A hybrid operating room is an advanced surgical theatre that is equipped with advanced medical imaging devices such as fixed C-arms, X-ray tomography (CT) scanners, or magnetic resonance imaging (MRI) scanners. These imaging devices enable minimally-invasive surgery. Minimally-invasive surgery is intended to be less traumatic for the patient and minimize incisions on the patient and perform surgery procedure through one or several small cuts.
Though imaging has been a standard part of operating rooms for a long time in the form of mobile C-arms, ultrasound, and endoscopy, these minimally-invasive procedures require imaging techniques that can visualize smaller body parts such as thin vessels in the heart muscle and can be facilitated through intraoperative 3D imaging.
Clinical applications Hybrid operating rooms are currently used mainly in cardiac, vascular, and neurosurgery, but could be suitable for a number of other surgical disciplines.
Cardiovascular surgery The repair of diseased heart valves and the surgical treatment of rhythm disturbances and aortic aneurysms can benefit from the imaging capabilities of a hybrid OR. Hybrid Cardiac Surgery is a widespread treatment for these diseases.
The shift toward endovascular treatment of abdominal aortic aneurysms also pushed the spread of angiographic systems in vascular operating room environments. Particularly for complex endografts, a hybrid operating theater should be a basic requirement. Also, it is well-suited for emergency treatment.
Some surgeons not only verify the placement of complex endografts intraoperatively, they also use their angiography system and the applications it offers for planning the procedure. As anatomy changes between a preoperative CT and intraoperative fluoroscopy because of patient positioning and the insertion of stiff material, more precise planning is possible if the surgeon performs an intraoperative rotational angiography, takes an automatic segmentation of the aorta, places markers for the renal arteries and other landmarks in 3D and then overlays the contours on 2D fluoroscopy. This guidance is updated with any change in C-arm angulation/position or table position.
Neurosurgery
In neurosurgery, applications for hybrid ORs are for example spinal fusion and intracranial aneurysm coiling. In both cases, they have been rated promising to improve outcomes. For spinal fusion procedures, an integration with a navigation system can further improve the workflow. Intraoperative acquisition of a cone beam computed tomography image can also be used to reconstruct three dimensional CT-like images. This may be useful for the applications above and also for confirmation of targeting for placement of ventricular catheters, biopsies, or deep brain stimulation electrodes. Intra-operative MRI is used to guide brain tumor surgery as well as placement of deep brain stimulation electrodes and interstitial laser thermal therapy.
Thoracic surgery and endobronchial procedures
Procedures to diagnose and treat small pulmonary nodules have also recently been performed in hybrid operating rooms. Interventional image guidance thereby offers the advantage of precisely knowing the position of the nodules, particularly in small or "ground-glass" opaque tumors, metastases, and/or patients with reduced pulmonary function. This allows for a precise navigation in biopsies, and resection in video-assisted thoracoscopic surgery. Most importantly, using interventional imaging in video-assisted thoracoscopic surgery can substitute for the loss of tactile sensing. This approach also delivers the potential to spare healthy lung tissue by knowing the exact position of the nodule which increases the quality of life for the patient after the operation.
The process for diagnosis and treatment usually comprises 3 steps: Detection of nodules on CT or chest X-ray Biopsy of nodule to evaluate malignancy If necessary, treatment of nodule through surgery, radiotherapy, and chemotherapy (curative approach) or through chemoembolization and ablation (palliative approach)
A hybrid operating room supports steps 2 and 3 (if surgery is performed) of this workflow:
Biopsy Small lung nodules identified on a thorax CT need to be examined for malignancy, thus a small portion of sample tissue is taken out in a needle procedure. The needle is advanced through the bronchial tree, or trans-thoracically, toward the position of the nodule. To make sure tissue is captured from the nodule as opposed to accidentally taking healthy lung tissue, imaging modalities such as mobile C-arms, ultrasound, or bronchoscopes are used. The yield rate of biopsies in small nodules is reported to be between 33 and 50% in tumors smaller than 3 cm.
To increase the yield rate, advanced interventional imaging with angiographic C-arms has proven to be beneficial. The advantage of intra-procedural imaging is that the patient and the diaphragm are in exactly the same position during 2D/3D imaging and the actual biopsy. Hence the accuracy is usually much higher than using pre-operative data. Rotational angiography visualizes the bronchial tree in 3D during the procedure. The air thereby serves as a 'natural' contrast agent, thus the nodules are well visible. On this 3D image, using dedicated software, the nodules can be marked, along with a planned needle path for the biopsy (endobronchially or trans-thoracically). These images can then be overlaid on live fluoroscopy. This gives the pulmonologist improved guidance toward the nodules. Yield rates of 90% in nodules of 1–2 cm, and 100% in nodules > 2 cm have been reported with this approach.
