Image-guided neuroendovascular intervention is used in modern day minimally invasive treatment of cerebrovascular diseases such as strokes and aneurysms. With the increasing complexity of treatment devices, such as intraluminal and intrasaccular flow diverters, aneurysm bridging stents, and intrasaccular coils used, have tiny sub millimeter sizes with fluoroscopic markers. During intricate deployment of such devices, it is critically important to precisely and accurately visualization the treatment area.

The high definition technology from Canon Medical is based on the concept that a better resolving flat panel detector that detects images drastically better than current flat panel technology can significantly facilitate device visualization during complex endovascular procedures. The ability to view a region of interest all the way down to 76 microns using a 1.5” field of view (FOV) resolution which translates into a much more accurate and precise live visualization of devices as neurosurgeons position and deploy them during complex Neuroendovascular procedures.

“All these various and critical surgical intricacies during the procedure are much better seen with the such accurate resolution than with the standard flat panel detector technology that is used in common angiography systems.”

The researchers located here at the Canon Stroke and Vascular Research Center, University at Buffalo, SUNY performed a preliminary Hi-Def pilot evaluation for a future Alphenix interventional system. In addition to the evaluations, the research resulted in a scientific publication on this new proprietary detector, which had high resolution (Hi-Def) capability coupled with the flat panel detector (FPD) built into one unified housing whose physical appearance was like that of the original FPD. The new detector implementation enabled rapid switching by the operator between Hi-Def and FPD modes. Semi-quantitative subjective studies involving qualitative clinician feedback on images of interventional devices such as a Pipeline Embolization Device (PED) were acquired in both Hi-Def and normal FPD modes.

An image pair consisting of a Hi-Def image and FPD image of the same PED object, FOV and exposure conditions were acquired using the setup described above. A total of 10 different image pairs were obtained by changing PED’s of diff erent sizes, configurations and its positions in the 3D printed neuro-vasculature placed within the skull.

Figure 4 and 5 gives an example of two different image pairs shown to the neuro-interventionalists. Fig. 4a and 5a are the Hi-Def images, and Fig. 4b and 5b are the corresponding FPD images. The images were displayed at their native resolution with a matrix size of 1024 x 1024 pixels.

Image pairs were presented to the neuro-interventionalists, who were asked to select their preferred image within the pair and were asked to rate their choice in comparison with the other image with the following three options: Similar (~), Better (>), or Superior (>>). For a fair and unbiased comparison, the position of the Hi-Def and FPD images within an image pair was not the same but was randomized for all the pairs and was not made known to the raters.

Due to the higher resolution of the Hi-Def technology, images are sharper, and hence are visually improved compared to the images of the FPD. This is supported by the positive results of the comparative physician observer preference study presented here. These results suggest that the improved imaging provided by the HRF can provide an advantage during neurointerventions. The new detector having both Hi-Def and FPD modes can off er an advantage in the clinical setting compared to the existing conventional commercial FPD-only detector systems used in typical interventions.

Although any surgery, especially to the brain, poses risks, some of the risks related to pipeline embolization can be reduced or avoided altogether. These procedural complications bring attention to the importance of an experienced endovascular surgeon, clinical support staff , and research institution with extensive training in performing these is a key factor in reducing the risk of adverse procedural outcomes. It is for these procedural reasons the Hi-Def technology was purposefully engineered for enhanced, precise live intraprocedural visualization.

Hi-Def imaging is most beneficial during the critical parts of the case where you are utilizing high magnifi cation imagery to deploy a complex intravascular device. The best examples of that are currently deployment of coils, deployment of stents, deployments of intraluminal flow diverters, endosaccular flow disrupters, or anything where you really need to appreciate how the device is behaving in a small space and it is of critical implication, there’s nothing that comes close to the ability to visualize these implements than Hi-Def technology.

The ability to transform the field of view with Hi-Def technology in my mind is like what the operating microscope did with open neurosurgery. Prior to the availability of the operating microscope, surgeons would use loops to magnify the visualized anatomy and it was grossly inadequate and the complication rates were very high. The operating microscope opened an entire new era of open neurosurgery, I relate Hi-Def technology to the same kind of transformation when it comes to complex endovascular procedures because it allows us to see things better than we ever saw before, perforators, smaller details in the anatomy, vessel wall apposition. As we start becoming more advanced with materials and methods to access these smaller more delicate structures, Hi-Def technology will make that possible for us.

