ControversiesChallengesConsensus

Developments in imaging go under the scanner at CX35

Identifying the various strengths and limitations of the state-of-the-art imaging systems was at the core of Sunday’s morning session.

CX chairman Roger Greenhalgh said: “It is imagined that many of the post-operative problems of EVAR and TEVAR could relate to inadequate preparation and imaging. At CX35, there are three full-sized imaging suites from GE Healthcare, Philips and Siemens because imaging in three dimensions before the deployment of devices is crucial to getting the size right, meaning the central luminal line and properly measuring neck lengths, landing zones and establishing whether there is thrombus and calcium, to avoid endoleaks. So whatever the specialty—vascular surgery, interventional radiology or interventional cardiologyknowledge of imaging is crucial. There is also a need for simulation and rehearsal.”


A panel comprising of Nung Rudarakanchana, London, UK, Lieven Maene, Aalst, Belgium, and Stéphan Haulon, Lille, France, discussed the advantages of using hybrid imaging suites in the diagnosis, planning and intra-operative imaging guidance of minimally-invasive endovascular procedures. Janet Powell, London, UK, chaired the session.


The panel told delegates that vascular surgical training needed to ensure that young surgeons learn how to use 3D workstations. Haulon made the point that with complex new techniques that take time to perform, there was significant radiation exposure to both patient and operator. “We need to use every available tool to reduce the radiation dose,” he said.

Maene, agreeing, also highlighted that trainees needed to be aware about all different techniques. “You need to  know about fusion imaging, cone beam CT and intraoperative marking to get the best out of all these systems. It is important to reduce the radiaition and also not lose important information for your procedure,” he noted. Rudarakanchana added concurrent advances in simulation and hybrid suite imaging now also allowed for whole teams to be trained with a view to reducing radiation dose and improving procedural outcomes.


Advanced hybrid suite imaging is the key to surgical advance


“Advanced hybrid suite imaging is said to be on key to surgical advance, 
allowing us to improve the quality, effectiveness and efficiency of the treatments we offer to patients with the long-term goal of improving patient outcomes,” Rudarakanchana told delegates.


“The rise of catheter-based procedures and minimally invasive surgery has led to the evolution of hybrid suites, which combine state-of-the-art imaging with the sterility of an operating theatre. These provide fertile ground for surgical innovation and opportunities to expand treatment possibilities,” she said.


 “Three-dimensional image guided navigation is now possible and further innovations in robotics, advanced endoscopic vision and precise manipulation are on the horizon.”


She explained that hybrid suites accomplish imaging purposes via fixed C-arms, either floor or ceiling- mounted, which incorporate digital flat panel detectors for high image quality, large fields of view and, in some cases, three-dimensional imaging with soft-tissue contrast resolution.


Recent developments in hybrid suite imaging, Rudarakanchana commented, have now expanded capabilities beyond the traditional two-dimensional fluoroscopy and three-dimensional rotational angiography, to enable acquisition of CT-like three-dimensional imaging for image-based guidance and intra-operative functional imaging such as flow analysis.

Referring to long-term endovascular aneurysm repair (EVAR) outcomes, Rudarakanchana highlighted that  “advanced hybrid suite imaging may be key to improving optimal sizing and more precise graft deployment and immediate quality control in a sterile environment. Accurate deployment of endovascular grafts and optimal stent positioning can be expected to reduce the risk of endoleaks and other complications, leading to a sustained benefit in terms of aneurysm-related survival in patients undergoing endovascular repair.”


She also noted that a wide range of surgical specialties, including cardio-thoracic, trauma, orthopaedics, urology, neurosurgery, gynaecology, maxillo-facial and hepatobiliary surgery could benefit from hybrid suite imaging facilities.

 

 

Optimal imaging and planning for abdominal aneurysm


Lieven Maene, Aalst, Belgium, explained that 3D endovascular guidance had multiple benefits in preoperative and intra-operative EVAR management with direct impact on device deployment, as problems with parallax and distortion, sizing and navigation remained areas of concern.


