Accurate and patient-friendly intraoperative lung nodule localization method for sublobar resection using a hybrid operating room

A hybrid operating room (OR) is an OR that uses advanced imaging techniques, such as multidetector computed tomography (CT), cone-beam computed tomography (CBCT), fluorescence imaging and magnetic resonance imaging [1]. Hybrid ORs were originally developed for cardiovascular surgery, but they are now used for many other clinical areas including thoracic surgery, neurosurgery, vascular surgery, urology and orthopaedic surgery. In thoracic surgery, a hybrid OR has been used as an intraoperative localization method for pulmonary nodules that are difficult to identify visually or by finger palpation.

Yang et al. [2] reported a feasibility study of single-stage augmented fluoroscopic bronchoscopy localization and thoracoscopic resection of small pulmonary nodules in a hybrid OR. Their localization method had 2 main characteristics: a single-stage procedure performed in a hybrid OR and marking under an augmented fluoroscopic bronchoscopy. Marking is important for localizing small pulmonary nodules that are otherwise difficult to identify intraoperatively, especially subsolid nodules or deep-seated nodules.

There are 2 main controversies regarding marking methods: the appropriate material to use for marking and the approach. Markers reported to be useful for marking include hook wire, methylene blue, barium, lipiodol, indocyanine green, indigo carmine, radiofrequency identification and coils [3–5]. There are 2 ways to place the marker at the planned location: the percutaneous needle approach and the bronchoscopic approach [4]. The percutaneous needle approach under CT guidance is simpler and easier to perform than the bronchoscopic approach. However, the percutaneous needle approach is reported to have risks of complication, such as pneumothorax or air embolism. Therefore, there have been increasing reports of marking by bronchoscopy in recent years [6].

Bronchoscopic marking is more difficult to perform than the percutaneous needle approach; therefore, various technologies are used to support it such as virtual navigation, electromagnetic navigation and augmented fluoroscopic guidance [6]. Virtual navigation bronchoscopy is a method that uses 3-dimensional (3D) images created from CT data. A route is planned through the bronchus to the target lesion, and the placement of marking by bronchoscopy is performed using the image as a reference [7]. Electromagnetic navigation bronchoscopy is a CT image-based virtual bronchoscopy technique combined with an electromagnetic positioning system [8]. Augmented fluoroscopy combines augmented imaging data with real-time fluoroscopy. Yang et al. reported a procedure using augmented fluoroscopy using co-registration of annotated CBCT data and C-arm fluoroscopy. In their study, spatial information of the target lesion was displayed during the bronchoscopic marking procedure [9].

Yang et al. conducted single-stage augmented fluoroscopic bronchoscopy and subsequent surgical resection in a hybrid OR. Their previous method of augmented fluoroscopic bronchoscopy was performed in the angiography room on the same day or the day before [9]. Their augmented fluoroscopic bronchoscopic marking method was as follows. First, a 3D CBCT image was obtained in the inspiration phase of tidal breathing during a single breath hold and transferred to a nearby workstation. After identifying the target lesion on the CBCT image, the lesion was annotated using semi-auto segmentation software (syngo iGuide Toolbox, Siemens Healthcare GmbH, Forchheim, Germany). Then, the marked contours were shown on a 2-dimensional fluoroscopy live screen in accordance with their corresponding 3D locations. Under the augmented fluoroscopy guidance, the catheter direction was repeatedly adjusted until the metal tip reached the annotated target, as observed on the live screen. Thereafter, dye [indigo carmine mixed with iopromide (Ultravist 370; Bayer, Berlin, Germany)] was sprayed onto the target area. Multiple dye marking instead of single dye marking was used when the lesion could not be reached. Microcoil was used to mark the central margin if needed. After the marking, confirmation CT was performed to confirm the location of the dye markers and their geometric relationship to the target lesion. A 3D CT image was also created to show the geometric relationship to the target lesion to support the planned operation. After the hybrid OR became available, they changed all the procedures to single stage at the OR. They reported that there were 2 significant improvements in their new method. First, CT images became clearer because breathing was completely controlled after intubation. Second, it is a patient-friendly treatment that can be completed from marking to operation using 1 general anaesthesia. Disadvantages include longer occupancy time in the OR. They reported that all nodules were successfully marked and resected in their feasibility study.

As marking is complex and time-consuming, reducing the number of cases in which marking is required is also important. For deep-seated lesions, segmentectomy can be considered instead of wedge resection with marking. Appropriate CT follow-up to increase the likelihood of lung cancer is another way to reduce unnecessary markings [10]. However, there are still a certain number of operations that require marking. This method may become an effective means of marking in facilities with hybrid OR.

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