RETRACTED: Image-guided procedures in the hybrid operating room: A systematic scoping review

Over the past decade, hybrid operating rooms (OR) have revolutionized the way image-guided procedures are performed. In a hybrid OR, the properties of an aseptic OR are combined with advanced imaging techniques like multidetector computed tomography (MDCT), cone-beam computed tomography (CBCT), fluorescence imaging, and magnetic resonance imaging (MRI). These properties of the hybrid OR allow the combination of open and percutaneous interventions, which avoids the need to perform multiple consecutive procedures or intraoperative patient transport. The advanced imaging techniques facilitate planning of the procedure based on the current intraoperative situation, real-time intraoperative guidance, and direct assessment of technical success at the end of the procedure [ 1 , 2 ]. The first procedure that induced the development of the hybrid OR, was a cardiovascular procedure. Barstad et al. described a procedure that combined percutaneous transluminal coronary angioplasty and minimally invasive direct coronary artery bypass grafting in the same anesthetic setting [ 3 ]. This combination of procedures required imaging in the OR. In earlier days, imaging was mainly performed using mobile equipment. However, with an increase in complex and demanding procedures, a new type of OR was designed. Barstad et al. already mentioned a specially designed surgical-radiologic suite for their hybrid procedure [ 3 ]. Later on, the term ‘hybrid operating room’ was introduced for ORs that enabled specialists to perform procedures that require imaging in a sterile environment. Only recently, a definition of ‘hybrid operating room’ was established in an expert consensus meeting [ 4 ]. According to this definition, the OR should at least be equipped with a coordinate system-based imaging technique. In this review, we follow this definition and explore procedures in which intra-operative 3D imaging is performed within the OR. Nowadays, cardiovascular surgeons are still major users of the hybrid OR, but due to improvements in imaging modalities, computer graphics, and surgical instruments, the use of hybrid ORs is no longer limited to cardiovascular procedures [ 5 ]. For example, orthopedic and neurosurgeons also perform minimally invasive image-guided procedures in the hybrid OR and other potential areas of application are still arising [ 6 , 7 ]. The aim of this scoping review therefore is to provide an overview of the use of the hybrid OR over the years, and to report on the advantages and challenges that were encountered during procedures performed in the hybrid OR.

A total of 9426 records were identified of which 5357 unique studies were screened based on title, abstract and full text. Inter-rater agreements of 92% (kappa: 0.81, 95% CI: 0.63–0.99) and 90% (kappa: 0.74, 95% CI: 0.55–0.95) were reached for the abstract and full-text screening, respectively. Finally, 123 studies did fulfill the inclusion criteria for this scoping review. A flowchart of this literature search can be found in Fig 1 , and an overview of the included studies can be found in S1 Table . The number of studies increased over the years, from two in 2010 to fifteen in the first five months of 2020, as has the number of clinical disciplines that use the hybrid OR. ( Fig 2 ). In 2010, the hybrid OR was only used by the cardiac surgeons, whereas there were nine different disciplines using the hybrid OR in 2020: Thoracic surgery (n = 42), Neurosurgery (n = 37), Vascular surgery (n = 21), Cardiac surgery (n = 8), Urology (n = 6), Orthopedic surgery (n = 6), Ophthalmology (n = 1), Oral and maxillofacial surgery (n = 1), and Otolaryngology/cervicofacial surgery (n = 1). The studies were performed in 21 different countries. Most of them originated from Europe (n = 38, 31%), followed by the USA (n = 26, 21%), Taiwan (n = 23, 18%), and Japan (n = 17, 14%). The median number of included patients was 15 (range 1–1027). Fifty-one studies (41%) enrolled 10 or fewer patients. Furthermore, only 15 studies (12%) compared the outcomes of a patient group treated in the hybrid OR with those of a patient group treated in a standard procedure room. Ninety-nine (80%) of the included studies described how 3D imaging in the hybrid OR was performed. Ninety-five (96%) of these studies used CBCT as a coordinate-based imaging system, while four studies (4%) used MDCT. We identified three stages in which 3D imaging was performed: at the start of the procedure, during the procedure, and at the end of the procedure. 3D imaging was performed at the start of the procedure in 68/99 (69%) studies. In this stage, imaging was used to acquire insight into the patient’s anatomy in surgical position; to translate a pre-operative procedure plan to the intraoperative situation; or to make a procedure plan. The procedure plan was made either using the software of the 3D imaging modality itself, or by using other navigation technology. 