Original article
General thoracic
Localization of Pulmonary Nodules Using Navigation Bronchoscope and a Near-Infrared Fluorescence Thoracoscope

https://doi.org/10.1016/j.athoracsur.2014.07.050Get rights and content

Background

Video-assisted thoracoscopic wedge resection of multiple small, non-visible, and nonpalpable pulmonary nodules is a clinical challenge. We propose an ultra-minimally invasive technique for localization of pulmonary nodules using the electromagnetic navigation bronchoscope (ENB)-guided transbronchial indocyanine green (ICG) injection and intraoperative fluorescence detection with a near-infrared (NIR) fluorescence thoracoscope.

Methods

Fluorescence properties of ICG topically injected into the lung parenchyma were determined using a resected porcine lung. The combination of ENB-guided ICG injection and NIR fluorescence detection was tested using a live porcine model. An electromagnetic sensor integrated flexible bronchoscope was geometrically registered to the three-dimensional chest computed tomographic image data by way of a real-time electromagnetic tracking system. The ICG mixed with iopamidol was injected into the pulmonary nodules by ENB guidance; ICG fluorescence was visualized by a near-infrared (NIR) thoracoscope.

Results

The ICG existing under 24-mm depth of inflated lung was detectable by the NIR fluorescence thoracoscope. The size of the fluorescence spot made by 0.1 mL of ICG was 10.4 ± 2.2 mm. An ICG or iopamidol spot remained at the injected point of the lung for more than 6 hours in vivo. The ICG fluorescence spot injected into the pulmonary nodule with ENB guidance was identified at the pulmonary nodule with the NIR thoracoscope.

Conclusions

The ENB-guided transbronchial ICG injection and intraoperative NIR thoracoscopic detection is a feasible method to localize multiple pulmonary nodules.

Section snippets

Fluorescence intensity of ICG in lung tissue

Indocyanine green has a binding ability of 98% to plasma proteins; 80% to globulins and 20% to alpha-lipoprotein and albumin [14]. In exciting with 780 to 820 nm of infrared light, ICG emits the fluorescence of the peak wavelength of 810 nm in water and approximately 830 nm in blood. The fluorescence of different dilutions of ICG mixed with albumin was imaged and semiquantified by the Maestro imaging system (Cambridge Research & Instrumentation, Inc, Woburn, MA) in vitro. Each 100 mcL of ICG

In Vitro and Ex Vivo Study

The ICG exhibited a maximum fluorescence of 830 nm infrared light at a concentration of 1.5 × 10−1 (mg/mL) with the presence of 2.0 g/dL of albumin (Figs 1A, 1B). The different concentrations of albumin were mixed to 1.5 × 10−1 g/L of ICG in vitro (Fig 1D). The level of fluorescence increased with a logarithmic curve (Fig 1D). When ICG was dropped onto the sliced porcine lung tissue (Fig 1C), ICG alone (1.5 × 10−1 g/L) showed an increased fluorescence that is equivalent to that of ICG with

Comment

The current study demonstrates that the application of ICG fluorescence dye can be used to localize small-sized pulmonary nodules during minimally invasive thoracic surgery. The excitation of ICG by a class 3 laser light and the deep tissue penetration properties of NIR emission light both contribute to the visualization of the small amount of diluted ICG staying in lung parenchyma. Unlike color dye detection by a white light endoscope, the specific wavelength of ICG fluorescence is always

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