Bronchoscopy for small pulmonary nodules and mediastinal staging of lung cancer: just do it!

Optimal procedure planning and guidance system for peripheral bronchoscopy

With the development of multidetector computed-tomography (MDCT) scanners and ultrathin bronchoscopes, the use of bronchoscopy for diagnosing peripheral lung-cancer nodules is becoming a viable option. The work flow for assessing lung cancer consists of two phases: 1) 3-D MDCT analysis and 2) live bronchoscopy. Unfortunately, the yield rates for peripheral bronchoscopy have been reported to be as low as 14%, and bronchoscopy performance varies considerably between physicians. Recently, proposed image-guided systems have shown promise for assisting with peripheral bronchoscopy. Yet, MDCT-based route planning to target sites has relied on tedious error-prone techniques. In addition, route planning tends not to incorporate known anatomical, device, and procedural constraints that impact a feasible route. Finally, existing systems do not effectively integrate MDCT-derived route information into the live guidance process. We propose a system that incorporates an automatic optimal route-planning method, which integrates known route constraints. Furthermore, our system offers a natural translation of the MDCT-based route plan into the live guidance strategy via MDCT/video data fusion. An image-based study demonstrates the route-planning method's functionality. Next, we present a prospective lung-cancer patient study in which our system achieved a successful navigation rate of 91% to target sites. Furthermore, when compared to a competing commercial system, our system enabled bronchoscopy over two airways deeper into the airway-tree periphery with a sample time that was nearly 2 min shorter on average. Finally, our system's ability to almost perfectly predict the depth of a bronchoscope's navigable route in advance represents a substantial benefit of optimal route planning.

Computer-based route-definition system for peripheral bronchoscopy

Multi-detector computed tomography (MDCT) scanners produce high-resolution images of the chest. Given a patient's MDCT scan, a physician can use an image-guided intervention system to first plan and later perform bronchoscopy to diagnostic sites situated deep in the lung periphery. An accurate definition of complete routes through the airway tree leading to the diagnostic sites, however, is vital for avoiding navigation errors during image-guided bronchoscopy. We present a system for the robust definition of complete airway routes suitable for image-guided bronchoscopy. The system incorporates both automatic and semiautomatic MDCT analysis methods for this purpose. Using an intuitive graphical user interface, the user invokes automatic analysis on a patient's MDCT scan to produce a series of preliminary routes. Next, the user visually inspects each route and quickly corrects the observed route defects using the built-in semiautomatic methods. Application of the system to a human study for the planning and guidance of peripheral bronchoscopy demonstrates the efficacy of the system.

Investigation of the flexibility of bronchoscopes

Objective

For transbronchial biopsy of peripheral pulmonary lesions manouevering the biopsy instrument into acutely angulated subsegmental ostia is frequently problematic. The aim of the present study was to compare the stiffness of various biopsy instruments with regard to their use in the clinical setting.

Methods

The maximal anterograde and retrograde bending angles, were measured for various bronchoscopes and biopsy instruments. Measurement was made with the distal tip of the biopsy instrument either flush with the distal end of the bronchoscope, or extending 1.5 cm beyond it. The following scopes and biopsy instruments were investigated: 1. the 6.2 mm outside diameter (OD) bronchoscope, with the 2.4 mm OD forceps, 0.7 mm needle, 2.3 mm catheter, and the 1.9 mm cryoprobe. 2. the 5.1 mm OD bronchoscope, with the 1.8 mm forceps, 0.7 mm needle, and the 1.8 mm catheter. 3. the 3.7 mm bronchoscope, with the 1.0 mm forceps and the 0.8 mm forceps.

Results

Maximum angulation was greater by 35.4° with the needle extended, vis-à-vis the needle "flush". Both needle and catheter were associated with a greater angulation of up to 20.5° in comparison with the forceps. With an instrument in the working channel the largest anterograde angles were measured for the 5.1 mm bronchoscope, and the largest retrograde angles for the 6.2 mm bronchoscope.

Conclusion

When selecting the optimal instrument for transbronchial biopsy specimen collection, account must be taken of the fact that the degree of angulation will depend on the type and diameter of the instrument employed.