3D imaging was performed during the procedure in 41/99 (41%) studies. In this stage, the images were used to acquire an updated view of the anatomy; to update the navigation; to assess the presence of accidental tissue damage; or to assess the position of a needle/probe/catheter after which the next stage of the procedure started. In 40/99 (40%) studies 3D imaging was performed at the end of the procedure to assess the results of the treatment and to continue the procedure to make adjustments if necessary. In five studies, some patients received a repeated confirmation scan after the adjustments. Twenty-four (20%) of the included studies described the presence of a coordinate-based imaging system in the hybrid OR, but they did not report the use of 3D imaging during the procedure. In 20/24 (83%) studies, the use of 2D imaging, that is, mainly fluoroscopy or 2D angiography, was described. Three of 24 (13%) studies did not describe performing imaging at all, and 1/24 (4%) studies used the imaging facilities of the hybrid OR but performed surgery in the standard OR. Most of the studies (16/24, 67%) described a vascular procedure performed by vascular surgeons (n = 10, 42%) or neurosurgeons (n = 6, 25%). In addition to 3D imaging, other medical technologies were used in the hybrid OR, namely surgical navigation and fluorescence imaging. Infrared- and electromagnetic tracking-based surgical navigation was used in 12/123 (10%) and 6/123 (5%) studies, respectively. Infrared-based navigation was mainly used by thoracic, orthopedic, and neurosurgeons, while electromagnetic tracking was used by thoracic surgeons only. Fluorescence imaging was performed in 8/123 (7%) studies, in which a near-infrared camera is used to image the administered indocyanine green (ICG). It was mainly used in thoracic and neurovascular interventions. In thoracic surgery, tumors were marked with an ICG-dye for minimally invasive localization of non-palpable small pulmonary nodules. In the neurovascular procedures, ICG video angiography was used to visualize the patency of blood vessels. We identified four different thoracic surgical procedures that were performed in the hybrid OR; image-guided video-assisted thoracoscopic surgery (iVATS), lung biopsy, pulmonary tumor ablation, and rib tumor resection. The reasons to perform these procedures in the hybrid OR were: to enable the localization and resection in one setting for the iVATS procedure; to improve needle positioning and by that the tumor yield of the lung biopsy; to use image-guidance for planning and positioning of the probe to improve tumor targeting during the ablation procedure; and to minimize tissue damage and evaluate the completeness of the resection of non-palpable rib tumors. We identified twelve types of neurosurgical procedures, of which seven were cerebrovascular procedures: clipping of aneurysms, vessel embolization, aspiration of hematomas and abscesses, excision of arteriovenous malformations (AVM), angioplasties, vessel coiling, and endarterectomies. The reason to perform these procedures in the hybrid OR was the availability of real-time feedback regarding the angioarchitecture to directly assess the treatment result, which improves patient safety as well as the accuracy of the treatment results. This in turn helps preventing hemorrhages and detecting iatrogenic traumas. In clipping of aneurysm, vessel embolization, and endarterectomy procedures, ICG fluorescence and infrared-based neuronavigational techniques were used in addition to 3D imaging. The other five neurosurgical procedures were: tumor resection, shunt placement, odontoidectomy, lead positioning, and percutaneous sclerotization and vertebroplasty combined with surgical decompression. Tumor resection and odontoidectomy procedures were performed in the hybrid OR to avoid complications and improve resection completeness. This was realized by using infra-red-based navigation and assessed by intra-operative 3D imaging. For all other neurosurgical procedures, the reason to perform the procedure in the hybrid OR was to assess treatment results using 3D imaging to improve accuracy. Furthermore, in shunt placement, the burr hole and catheter positions were planned using 3D imaging to improve patient safety. Within vascular surgery, five procedures were identified: endovascular aortic repair (EVAR), embolization procedures, stenting procedures, removal of a catheter remnant, and detection and treatment of pulmonary embolism in hemodynamically unstable patients. The reason to perform EVARs, embolization, and stenting procedures in the hybrid OR was to limit the contrast and radiation doses by using image fusion possibilities or by performing an intraoperative control CBCT instead of a control computed tomography angiography