Intraoperative near-infrared imaging can identify pulmonary nodules

Abstract

Background: Over 80,000 people undergo pulmonary resection for a lung nodule in the United States each year. Small nodules are frequently missed or difficult to find despite preoperative imaging. We hypothesized that near-infrared (NIR) imaging technology could be used to identify and locate lung nodules during surgery.

Methods: We enrolled 18 patients who were diagnosed with a pulmonary nodule that required resection. All patients had a fine-cut 1-mm computed tomography scan preoperatively. The patients were given systemic 5 mg/kg indocyanine green and then underwent an open thoracotomy 24 hours later. The NIR imaging was used to identify the primary nodule and search for additional nodules that were not found by visual inspection or manual palpation of the ipsilateral lung.

Results: Manual palpation and visual inspection identified all 18 primary pulmonary nodules and no additional lesions. Intraoperative NIR imaging detected 16 out of the 18 primary nodules. The NIR imaging also identified 5 additional subcentimeter nodules; 3 metastatic adenocarcinomas and 2 metastatic sarcomas. This technology could identify nodules as small as 0.2 cm and as deep as 1.3 cm from the pleural surface. This approach discovered 3 nodules that were in different lobes than the primary tumor. Nodule fluorescence was independent of size, metabolic activity, histology, tumor grade and vascularity.

Conclusions: This is the first-in-human demonstration of identifying pulmonary nodules during thoracic surgery with NIR imaging without a priori knowledge of their location or existence. The NIR imaging can detect pulmonary nodules during lung resections that are poorly visualized on computed tomography and difficult to discriminate on finger palpation.

Figure 1

Patient #3: A 64 year old female presented with a ¹⁸FDG-avid (SUV 9.3) 6 cm right upper lobe tumor. (A) CT scan; (B) PET scan; (C) Conventional camera; (D) Near-infrared camera; (E) Near-infrared heat map; (F) Fluorescence; (G) Hematoxylin & Eosin; (H) 780 nm light source; (I) Miscroscopic overlay.

Figure 2

Patient #12: A 29 year old male presented with a ¹⁸FDG-avid (SUV 7) 2.7 cm right upper lobe tumor.

Figure 3

Overview of results from NIR imaging study.

Figure 4

A. In situ, fluorescent nodules are more likely to be closer to the pleural surface (p=0.044). B. Smaller nodules (<2 cm) trended towards less fluorescence but this did not reach statistical significance nor did it have clinical impact. C. There is no correlation of microvascular density (CD31 staining) to degree of fluorescence.