Enhancing Visualization in Interventional Procedures Using Alphenix High-Definition (Hi-Def) Technology

Since its introduction in late 2018, Canon’s Alphenix Hi-Def Detector – the world’s first true Hi-Def detector for all X-ray guided therapies – has been integrated into clinical practices in many centers across the world. Dr. Barry Bertolet, an interventional cardiologist at North Mississippi Medical Center in Tupelo, Mississippi, USA, describes the benefits that Hi-Def imaging has made at the largest rural hospital in the USA, aiding not only in diagnosis, but also performing interventions across a wide apectrum of cardiovascular diseases.

The North Mississippi Medical Center is a 640-bed regional referral center in Tupelo, MS, USA. The hospital is the largest private not-for-profit hospital in Mississippi and the largest non-metropolitan hospital in America. It serves almost 730,000 people from 24 counties in North Mississippi, Northwest Alabama and parts of Tennessee. The North Mississippi Medical Center is also a two-time U.S. Congress Baldrige Award Winner and an IBM Watson Top 50 CardioVascular Hospital. However, Mississippi faces a common public health problem: it has one of the largest obese populations in USA, and the disease states associated with obesity – such as diabetes, hypertension, and dyslipidemia – have a high prevalence. Acquiring an Alphenix system with Hi-Def Detector in 2022 has enabled North Mississippi Medical Center to enhance the delivery of care to this high-risk patient population.

“Being able to see what you're doing in the Cath Lab is key for diagnosis and optimal delivery of therapy, and that ends up being the beauty of Hi-Def,” said Dr. Bertolet. “Canon’s Hi-Def imaging modality allows us to now zoom the image up to 1.5 inches at a 76-micron resolution, without losing image quality. This helps us look at the fine details, visualize anatomic structures, and deploy devices in precise location with extra confidence.” “There are a wide variety of cases in which I've used the Hi-Def and it has helped me in my clinical practice,” he continued.
Canon invented the world’s first Hi-Def detector – offering more than twice the spatial resolution of conventional flat panel detectors (FPD) – for resolving fine anatomical and device details. This unique hybrid 12” × 12” or 12” × 16” FPD combines Hi-Def imaging technology based on crystalline silicon that boosts spatial resolution up to 6.6 line pairs per millimeter (lp/mm) with 76 micron pixels (Figure 1). With the Hi-Def detector, Alphenix system offers six standard modes with 16”, 12”, 8”, 6”, 4.3” or 3.3” fields of view (FOV) and three Hi-Def modes with 3”, 2.3” or 1.5” FOV, allowing increased spatial resolution without interruption of procedure workflow. At any given point in time, both modes are available, and when needed, the selection between the two modes can be quickly changed using an FOV switch, without adding additional delay to the procedure.

Confirm with confidence

“In this very nice example of septal occluder case, Hi-Def makes a big difference. With the Gore® Cardioform Device, the FDA recommends fluoroscopic evaluation to ensure that the locking the loop is complete. If the locking the loop does not go through the eyelets, then you need to remove it at that time. The Hi-Def view enables me to confirm with confidence that the lock loop has gone through, and it captured all the eyelets before releasing the occluder. The details in the Hi-Def image are superior to those captured under traditional magnification” (Figure 1)

Figure 1: Multi-detector design maximizes efficiency and fundamentally offers more than 2x higher spatial resolution than any other available system.* Images of a line pair test object acquired using the standard resolution of 194 μm pixel FPD mode (left) and high-resolution 76 μm Hi-Def mode (right). Due to the larger pixel sizes of the FPD mode, only up to 2.6 lp/mm can be visualized without any aliasing. In the Hi-Def mode, due to the smaller pixel sizes, up to 6.6 lp/mm can be visualized without any aliasing or loss in information.

(Left) Traditional magnification mode degrades image quality and poses big challenge for physicians to verify the septal occludes device during the interventional procedure. (Right) With more than 2.5 times the resolution of FPD, Hi-Def provides a clear visualization of the septal occluder device with enhanced image quality, aiding physicians to confirm the device positioning with confidence.

Evaluate stent structure

Stent fracture is associated with restenosis, thrombosis, ischemic events, and need for target lesion revascularization. “Most relevant studies that are available today still say that we ought to utilize fluoroscopy to evaluate stent fracture, with or without contrast. In order to determine if there's evidence of stent fracture, and in fact, based on the fracture pattern, there are different stages of the fracture that can be determined by this fluoroscopic imaging.” Dr. Bertolet explained while pointing on the Figure 2 “In this case, when I go into the hi-def mode, I can visualize where we have done the metal bypass, and where there is in-stent restenosis. More importantly, I can actually see almost where these stents overlap under Hi-Def mode and there's a large area of overlap where I can’t see the stent struts as well (asterisk in Figure 2). This is suggestive of a Type 1 stent fracture in this particular zone as a cause of the in-stent restenosis in this area, which helped us then determine the method of therapy that I needed to deliver to this area.”

