccharide vaccine can be safely administered by controlled inhalation and that it can induce good, albeit lower, serum antibody responses.