The SiemensArtis Zeego Endovascular Guidance system, Maene noted, had multiple benefits: precise endovascular action; control in allowed interactive imaging during EVAR with precise endovascular action; control in 3D; parallax quantification; evaluation of distortion and aortic changes; and limited use of contrast.


“3D imaging can become a vital part in our daily life, at home and in our professional life, if we give it a chance,” he said.

Maene highlighted that computed tomography angiography (CTA) delivers accurate measurements and 3D reconstructions. Also, magnetic resonance angiography (MRA) reduces radiation and nephrotoxicity, volume rendering with centerline calculation and stretch-views eliminate angulation errors. However, he said: “The most crucial phase in EVAR, the accurate deployment of the stent graft, is often poorly controlled with 2D fluoroscopy.”


To overcome this problem, Maene commented: “The use of a hybrid operating room with 3D imaging and perioperative guidance allows the physician to evaluate the patient’s anatomy in a new dimension.” Intra-operative systems such as the 3D syngo Dyna CT (Siemens) are able to reflect the possible anatomical changes and distortion due to the large-bore devices and stiff wires.


Maene explained that the system allows visualising perpendicular planes that can be quantified along the centerline of the aorta during the operation and used as markers (guidance ring) for accurate deployment taking into account these anatomical changes of the aorta.


“Partial stent graft deployment allows alignment of the guiding planes with stent graft markers to avoid parallax errors. Ostia of aortic side branches and vessel contours can be marked for navigation and move along in the three-dimensional images even when changing the position of the C-arm,” he said.


In conclusion, Maene told delegates: “Three-dimensional endovascular guidance offers a new perspective during EVAR performed in a hybrid operating room. Marking of the landing zones and side-branch ostia improves the accuracy of graft deployment and guides the physician through the challenging aortic anatomy.”


“This system may improve long-term EVAR results by decreasing type I endoleak, avoiding inadvertent side branch occlusion and may support diagnosis and treatment of postoperative endoleaks. Preoperative sizing at a multimodality workstation with current software tools remains very helpful,” he added.


Benefits of Innova Vision Technology with first GE Discovery experience


Stéphan Haulon, Lille, France, shared his experience using the GE Discovery IGS730 at Lille University Hospital. He said that the hospital installed this hybrid suite six months ago and so far has performed over 200 procedures including electrophysiology, transcatheter aortic valve implantation (TAVI) and EVAR.


“In all of the EVAR cases we performed (including standard infra-renal cases and complex cases such as fenestrated and branched endografts), we used Innova Vision to fuse 3D pre-operative CT on top of the fluoroscopy images,” he said. “With this technique, we could benefit from a 3D vascular map without the need to perform any 3D rotational acquisition or additional contrast injection at the time of the intervention.”


He also explained that access to the fused image takes a few minutes including CTA images preparation and registration on the current patient position on the operating room table. “The 3D overlay then adapts to table and C-arm movement allowing patient centering and C-arm positioning without the need to shoot X-ray,” he added.


Haulon concluded: “With our new hybrid room, we are able to keep the mobility and sterility management of a mobile C-arm while benefiting from easy to use 3D imaging techniques that help us decrease contrast media injection and radiation exposure for us and for the patients.” He added, “The mobility of the system has a clear benefit for the entire team allowing us to perform a wide variety of vascular access including axillary and carotid access.”


Haulon told delegates that he did not routinely use cone beam CT in fusion imaging as the mean dose area product (DAP) was 1200 cGy.cm², which was 10% of the DAP to implant  branched endgrafts for thoracoabdominal aneurysms, 50% of the DAP for TEVAR procedures and 70%  of the DAP for EVAR.


In order to keep the radiation dose down, Haulon said the team’s favourite approach for 3D overlay was fusion with 2D fluoroscopy. “One of the benefits of Innova Vision technology is that it is a workflow for dummies, even a vascular surgeon like myself can do it,” he joked. He also said: “You need to have full control of the system at the tableside and, in our practice, it has helped decrease fluoro time, X-ray dose and contrast volume.” 

2016-10-12T13:01:25+00:00