Surgery
Video-assisted thoracoscopic surgery is a minimally-invasive technique to resect lung nodules that saves the patient the trauma of a thoracotomy. Thereby, small ports are used to access the pulmonary lobes and introduce a camera on a thoracoscope, along with the necessary instruments. While this procedure speeds up recovery and potentially reduces complications, the loss of natural vision and tactile sensing makes it difficult for the surgeon to locate the nodules, especially in cases of non-superficial, ground-glass opaque, and small lesions. The yield rate for nodules < 1 cm can be below 40% as studies show. As a consequence sometimes more healthy tissue is resected than actually necessary in order to avoid missing (parts of) the lesion. Using advanced intra-operative imaging in the operating rooms helps to precisely locate and resect the lesion in a potentially tissue-sparing and quick fashion. In order to be able to use image guidance during video-assisted thoracoscopic surgery, rotational angiography has to be performed before the introduction of ports, thus before the lobe in question deflates. This way the lesion is visible through the natural contrast of air. In a second step, hook wires, thread needles, or contrast agent (lipiodol, iopamidol) are introduced into or next to the lesion to ensure visibility on the angiogram after lung deflation. Then, the conventional part of video-assisted thoracoscopic surgery starts with the introduction of thoracoscopes. The imaging system is used in fluoroscopic mode now, where both the inserted instruments and the previously marked lesion are well visible. A precise resection is now possible. In case contrast agent has been used to mark the lesion, it will also drain into the regional lymph nodes, which then can be resected within the same procedure.
Orthopedic trauma surgery
Complex fractures like pelvis fractures, calcaneal, or tibia head fractures, etc. need an exact placement of screws and other surgical implants to allow quickest possible treatment of the patients. Minimally invasive surgical approaches result in less trauma for the patient and quicker recovery. However, the risk of malpositionins, revisions, and nerval damage cannot be underestimated (Malposition and revision rates of different imaging modalities for percutaneous iliosacral screw fixation following pelvic fractures: a systematic review and meta-analysis). The possibility of the use of an angio system with a spatial resolution of 0.1 mm, the large field of view to image the entire pelvis in one image and the high kW rate allows the surgeon high precision images while not impairing hygiene (floor-mounted systems) or access to the patient (CT). Degenerative spine surgery, traumatic spinal fractures, oncologic fractures, or scoliosis surgery are other types of surgery that can be optimized in a hybrid OR.AO Foundation, AOTrauma Webcast: Intraoperative 3D Imaging and Computer Guidance for MIS in Spinal Trauma , University Hospital Um, Univ. Prof. Dr. Florian Gebhard, MD; Prof. Dr. Thomas R. Blattert, MD, July 10th, 2014 The large field of view and the high kW rate allow to optimally image even obese patients. Navigations systems or the use of integrated laser guidance can support and improve the workflow.
Laparoscopic surgery
As in other minimally invasive surgery, not everybody in the surgical community did not believe in this technology. Today it is the gold standard for many types of surgery. Starting with a simple appendectomy, cholecystectomy, partial kidney resections and partial liver resections, the laparoscopic approach is expanding. The image quality, the possibility of imaging the patient in the surgical position and the guidance of the instruments facilitate this approach.(Efficacy of DynaCT for surgical navigation during complex laparoscopic surgery: an initial experience. Partial resection of the kidney, leaving as much healthy tissue, meaning kidney function to the patient has been described.). The challenges the surgeons face is the loss of natural 3D vision and tactile sensing. Through small ports he/she has to rely on the images provided by the endoscope and is unable to feel the tissue. In a hybrid operating room the anatomy can be updated and imaged in real time. 3D images can be fused and/or overlaid on live fluoroscopy or the endoscope. (Real-time image guidance in laparoscopic liver surgery: first clinical experience with a guidance system based on intraoperative CT imaging.) Crucial anatomy like vessels or a tumor can be avoided and complications reduced. Further investigations are under trial at the moment. (Surgical navigation in urology: European perspective)
Emergency care
For the treatment of trauma patients, every minute counts. Patients with severe bleeding after car accidents, explosions, gunshot wounds, aortic dissections, etc. need immediate care due to the life-threatening blood loss. In a hybrid operating room both open and endovascular treatment of the patient can be performed. For example, the tension in the brain due to a severe haemorrhage can be relieved and the aneurysm can be coiled. The concept of placing the emergency patient on an operating table as soon as he/she enters the hospital, if stable perform a trauma scan in the CT or if unstable immediate procedure in the hybrid operating room without having to reposition the patient can save valuable time and reduce risk of further injury.
Imaging techniques
Imaging techniques with a fixed C-arm
Fluoroscopy and data acquisition
Fluoroscopy is performed with continuous X-ray to guide the progression of a catheter or other devices within the body in live images. To depict even fine anatomic structures and devices, brilliant image quality is required. In particular, in cardiac interventions, imaging the moving heart requires a high frame rate (30 fps , 50 Hz) and high power output (at least 80 kW). Image quality needed for cardiac applications can only be achieved by high powered fixed angiography systems, not with mobile C-arms.
Angiographic systems provide a so-called acquisition mode, which stores the acquired images automatically on the system to be uploaded into an image archive later. While standard fluoroscopy is predominantly used to guide devices and to re-position the field of view,