at discharge. Removal of a catheter remnant was performed in the hybrid OR because 3D imaging enabled surgeons to perform the operation minimally invasively. The procedure involving pulmonary embolisms was the only procedure in which patients were brought to the hybrid OR for a diagnosis, in order to immediately perform a treatment if necessary. Four procedures were reported in urology: percutaneous nephrolithotomies, retrograde intrarenal surgery with lithotripsy, super-selective tumoral embolization, and laparoscopic thermal ablation. The procedures regarding kidney stones were performed in the hybrid OR because it was expected that 3D imaging would improve patient safety in complex cases and increased effectiveness in finding residual stones were expected when 3D imaging was used compared to using fluoroscopic or endoscopic techniques. The super-selective tumoral embolization combined with a partial nephrectomy was performed in the hybrid OR because intraoperative 3D imaging of the vasculature facilitated performing the procedure in a clampless fashion. The reason to perform the laparoscopic thermal ablation procedure in the hybrid OR was that the procedure could then be performed minimally invasively. 3D imaging was used for tumor targeting, verification of the position of the probe, and evaluation of the ablation zone. Within orthopedic surgery, fixation of ankle bones and intralesional curettage of bone tumors were reported. In the fixation of ankle fractures, 3D imaging was used to assess the syndesmotic reduction by comparing both ankles to prevent malreduction after fixation, which could occur when fluoroscopy alone would have been used. The reason to perform the intralesional curettage procedure in the hybrid OR was to facilitate surgical navigation based on the current anatomical situation and to have the possibility of assessing the resection results. The hybrid OR was used by cardiac surgeons for performing a transapical aortic valve implantation, a ventricular pseudoaneurysm repair, placement of a stent graft in an atrial septal defect, and for object removal from a ventricle. In all procedures, the 3D imaging possibilities in the hybrid OR were used for image fusion. This transformed the preoperative plan to the current anatomical situation, which increased patient safety Placement of spinal screws is a procedure that was performed by neurosurgeons and orthopedic surgeons, in seven and three studies, respectively. This procedure was performed in the hybrid OR because 3D imaging allowed surgical navigation based on the current intraoperative situation. It was expected that this improved the accuracy and lowered the complication risks and radiation dose. Procedures performed by other clinical disciplines were also found, e.g. by ophthalmology, oral and maxillofacial surgery, otolaryngology/cervicofacial surgery. These are described in S1 Table . Advantages of performing procedures in the hybrid OR were explicitly mentioned in 94 (76%) studies. The advantages that were most often described were the improved accuracy of treatment results and the improved patient safety (both mentioned by 33/94 (35%) studies). The improved patient safety is partly associated with the fact that the patient does not have to be transported to an imaging facility (27/94, 29%). Furthermore, 3D imaging for planning and the procedure itself can be performed without adjusting the patient position, which benefits the accuracy. Patient safety is further increased since accidental tissue trauma and complications can be visualized and treated instantaneously (10/94, 11%). Another often mentioned advantage is that the treatment result can be assessed before closing the patient. This allows continuation of the procedure if the result turns out to be unsatisfactory (16/94, 17%). As a result, the number of reinterventions might be reduced, as mentioned by 8/94 (9%) studies, and it could possibly eliminate the need for postoperative control imaging (7/94, 7%). Furthermore, 16/94 (17%) of the studies acknowledged that being able to combine minimally invasive and open procedures was an advantage of the hybrid OR. Other advantages are visualized in Fig 3 and described per procedure in S2 and S3 Tables. The numbers and grayscale indicate how many studies mentioned the advantage. Thirty-four of the 99 (35%) included studies that performed 3D imaging mentioned challenges of performing a procedure in the hybrid OR. A longer OR utilization time was mentioned in 11/34 (32%) studies. These studies described iVATS procedures (8/11, 73%), spinal screw positioning (2/11, 18%), and a navigational bronchoscopy procedure (1/11, 9%). The longer procedure times were mainly caused by a more complex patient positioning compared to the standard procedure and the extension of the anesthesia equipment, which were required for a CBCT-scan acquisition. Five of the studies