This is especially true for appreciating nuances such as perforators and small distal branches arising in the brain. Which has more to do with our ability to visualize the current devices and its proper placement within vessel anatomy. As these technologies further develop, I suspect that we will develop means to be able to access these smaller distal blood vessels in the brain, we would develop means to develop asymmetric devices, which deal with the aneurysm and only the aneurysm rather than trying to treat the entire blood vessel that includes even the healthy tissue. Currently all the device therapies we use are based on symmetry, all devices are visualized at either ends with the difficulty to see what is happening at the middle. As interventional imaging technology develops such as Hi-Def, we should be able to develop tools that can precisely treat the injured segments.

A very common question that’s posed to me often is, what kind of increase tradeoff in radiation exposure is a result to this improved and increased visualization? It stands to reason clinicians believe that there would be an increased radiation exposure to the patient, however in this case this is a false statement.

Given the improved collimation and the considerably smaller Hi-Def fields of view (FOV), the average amount of radiation being exposed to the patient and staff is even lower than with conventional standard flat panel (FPD) technology for the same procedure case. In addition, the procedures are more precise, making them faster, more accurate and ultimately safer in the end. When considering all the benefits of the Hi-Def technology factored together, the clinician is getting improved visualization, without the penalty in the total radiation being exposed to the patient, in fact in most cases a reduction.

When we think of neuro interventional procedures we think of treating brain aneurysms, treating AVMs, treating strokes, these are the very early phases of utilizing Neuroendovascular access to treat brain diseases. While these are the common applications currently, I believe that our Hi-Def technology is one of many profound clinical tools evolving towards the enhancement of treating cerebrovascular brain diseases through endovascular therapy.

Based upon my experience and expertise in neurointervention, the Hi-Def technology by Canon Medical, provides a new visualization gateway to clinically expand the horizons of neuro intervention beyond the standard conventional imaging technology today. These clinically-driven features and tools to treat the neurovascular brain and its related affecting diseases, are currently not common to neuroendovascular surgery.

I believe there is potential for this type of enhanced live visualization technology to be utilized in other circulatory beds, be it the kidneys to modulate high-blood pressure, the heart to affect functional change or ablation procedures, or other procedures in other parts of the body where intricate detail is critically important. Hi-Def technology allows you to see things better than you have ever been able to before and I believe this technology feature will be equally useful in other vascular beds or other solid organs as it is in the vascular brain.

¹ Nagesh SVS, Shankar A, Krebs J, Hinaman J, Bednarek DR, Rudin S. (2018). Initial investigations of a special high-defi nition (Hi-Def) zoom capability in a new detector system for neuro-interventional procedures. Proc SPIE Int Soc Opt Eng, 10573: 10.1117/12.2294535.
² Jain A, Bednarek DR, Rudin S: Evaluation of the microangiographic fluoroscope (MAF) using generalized system performance metrics. Medical Physics. 2013; 40(3):031915. doi:10.1118/1.4792460.
³ Jain A, Bednarek DR, Rudin S: Experimental and theoretical performance analysis for a CMOS-based high resolution image detector. Proceedings of SPIE Vol. 9033, 90333P (2014); SPIE Digital Library
⁴ Russ, M, O'Hara, R, Setlur Nagesh, SV, Mokin, M, Jimenez, C, Siddiqui, A, Bednarek, D, Rudin, S, Ionita, C (2015). Treatment Planning for Image- Guided Neuro-Vascular Interventions Using Patient-Specifi c 3D Printed Phantoms. Proc SPIE Int Soc Opt Eng, 9417
⁵ Ionita, CN, Mokin, M, Varble, N, Bednarek, DR, Xiang, J, Snyder, KV, Siddiqui, AH, Levy, EI, Meng, H, Rudin, S (2014). Challenges and limitations of patient-specifi c vascular phantom fabrication using 3D Polyjet printing. Proc SPIE Int Soc Opt Eng, 9038:90380M.