1.7 Imaging and navigation tools

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How accurate is intraoperative overlay imaging?
H. Kobeiter

The author started by defining accuracy as the quality or state of being correct or precise, and, technically, it is the degree to which the result of a measurement, calculation, or specification conforms to the correct value or the standard.

Next, he stated that in the last decade, there have been significant improvements and new developments in image guidance. Two-dimensional (2D) angiography has developed into three-dimensional (3D) rotational angiography, and more recently, C-arm cone-beam computed tomography (CBCT) has enabled 3D volumetric imaging. These recent image acquisition capabilities have been developed to assist clinicians in performing procedures that could not be easily done with traditional fluoroscopy or digital subtraction angiography alone. CBCT can be used to guide catheter placement for intra-arterial therapy, stent positioning in arterial or venous disease, needle placement, and coil placement. In addition to image acquisition development, significant achievements have been seen in intraprocedural guidance software advancement that enables the use of multimodality image fusion to guide procedures. Image fusion and coregistration bring different imaging modalities together for targeting a specific location. The image fusion guidance has been reported to be accurate and useful for multiple applications in interventional radiology and endovascular procedures.

Subsequently, he presented several studies and concluded that all aortic parts and vessels are not equal to deformations; technology is accurate, but errors can be induced (vessel shifts, patient movements, or errors in overlay, for instance, as a result of a delay between diagnostic imaging and treatment), even though the majority can be corrected; 3D/3D fusion appears to be more precise than 2D/3D fusion; this technology is sufficient for current clinical requests, but for future applications (eg, robotics and automatic navigation) more accuracy may be needed.

Endovascular navigation: pros and cons of the Magellan system.
F. Cochennec

The Magellan robotic system combines a 9F OD robotically steerable guiding catheter 3D with a distal bend up to 90 degrees, a 6F OD robotically steerable leader catheter 3D with a distal bend up to 180 degrees, and 0.014” to 0.035” guidewires with full-roll capability. Approximately 300 cases were performed worldwide. The author presented the experience of his center from February 2013 to October 2013, totaling 28 cases. Most of them represented complex aortic aneurysms in which a total of 34 vessels were cannulated, with a mean cannulation time of 4 min 10 s, with no target vessel injury. The author concluded that the Magellan robotic system improves stability and pushability, facilitates navigation in complex anatomies, may reduce x-ray exposure and trauma, and has an acceptable learning curve. However, he also highlighted that the device is expensive, cumbersome, and not readily accessible.