that performed these procedures also mention the existence of a learning curve that is induced by the more complex patient positioning and preparation [ 12 – 16 ]. Another challenge of performing 3D imaging in the hybrid OR is a possible increase in radiation dose compared to the use of 2D fluoroscopy alone (mentioned by 8/34, 24% of the studies). The challenge of potential collisions between the C-arm and the surgical equipment, which could impede the procedure, was mentioned in 7/34 (21%) studies. Furthermore, the use of 3D imaging to confirm the treatment results within the hybrid OR could lead to overtreatment. Lerisson et al. evaluated the influence of continuation of the treatment of anomalies that were detected by control CBCT on the long-term results in patients with abdominal aneurysms of the aorta [ 17 ]. These anomalies encompass endoleaks, bridging stent through the fenestration, and kinks. They found that immediate corrective treatment of endoleaks did not lead to a significant decrease in the number of reinterventions and number of late events compared to a patient group that was treated without an intra-operative 3D scan. This could be explained by possible spontaneous sealing of the endoleaks within a short period after the procedure, which suggests that not all intraoperatively found endoleaks require further treatment [ 17 ]. Other challenges are visualized in Fig 4 , and described per procedure in S2 and S3 Tables. No challenges were mentioned by studies that performed the procedures in the hybrid OR without performing 3D imaging. The numbers and grayscale indicate how many studies mentioned the challenge.

In conclusion, the increase in the number of clinical disciplines shows the wide functionality of the hybrid OR. The most reported advantage of using a hybrid OR is achievement of more accurate treatment results, whereas elongation of the procedure time is the most important challenge faced in the hybrid OR, followed by an increased radiation dose. To optimize the use of the hybrid OR, comparative studies should be performed in order to identify which procedures benefit of being performed in this facility.

This systematic scoping review was conducted following the Arksey and O’Malley framework and the revisions made by Levac et al. [ 8 , 9 ] The results were reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Extension for Scoping Reviews (PRISMA-ScR) guidelines [ 10 ]. PubMed, Embase, Web of Science, and Cochrane Library databases were systematically searched using the combined synonyms for the following search terms: hybrid, operating, operation, surgery, room, and theater ( S1 File ). No date or language limits were applied. The last search was performed in May 2020. Reference lists of included documents were reviewed to identify related and relevant studies. After removal of duplicates, one author (IS) reviewed the retrieved citations for potential eligibility by screening the titles. Subsequently, two authors (IS, JH) independently reviewed a random sample of fifty citations for potential eligibility by screening the titles and abstracts. After an inter-rater agreement of more than 80% was achieved, one author (IS) reviewed the remaining citations [ 11 ]. Any cases of doubt were solved by independent assessment of, and discussion with, a second author (JH). The full-text was retrieved for all citations identified for potential inclusion. Studies were included if they described a procedure that used intra-operative 3D imaging techniques for planning, guidance or control in human patients, and that was carried out in a hybrid OR. Again, two authors (IS, JH) independently reviewed fifty randomly sampled full-texts for eligibility. After an inter-rater agreement of more than 80% was reached, one author (IS) reviewed the remaining studies. In case studies had overlapping patient cohorts, the most recent study was included. Using a pre-defined form, the following data were extracted: authors, year, country, clinical discipline, disease, intervention, number of patients, main imaging technique, additional technologies, advantages of the hybrid OR, and challenges of the hybrid OR. The data were summarized based on the use of 3D imaging techniques in the hybrid OR. Furthermore, the studies were grouped based on the procedure and categorized into main clinical discipline that performed the procedures. A descriptive analysis of the advantages and challenges was conducted within these groups.

(DOCX) Search query and number of results per database. (DOCX) Information about the included studies regarding number of patients, disease, and procedure. (DOCX) Overview of how 3D imaging is used in the hybrid OR per clinical discipline and information about its advantages and challenges. (DOCX) Overview of how the hybrid OR is used per clinical discipline and information about its advantages and challenges. (DOCX)