New noncontact sensor for detecting pulmonary tumors during video-assisted thoracic surgery

Small pulmonary tumors are difficult to localize during video-assisted thoracic surgery (VATS) because of lack of direct tissue contact. However, in partial lung resection, tumor localization is quite important. The aim of this study was to evaluate the safety and feasibility of a new noncontact sensor for detecting pulmonary nodules during VATS using human and porcine models.

The sensor, based on the principle of phase differences, comprises an air nozzle for producing air pulse jets and an optical fiber sensor to measure phase differences and visualize object stiffness. For in vivo assessment, we developed a porcine model by inserting plastic balls mimicking tumors into the pig lungs after thoracotomy and then scanned the lungs. The sensor sensitivity was evaluated by measuring the ratio of the depth of the ball from the lung surface to the ball diameter (D/S). For the ex vivo human model, partially resected lung tissue with tumors was obtained from six patients and then scanned.

In the porcine model, 32 of 37 (86.5%), 70 of 94 (74.5%), and 60 of 100 (60.0%) tumors were detected in the categories D/S ≤ 1, 1 < D/S ≤ 2, and D/S > 2, respectively. Sensor safety was confirmed with an air jet at pressures between 0.05 and 0.15 MPa directed onto the lung surface; all the examined lungs including the pleura remained intact microscopically. In six patients, all nodules were successfully detected.

Our noncontact sensor is a safe and feasible tool for detecting small pulmonary tumors during VATS.