Figure 2: Overlapping stents (+) and stent fracture (*) under Hi-Def mode.

“Being able to use Hi-Def to accurately deploy cardiovascular devices adds to the procedualist’s confidence and is a huge in achieving a successful result and better patient outcome.”
Dr. Barry Bertolet, Director of the Cardiac Catheterization Lab at the North Mississippi Medical Center in Tupelo, Mississippi, USA.

Avoid complications

“Another thing that I think that Hi-Def can really help with in interventional cardiology is placement of devices to avoid complications.” commented by Dr. Bertolet. When treating in-stent restenosis with Plain Old Balloon Angioplasty (POBA), one of the limitations is edge-related complications with balloon dilation outside the stent that leads to edge dissections and suboptimal outcomes. “In this case, there was a mid left anterior descending instent restenosis lesion in a tough area to see. To avoid complications of edge dissection, I was able to place the markers of the balloon within the stent by using Hi-Def mode and had a controlled inflation under Hi-Def (Figure 3). This could be very important if we move to use drug-eluting balloons for coronary in-stent restenosis, which hopefully will come soon.”

Figure 3: Hi-Def mode assists operators to precisely place the PTCA balloon and avoid the risk of dissection.

Complex Peripheral Arterial Intervention

In addition to interventional cardiology cases, Dr. Bertolet also performed peripheral arterial interventions under Hi-Def imaging. When using the TACK Endovascular System, a minimal-metal dissection repair device purposely built for precision treatment of post- PTA peripheral arterial dissections, Dr. Bertolet finds conventional fluoroscopy poses big challenge in visualizing the TACK scaffolds.

Figure 4: Changing from the FPD mode (A) to Hi-Def mode is seamless with an FOV switch button. Hi-Def can be used to improve real time visualization of stent structure (B-D) during complex peripheral arterial interventions.

“With Hi-Def, I can actually see individual TACK scaffolds (Figure 4). Not only I can see them much more clearly, but also see precisely how to deploy them. Being able to see the deployment and accurately place these devices where we want them under Hi-Def is a huge advantage in the specialists’ confidence in achieving a successful result and better patient outcome.” said Dr. Bertolet.

In another peripheral arterial intervention case, Dr. Bertolet successfully resolved complication with Hi-Def. “This is another leg case that I did that ended up with an occlusive dissection of the popliteal blood vessel and some reconstitutional flow very distally. In Hi-Def mode, the end of the tape can be seen. I was able to see where exactly to place my Supera™ stent and deploy it under Hi-Def. Precisely placing this stent allowed me to ensure that I covered the zone of dissection and provided the appropriate therapy for the patient.” (Figure 5)

Figure 5: Precisely placing the stent under Hi-Def mode allowed the operator to ensure the zone of dissection is covered along the popliteal artery.

Diagnosis of Small Vessel Disease

Thromboangiitis obliterans (Buerger’s Disease) is caused by small blood vessels that become inflamed and swollen – usually as an adverse reaction to tobacco. The blood vessels then narrow or get blocked by blood clots (thrombosis).
Blood vessels of the hands and feet are mostly affected.
“Seeing what you need to, particularly in the small vessels can be a big advantage in diagnosis.” Dr. Bertolet shared his experience of using Hi-Def to diagnose small vessel disease.
“This gentleman was suspected to have Buerger’s Disease. We wanted to do an angiogram in order to help us make that diagnosis. With hi-def mode we could detect the corkscrew appearance of the vessels that is classic in Thromboangiitis obliterans (Figure 6). It really helped in this gentleman to have a clearer angiographic diagnosis of Buerger Disease.”

Figure 6: Corkscrew appearance of thromboangiitis obliterans (Buerger Disease) is revealed under Hi-Def mode.

Hi-Def: A Helpful Tool In The Cath Lab

Dr. Bertolet stated, “I have found hi-def imaging extremely helpful in a variety of Cath Lab Imaging cases. “These examples show that the modality has been useful not only in achieving proper diagnosis, such as for coronary dissection, and small vessel disease like Buerger disease, but also to help with successful Interventions in a variety of cases right across the cardiovascular spectrum.” //

The clinical results, performance and views described in this case study are the experience of the clinician. Results may vary due to clinical setting, patient presentation and other factors. Many factors could cause the actual results and performance of Canon’s product to be materially different from any of the aforementioned.

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