Multidimensional Precision

Abstract

Lung nodule evaluation accounts for a significant proportion of the practice of pulmonary medicine, thoracic surgery, and interventional radiology. Bronchoscopic sampling of small peripheral nodules frequently requires the assistance of an additional imaging or navigation tool: electromagnetic navigation, virtual bronchoscopy, fluoroscopic navigation, cone-beam computed tomography (CBCT), robot-assisted, etc.1–3 Except for the results from the NAVIGATE study, a majority of the data regarding peripheral nodule sampling is from retrospective or small studies.4 CBCT assisted sampling is gaining popularity due to the ability to obtain real-time cross-sectional/3-dimensional (3D) imaging to confirm the location of an instrument inside of the target lesion. It has been shown to have acceptable yields for nodules <20 mm in size.5,6 The high overhead costs and operational space needed for the CBCT system may preclude its use among most pulmonologists. Mobile C-arm fluoroscopic systems are commonly used within bronchoscopy suites. They are less expensive than CBCT and have a much smaller footprint. We report our experience using a hybrid mobile 2-dimensional (2D)/3D C-arm system for the sampling of peripheral lung nodules. The Cios Spin1 (Siemens Medical Solutions, Malvern, PA) (Fig. 1) is a hybrid mobile 2D/3D C-arm platform that was designed to obtain precise imaging for surgical procedures. It relies on complementary metal-oxide-semiconductor detector technology. It possesses a 30 cm2 field of view and an image resolution of 1952 pixels.7 Orbital movement is ±100 degrees. What makes this system unique is the ability to provide 3D imaging in a mobile platform. It has several distinctive features for the 3D imaging component: the resolution of 512 pixels,3 30-second scan speed, and simultaneous display of 3 projections (transversal, coronal, and sagittal).7 Thus far, its primary applications have been within orthopedic and spinal surgery. With the implementation of a novel soft tissue algorithm (VA30C), new procedural avenues have been opened. Its use in the context of sampling peripheral lung nodules in humans has yet to be reported. In our series, the Cios Spin1 was used as a complementary imaging modality to assist with the sampling of peripheral lung nodules. Patients (or their health care proxies) signed informed consent for the universal procedure of bronchoscopy with biopsies. For data collection, informed consent was waived due to our maintenance of an institutional review board-approved prospective bronchoscopy registry (institutional review board 12-1009).FIGURE 1: The Siemens Cios Spin1 system is a hybrid mobile 2-dimensional (2D)/3-dimensional C-arm system. A, The viewing console houses two screens that can display 2D fluoroscopic images and 3-dimensional reconstructed images. B, The system has a similar footprint to some traditional 2D fluoroscopic units that are currently on the market. C, As with cone-beam computed tomography imaging, a compatible table is needed to allow for spins to occur unhindered.The lesions of 8 patients were sampled using image guidance with the Cios Spin1 system. All procedures were performed with the use of total intravenous general anesthesia. The mean age of the group was 66 years; there were 5 males and 3 females. The mean lesion size was 26 mm×24 mm. The mean radiation time per procedure was 8 minutes and 24 seconds; the mean radiation exposure per procedure was 4092.53 µGy×m2. All procedures employed the use of a radial probe endobronchial ultrasound as a complementary imaging modality. Electromagnetic navigational bronchoscopy (superDimension Navigation System version 7.0; Medtronic, Minneapolis, MN) was used in 2 cases. Tool-in-lesion visualization was obtained in all procedures. On the basis of intraprocedural computed tomography spins, atelectasis was seen in the target lung of 6 patients (75%). In 3 patients (38%), the atelectasis was in the same segment as the lesion, which obscured the borders of the lesion. Rapid on-site pathology was suggestive of a malignant diagnosis in 2/7 patients (29%); 1 procedure did not utilize rapid on-site pathology to assess transbronchial needle aspiration of the parenchymal lesion. Final cytology results were indicative of malignancy in 2 patients (25%). In addition, 1 patient had atypical cells that were suspicious for malignancy. The mean number of computed tomography spins per case was 3 (Video 1, Supplemental Digital Content 1, https://links.lww.com/LBR/A196). The system provided excellent visualization and confirmation of tool-in-lesion (Fig. 2), but atelectasis did obscure some posteriorly located lesions. Additional details of patient, procedure, and lesion characteristics can be found in Table 1.FIGURE 2: A left lower lobe nodule in a 67-year-old woman (patient #7). A, An axial image generated by the 3-dimensional component of the Cios Spin1 showing the bronchoscope in the airway (solid white arrow) and portions of the superDimension Triple Needle Cytology Brush (Medtronic) in the nodule (dashed white arrow). B, A traditional fluoroscopic image by the Cios Spin1 during the same case showing the superDimension Triple Needle Cytology Brush in the nodule (in a 2-dimensional plane). C, The console’s inbuilt monitors allow for the review of 3-dimensional reconstructed images within the procedural room.TABLE 1: Additional Characteristics of the Lesions Sampled With the Cios Spin1 SystemFrom this initial experience, the technology could potentially be useful as another tool to assist with the localization of suspicious pulmonary nodules. We believe the 100% rate of “tool-in-lesion” is beneficial. However, it has yet to be consistently linked to positive outcomes in bronchoscopy. This series is not intended to describe the diagnostic yield of the samples that were acquired as the patients represented a heterogenous population, and they were not followed longitudinally for the attainment of a final diagnosis. In summary, the use of a hybrid mobile 2D/3D C-arm with the ability to provide real-time 3D imaging in place of CBCT has the potential for saving money on upfront equipment costs, saving space, and allowing pathways that augment existing 2D fluoroscopy with advanced 3D imaging. We report the first use of this US Food and Drug Administration approved technology within our field; this initial data shows that it is a safe and feasible imaging modality option for peripheral bronchoscopy. In addition, more extensive studies are required to define the extent of its utility.